Medicine › Critical Care and Intensive Care Medicine

Thermal Regulation in Medicine

Works Count: 35972

Wikipedia

Description

This cluster of papers focuses on the use of therapeutic hypothermia and fever management in the context of brain injury, stroke, and critical care. It explores the effects of hypothermia on neuroprotection, inflammation, and body temperature regulation, as well as its potential therapeutic mechanisms.

Keywords

Hypothermia; Fever; Brain Injury; Thermoregulation; Neuroprotection; Stroke; Inflammation; Body Temperature; Critical Care; Therapeutic Mechanisms

Stress distribution in lungs: a model of pulmonary elasticity.

1970-05-01

J. Mead , Tamotsu Takishima , David Leith

Mechanisms of circulatory and intestinal barrier dysfunction during whole body hyperthermia

2001-02-01

David Hall , Garry R. Buettner , Larry W. Oberley +3 more

This work tested the hypotheses that splanchnic oxidant generation is important in determining heat tolerance and that inappropriate ·NO production may be involved in circulatory dysfunction with heat stroke. We … This work tested the hypotheses that splanchnic oxidant generation is important in determining heat tolerance and that inappropriate ·NO production may be involved in circulatory dysfunction with heat stroke. We monitored colonic temperature (T c ), heart rate, mean arterial pressure, and splanchnic blood flow (SBF) in anesthetized rats exposed to 40°C ambient temperature. Heating rate, heating time, and thermal load determined heat tolerance. Portal blood was regularly collected for determination of radical and endotoxin content. Elevating T c from 37 to 41.5°C reduced SBF by 40% and stimulated production of the radicals ceruloplasmin, semiquinone, and penta-coordinate iron(II) nitrosyl-heme (heme-·NO). Portal endotoxin concentration rose from 28 to 59 pg/ml ( P < 0.05). Compared with heat stress alone, heat plus treatment with the nitric oxide synthase (NOS) antagonist N ω -nitro-l-arginine methyl ester (l-NAME) dose dependently depressed heme-·NO production and increased ceruloplasmin and semiquinone levels. l-NAME also significantly reduced lowered SBF, increased portal endotoxin concentration, and reduced heat tolerance ( P < 0.05). The NOS II and diamine oxidase antagonist aminoguanidine, the superoxide anion scavenger superoxide dismutase, and the xanthine oxidase antagonist allopurinol slowed the rates of heme-·NO production, decreased ceruloplasmin and semiquinone levels, and preserved SBF. However, only aminoguanidine and allopurinol improved heat tolerance, and only allpourinol eliminated the rise in portal endotoxin content. We conclude that hyperthermia stimulates xanthine oxidase production of reactive oxygen species that activate metals and limit heat tolerance by promoting circulatory and intestinal barrier dysfunction. In addition, intact NOS activity is required for normal stress tolerance, whereas overproduction of ·NO may contribute to the nonprogrammed splanchnic dilation that precedes vascular collapse with heat stroke.

Effect of mild hypothermia on ischemia-induced release of neurotransmitters and free fatty acids in rat brain.

1989-07-01

Raul Busto , M Globus , W. Dalton Dietrich +3 more

We have demonstrated previously that mild intraischemic hypothermia confers a marked protective effect on the final histopathological outcome. The present study was carried out to evaluate whether this protective effect … We have demonstrated previously that mild intraischemic hypothermia confers a marked protective effect on the final histopathological outcome. The present study was carried out to evaluate whether this protective effect involves changes in the degree of local cerebral blood flow reductions, tissue accumulation of free fatty acids, or alterations in the extracellular release of glutamate and dopamine. Rats whose intraischemic brain temperature was maintained at 36 degrees C, 33 degrees C, or 30 degrees C were subjected to 20 minutes of ischemia by four-vessel occlusion combined with systemic hypotension. Levels of local cerebral blood flow, as measured autoradiographically, were reduced uniformly in all experimental animals at the end of ischemia by gas chromatography after tissue extraction and separation by thin layer chromatography. A massive ischemia-induced accumulation of individual free fatty acids was observed in animal groups whose intraischemic brain temperature was maintained at either 36 degrees C or 30 degrees C. Extracellular neurotransmitter levels were measured by microdialysis; the perfusate was collected before, during, and after ischemia. In rats whose intraischemic brain temperature was maintained at 36 degrees C, dopamine and glutamate increased significantly during ischemia and the early period of recirculation (by 500-fold and sevenfold, respectively). In animals whose brain temperature was maintained at 33 degrees C and 30 degrees C, the release of glutamate was completely inhibited, and the release of dopamine was significantly attenuated (by 60%). These results suggest that mild intraischemic hypothermia does not affect the ischemia-induced local cerebral blood flow reduction or free fatty acid accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

View PDF Chat

Temperature Monitoring and Perioperative Thermoregulation

2008-08-01

Daniel I. Sessler , David S. Warner , Mark A. Warner

Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature-measuring sites are completely noninvasive and easy to use-especially in … Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature-measuring sites are completely noninvasive and easy to use-especially in patients not undergoing general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients undergoing general anesthesia exceeding 30 min in duration and in patients undergoing major operations during neuraxial anesthesia. Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature, triggering cold defenses, including arteriovenous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, with the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extent than does general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown.

View PDF Chat

Neuroprotective mechanisms of hypothermia in brain ischaemia

2012-02-22

Midori A. Yenari , Hyung Soo Han

Glutamate Release and Free Radical Production Following Brain Injury: Effects of Posttraumatic Hypothermia

1995-10-01

Mordecai Y.‐T. Globus , Ofelia F. Alonso , W. Dalton Dietrich +2 more

Abstract: Posttraumatic hypothermia reduces the extent of neuronal damage in remote cortical and subcortical structures following traumatic brain injury (TBI). We evaluated whether excessive extracellular release of glutamate and generation … Abstract: Posttraumatic hypothermia reduces the extent of neuronal damage in remote cortical and subcortical structures following traumatic brain injury (TBI). We evaluated whether excessive extracellular release of glutamate and generation of hydroxyl radicals are associated with remote traumatic injury, and whether posttraumatic hypothermia modulates these processes. Lateral fluid percussion was used to induce TBI in rats. The salicylate‐trapping method was used in conjunction with microdialysis and HPLC to detect hydroxyl radicals by measurement of the stable adducts 2,3‐ and 2,5‐dihydroxybenzoic acid (DHBA). Extracellular glutamate was measured from the same samples. Following trauma, brain temperature was maintained for 3 h at either 37 or 30°C. Sham‐trauma animals were treated in an identical manner. In the normothermic group, TBI induced significant elevations in 2,3‐DHBA (3.3‐fold, p < 0.01), 2,5‐DHBA (2.5‐fold, p < 0.01), and glutamate (2.8‐fold, p < 0.01) compared with controls. The levels of 2,3‐DHBA and glutamate remained high for approximately 1 h after trauma, whereas levels of 2,5‐DHBA remained high for the entire sampling period (4 h). Linear regression analysis revealed a significant positive correlation between integrated 2,3‐DHBA and glutamate concentrations ( p < 0.05). Posttraumatic hypothermia resulted in suppression of both 2,3‐ and 2,5‐DHBA elevations and glutamate release. The present data indicate that TBI is followed by prompt increases in both glutamate release and hydroxyl radical production from cortical regions adjacent to the impact site. The magnitude of glutamate release is correlated with the extent of the hydroxyl radical adduct, raising the possibility that the two responses are associated. Posttraumatic hypothermia blunts both responses, suggesting a mechanism by which hypothermia confers protection following TBI.

Marked Protection by Moderate Hypothermia after Experimental Traumatic Brain Injury

1991-01-01

Guy L. Clifton , Ji Y. Jiang , Bruce G. Lyeth +3 more

These experiments examined the effects of moderate hypothermia on mortality and neurological deficits observed after experimental traumatic brain injury (TBI) in the rat. Brain temperature was measured continuously in all … These experiments examined the effects of moderate hypothermia on mortality and neurological deficits observed after experimental traumatic brain injury (TBI) in the rat. Brain temperature was measured continuously in all experiments by intraparenchymal probes. Brain cooling was induced by partial immersion (skin protected by a plastic barrier) in a water bath (0 degrees C) under general anesthesia (1.5% halothane/70% nitrous oxide/30% oxygen). In experiment I, we examined the effects of moderate hypothermia induced prior to injury on mortality following fluid percussion TBI. Rats were cooled to 36 degrees C (n = 16), 33 degrees C (n = 17), or 30 degrees C (n = 11) prior to injury and maintained at their target temperature for 1 h after injury. There was a significant (p less than 0.04) reduction in mortality by a brain temperature of 30 degrees C. The mortality rate at 36 degrees C was 37.5%, at 33 degrees C was 41%, and at 30 degrees C was 9.1%. In experiment II, we examined the effects of moderate hypothermia or hyperthermia initiated after TBI on long-term behavioral deficits. Rats were cooled to 36 degrees C (n = 10), 33 degrees C (n = 10), or 30 degrees C (n = 10) or warmed to 38 degrees C (n = 10) or 40 degrees C (n = 12) starting at 5 min after injury and maintained at their target temperatures for 1 h. Hypothermia-treated rats had significantly less beam-walking, beam-balance, and body weight loss deficits compared to normothermic (38 degrees C) rats. The greatest protection was observed in the 30 degrees C hypothermia group.(ABSTRACT TRUNCATED AT 250 WORDS)

View PDF Chat

Heat Flow and Distribution during Induction of General Anesthesia

1995-03-01

Takashi Matsukawa , Daniel I. Sessler , Andrew M. Sessler +4 more

Background Core hypothermia after induction of general anesthesia results from an internal core-to-peripheral redistribution of body heat and a net loss of heat to the environment. However, the relative contributions … Background Core hypothermia after induction of general anesthesia results from an internal core-to-peripheral redistribution of body heat and a net loss of heat to the environment. However, the relative contributions of each mechanism remain unknown. The authors evaluated regional body heat content and the extent to which core hypothermia after induction of anesthesia resulted from altered heat balance and internal heat redistribution. Methods Six minimally clothed male volunteers in an approximately 22 degrees C environment were evaluated for 2.5 control hours before induction of general anesthesia and for 3 subsequent hours. Overall heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Arm and leg tissue heat contents were determined from 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. To separate the effects of redistribution and net heat loss, we multiplied the change in overall heat balance by body weight and the specific heat of humans. The resulting change in mean body temperature was subtracted from the change in distal esophageal (core) temperature, leaving the core hypothermia specifically resulting from redistribution. Results Core temperature was nearly constant during the control period but decreased 1.6 +/- 0.3 degree C in the first hour of anesthesia. Redistribution contributed 81% to this initial decrease and required transfer of 46 kcal from the trunk to the extremities. During the subsequent 2 h of anesthesia, core temperature decreased an additional 1.1 +/- 0.3 degree C, with redistribution contributing only 43%. Thus, only 17 kcal was redistributed during the second and third hours of anesthesia. Redistribution therefore contributed 65% to the entire 2.8 +/- 0.5 degree C decrease in core temperature during the 3 h of anesthesia. Proximal extremity heat content decreased slightly after induction of anesthesia, but distal heat content increased markedly. The distal extremities thus contributed most to core cooling. Although the arms constituted only a fifth of extremity mass, redistribution increased arm heat content nearly as much as leg heat content. Distal extremity heat content increased approximately 40 kcal during the first hour of anesthesia and remained elevated for the duration of the study. Conclusions The arms and legs are both important components of the peripheral thermal compartment, but distal segments contribute most. Core hypothermia during the first hour after induction resulted largely from redistribution of body heat, and redistribution remained the major cause even after 3 h of anesthesia.

View PDF Chat

Mild Intraoperative Hypothermia Prolongs Postanesthetic Recovery

1997-12-01

Rainer Lenhardt , E. Marker , V. Goll +5 more

Intraoperative hypothermia is common and persists for several hours after surgery. Hypothermia may prolong immediate recovery by augmenting anesthetic potency, delaying drug metabolism, producing hemodynamic instability, or depressing cognitive function. … Intraoperative hypothermia is common and persists for several hours after surgery. Hypothermia may prolong immediate recovery by augmenting anesthetic potency, delaying drug metabolism, producing hemodynamic instability, or depressing cognitive function. Accordingly, the authors tested the hypothesis that intraoperative hypothermia prolongs postoperative recovery.Patients undergoing elective major abdominal surgery (n = 150) were anesthetized with isoflurane, nitrous oxide, and fentanyl. They were randomly assigned to routine thermal management (hypothermia) or extra warming (normothermia). Postoperative surgical pain was treated with patient-controlled analgesia. Fitness for discharge from the postanesthesia care unit was evaluated at 20-min intervals by investigators blinded to group assignment and postoperative core temperatures. Scoring was based on a modification of a previously published system that included activity, ventilation, consciousness, and hemodynamic responses. Patients were considered fit for discharge when they sustained a score of 80% (13 points) for at least two consecutive measurement periods.Morphometric characteristics and anesthetic management were similar in each group. Final intraoperative core temperatures differed by approximately 2 degrees C: 34.8 +/- 0.6 versus 36.7 +/- 0.6 degrees C (mean +/- SD, P < 0.001). Postoperative pain scores and postoperative use of patient-controlled opioid were similar. Hypothermic patients required approximately 40 min longer (94 +/- 65 vs. 53 +/- 36 min) to reach fitness for discharge, even when return to normothermia was not a criterion (P < 0.001). Duration of recovery in the two groups differed by approximately 90 min when a core temperature >36 degrees C was also required (P < 0.001).Maintaining core normothermia decreases the duration of postanesthetic recovery and may, therefore, reduce costs of care.

View PDF Chat

Fever Phobia Revisited: Have Parental Misconceptions About Fever Changed in 20 Years?

2001-06-01

Michael Crocetti , Nooshi Moghbeli , Janet R. Serwint

Fever is one of the most common reasons that parents seek medical attention for their children. Parental concerns arise in part because of the belief that fever is a disease … Fever is one of the most common reasons that parents seek medical attention for their children. Parental concerns arise in part because of the belief that fever is a disease rather than a symptom or sign of illness. Twenty years ago, Barton Schmitt, MD, found that parents had numerous misconceptions about fever. These unrealistic concerns were termed "fever phobia." More recent concerns for occult bacteremia in febrile children have led to more aggressive laboratory testing and treatment. Our objectives for this study were to explore current parental attitudes toward fever, to compare these attitudes with those described by Schmitt in 1980, and to determine whether recent, more aggressive laboratory testing and presumptive treatment for occult bacteremia is associated with increased parental concern regarding fever.Between June and September 1999, a single research assistant administered a cross-sectional 29-item questionnaire to caregivers whose children were enrolled in 2 urban hospital-based pediatric clinics in Baltimore, Maryland. The questionnaire was administered before either health maintenance or acute care visits at both sites. Portions of the questionnaire were modeled after Schmitt's and elicited information about definition of fever, concerns about fever, and fever management. Additional information included home fever reduction techniques, frequency of temperature monitoring, and parental recall of past laboratory workup and treatment that these children had received during health care visits for fever.A total of 340 caregivers were interviewed. Fifty-six percent of caregivers were very worried about the potential harm of fever in their children, 44% considered a temperature of 38.9 degrees C (102 degrees F) to be a "high" fever, and 7% thought that a temperature could rise to >/=43.4 degrees C (>/=110 degrees F) if left untreated. Ninety-one percent of caregivers believed that a fever could cause harmful effects; 21% listed brain damage, and 14% listed death. Strikingly, 52% of caregivers said that they would check their child's temperature </=1 hour when their child had a fever, 25% gave antipyretics for temperatures <37.8 degrees C (<100 degrees F), and 85% would awaken their child to give antipyretics. Fourteen percent of caregivers gave acetaminophen, and 44% gave ibuprofen at too frequent dosing intervals. Of the 73% of caregivers who said that they sponged their child to treat a fever, 24% sponged at temperatures </=37.8 degrees C (</=100 degrees F); 18% used alcohol. Forty-six percent of caregivers listed doctors as their primary resource for information about fever. Caregivers who stated that they were very worried about fever were more likely in the past to have had a child who was evaluated for a fever, to have had blood work performed on their child during a febrile illness, and to have perceived their doctors to be very worried about fever. Compared with 20 years ago, more caregivers listed seizure as a potential harm of fever, woke their children and checked temperatures more often during febrile illnesses, and gave antipyretics or initiated sponging more frequently for possible normal temperatures.Fever phobia persists. Pediatric health care providers have a unique opportunity to make an impact on parental understanding of fever and its role in illness. Future studies are needed to evaluate educational interventions and to identify the types of medical care practices that foster fever phobia.fever, fever phobia, child, children, antipyretics, sponging, health care practices.

Moderate Hypothermia in the Treatment of Patients With Severe Middle Cerebral Artery Infarction

1998-12-01

Stefan Schwab , S. Schwarz , Matthias Spranger +3 more

Background and Purpose —Animal research and clinical studies in head trauma patients suggest that moderate hypothermia may improve outcome by attenuating the deleterious metabolic processes in neuronal injury. Clinical studies … Background and Purpose —Animal research and clinical studies in head trauma patients suggest that moderate hypothermia may improve outcome by attenuating the deleterious metabolic processes in neuronal injury. Clinical studies on moderate hypothermia in the treatment of acute ischemic stroke patients are still lacking. Methods —Moderate hypothermia was induced in 25 patients with severe ischemic stroke in the middle cerebral artery (MCA) territory for therapy of postischemic brain edema. Hypothermia was induced within 14±7 hours after stroke onset and achieved by external cooling with cooling blankets, cold infusions, and cold washing. Patients were kept at 33°C body-core temperature for 48 to 72 hours, and intracranial pressure (ICP), cerebral perfusion pressure, and brain temperature were monitored continuously. Outcome at 4 weeks and 3 months after the stroke was analyzed with the Scandinavian Stroke Scale (SSS) and Barthel index. The side effects of induced moderate hypothermia were analyzed. Results —Fourteen patients survived the hemispheric stroke (56%). Neurological outcome according to the SSS score was 29 (range, 25 to 37) 4 weeks after stroke and 38 (range 28 to 48) 3 months after stroke. During hypothermia, elevated ICP values could be significantly reduced. Herniation caused by a secondary rise in ICP after rewarming was the cause of death in all remaining patients. The most frequent complication of moderate hypothermia was pneumonia in 10 of the 25 patients (40%). Other severe side effects of hypothermia could not be detected. Conclusions —Moderate hypothermia in the treatment of severe cerebral ischemia is not associated with severe side effects. Moderate hypothermia can help to control critically elevated ICP values in severe space-occupying edema after MCA stroke and may improve clinical outcome in these patients.

View PDF Chat

Penumbral tissues salvaged by reperfusion following middle cerebral artery occlusion in rats.

1992-04-01

Hajime Memezawa , M L Smith , Bo K. Siesjö

The rat is now extensively used for studies on focal cerebral ischemia, and several novel pharmacological principles have been worked out in rat models of middle cerebral artery occlusion. The … The rat is now extensively used for studies on focal cerebral ischemia, and several novel pharmacological principles have been worked out in rat models of middle cerebral artery occlusion. The objective of the present study was to assess how ischemic tissue can be salvaged by reperfusion in a model of transient focal ischemia that gives infarction of both the caudoputamen and the neocortex. The middle cerebral artery of anesthetized rats was occluded for 15, 30, 60, 90, 120, or 180 minutes by an intraluminal filament, and recirculation was instituted for 7 days to allow assessment of the density and localization of ischemic brain damage using histopathologic techniques. Local cerebral blood flow was measured in separate animals to verify that removal of the filament was followed by adequate recirculation. Following 15 minutes of middle cerebral artery occlusion seven of eight rats showed selective neuronal necrosis in the caudoputamen, while the neocortex was normal. After 30 minutes of occlusion, seven of eight animals had infarcts localized to the lateral caudoputamen, and four of eight had selective neuronal necrosis in the neocortex. Prolongation of the ischemia to 60 minutes induced cortical infarction in all eight rats. The infarct size increased progressively with increasing occlusion time, up to 120-180 minutes, when the infarcts were as extensive as those observed following 24 hours of permanent middle cerebral artery occlusion. The results demonstrate a time window for salvage of penumbral tissues by reperfusion that is shorter than that suggested on the basis of previous data in other species. The results probably reflect a lower collateral blood flow in the rat than in other species. This should be taken into account when the effect of pharmacological agents is studied in rats.

Microdialysis—Theory and application

1990-01-01

Helene Benveniste , Peter C. Hüttemeier

Mild hypothermia increases blood loss and transfusion requirements during total hip arthroplasty

1996-02-01

Harald Schmied , Audra J. Reiter , Andrea Kurz +2 more

Mechanisms of action, physiological effects, and complications of hypothermia

2009-06-15

Kees H. Polderman

Mild to moderate hypothermia (32-35 degrees C) is the first treatment with proven efficacy for postischemic neurological injury. In recent years important insights have been gained into the mechanisms underlying … Mild to moderate hypothermia (32-35 degrees C) is the first treatment with proven efficacy for postischemic neurological injury. In recent years important insights have been gained into the mechanisms underlying hypothermia's protective effects; in addition, physiological and pathophysiological changes associated with cooling have become better understood.To discuss hypothermia's mechanisms of action, to review (patho)physiological changes associated with cooling, and to discuss potential side effects.Review article.None.A myriad of destructive processes unfold in injured tissue following ischemia-reperfusion. These include excitotoxicty, neuroinflammation, apoptosis, free radical production, seizure activity, blood-brain barrier disruption, blood vessel leakage, cerebral thermopooling, and numerous others. The severity of this destructive cascade determines whether injured cells will survive or die. Hypothermia can inhibit or mitigate all of these mechanisms, while stimulating protective systems such as early gene activation. Hypothermia is also effective in mitigating intracranial hypertension and reducing brain edema. Side effects include immunosuppression with increased infection risk, cold diuresis and hypovolemia, electrolyte disorders, insulin resistance, impaired drug clearance, and mild coagulopathy. Targeted interventions are required to effectively manage these side effects. Hypothermia does not decrease myocardial contractility or induce hypotension if hypovolemia is corrected, and preliminary evidence suggests that it can be safely used in patients with cardiac shock. Cardiac output will decrease due to hypothermia-induced bradycardia, but given that metabolic rate also decreases the balance between supply and demand, is usually maintained or improved. In contrast to deep hypothermia (<or=30 degrees C), moderate hypothermia does not induce arrhythmias; indeed, the evidence suggests that arrhythmias can be prevented and/or more easily treated under hypothermic conditions.Therapeutic hypothermia is a highly promising treatment, but the potential side effects need to be properly managed particularly if prolonged treatment periods are required. Understanding the underlying mechanisms, awareness of physiological changes associated with cooling, and prevention of potential side effects are all key factors for its effective clinical usage.

A Phase II Study of Moderate Hypothermia in Severe Brain Injury

1993-01-01

Guy L. Clifton , Steven J. Allen , Patricia M. Barrodale +6 more

Forty-six patients with severe nonpenetrating brain injury [Glasgow Coma Scale (GCS) 4–7] were randomized to standard management at 37°C (n = 22) and to standard management with systemic hypothermia to … Forty-six patients with severe nonpenetrating brain injury [Glasgow Coma Scale (GCS) 4–7] were randomized to standard management at 37°C (n = 22) and to standard management with systemic hypothermia to 32 to 33°C (n = 24). The two groups were balanced in terms of age (Wilcoxon's rank sum test, p > 0.95), randomizing GCS (chi-square test, p = 0.54), and primary diagnosis. Cooling was begun within 6 h of injury by use of cooling blankets. Metocurine and morphine were given hourly during induction and maintenance of hypothermia. Rewarming was at a rate of 1°C per 4 h beginning 48 h after intravascular temperature had reached 33°C. Muscle relaxants and sedation were continued until core temperature reached 35°C. There were no cardiac or coagulopathy-related complications. Seizure incidence was lower in the hypothermia group (Fisher's exact text, p = 0.019). Sepsis was seen more commonly in the hypthermia group, but difference was not statistically significant (chi-square test). Mean Glasgow Outcome Scale (GOS) score at 3 months after injury showed an absolute increase of 16% (i.e., 36.4–52.2%) in the number of patients in the Good Recovery/Moderate Disability (GR/MD) category as compared with Severe Disability/ Vegetative/Dead (SD/V/D) (chi-square test, p > 0.287). Based on evidence of improved neurologic outcome with minimal toxicity, we believe that phase III testing of moderate systemic hypothermia in patients with severe head injury is warranted.

Intraischemic but Not Postischemic Brain Hypothermia Protects Chronically following Global Forebrain Ischemia in Rats

1993-07-01

W. Dalton Dietrich , Raul Busto , Ofelia F. Alonso +2 more

We investigated whether postischemic brain hypothermia (30°C) would permanently protect the hippocampus following global forebrain ischemia. Global ischemia was produced in anesthetized rats by bilateral carotid artery occlusion plus hypotension … We investigated whether postischemic brain hypothermia (30°C) would permanently protect the hippocampus following global forebrain ischemia. Global ischemia was produced in anesthetized rats by bilateral carotid artery occlusion plus hypotension (50 mm Hg). In the postischemic hypothermic group, brain temperature was maintained at 37°C during the 10-min ischemic insult but reduced to 30°C starting 3 min into the recirculation period and maintained at 30°C for 3 h. In normothermic animals, intra- and postischemic brain temperature was maintained at 37°C. After recovery for 3 days, 7 days, or 2 months, the extent of CA 1 hippocampal histologic injury was quantitated. At 3 days after ischemia, postischemic hypothermia significantly protected the hippocampal CA 1 sector compared with normothermic animals. For example, within the medial, middle, and lateral CA 1 subsectors, the numbers of normal neurons were increased 20-, 13-, and 9-fold by postischemic hypothermia (p < 0.01). At 7 days after the ischemic insult, however, the degree of postischemic hypothermic protection was significantly reduced. In this case, the numbers of normal neurons were increased an average of only threefold compared with normothermia. Ultrastructural analysis of 7-day postischemic hypothermic rats demonstrated CA 1 pyramidal neurons showing variable degrees of injury surrounded by reactive astrocytes and microglial cells. At 2 months after the ischemic insult, no trend for protection was demonstrated. In contrast to postischemic hypothermia, significant protection was seen at 2 months following intraischemic hypothermia. These data indicate that intraischemic, but not postischemic, brain hypothermia provides chronic protection to the hippocampus after transient brain ischemia. The inability of postischemic hypothermia to protect chronically after 3 days could indicate that (a) postischemic hypothermia merely delays ischemic cell death and/or (b) the postischemic brain undergoes a secondary insult. In postischemic treatment protocols, chronic survival studies are required to determine accurately the ultimate histopathological outcome following global cerebral ischemia.

View PDF Chat

Hypothermia: Pathophysiology, Clinical Settings, and Management

1978-10-01

James B. Reuler

Hypothermia, defined as a core temperature less than 35 °C, is frequently not recognized, in part because of the inadequacy of standard thermometers. This entity has multiple causes and unique … Hypothermia, defined as a core temperature less than 35 °C, is frequently not recognized, in part because of the inadequacy of standard thermometers. This entity has multiple causes and unique pathophysiologic consequences that complicate diagnosis and treatment. Understanding of the physiology of thermoregulation is important in light of recent advances in therapy using core rewarming. Pathophysiology, etiology and management of the hypothermia syndrome are reviewed.

Body temperature in acute stroke: relation to stroke severity, infarct size, mortality, and outcome

1996-02-01

Jakob Reith , Henrik Jørgensen , Palle Møller Pedersen +4 more

Effect of Hypothermia on the Coagulation Cascade

1993-08-01

Michael J. Rohrer , A Natale

Division of Vascular Surgery, University of Massachusetts Medical School, and Division of Hematology, The Medical Center of Central Massachusetts-Memorial, Worcester, Massachusetts Division of Vascular Surgery, University of Massachusetts Medical School, and Division of Hematology, The Medical Center of Central Massachusetts-Memorial, Worcester, Massachusetts

The Effects of Mild Perioperative Hypothermia on Blood Loss and Transfusion Requirement

2008-01-01

Suman Rajagopalan , Edward J. Mascha , Jie Na +1 more

Background Anesthetic-induced hypothermia is known to reduce platelet function and impair enzymes of the coagulation cascade. The objective of this meta-analysis and systematic review was to evaluate the hypothesis that … Background Anesthetic-induced hypothermia is known to reduce platelet function and impair enzymes of the coagulation cascade. The objective of this meta-analysis and systematic review was to evaluate the hypothesis that mild perioperative hypothermia increases surgical blood loss and transfusion requirement. Methods The authors conducted a systematic search of published randomized trials that compared blood loss and/or transfusion requirements in normothermic and mildly hypothermic (34-36 degrees C) surgical patients. Results are expressed as a ratio of the means or relative risks and 95% confidence intervals (CI); P &lt; 0.05 was considered statistically significant. Results Fourteen studies were included in analysis of blood loss, and 10 in the transfusion analysis. The median (quartiles) temperature difference between the normothermic and hypothermic patients among studies was 0.85 degrees C (0.60 degrees C versus 1.1 degrees C). The ratio of geometric means of total blood loss in the normothermic and hypothermic patients was 0.84 (0.74 versus 0.96), P = 0.009. Normothermia also reduced transfusion requirement, with an overall estimated relative risk of 0.78 (95% CI 0.63, 0.97), P = 0.027. Conclusion Even mild hypothermia (&lt;1 degree C) significantly increases blood loss by approximately 16% (4-26%) and increases the relative risk for transfusion by approximately 22% (3-37%). Maintaining perioperative normothermia reduces blood loss and transfusion requirement by clinically important amounts.

View PDF Chat

Postischemic moderate hypothermia inhibits CA1 hippocampal ischemic neuronal injury

1989-07-01

Raul Busto , W. Dalton Dietrich , Mordecai Y.‐T. Globus +1 more

Perioperative Heat Balance

2000-02-01

Daniel I. Sessler , Michael M. Todd

Hypothermia during general anesthesia develops with a characteristic three-phase pattern. The initial rapid reduction in core temperature after induction of anesthesia results from an internal redistribution of body heat. Redistribution … Hypothermia during general anesthesia develops with a characteristic three-phase pattern. The initial rapid reduction in core temperature after induction of anesthesia results from an internal redistribution of body heat. Redistribution results because anesthetics inhibit the tonic vasoconstriction that normally maintains a large core-to-peripheral temperature gradient. Core temperature then decreases linearly at a rate determined by the difference between heat loss and production. However, when surgical patients become sufficiently hypothermic, they again trigger thermoregulatory vasoconstriction, which restricts core-to-peripheral flow of heat. Constraint of metabolic heat, in turn, maintains a core temperature plateau (despite continued systemic heat loss) and eventually reestablishes the normal core-to-peripheral temperature gradient. Together, these mechanisms indicate that alterations in the distribution of body heat contribute more to changes in core temperature than to systemic heat imbalance in most patients. Just as with general anesthesia, redistribution of body heat is the major initial cause of hypothermia in patients administered spinal or epidural anesthesia. However, redistribution during neuraxial anesthesia is typically restricted to the legs. Consequently, redistribution decreases core temperature about half as much during major conduction anesthesia. As during general anesthesia, core temperature subsequently decreases linearly at a rate determined by the inequality between heat loss and production. The major difference, however, is that the linear hypothermia phase is not discontinued by reemergence of thermoregulatory vasoconstriction because constriction in the legs is blocked peripherally. As a result, in patients undergoing large operations with neuraxial anesthesia, there is the potential of development of serious hypothermia. Hypothermic cardiopulmonary bypass is associated with enormous changes in body heat content. Furthermore, rapid cooling and rewarming produces large core-to-peripheral, longitudinal, and radial tissue temperature gradients. Inadequate rewarming of peripheral tissues typically produces a considerable core-to-peripheral gradient at the end of bypass. Subsequently, redistribution of heat from the core to the cooler arms and legs produces an afterdrop. Afterdrop magnitude can be reduced by prolonging rewarming, pharmacologic vasodilation, or peripheral warming. Postoperative return to normothermia occurs when brain anesthetic concentration decreases sufficiently to again trigger normal thermoregulatory defenses. However, residual anesthesia and opioids given for treatment of postoperative pain decreases the effectiveness of these responses. Consequently, return to normothermia often needs 2-5 h, depending on the degree of hypothermia and the age of the patient.

View PDF Chat

Normal oral, rectal, tympanic and axillary body temperature in adult men and women: a systematic literature review

2002-05-09

Märtha Sund‐Levander , Christina Forsberg , Lis Karin Wahren

Normal oral, rectal, tympanic and axillary body temperature in adult men and women: a systematic literature review The purpose of this study was to investigate normal body temperature in adult … Normal oral, rectal, tympanic and axillary body temperature in adult men and women: a systematic literature review The purpose of this study was to investigate normal body temperature in adult men and women. A systematic review of data was performed. Searches were carried out in MEDLINE, CINAHL, and manually from identified articles reference lists. Studies from 1935 to 1999 were included. Articles were classified as (1) strong, (2) fairly strong and (3) weak evidence. When summarizing studies with strong or fairly strong evidence the range for oral temperature was 33.2–38.2 °C, rectal: 34.4–37.8 °C, tympanic: 35.4– 37.8 °C and axillary: 35.5–37.0 °C. The range in oral temperature for men and women, respectively, was 35.7–37.7 and 33.2–38.1 °C, in rectal 36.7–37.5 and 36.8–37.1 °C, and in tympanic 35.5–37.5 and 35.7–37.5 °C. The ranges of normal body temperature need to be adjusted, especially for the lower values. When assessing body temperature it is important to take place of measurement and gender into consideration. Studies with random samples are needed to confirm the range of normal body temperature with respect to gender and age.

Combating Hyperthermia in Acute Stroke

1998-02-01

Myron D. Ginsberg , Raul Busto

Background —Moderate elevations of brain temperature, when present during or after ischemia or trauma, may markedly worsen the resulting injury. We review these provocative findings, which form the rationale for … Background —Moderate elevations of brain temperature, when present during or after ischemia or trauma, may markedly worsen the resulting injury. We review these provocative findings, which form the rationale for our recommendation that physicians treating acute cerebral ischemia or traumatic brain injury diligently monitor their patients for incipient fever and take prompt measures to maintain core-body temperature at normothermic levels. Summary of Review —In standardized models of transient forebrain ischemia, intraischemic brain temperature elevations to 39°C enhance and accelerate severe neuropathological alterations in vulnerable brain regions and induce damage to structures not ordinarily affected. Conversely, the blunting of even mild spontaneous postischemic hyperthermia confers neuroprotection. Mild hyperthermia is also deleterious in focal ischemia, particularly in reversible vascular occlusion. The action of otherwise neuroprotective drugs in ischemia may be nullified by mild hyperthermia. Even when delayed by 24 hours after an acute insult, moderate hyperthermia can still worsen the pathological and neurobehavioral outcome. Hyperthermia acts through several mechanisms to worsen cerebral ischemia. These include (1) enhanced release of neurotransmitters; (2) exaggerated oxygen radical production; (3) more extensive blood-brain barrier breakdown; (4) increased numbers of potentially damaging ischemic depolarizations in the focal ischemic penumbra; (5) impaired recovery of energy metabolism and enhanced inhibition of protein kinases; and (6) worsening of cytoskeletal proteolysis. Recent studies demonstrate the feasibility of direct brain temperature monitoring in patients with traumatic and ischemic injury. Moderate to severe brain temperature elevations, exceeding core-body temperature, may occur in the injured brain. Cerebral hyperthermia also occurs during rewarming after hypothermic cardiopulmonary bypass procedures. Several studies have now shown that elevated temperature is associated with poor outcome in patients with acute stroke. Finally, recent clinical trials in severe closed head injury have shown a beneficial effect of moderate therapeutic hypothermia. Conclusions —The acutely ischemic or traumatized brain is inordinately susceptible to the damaging influence of even modest brain temperature elevations. While controlled clinical investigations will be required to establish the therapeutic efficacy and safety of frank hypothermia in patients with acute stroke, the available evidence is sufficiently compelling to justify the recommendation, at this time, that fever be combated assiduously in acute stroke and trauma patients, even if “minor” in degree and even when delayed in onset. We suggest that body temperature be maintained in a safe normothermic range (eg, 36.7°C to 37.0°C [98.0°F to 98.6°F]) for at least the first several days after acute stroke or head injury.

View PDF Chat

Fever in Acute Stroke Worsens Prognosis

1995-11-01

G. Azzimondi , Leona Bassein , Francesco Nonino +4 more

Background and Purpose No definitive data are yet available on the effects of body temperature on neurological damage after cerebral ischemia in humans. Experimental animal models have provided much evidence, … Background and Purpose No definitive data are yet available on the effects of body temperature on neurological damage after cerebral ischemia in humans. Experimental animal models have provided much evidence, but to our knowledge, only two studies on the relationship between fever and prognosis of stroke in humans have been published. The aim of our study was to investigate the prognostic role of fever in the first 7 days of hospitalization in a cohort of patients admitted to our hospital for acute stroke. Methods We analyzed the data of 183 patients included in a prospective observational prognostic study. Vital status at 30 days was considered the main outcome and was obtained for all patients. Age, level of consciousness, and glycemia at the time of hospitalization were considered covariates for an exact logistic regression analysis. The maximum temperature recorded during the first 7 days dichotomized as “no or low fever” versus “high fever” was added to the model. Death within 10 days, taken as a secondary outcome suggestive of death from neurological causes, was analyzed with exact permutation tests. Results Of the 183 patients analyzed in this study, 43% had fever during the first 7 days after hospitalization. The mean value of the maximum temperature recorded during the first 7 days in the 78 febrile patients was 38.3°C, and the median was 37.9°C. Onset of fever occurred in only 15% of febrile patients during the first day and in 49% on the second. The prognostic roles of age, level of consciousness, and glycemia were confirmed by exact logistic regression. Degree of consciousness impairment was the strongest prognostic variable, with an odds ratio (OR) of 11.4 (95% confidence interval [CI], 4.4 to 31.6). High fever (maximum temperature recorded during the first 7 days ≥37.9°C) was an independent factor for a worse prognosis, with an OR of 3.4 (95% CI, 1.2 to 9.5). The OR of dying within 10 days versus dying between 11 and 30 days was 4.9 (95% CI, 1.2 to 25.2) in patients with high fever with respect to all other patients. Conclusions Fever in the first 7 days was an independent predictor of poor outcome during the first month after a stroke. No data were available on the underlying causes of fever, but the higher risk of death in the first 10 days, most frequently attributed to neurological mechanisms, suggested that high temperature was an independent component of poor prognosis and not only an epiphenomenon of other complications in the course after a stroke. In agreement with animal studies, we found that patients with higher temperature had a worse stroke outcome.

Therapeutic hypothermia and controlled normothermia in the intensive care unit: Practical considerations, side effects, and cooling methods*

2009-02-23

Kees H. Polderman , I Herold

Hypothermia is being used with increasing frequency to prevent or mitigate various types of neurologic injury. In addition, symptomatic fever control is becoming an increasingly accepted goal of therapy in … Hypothermia is being used with increasing frequency to prevent or mitigate various types of neurologic injury. In addition, symptomatic fever control is becoming an increasingly accepted goal of therapy in patients with neurocritical illness. However, effectively controlling fever and inducing hypothermia poses special challenges to the intensive care unit team and others involved in the care of critically ill patients.To discuss practical aspects and pitfalls of therapeutic temperature management in critically ill patients, and to review the currently available cooling methods.Review article.None.Cooling can be divided into three distinct phases: induction, maintenance, and rewarming. Each has its own risks and management problems. A number of cooling devices that have reached the market in recent years enable reliable maintenance and slow and controlled rewarming. In the induction phase, rapid cooling rates can be achieved by combining cold fluid infusion (1500-3000 mL 4 degrees C saline or Ringer's lactate) with an invasive or surface cooling device. Rapid induction decreases the risks and consequences of short-term side effects, such as shivering and metabolic disorders. Cardiovascular effects include bradycardia and a rise in blood pressure. Hypothermia's effect on myocardial contractility is variable (depending on heart rate and filling pressure); in most patients myocardial contractility will increase, although mild diastolic dysfunction can develop in some patients. A risk of clinically significant arrhythmias occurs only if core temperature decreases below 30 degrees C. The most important long-term side effects of hypothermia are infections (usually of the respiratory tract or wounds) and bedsores.Temperature management and hypothermia induction are gaining importance in critical care medicine. Intensive care unit physicians, critical care nurses, and others (emergency physicians, neurologists, and cardiologists) should be familiar with the physiologic effects, current indications, techniques, complications and practical issues of temperature management, and induced hypothermia. In experienced hands the technique is safe and highly effective.

Application of therapeutic hypothermia in the ICU: opportunities and pitfalls of a promising treatment modality. Part 1: Indications and evidence

2004-03-30

Kees H. Polderman

Dramatic neuronal rescue with prolonged selective head cooling after ischemia in fetal lambs.

1997-01-15

Alistair J. Gunn , Tania R. Gunn , Harmen H. de Haan +2 more

Hypothermia has been proposed as a neuroprotective strategy. However, short-term cooling after hypoxia-ischemia is effective only if started immediately during resuscitation. The aim of this study was to determine whether … Hypothermia has been proposed as a neuroprotective strategy. However, short-term cooling after hypoxia-ischemia is effective only if started immediately during resuscitation. The aim of this study was to determine whether prolonged head cooling, delayed into the late postinsult period, improves outcome from severe ischemia. Unanesthetized near term fetal sheep were subject to 30 min of cerebral ischemia. 90 min later they were randomized to either cooling (n = 9) or sham cooling (n = 7) for 72 h. Intrauterine cooling was induced by a coil around the fetal head, leading initially to a fall in extradural temperature of 5-10 degrees C, and a fall in esophageal temperature of 1.5-3 degrees C. Cooling was associated with mild transient systemic metabolic effects, but not with hypotension or altered fetal heart rate. Cerebral cooling reduced secondary cortical cytotoxic edema (P < 0.001). After 5 d of recovery there was greater residual electroencephalogram activity (-5.2+/-1.6 vs. -15.5+/-1.5 dB, P < 0.001) and a dramatic reduction in the extent of cortical infarction and neuronal loss in all regions assessed (e.g., 40 vs. 99% in the parasagittal cortex, P < 0.001). Selective head cooling, maintained throughout the secondary phase of injury, is noninvasive and safe and shows potential for improving neonatal outcome after perinatal asphyxia.

View PDF Chat

Hypothermia Therapy after Traumatic Brain Injury in Children

2008-06-04

James S. Hutchison , Roxanne Ward , Jacques Lacroix +7 more

Hypothermia therapy improves survival and the neurologic outcome in animal models of traumatic brain injury. However, the effect of hypothermia therapy on the neurologic outcome and mortality among children who … Hypothermia therapy improves survival and the neurologic outcome in animal models of traumatic brain injury. However, the effect of hypothermia therapy on the neurologic outcome and mortality among children who have severe traumatic brain injury is unknown.In a multicenter, international trial, we randomly assigned children with severe traumatic brain injury to either hypothermia therapy (32.5 degrees C for 24 hours) initiated within 8 hours after injury or to normothermia (37.0 degrees C). The primary outcome was the proportion of children who had an unfavorable outcome (i.e., severe disability, persistent vegetative state, or death), as assessed on the basis of the Pediatric Cerebral Performance Category score at 6 months.A total of 225 children were randomly assigned to the hypothermia group or the normothermia group; the mean temperatures achieved in the two groups were 33.1+/-1.2 degrees C and 36.9+/-0.5 degrees C, respectively. At 6 months, 31% of the patients in the hypothermia group, as compared with 22% of the patients in the normothermia group, had an unfavorable outcome (relative risk, 1.41; 95% confidence interval [CI], 0.89 to 2.22; P=0.14). There were 23 deaths (21%) in the hypothermia group and 14 deaths (12%) in the normothermia group (relative risk, 1.40; 95% CI, 0.90 to 2.27; P=0.06). There was more hypotension (P=0.047) and more vasoactive agents were administered (P<0.001) in the hypothermia group during the rewarming period than in the normothermia group. Lengths of stay in the intensive care unit and in the hospital and other adverse events were similar in the two groups.In children with severe traumatic brain injury, hypothermia therapy that is initiated within 8 hours after injury and continued for 24 hours does not improve the neurologic outcome and may increase mortality. (Current Controlled Trials number, ISRCTN77393684 [controlled-trials.com].).

View PDF Chat

Delayed postischemic hypothermia: a six month survival study using behavioral and histological assessments of neuroprotection

1995-11-01

Frederick Colbourne , Dale Corbett

In the gerbil, brief global forebrain ischemia induces profound habituation and working memory impairments that stem from delayed hippocampal CA1 death. Short duration postischemic hypothermia has been shown to reduce … In the gerbil, brief global forebrain ischemia induces profound habituation and working memory impairments that stem from delayed hippocampal CA1 death. Short duration postischemic hypothermia has been shown to reduce CA1 loss, but such reports are controversial, as it is thought that protection may be transient. The purpose of this study was to investigate whether prolonged postischemic hypothermia provided long-term CA1 and functional neuroprotection. Previously, 90% of anterior CA1 neurons were rescued (30 d survival) when 24 hr of hypothermia (32 degrees C) was induced 1 hr following a 5 min occlusion that otherwise produced more than 95% loss (Colbourne and Corbett, 1994). We now find about 70% CA1 savings with this same hypothermic treatment in gerbils that survived for 6 months postischemia. While this is a significant reduction from 30 day survival (medial CA1 only), it nonetheless shows, for the first time, persistent, if not permanent neuroprotection, especially in middle and lateral CA1. In addition, in non-treated animals, ischemia impaired learning in an open field and T-maze for up to 6 months. Postischemic hypothermia significantly reduced these deficits. Hypothermia (32 degrees), when initiated 4 hr after ischemia, rescued approximately 12% of CA1 neurons at 6 months with a slight behavioral benefit. Milder hypothermia (34 degrees C, 1-25 hr postischemia, 30 d survival) also reduced habituation impairments and saved approximately 60% of CA1 neurons. Similar trends were found at more caudal CA1 levels. These results clearly show that postischemic hypothermia provides effective and long-lasting neuroprotection, which depends upon the delay to initiation, duration, and degree of cooling and survival time. The protracted functional and histological benefit observed justifies further basic and clinical investigation.

View PDF Chat

Very early hypothermia induction in patients with severe brain injury (the National Acute Brain Injury Study: Hypothermia II): a randomised trial

2010-12-18

Guy L. Clifton , Alex B. Valadka , David Zygun +7 more

View PDF Chat

A Systematic Evaluation of the Effect of Temperature on Coagulation Enzyme Activity and Platelet Function

2004-06-01

Alisa S. Wolberg , Zhi Hong Meng , Dougald M. Monroe +1 more

Background: Hypothermia is associated with an increased risk of bleeding and is a significant contributing factor to the morbidity and mortality of trauma and complicated surgical procedures. A core temperature … Background: Hypothermia is associated with an increased risk of bleeding and is a significant contributing factor to the morbidity and mortality of trauma and complicated surgical procedures. A core temperature of 33°C is associated with a significantly increased risk of death after trauma compared with 37°C. Hypothermia-associated bleeding has been hypothesized to result from dysregulation of enzymatic function, reduced platelet activity, and/or altered fibrinolysis. Methods: We systematically evaluated the effects of temperature on isolated pro- and anticoagulant enzyme processes and platelet activation and adhesion. We also evaluated the effects of temperature on complete coagulation systems (activated partial thromboplastin time and an in vitro, cell-based model of coagulation). Results: Enzyme activities were only slightly reduced at 33°C versus 37°C, and this reduction was not statistically significant (p > 0.05). Platelet activation was also not significantly reduced at 33°C versus 37°C. Conversely, platelet aggregation and adhesion were significantly reduced at 33°C compared with 37°C (p < 0.05). Below 33°C, however, both enzyme activity and platelet function were significantly reduced. Conclusion: Our results suggest that bleeding observed at mildly reduced temperatures (33°–37°C) results primarily from a platelet adhesion defect, and not reduced enzyme activity or platelet activation. However, at temperatures below 33°C, both reduced platelet function and enzyme activity likely contribute to the coagulopathy.

Hypothermia in animal models of acute ischaemic stroke: a systematic review and meta-analysis

2007-05-03

H. Bart van der Worp , Emily S. Sena , Geoffrey A. Donnan +2 more

Induced hypothermia is proposed as a treatment for acute ischaemic stroke, but there have been too few clinical trials involving too few patients to draw any conclusions about the therapeutic … Induced hypothermia is proposed as a treatment for acute ischaemic stroke, but there have been too few clinical trials involving too few patients to draw any conclusions about the therapeutic benefit of cooling. Animal studies of induced hypothermia in focal cerebral ischaemia have tested cooling throughout a wide range of target temperatures, durations and intervals between stroke onset and the initiation of hypothermia. These studies, therefore, provide an opportunity to evaluate the effectiveness of different treatment strategies in animal models to inform the design of future clinical trials. We performed a systematic review and meta-analysis of the evidence for efficacy of hypothermia in animal models of ischaemic stroke, and identified 101 publications reporting the effect of hypothermia on infarct size or functional outcome, including data from a total of 3353 animals. Overall, hypothermia reduced infarct size by 44% [95% confidence interval (CI), 40–47%]. Efficacy was highest with cooling to lower temperatures (≤31°C), where treatment was started before or at the onset of ischaemia and in temporary rather than permanent ischaemia models. However, a substantial reduction in infarct volume was also observed with cooling to 35°C (30%; 95% CI, 21–39%), with initiation of treatment between 90 and 180 min (37%; 95% CI, 28–46%) and in permanent ischaemia models (37%; 95% CI, 30–43%). The effects of hypothermia on functional outcome were broadly similar. We conclude that in animal models of focal cerebral ischaemia, hypothermia improves outcome by about one-third under conditions that may be achievable for large numbers of patients with ischaemic stroke. Large randomized clinical trials testing the effect of hypothermia in patients with acute ischaemic stroke are warranted.

View PDF Chat

Unintentional Hypothermia Is Associated with Postoperative Myocardial Ischemia

1993-03-01

Steven M. Frank , Charles Beattie , Rose Christopherson +4 more

Hypothermia occurs commonly during surgery and can be associated with increased metabolic demands during rewarming in the postoperative period. Although cardiac complications remain the leading cause of morbidity after anesthesia … Hypothermia occurs commonly during surgery and can be associated with increased metabolic demands during rewarming in the postoperative period. Although cardiac complications remain the leading cause of morbidity after anesthesia and surgery, the relationship between unintentional hypothermia and myocardial ischemia during the perioperative period has not been studied.One hundred patients undergoing lower extremity vascular reconstruction received continuous Holter monitoring throughout the first 24 h postoperatively. Myocardial ischemia was determined by a cardiologist masked to clinical variables. The patient's sublingual temperature on arrival at the intensive care unit immediately after the surgical procedure was used to divide the patients into two groups: hypothermic (temperature, < 35 degrees C; n = 33) and normothermic (temperature, > or = 35 degrees C; n = 67). The relationship between intentional hypothermia and myocardial ischemia occurring during the first postoperative day was evaluated by univariate and multivariate analyses.A greater percentage of patients had electrocardiographic changes consistent with myocardial ischemia in the hypothermic group (36%, 12 of 33) compared with those in the normothermic group (13%, 9 of 67, P = 0.008). Preoperative risk factors for perioperative cardiac morbidity were similar between the two groups, except for patient age. The mean age was 70 +/- 2 yr and 62 +/- 1 yr in the hypothermic and normothermic groups, respectively (P = 0.001). When subgroup and multivariate analyses were used to adjust for differences in age, temperature remained an independent predictor of ischemia (odds ratio, 1.82 per degree Celsius; 95% confidence interval, 1.09-3.02). The incidence of postoperative angina was greater in the hypothermic group (18%, 6 of 33) than in the normothermic group (1.5%, 1 of 67, P = 0.002). The incidence of PaO2 < 80 mmHg in the arterial blood was greater in the hypothermic group (52%, 17 of 33) than in the normothermic group (30%, 20 of 67, P = 0.03).Unintentional hypothermia is associated with myocardial ischemia, angina, and PaO2 < 80 mmHg during the early postoperative period in patients undergoing lower extremity vascular surgery.

View PDF Chat

Hypothermia but not the N-methyl-D-aspartate antagonist, MK-801, attenuates neuronal damage in gerbils subjected to transient global ischemia

1990-01-01

Alastair M. Buchan , W. A. Pulsinelli

Several laboratories have reported a significant reduction of ischemia-induced injury to hippocampal neurons in rodents treated with competitive and noncompetitive N-methyl-D-aspartate (NMDA) receptor-channel antagonists. This study examined the effects of … Several laboratories have reported a significant reduction of ischemia-induced injury to hippocampal neurons in rodents treated with competitive and noncompetitive N-methyl-D-aspartate (NMDA) receptor-channel antagonists. This study examined the effects of the noncompetitive antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) in Mongolian gerbils subjected to 5 min of bilateral carotid artery occlusion. In adult female gerbils, single doses of MK-801 injected 1 hr prior to ischemia significantly (p less than 0.01) reduced damage to CA1 hippocampal neurons. However, the drug rendered the postischemic animals comatose and hypothermic for several hours compared with the saline-treated animals. In subsequent experiments, animals pretreated with MK-801 and maintained normothermic during and after forebrain ischemia demonstrated no amelioration of hippocampal damage. Gerbils not treated with MK-801, but kept hypothermic in the postischemic period to approximately the same degree (34.5 degrees C) and duration (8 hr) as was induced by MK-801 therapy showed significant (p less than 0.01) protection of CA1 neurons against ischemia. The neuroprotective activity of MK-801 against transient global ischemia appears to be largely a consequence of postischemic hypothermia rather than a direct action on NMDA receptor-channels.

View PDF Chat

Hypothermia in Trauma Victims

1987-09-01

Gregory J. Jurkovich , WILLIAM B. GREISER , Arnold Luterman +1 more

Hypothermia in trauma patients is generally considered an ominous sign, although the actual temperature at which hypothermia affects survival is ill defined. In this study, the impact of body core … Hypothermia in trauma patients is generally considered an ominous sign, although the actual temperature at which hypothermia affects survival is ill defined. In this study, the impact of body core hypothermia on outcome in 71 adult trauma patients with Injury Severity Scores (ISS) ≥25 was analyzed. Forty-two per cent of the patients had a core temperature (Tc) below 34°C, 23% below 33°C, and 13% below 32°C. The mortality of hypothermia patients was consistently greater than those who remained warm, regardless of index core temperature. Mortality if Tc < 34°C = 40%, < 33°C = 69%, < 32°C = 100%, whereas mortality if Tc ≥ 34°C = 7%, ≥ 33°C = 7%, and ≥ 32°C = 10%. Mortality and the incidence of hypothermia increased with higher ISS, massive fluid resuscitation, and the presence of shock. Within each subgroup (i.e., greater ISS, massive fluid administration, shock) the mortality of hypothermic patients was significantly higher than those who remained warm. No patient whose core temperature fell below 32°C survived.

Fever: Role of Pyrogens and Cryogens

1991-01-01

Matthew J. Kluger

The biology of cytokines is one of the most rapidly growing areas of biomedical research. It is understandable why the assumption was made several years ago that EP was equivalent … The biology of cytokines is one of the most rapidly growing areas of biomedical research. It is understandable why the assumption was made several years ago that EP was equivalent to IL-1 (both alpha and beta) and subsequently to IL-1 alpha, IL-1 beta, and TNF. However, as more data have been obtained, it has become clearer that many cytokines and hormones are capable of participating in the febrile response. It is also becoming apparent that EPs and ECs might influence body temperature during nonpathological states, perhaps contributing to the elevation in temperature during or after exercise, the circadian variation in temperature, and others. Medical textbooks have begun to list IL-1 as the EP. As I attempted to make clear in this review, evidence that IL-1 alpha is a circulating EP is poor. The evidence is considerably stronger that IL-1 beta is an EP, at least during LPS-induced fever in rodents. The point I have tried to emphasize is that before any cytokine or hormone can be characterized as an EP or EC (or, for that matter, as being involved in any of the acute phase responses), clearly established rules must be followed, which are patterned after the traditional criteria used by Koch to distinguish a pathogenic microorganism from a benign one. As summarized in Tables 4 and 5, there are many candidates for EPs and ECs, but much more experimental evidence is essential before we gain a clear understanding of the relationship between contact with an exogenous pyrogen, the release of EPs and ECs, and the development of fever.

Guidelines for evaluation of new fever in critically ill adult patients: 2008 update from the American College of Critical Care Medicine and the Infectious Diseases Society of America

2008-04-01

Naomi P. O’Grady , Philip S. Barie , John G. Bartlett +7 more

Objective: To update the practice parameters for the evaluation of adult patients who develop a new fever in the intensive care unit, for the purpose of guiding clinical practice. Participants: … Objective: To update the practice parameters for the evaluation of adult patients who develop a new fever in the intensive care unit, for the purpose of guiding clinical practice. Participants: A task force of 11 experts in the disciplines related to critical care medicine and infectious diseases was convened from the membership of the Society of Critical Care Medicine and the Infectious Diseases Society of America. Specialties represented included critical care medicine, surgery, internal medicine, infectious diseases, neurology, and laboratory medicine/microbiology. Evidence: The task force members provided personal experience and determined the published literature (MEDLINE articles, textbooks, etc.) from which consensus was obtained. Published literature was reviewed and classified into one of four categories, according to study design and scientific value. Consensus Process: The task force met twice in person, several times by teleconference, and held multiple e-mail discussions during a 2-yr period to identify the pertinent literature and arrive at consensus recommendations. Consideration was given to the relationship between the weight of scientific evidence and the strength of the recommendation. Draft documents were composed and debated by the task force until consensus was reached by nominal group process. Conclusions: The panel concluded that, because fever can have many infectious and noninfectious etiologies, a new fever in a patient in the intensive care unit should trigger a careful clinical assessment rather than automatic orders for laboratory and radiologic tests. A cost-conscious approach to obtaining cultures and imaging studies should be undertaken if indicated after a clinical evaluation. The goal of such an approach is to determine, in a directed manner, whether infection is present so that additional testing can be avoided and therapeutic decisions can be made.

Induced hypothermia and fever control for prevention and treatment of neurological injuries

2008-06-01

Kees H. Polderman

Complications and Treatment of Mild Hypothermia

2001-08-01

Daniel I. Sessler

THE combination of anesthetic-induced impairment of thermoregulatory control and exposure to a cool operating room environment makes most surgical patients hypothermic. Several prospective, randomized trials have demonstrated various hypothermia-induced complications. … THE combination of anesthetic-induced impairment of thermoregulatory control and exposure to a cool operating room environment makes most surgical patients hypothermic. Several prospective, randomized trials have demonstrated various hypothermia-induced complications. There is no widely accepted definition for the term mild hypothermia. Furthermore, the term is not even used consistently in the literature. For the purpose of this review, mild hypothermia refers to core temperatures between 34 and 36°C.

View PDF Chat

Regulation of Internal Body Temperature

1968-03-01

H. T. Hammel , JH Pierce

Macrophage polarization refers to how macrophages have been activated at a given point in space and time. Polarization is not fixed, as macrophages are sufficiently plastic to integrate multiple signals, … Macrophage polarization refers to how macrophages have been activated at a given point in space and time. Polarization is not fixed, as macrophages are sufficiently plastic to integrate multiple signals, such as those from microbes, damaged tissues, and ...Read More

Perioperative thermoregulation and heat balance

2016-01-08

Daniel I. Sessler

Hypothermia for Intracranial Hypertension after Traumatic Brain Injury

2015-10-07

Peter J. D. Andrews , H. Louise Sinclair , Aryelly Rodríguez +4 more

In patients with traumatic brain injury, hypothermia can reduce intracranial hypertension. The benefit of hypothermia on functional outcome is unclear.We randomly assigned adults with an intracranial pressure of more than … In patients with traumatic brain injury, hypothermia can reduce intracranial hypertension. The benefit of hypothermia on functional outcome is unclear.We randomly assigned adults with an intracranial pressure of more than 20 mm Hg despite stage 1 treatments (including mechanical ventilation and sedation management) to standard care (control group) or hypothermia (32 to 35°C) plus standard care. In the control group, stage 2 treatments (e.g., osmotherapy) were added as needed to control intracranial pressure. In the hypothermia group, stage 2 treatments were added only if hypothermia failed to control intracranial pressure. In both groups, stage 3 treatments (barbiturates and decompressive craniectomy) were used if all stage 2 treatments failed to control intracranial pressure. The primary outcome was the score on the Extended Glasgow Outcome Scale (GOS-E; range, 1 to 8, with lower scores indicating a worse functional outcome) at 6 months. The treatment effect was estimated with ordinal logistic regression adjusted for prespecified prognostic factors and expressed as a common odds ratio (with an odds ratio <1.0 favoring hypothermia).We enrolled 387 patients at 47 centers in 18 countries from November 2009 through October 2014, at which time recruitment was suspended owing to safety concerns. Stage 3 treatments were required to control intracranial pressure in 54% of the patients in the control group and in 44% of the patients in the hypothermia group. The adjusted common odds ratio for the GOS-E score was 1.53 (95% confidence interval, 1.02 to 2.30; P=0.04), indicating a worse outcome in the hypothermia group than in the control group. A favorable outcome (GOS-E score of 5 to 8, indicating moderate disability or good recovery) occurred in 26% of the patients in the hypothermia group and in 37% of the patients in the control group (P=0.03).In patients with an intracranial pressure of more than 20 mm Hg after traumatic brain injury, therapeutic hypothermia plus standard care to reduce intracranial pressure did not result in outcomes better than those with standard care alone. (Funded by the National Institute for Health Research Health Technology Assessment program; Current Controlled Trials number, ISRCTN34555414.).

View PDF Chat

Prognostic Values of Tumor Necrosis Factor/Cachectin, Interleukin-l, Interferon- , and Interferon- in the Serum of Patients with Septic Shock

1990-05-01

Thierry Calandra , J. D. Baumgartner , Georges E. Grau +5 more

Serum concentrations of immunoreactive tumor necrosis factor/cachectin (TNF), interleukin-1 beta (IL-1 beta), interferon-gamma (IFN gamma), and interferon-alpha (IFN alpha) were prospectively measured in 70 patients with septic shock to determine … Serum concentrations of immunoreactive tumor necrosis factor/cachectin (TNF), interleukin-1 beta (IL-1 beta), interferon-gamma (IFN gamma), and interferon-alpha (IFN alpha) were prospectively measured in 70 patients with septic shock to determine their evolution and prognostic values. In a univariate analysis, levels of TNF (P = .002) and IL-1 beta (P = .05) were associated with the patient's outcome, but not IFN alpha (P = .15) and IFN gamma (P = .26). In contrast, in a stepwise logistic regression analysis, the severity of the underlying disease (P = .01), the age of the patient (P = .02), the documentation of infection (nonbacteremic infections vs. bacteremias, P = .03), the urine output (P = .04), and the arterial pH (P = .05) contributed more significantly to prediction of patient outcome than the serum levels of TNF (P = .07). After 10 days, the median concentration of TNF was undetectable (less than 100 pg/ml) in the survivors, whereas it remained elevated (305 pg/ml, P = .002) in the nonsurvivors. Thus, in patients with septic shock due to various gram-negative bacteria, other parameters than the absolute serum concentration of immunoreactive TNF contributed significantly to the prediction of outcome.

View PDF Chat

Treatment of Traumatic Brain Injury with Moderate Hypothermia

1997-02-20

Donald W. Marion , Louis E. Penrod , Sheryl F. Kelsey +5 more

Traumatic brain injury initiates several metabolic processes that can exacerbate the injury. There is evidence that hypothermia may limit some of these deleterious metabolic responses. Traumatic brain injury initiates several metabolic processes that can exacerbate the injury. There is evidence that hypothermia may limit some of these deleterious metabolic responses.

View PDF Chat

Lack of Effect of Induction of Hypothermia after Acute Brain Injury

2001-02-22

Guy L. Clifton , Emmy R. Miller , Sung C. Choi +7 more

Induction of hypothermia in patients with brain injury was shown to improve outcomes in small clinical studies, but the results were not definitive. To study this issue, we conducted a … Induction of hypothermia in patients with brain injury was shown to improve outcomes in small clinical studies, but the results were not definitive. To study this issue, we conducted a multicenter trial comparing the effects of hypothermia with those of normothermia in patients with acute brain injury.

View PDF Chat

Perioperative Normothermia to Reduce the Incidence of Surgical-Wound Infection and Shorten Hospitalization

1996-05-09

Andrea Kurz , Daniel I. Sessler , Rainer Lenhardt

Mild perioperative hypothermia, which is common during major surgery, may promote surgical-wound infection by triggering thermoregulatory vasoconstriction, which decreases subcutaneous oxygen tension. Reduced levels of oxygen in tissue impair oxidative … Mild perioperative hypothermia, which is common during major surgery, may promote surgical-wound infection by triggering thermoregulatory vasoconstriction, which decreases subcutaneous oxygen tension. Reduced levels of oxygen in tissue impair oxidative killing by neutrophils and decrease the strength of the healing wound by reducing the deposition of collagen. Hypothermia also directly impairs immune function. We tested the hypothesis that hypothermia both increases susceptibility to surgical-wound infection and lengthens hospitalization.

View PDF Chat

Untersuchungen am überlebenden Säugethierherzen

1895-08-01

O. Langendorff

Accidental Hypothermia.

1978-03-01

Experimental Evaluation of the Effectiveness of Antishock Therapy for Severe Combined Mechanical and Thermal Injury

2025-06-23

Tsygan Vn , E V Ivchenko , Nikolay K. Sokolov +1 more | Bulletin of the Russian Military Medical Academy

BACKGROUND: Modern combat-related surgical trauma is characterized by the combined impact of multiple detrimental factors. This often leads to the simultaneous development of several critical conditions in the body, such … BACKGROUND: Modern combat-related surgical trauma is characterized by the combined impact of multiple detrimental factors. This often leads to the simultaneous development of several critical conditions in the body, such as burn disease and crush syndrome. The cross-interaction of these pathogenetic pathways contributes to the development of mutual aggravation syndrome, thereby increasing the likelihood of an unfavorable trauma outcome. Research into the mechanisms of these conditions and the development of pathogenetically justified approaches to correcting these homeostatic disturbances remains highly relevant. AIM: To evaluate the effectiveness of antishock therapy in a combined experimental model of crush syndrome and burn disease. METHODS: The study was performed using 360 rats weighing 240–250 g, in which both crush syndrome and deep skin burns were induced. Mortality rates were analyzed depending on the volume and composition of the antishock therapy delivered. Data processing was performed using the standard methods for variation statistics. The alternative hypothesis was accepted at p 0.05. RESULTS: It was found that in the combined model of crush syndrome and burn disease, the volume of infused fluids should be increased by 40%. Based on this result, the standard Parkland formula was modified to V = 6,5 × S × M. Among the evaluated antishock therapy regimens, the combination of crystalloid and colloid solutions in a 40:60 ratio exhibited the highest efficacy. The mortality rate in this group was 28.9%, which was 2.4 (p 0.05) and 2.6 (p 0.05) times lower than that with 0.9% sodium chloride solution and 10% albumin solution, respectively. The high effectiveness of the substrate-based antihypoxants for the treatment of mechanical and thermal shock was demonstrated. Their administration reduced the mortality rate to 30.4%, which was 2.2 times (p 0.05) lower than the results observed when normal saline was administered. The use of analgesics and antioxidants did not significantly influence the animals’ survival rate. CONCLUSION: The results of this study indicate the potential use of metabolic (substrate-based) antihypoxants in antishock therapy for patients with combined crush syndrome and burn disease. This research direction requires further development and in-depth investigation.

Nursing Care for Hydronephrosis Patients Through Deep Breathing Relaxation Techniques Implementation to Reduce Pain: A Case Report

2025-06-21

Miftah Salsabila , Muhamad Zulfatul A’la , Murtaqib +1 more | Health and Technology Journal (HTechJ)

Hydronephrosis occurs due to a disorder in the urinary tract that causes the flow of urine from the urinary tract to be obstructed, causing the dilation of the channels in … Hydronephrosis occurs due to a disorder in the urinary tract that causes the flow of urine from the urinary tract to be obstructed, causing the dilation of the channels in the kidneys. The main symptoms that hydronephrosis patients commonly feel are pain in the lower back, nausea, and fatigue. Deep breath relaxation therapy, as a non-pharmacological therapy, has the effect of reducing pain. This study aims to determine the effect of deep breath relaxation techniques in patients with hydronephrosis and pain complaints. The method used in this study was a case study of one patient who was given an intervention for three days. The pain intensity scale was measured using the Numeric Rating Scale (NRS). This study showed a significant reduction in pain intensity in hydronephrosis patients from a scale of 6 to a scale of 3, where the deep breath relaxation technique intervention was given for three consecutive days for three sets per day in patients. Based on the results of the study, the researcher suggests the use of deep breath relaxation techniques as a non-pharmacological therapy in hydronephrosis patients with pain complaints in clinical practice, which can be provided by health workers, especially nurses or as patient-independent therapy because deep breath relaxation techniques are easy to do therapy and do not require additional tools and materials to do so.

Hypothermia as a factor in enhancing the effect of antihypoxants

2025-06-20

Natalya Urakova , Aleksandr Urakov , А. П. Решетников +7 more | Reviews on Clinical Pharmacology and Drug Therapy

It is reported that selective hypothermia of organs and tissues reduces the intensity of biological combustion in mitochondria regardless of whether these organs and tissues are associated with the human … It is reported that selective hypothermia of organs and tissues reduces the intensity of biological combustion in mitochondria regardless of whether these organs and tissues are associated with the human body (in vivo) or completely isolated from it (in vitro). Therefore, local cooling of a selected part of the body reduces its oxygen demand and prolongs survival under hypoxia, i.e. it has a local antihypoxic effect. General hypothermia of warm-blooded animals and humans can both increase and decrease their survival rate under hypoxia conditions. This is due to the fact that in normal conditions external cooling effect on the organism of a warm-blooded animal increases oxygen-dependent thermogenesis in it. Therefore, in the norm, the process of general cooling of the human body does not contribute to the development of antihypoxic action in it. But oxygen-dependent thermogenesis can be turned off in the hospital setting with special hibernator drugs. Effectively shutting down thermogenesis in the patient's body before general cooling can provide the antihypoxic activity of general hypothermia. It is shown that at the beginning of the 21st century a group of oxygen-producing antihypoxants, the main ingredient of which is hydrogen peroxide, was discovered in Russia. A formulation of injectable hydrogen peroxide solution intended for local cooling of tissues at the injection site and providing them with oxygen is given. It is shown that injection of the invented cold solution of hydrogen peroxide into soft tissues (myocardium, brain, etc.) provides immediate local antihypoxic action, which develops due to local hypothermia of the tissue at the injection site by means of its physical cooling with cold solution and generation of oxygen gas in it by means of catalase cleavage of hydrogen peroxide into water and molecular oxygen. Since local hypothermia is an unrivaled way to preserve mitochondria during oxygen deprivation, and hydrogen peroxide is the leader among oxygen-producing antihypoxants, modernizing the administration of cold hydrogen peroxide solutions into the brain may in the future provide instant local cooling of the brain with simultaneous local oxygenation.

Relationship between earthquake ınjuries and ınflammatory blood parameters

2025-06-20

Seda Kumbasar | Dicle Medical Journal / Dicle Tip Dergisi

Objective: An earthquake is a significant natural disaster with the potential to cause considerable mortality, economic disruption, and psychological effects. The purpose of this study was to investigate the impact … Objective: An earthquake is a significant natural disaster with the potential to cause considerable mortality, economic disruption, and psychological effects. The purpose of this study was to investigate the impact of laboratory parameters on the triage, treatment, and survival of patients with injuries of varying severity who sustained traumatic injuries amid debris. Methods: This retrospective study included 1250 adult earthquake victims who were received outpatients and inpatient treatment in our hospital between February 6 and February 23, 2023. The patients were classified into three categories. The first group includ ed individuals with soft tissue injuries but no fractures or major injuries. The second group included those with fractures but no major visceral injuries and crush syndrome. The third group included individuals with lung contusion, pneumothorax, intracranial hemorrhage, intra-abdominal hemorrhage, crush syndrome and compartment syndrome. Results: Alanine transaminase, creatine kinase, myoglobin, D-dimer, white blood cell count, absolute neutrophil count, absolute monocyte count, C- aspartate transaminase reactive protein, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, monocyte/lymphocyte ratio, and the systemic inflammatory index were progressively higher in all three groups. Absolute-lymphocyte counts and calcium were progressively less different (p

It Takes a Network to Care for Kids With Fever

2025-06-19

Anand K Swaminathan , Brendan Freeman , William K. Milne | Annals of Emergency Medicine

Hypothermia in Microvascular Head and Neck Reconstruction—Risk of Venous Thromboembolism and Flap Pedicle Thrombosis—Reply

2025-06-18

Rakan Saadoun , Mario G. Solari | JAMA Otolaryngology–Head & Neck Surgery

Seasonal Thrombocytopenia Induced by Hypothalamic Hypothermia: A Case Report

2025-06-18

Masahiro Tanji , Noritaka Sano , Hiroyuki Ikeda +6 more | Research Square (Research Square)

<title>Abstract</title> <bold>Background</bold> The hypothalamus plays a central role in thermoregulation. In brain tumors involving the hypothalamus, hypothermia can lead to rare but serious complications such as impaired consciousness and thrombocytopenia. … <title>Abstract</title> <bold>Background</bold> The hypothalamus plays a central role in thermoregulation. In brain tumors involving the hypothalamus, hypothermia can lead to rare but serious complications such as impaired consciousness and thrombocytopenia. <bold>Case Presentation</bold> An 80-year-old man was brought to our hospital in February after being found unresponsive in his bedroom. He had a history of surgery for a giant PitNET at another institution and was subsequently followed at our hospital. Having declined further surgical intervention, he was managed conservatively. During follow-up, episodes of unexplained paroxysmal thrombocytopenia were occasionally observed. Upon arrival, he was comatose with a core body temperature of 32.1°C. Laboratory tests revealed marked thrombocytopenia (55,000/µL) and widespread subcutaneous hemorrhages. Hypothermia was considered the primary cause of the impaired consciousness. Because the patient’s body temperature was gradually normalized by external warming, his level of consciousness improved, and his platelet count also began to recover over the following days. A retrospective review of prior laboratory data revealed a seasonal pattern in the thrombocytopenia. Based on these findings, the thrombocytopenia was considered secondary to hypothalamic hypothermia. <bold>Conclusions</bold> Hypothalamic tumors can precipitate hypothermia and seasonal hematologic disturbances. In patients with brain tumors presenting with unexplained, seasonal, or periodic thrombocytopenia, underlying thermoregulatory dysfunction due to hypothalamic involvement should be considered.

Hypothermia in Microvascular Head and Neck Reconstruction—Risk of Venous Thromboembolism and Flap Pedicle Thrombosis

2025-06-18

John D. Cramer , Trinitia Y. Cannon , Michael Brenner | JAMA Otolaryngology–Head & Neck Surgery

Association between postoperative body temperature and in-hospital mortality: a nationwide cohort study of 157,028 critically ill patients in Japan

2025-06-16

Yoshitaka Aoki , Mikio Nakajima , Soichiro Mimuro +6 more | Canadian Journal of Anesthesia/Journal canadien d anesthésie

Perioperative temperature management and coagulation: effects of mild hypothermia in a prospective study

2025-06-16

Alena Trčková , Tereza Bönischová , Hana Zelinková +1 more | Frontiers in Medicine

Background Perioperative hypothermia is a common complication of general and regional anesthesia in children and is a known risk factor for the development of coagulation disorders. The primary aim of … Background Perioperative hypothermia is a common complication of general and regional anesthesia in children and is a known risk factor for the development of coagulation disorders. The primary aim of the study was to assess the occurrence of coagulopathy in hypothermic pediatric patients (0–18 years) undergoing arthroscopic surgery and open abdominal surgery. The secondary objective was to identify potential risk factors for the development of both hypothermia and coagulopathy. Methods A prospective cohort study was conducted, forming the second part of our study “Perioperative Management of Temperature in Children and the Influence of Hypothermia on Blood Clotting in Children” (Peritemp). We observed the incidence of body temperatures below normal values—specifically, below 36.5°C and 36°C—as well as the incidence of pathological values in thromboelastometry (ROTEM) (EXTEM and FIBTEM) and standard coagulation tests, including activated partial thromboplastin time (aPTT) and prothrombin time (PT). Results A total of 102 patients (55 female and 47 male patients) were enrolled from 22nd January 2018 to 27th August 2021 at the Department of Pediatric Anesthesiology and Intensive Medicine, University Hospital Brno. An incidence of body temperature below 36.5°C was observed in 86 cases, and temperatures below 36.0°C were observed in 43 cases. The incidence of abnormalities in the individual parameters of the coagulation tests ranged from 5.9 to 32.4%. The ROTEM results were abnormal in 18.7% of the patients, while the standard coagulation test showed abnormalities in 15.9% of the cases. In the statistical comparison between the first and second coagulation test results, only the prothrombin time ratio (PT-R) showed a statistically significant difference. Low operating room (OR) temperature and patient age emerged as significant risk factors for the incidence of hypothermia. In addition, older age was associated with an increased likelihood of body temperature falling below 36.5°C and 36°C. Conclusion Our study confirmed that mild hypothermia (core temperature below 36.0°C) is common during pediatric surgeries, but it does not appear to result in clinically significant coagulation disorders requiring intervention. Despite the incidence of coagulation abnormalities, the absence of significant changes in coagulation parameters, outside of the PT-R, suggests that mild hypothermia may be well tolerated by the coagulation system in pediatric patients. Our study confirmed the previously established association between variability in operating room temperature and intraoperative hypothermia. Future research should focus on larger, more diverse pediatric populations to validate these findings and optimize perioperative temperature management strategies. Clinical trial registration ClinicalTrials.gov identifier: NCT03273894.

The optimal warming strategy to reduce perioperative hypothermia: A prospective randomized non-blinded clinical trial

2025-06-12

Ravi V. Desai , Jason Gosschalk , Noud van Helmond +7 more | PLoS ONE

Background To mitigate perioperative hypothermia, patients can be warmed preoperatively and intraoperatively with forced-air warming (FAW) and conductive warming (CW) methods. We examined the association of four combinations of pre- … Background To mitigate perioperative hypothermia, patients can be warmed preoperatively and intraoperatively with forced-air warming (FAW) and conductive warming (CW) methods. We examined the association of four combinations of pre- and intraoperative CW and FAW with the magnitude of intraoperative hypothermia. Methods We conducted a prospective randomized trial at a tertiary healthcare center in the United States (trial registration number ISRCTN23065394). Patients were randomized to 4 arms based on the following pre/intraoperative warming combinations: (1) CW/CW, (2) FAW/FAW, (3) no active prewarming (NAPW)/CW, (4) NAPW/FAW. Body temperature was measured using an esophageal probe. The area under the temperature curve (AUC) below 36°C was calculated according to the trapezoidal rule and quantified intraoperative hypothermia. A mixed model was used to estimate differences in AUC between the 4 arms. Results 182 patients were analyzed. Patients in the NAPW/FAW arm had the highest AUC values while those in the CW/CW arm had the lowest. AUC values [median (Q1, Q3] were as follows: CW/CW = 4.7 (0, 26.6); FAW/FAW = 8.0 (0, 30.8); NAPW/CW = 7.4 (0, 27.1); NAPW/FAW = 19.9 (5.0, 44.3). Mixed model results showed significant lower AUC values in CW/CW and NAPW/CW when compared to NAPW/FAW. The ratio of mean AUC [95% CI] between CW/CW vs NAPW/FAW was 0.49 [0.24, 0.98], 51% lower, and between NAPW/CW and NAPW/FAW, 0.46 [0.23, 0.91], 54% lower. When the AUC was normalized to the duration of surgery (AUC/case duration in°C, or “relative AUC”), significant lower relative AUC values were observed between FAW/FAW vs NAPW/FAW (48% lower, p = 0.0419) and NAPW/CW vs NAPW/FAW (48% lower, p = 0.0407). Conclusions CW is more effective than FAW at reducing intraoperative hypothermia when FAW is used without prewarming. When patients are actively prewarmed, CW and FAW show no difference in their ability to maintain patient temperature.

Comparison of pentazocine and pethidine for the treatment of shivering following subarachnoid block

2025-06-12

Mustapha Miko Mohammed Abdullahi , Datti Mohammed Alhassan , Stella Eguma +7 more | Pyramid Journal of Medicine

Pethidine is one of the known drugs for treating post-spinal shivering; however, it is a controlled drug. Pentazocine, a specific kappa agonist, is widely available in West Africa and is … Pethidine is one of the known drugs for treating post-spinal shivering; however, it is a controlled drug. Pentazocine, a specific kappa agonist, is widely available in West Africa and is not yet a controlled drug. A randomized, double-blind trial was performed to compare the efficacy of pentazocine and pethidine for the treatment of post-spinal shivering. One hundred ASA I and II patients undergoing surgeries below the umbilicus under spinal anesthesia were studied. Patients who developed shivering after the administration of intrathecal bupivacaine for spinal anesthesia were randomly allocated to 2 groups to receive either Intravenous (IV) pethidine 25mg (n=50) - group A, or IV pentazocine 30 mg (n=50) - group B. The time from the administration of the study drug to the reduction and complete disappearance of shivering, recurrence of shivering, and other adverse effects were determined. The two study groups did not differ significantly regarding patient characteristics. The difference between the mean time of administration of the study drug to the complete disappearance of shivering in group A (9.23±2.18 minutes) and B (6.70±1.15 minutes) was statistically significant (p<0.05). The onset of action was faster with pentazocine (94.04±16.20 seconds) compared with pethidine (151±34.01) (p<0.05). The pentazocine group had a higher recurrence of shivering than the pethidine group (30.8% vs 13.0%), though this difference was not statistically significant (p=0.14). Three patients (13.04%) had a recurrence of shivering in the pethidine group compared to 8 patients (30.77%) in the pentazocine group. There was no significant difference between the groups in terms of sedation, pulse rates, nausea, perioperative tympanic temperatures, and mean arterial pressures. No vomiting or respiratory depressions were observed. Pentazocine 30 mg and pethidine 25 mg were both equally effective in the treatment of shivering following subarachnoid block. Though pentazocine had a faster onset of action and abolished shivering earlier than pethidine, the rate of recurrence of shivering after treatment was however higher with pentazocine than with pethidine.

Recognition and Management of the Sick Patient

2025-06-09

| Cambridge University Press eBooks

H2OPulse: Smartphone-assisted Vein Evaluation for Early Recognition of Dehydration

2025-06-09

Towhidul Islam , Md. Mahedi Hasan Rigan , M. K. A. Bhuiyan +2 more | Proceedings of the ACM on Interactive Mobile Wearable and Ubiquitous Technologies

Maintaining human health relies on adequate water intake for digestion, waste elimination, and temperature regulation. Dehydration occurs when the body loses more fluids than it takes in, leading to electrolyte … Maintaining human health relies on adequate water intake for digestion, waste elimination, and temperature regulation. Dehydration occurs when the body loses more fluids than it takes in, leading to electrolyte imbalances and serious complications, especially in vulnerable populations. Traditional dehydration detection methods rely on laboratory tests and physical exams, which can be invasive, expensive, time-consuming, and often inaccessible in rural areas. Recent research has proposed several solutions, but these are often either unreliable or not widely accessible. We introduce H2OPulse, the first smartphone-based solution to use vein visibility patterns for dehydration detection, analyzing changes in dorsal and wrist veins to distinguish between hydrated and dehydrated states. Our detection pipeline uses optimized image segmentation and enhancement with transfer learning and Siamese networks to accurately learn and differentiate vein visibility features. Our dataset comprises 3,440 hand vein images from 86 healthy volunteers, captured in both hydrated and dehydrated conditions. Experimental results demonstrate that H2OPulse can accurately detect mild dehydration, making it a practical and accessible solution, with an accuracy of 83.1% and an F1-score of 80.8%. This system empowers early dehydration detection anywhere, enabling timely interventions to prevent further complications.

Relationship between the Level of Knowledge and Education of Mothers Regarding Fever Management in Children 1-5 Years: A Cross-sectional Study

2025-06-09

Apria Wilinda Sumantri | Lentera Perawat

Fever is one of the common health problems in children under five that can cause serious complications if not treated appropriately. Maternal knowledge and education level are important factors in … Fever is one of the common health problems in children under five that can cause serious complications if not treated appropriately. Maternal knowledge and education level are important factors in determining the quality of fever management in children. This study aims to analyze the relationship between the level of knowledge and education of mothers with fever management in children aged 1-5 years. This study used a cross-sectional design with a total of 30 maternal respondents who had children aged 1-5 years and visited the Penyandingan Health Center in January 2025. Total sampling technique was used, and data were collected through questionnaires and checklists. Bivariate analysis was performed using the Chi-Square test with a significance value of α = 0.05. The majority of respondents (70%) had good knowledge, and 63.3% of mothers performed fever management correctly. There was a significant relationship between maternal knowledge and fever management (p = 0.004), and between maternal education and fever management (p = 0.002). Maternal knowledge and education were significantly associated with the quality of fever management in children. Continuous educational interventions are needed for mothers of toddlers to improve knowledge and skills in fever management to prevent complications in children.

Relapsing Fever

2025-06-05

Geraint Davies | Cambridge University Press eBooks

The incidence and influencing factors of hypothermia in patients after transurethral prostatectomy: a systematic review and meta—analysis

2025-06-04

Xufa Ma , Jianhua Zhang , Miao Zhou +4 more | World Journal of Urology

Interest of ventilation/perfusion SPECT/CT in patients with post-COVID condition: a multicenter observational study

2025-06-03

P.B. Bonnefoy , Pierre Pascal , Q. Ceyrat +7 more | European Journal of Nuclear Medicine and Molecular Imaging

Dual forced-air warming improves intra-operative temperature management in lumbar spine surgeries

2025-06-01

Hsin-Yi Wang , Yu-Cheng Yao , Po‐Hsin Chou +2 more | Trends in Anaesthesia and Critical Care

Comment on “Intermittent Hypoxic–Hyperoxic Training During Inpatient Rehabilitation Improves Exercise Capacity and Functional Outcome in Patients With Long Covid: Results of a Controlled Clinical Pilot Trial” by Doehner et al.—The Authors' Reply

2025-06-01

Wolfram Doehner , Per Otto Schueller | Journal of Cachexia Sarcopenia and Muscle

Symptom‐modifying strategy to treat upper respiratory tract infections: a clinical and mechanistic evidence of ColdZyme

2025-05-31

Maulana A. Empitu , Jevon Aaron Lesmana , Derren David Christian Homenta Rampengan +1 more | The Journal of Physiology

Effect of Irrigation Fluid Temperature on Hypothermia and Complications in TURP Patients Under Spinal Anesthesia: A Randomized Clinical Trial

2025-05-31

Hossein Khoshrang , Samaneh Ghazanfar Tehran , Maryam Shakiba +5 more | Journal of Iranian Medical Council

Background: Hypothermia during surgical procedures increases the risk of complications. This study aimed to compare the effects of Irrigation Fluid (IF) temperature on hypothermia, hemodynamic changes, and complications in patients … Background: Hypothermia during surgical procedures increases the risk of complications. This study aimed to compare the effects of Irrigation Fluid (IF) temperature on hypothermia, hemodynamic changes, and complications in patients undergoing Transurethral Resection of the Prostate (TURP) surgery under Spinal Anesthesia (SA). Methods: In this double-blind clinical trial, 76 patients scheduled for TURP surgery were randomly assigned to two groups. The first group received warm IF heated to 37°C, while the second group received IF at room temperature. Body temperature and hemodynamic parameters were measured at five time points: upon entering the operating room (T0), after spinal anesthesia (T1), at the start of surgery (T2), at the end of surgery (T3), and during recovery (T4). Results: In evaluating the trend of core mean body temperature changes, there was a statistically significant difference over the study period (T0-T4) in each group (p<0.001). A significant difference in mean body temperature between the two groups was observed at T2 and T3 (p<0.05), indicating higher body temperatures in group one. Additionally, there was a statistically significant difference between the two groups in terms of shivering, the need for pethidine injection, and blood product transfusion. However, no statistically significant difference was found between the groups in terms of the trends of changes in hemodynamic parameters over the study period (T0-T4). Conclusion: Using IF heated to body temperature was associated with a lower incidence of hypothermia, reduced shivering, and fewer blood transfusions compared to room temperature IF during TURP surgery.

Comparison of explained and unexplained fevers in the postoperative period of open aortic surgery: A retrospective single center study

2025-05-31

Thibaut Noël , Ambroise Duprey , Xavier Bérard +2 more | Annals of Vascular Surgery

Therapeutic hypothermia for acute ischemic stroke: from preclinical studies to clinical trials

2025-05-30

Xi Chen , Jin Xu , Jiachen He +7 more | Science China Life Sciences

Impact of thermoneutral acclimation on a murine model of polymicrobial peritonitis

2025-05-30

Garrick Chan , Christopher H. Fry , Jean A. Nemzek | PLoS ONE

To examine the effects of ambient temperature on the reproducibility and translation of a murine sepsis model, we hypothesized that acclimation of mice in temperatures within their thermoneutral zone would … To examine the effects of ambient temperature on the reproducibility and translation of a murine sepsis model, we hypothesized that acclimation of mice in temperatures within their thermoneutral zone would alter immune responses and outcomes compared to standard housing temperatures. Mice housed for one week in thermoneutral (30°C) as compared to standard (22°C) conditions displayed lower counts of circulating neutrophils (0.52 ± 0.20 vs. 1.10 ± 0.54 x10 3 /μL; p = 0.011) and peritoneal macrophages (0.80 ± 0.57 vs. 1.62 ± 0.62 x 10 5 /μL; p = 0.002) as well as reduced in vitro production of IFN-γ by stimulated splenocytes (0.38 ± 0.68 vs 2.55 ± 0.76 x10 4 pg/mL, respectively, p = 0.004). After one week of temperature acclimation followed by CLP, the 7-day mortality was significantly lower under thermoneutral as compared to standard temperatures (80% vs 30%, respectively; p = 0.012), although core body temperature was preserved (average for 24 hours: 36.4 ± 1.3°C vs 31.7 ± 4.7°C; p < 0.0001). The lower survival was accompanied by increased systemic IL-6 levels (3.8 ± 3.3 vs 1.9 ± 1.3 x10 3 pg/mL; p = 0.04) and less robust influx of neutrophils into the peritoneum (1.68 ± 1.07 vs. 4.20 ± 2.46 x10 5 /μL, respectively; p = 0.0003). Overall, thermoneutral temperatures impacted innate immune parameters before and after CLP, producing distinctly different outcomes. Therefore, ambient temperature is an important variable that could impact model reproducibility and should be reported for the acclimation period and experimentation phases of murine sepsis studies.

Death of backcountry winter-sports practitioners in avalanches – A systematic review and meta-analysis of proportion of causes of avalanche death

2025-05-30

Guang Rong , Lauri Ahonen , Gerit Pfuhl +1 more | PLOS Global Public Health

This study estimates the proportions of the three major causes of avalanche death globally, and reviews potential factors influencing the proportions of causes of avalanche-related deaths (PCAD). By searching databases … This study estimates the proportions of the three major causes of avalanche death globally, and reviews potential factors influencing the proportions of causes of avalanche-related deaths (PCAD). By searching databases and consulting experts, we retrieved studies and registries in multiple languages, which examined PCAD. As a result, we retrieved 1,415 reports and included 37 for the study (22 for meta-analysis). We performed a meta-analysis to estimate pooled proportions. Between-study heterogeneity was assessed jointly by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="M1"><mml:mrow><mml:msup><mml:mtext mathvariant="italic">I</mml:mtext><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> and 95% prediction interval of pooled estimates. PCAD by trauma and asphyxia are 29% (95%CI 21–39%) and 82% (95%CI 72–88%), after the year of 2000. PCAD by hypothermia is 2% (95%CI 1–4%), estimated with studies having sufficient sample size. Time periods (before or after 2000), data representativeness (national subgroup), forensic procedures, and sample size explained between-study variation for proportions to a considerable extent. Factors influencing PCAD, that were either available or not available for quantitative synthesis, were summarized in a narrative systematic review (37 studies). In conclusion, we re-affirm asphyxia as the predominant cause of avalanche death, followed by trauma, and then hypothermia. Patterns of PCAD by trauma and asphyxia varied more after the year of 2000. A sample size > 75 is needed to estimate the proportion of hypothermia. PCAD discrepancies are lower in the data representing fatalities from a country than from regions. Without proper forensic diagnosis procedure, PCAD by trauma can be over-estimated. Under-reporting of forensic diagnostic criteria is an important bottleneck to the reliability of evidence in the field. Evidence on the role of other influencing factors to PCAD such as fatalities’ expertise and usage of mitigation gear is anecdotal and warrants further research. The results of meta-analysis build upon synthesizing and summarizing studies with moderate to high risk of bias and should be interpreted with caution.

Brain-targeted mild hypothermia ameliorates ischemic brain injury and promotes stroke recovery in aged mice

2025-05-30

Junxuan Lyu , Liqiang Liu , Mengyuan Guo +4 more | Journal of Cerebral Blood Flow & Metabolism

Therapeutic hypothermia represents a highly promising approach for alleviating ischemic brain injury. However, the majority of preclinical studies predominantly rely on reperfusion-based models using young animals, which poorly reflect the … Therapeutic hypothermia represents a highly promising approach for alleviating ischemic brain injury. However, the majority of preclinical studies predominantly rely on reperfusion-based models using young animals, which poorly reflect the clinical situation of elderly stroke patients with limited recanalization. This study sought to bridge these gaps and accelerate the clinical translation of therapeutic hypothermia while elucidating its neuroprotective mechanisms. In aged (18–20 months old) mice with permanent distal middle cerebral artery occlusion, brain-selective mild hypothermia mitigated acute F-actin stress fiber formation and junctional protein degradation in microvascular endothelial cells, thereby effectively reducing blood-brain barrier leakage and infiltration of peripheral inflammatory cells into the brain parenchyma. Hypothermia treatment induced anti-inflammatory polarization of microglia/macrophages acutely, attenuating white matter loss at both early (7 days) and chronic (35 days) stages of ischemic injury. Moreover, hypothermia treatment significantly promoted cognitive and sensorimotor recovery for at least 35 days after ischemic injury, as reflected in the electrophysiological preservation of compound action potentials in white matter tracts. Long-term behavioral recovery was strongly associated with angiogenesis and oligodendrogenesis, supporting that hypothermia-induced cell regeneration and neural tissue repair foster positive neurological outcomes. These findings underscore the potential of mild, brain-selective hypothermia for treating elderly stroke patients.

Comparison of the effects of two different local anesthetics used in spinal anesthesia on peripheral and central temperature change: a randomized controlled trial

2025-05-29

Azra Ozanbarcı , Hatice Kılınç , Bünyamin Muslu +7 more | BMC Anesthesiology

In this study, we aimed to compare the effects of two different local anesthetics with different baricity used in spinal anesthesia on thermoregulation. Our study was conducted on forty full-term … In this study, we aimed to compare the effects of two different local anesthetics with different baricity used in spinal anesthesia on thermoregulation. Our study was conducted on forty full-term pregnant women scheduled for elective cesarean sections under spinal anesthesia. At an operating room temperature of twenty-four degrees Celsius, peripheral body temperature was measured using temperature probes attached to the lower medial parts of the same side's lower and upper extremities, and central body temperature was measured with a tympanic thermometer. Isobaric levobupivacaine and hyperbaric bupivacaine were used in spinal anesthesia applications. After spinal anesthesia, tympanic temperature, arm and leg temperatures, mean arterial pressure, heart rate, and oxygen saturation were measured and recorded at baseline, the first, third, and fifth minutes, and every five minutes thereafter until the end of surgery. In the bupivacaine group, a decrease in tympanic temperature was observed at the third minute and an increase in leg skin temperature at the fifth minute compared to baseline values. In the levobupivacaine group, a decrease in tympanic temperature was observed at the fifth minute, and an increase in leg skin temperature was observed at the third minute. In both groups, within-group comparisons showed a continued decrease in tympanic temperature and increase in leg temperature at all subsequent time points compared to baseline. No statistically significant difference was observed in arm skin temperatures within groups in either group. We observed that the effects of hyperbaric bupivacaine and isobaric levobupivacaine used in spinal anesthesia on thermoregulation were similar.