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Aim: To evaluate delivery room (DR) interventions to prevent hypothermia and improve outcomes in preterm newborn infants <34 weeks' gestation., Methods: Medline, Embase, CINAHL and CENTRAL were searched till 22nd July 2022. Randomized controlled trials (RCTs), non-RCTs and quality improvement studies were considered. A random effects meta-analysis was performed, and the certainty of evidence was evaluated using GRADE guidelines., Results: DR temperature of ≥23 °C compared to standard care improved temperature outcomes without an increased risk of hyperthermia (low certainty), whereas radiant warmer in servo mode compared to manual mode decreased mean body temperature (MBT) (moderate certainty). Use of a plastic bag or wrap (PBW) improved normothermia (low certainty), but with an increased risk of hyperthermia (moderate certainty). Plastic cap improved normothermia (moderate certainty) and when combined with PBW improved MBT (low certainty). Use of a cloth cap decreased moderate hypothermia (low certainty). Though thermal mattress (TM) improved MBT, it increased risk of hyperthermia (low certainty). Heated-humidified gases (HHG) for resuscitation decreased the risk of moderate hypothermia and severe intraventricular hemorrhage (very low to low certainty). None of the interventions was shown to improve survival, but sample sizes were insufficient., Conclusions: DR temperature of ≥23 °C, radiant warmer in manual mode, use of a PBW and a head covering is suggested for preterm newborn infants <34 weeks' gestation. HHG and TM could be considered in addition to PBW provided resources allow, in settings where hypothermia incidence is high. Careful monitoring to avoid hyperthermia is needed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Aim: To elucidate the effectiveness of extracorporeal membrane oxygenation (ECMO) in accidental hypothermia (AH) patients with and without cardiac arrest (CA), including details of complications., Methods: This study was a multicentre, prospective, observational study of AH in Japan. All adult (aged ≥18 years) AH patients with body temperature ≤32 °C who presented to the emergency department between December 2019 and March 2022 were included. Among the patients, those with CA or circulatory instability, defined as severe AH, were selected and divided into the ECMO and non-ECMO groups. We compared 28-day survival and favourable neurological outcomes at discharge between the ECMO and non-ECMO groups by adjusting for the patients' background characteristics using multivariable logistic regression analysis., Results: Among the 499 patients in this study, 242 patients with severe AH were included in the analysis: 41 in the ECMO group and 201 in the non-ECMO group. Multivariable analysis showed that the ECMO group was significantly associated with better 28-day survival and favourable neurological outcomes at discharge in patients with CA compared to the non-ECMO group (odds ratio [OR] 0.17, 95% confidence interval [CI]: 0.05-0.58, and OR 0.22, 95%CI: 0.06-0.81). However, in patients without CA, ECMO not only did not improve 28-day survival and neurological outcomes, but also decreased the number of event-free days (ICU-, ventilator-, and catecholamine administration-free days) and increased the frequency of bleeding complications., Conclusions: ECMO improved survival and neurological outcomes in AH patients with CA, but not in AH patients without CA., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Aim: The International Hypothermia Registry (IHR) was created to increase knowledge of accidental hypothermia, particularly to develop evidence-based guidelines and find reliable outcome predictors. The present study compares hypothermic patients with and without cardiac arrest included in the IHR., Methods: Demographic, pre-hospital and in-hospital data, method of rewarming and outcome data were collected anonymously in the IHR between 2010 and 2020., Results: Two hundred and one non-consecutive cases were included. The major causeof hypothermia was mountain accidents, predominantly in young men. Hypothermic Cardiac Arrest (HCA) occurred in 73 of 201 patients. Core temperature was significantly lower in the patients in cardiac arrest (25.0 vs. 30.0 °C, p < 0.001). One hundred and fifteen patients were rewarmed externally (93% with ROSC), 53 by extra-corporeal life support (ECLS) (40% with ROSC) and 21 with invasive internal techniques (71% with ROSC). The overall survival rate was 95% for patients with preserved circulation and 36% for those in cardiac arrest. Witnessed cardiac arrest and ROSC before rewarming were positive outcome predictors, asphyxia, coagulopathy, high potassium and lactate negative outcome predictors., Conclusions: This first analysis of 201 IHR patients with moderate to severe accidental hypothermia shows an excellent 95% survival rate for patients with preserved circulation and 36% for HCA patients. Witnessed cardiac arrest, restoration of spontaneous circulation, low potassium and lactate and absence of asphyxia were positive survival predictors despite hypothermia in young, healthy adults after mountaineering accidents. However, accidental hypothermia is a heterogenous entity that should be considered in both treatment strategies and prognostication., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Aims: Cardiac arrest related to accidental hypothermia may occur at temperatures below 32 °C. Our goal was to describe the clinical characteristics and outcomes of patients who suffered from witnessed hypothermic cardiac arrest (CA) and assess the occurrence of hypothermic CA as a function of patient body temperature., Methods: We conducted a systematic review of the literature on cases of hypothermic CA due to rescue collapse. Patient information data from hypothermic CA patients were collected and combined with additional unpublished data to assess the clinical characteristics and outcome of hypothermic CA patients., Results: A total of 214 patients was included in this systematic review. Of the 206 witnessed hypothermic CA patients with a recorded body temperature, the average body temperature was 23.9 ± 2.7 °C with five patients (2.4%) having a core body temperature of >28 °C. The highest temperature of a patient surviving hypothermic witnessed cardiac arrest without other associated risk factors for cardiac arrest was 29.4 °C. The first recorded cardiac rhythm was asystole in 33 of the 112 patients (30%) for whom this information was available. The survival rate at hospital discharge of these hypothermic cardiac arrest patients was 73% (153 of 210 patients) and most survivors had favourable neurological outcome (89%; 102 of 105 patients)., Conclusions: CA that is solely caused by hypothermia did not occurs for patients with a body temperature >30 °C. Our findings provide valuable new information that can be incorporated into the international clinical management guidelines of accidental hypothermia., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Extra-corporeal life support (ECLS) is a life-saving intervention for patients with hypothermia induced cardiac arrest or severe cardiovascular instability. However, its application is highly variable due to a paucity of data in the literature to guide practice. Current guidelines and recommendations are based on expert opinion, single case reports, and small case series. Combining all of the published data in a patient-level analysis can provide a robust assessment of the influence of patient characteristics on survival with ECLS., Objective: To develop a prediction model of survival with good neurologic outcome for accidental hypothermia treated with ECLS., Methods: Electronic searches of PubMed, EMBASE, CINAHL were conducted with a hand search of reference lists and major surgical and critical care conference abstracts. Studies had to report the use of ECLS configured with a circuit, blood pump and oxygenator with an integrated heat exchanger. Randomized and observational studies were eligible for inclusion. Non-human, non-English and review manuscripts were deemed ineligible. Study authors were requested to submit patient level data when aggregate or incomplete individual patient data was provided in a study. Survival with good neurologic outcome was categorized for patients to last follow-up based on the reported scores on the Cerebral Performance Category (1 or 2), Glasgow Outcome Scale (4 or 5) and Pediatric Overall Performance Category (1 or 2). A one-stage, individual patient data meta-analysis was performed with a mixed-effects multi-level logistic regression model reporting odds ratio (OR) with a 95% confidence interval (CI)., Results: Data from 44 observational studies and 40 case reports (n = 658) were combined and analyzed to identify independent predictors of survival with good neurologic outcome. The survival rate with good neurologic outcome of the entire cohort was 40.3% (265 of 658). ECLS rewarming rate (OR: 0.93; 95% CI: 0.88, 0.98; p = .007), female gender (OR: 2.78; 95% CI: 1.69, 4.58; p < 0.001), asphyxiation (OR: 0.19; 95% CI: 0.11, 0.35; p < 0.001) and serum potassium (OR: 0.62; 95% CI: 0.53, 0.73; p < 0.001) were associated with survival with a good neurologic outcome. The logistic regression model demonstrated excellent discrimination (c-statistic: 0.849; 95% CI: 0.823, 0.875)., Conclusions: The use of extracorporeal life support in the treatment of hypothermic cardiac arrest provides a favourable chance of survival with good neurologic outcome. When used in a weighted scoring system, asphyxiation, serum potassium and gender can help clinicians prognosticate the benefit of resuscitating hypothermic patients with ECLS., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Aims: Currently, the decision to initiate extracorporeal life support for patients who suffer cardiac arrest due to accidental hypothermia is essentially based on serum potassium level. Our goal was to build a prediction score in order to determine the probability of survival following rewarming of hypothermic arrested patients based on several covariates available at admission., Methods: We included consecutive hypothermic arrested patients who underwent rewarming with extracorporeal life support. The sample comprised 237 patients identified through the literature from 18 studies, and 49 additional patients obtained from hospital data collection. We considered nine potential predictors of survival: age; sex; core temperature; serum potassium level; mechanism of hypothermia; cardiac rhythm at admission; witnessed cardiac arrest, rewarming method and cardiopulmonary resuscitation duration prior to the initiation of extracorporeal life support. The primary outcome parameter was survival to hospital discharge., Results: Overall, 106 of the 286 included patients survived (37%; 95% CI: 32-43%), most (84%) with a good neurological outcome. The final score included the following variables: age, sex, core temperature at admission, serum potassium level, mechanism of cooling, and cardiopulmonary resuscitation duration. The corresponding area under the receiver operating characteristic curve was 0.895 (95% CI: 0.859-0.931) compared to 0.774 (95% CI: 0.720-0.828) when based on serum potassium level alone., Conclusions: In this large retrospective study we found that our score was superior to dichotomous triage based on serum potassium level in assessing which hypothermic patients in cardiac arrest would benefit from extracorporeal life support. External validation of our findings is required., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Aim of the study was to investigate patient characteristics, survival rates and neurological outcome among hypothermic patients with out-of-hospital cardiac arrest (OHCA) admitted to a trauma center., Methods: A review of patients with OHCA and a core temperature ≤32°C admitted to a trauma center between 2004 and 2016., Results: Ninety-six patients (mean temperature 25.8°C±3.9°C) were entered in the study, 37 (39%) of them after avalanche burial. 47% showed return of spontaneous circulation (ROSC) prior to hospital admission. Survival with Glasgow-Pittsburgh Cerebral Performance Category (CPC) scale 1 or 2 was achieved in 25% of all patients and was higher in non-avalanche than in avalanche cases (35.6% vs 8.1%, p=0.002). Witnessed cardiac arrest was the most powerful predictor of favourable neurological outcome (RR: 10.8; 95% Confidence Interval: 3.2-37.1; Wald: 14.3; p<0.001), whereas ROSC prior to admission and body core temperature were not associated with survival with favourable neurological outcome. Cerebral CT scan pathology within 12h of admission increased the risk for unfavourable neurological outcome 11.7 fold (RR: 11.7; 95% CI: 3.1-47.5; p<0.001). Favourable neurological outcome was associated lower S 100-binding protein (0.69±0.5μg/l vs 5.8±4.9μg/l, p 0.002) and neuron-specific enolase (34.7±14.2μg/l vs 88.4±42.7μg/l, p 0.004) concentrations on intensive care unit (ICU) admission., Conclusions: Survival with favourable neurological outcome was found in about a third of all hypothermic non-avalanche patients with OHCA admitted to a trauma center., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: To describe the factors associated with outcome after accidental deep hypothermia., Methods: We conducted a retrospective cohort study on patients with accidental hypothermia (core temperature <28 °C) admitted to a Level I emergency room over a 10-year period., Results: Forty-eight patients were included with a median temperature of 26 °C (range, 16.3-28 °C) on admission. The etiology of hypothermia was exposure to a cold environment (n = 27), avalanche (n = 13) or immersion in cold water (n = 8). Mean age was 47 ± 22 years, and 58% were males. Thirty-two patients had a cardiac arrest (CA): 15 patients presented unwitnessed cardiac arrest (UCA) and 17 patients presented rescue collapse (RC). Extracorporeal life support (ECLS) was implemented in 21 patients with refractory cardiac arrest and in two patients with hemodynamic instability. Overall mortality was 50%. For cardiac arrest patients, only three out of 15 patients with UCA survived at day 28, whereas eight out of 17 patients with RC survived. The cerebral performance category score was 4 for all the survivors of UCA and 1 [range, 1-2] for survivors of RC. Patients with poor outcome presented more UCA, a lower pH, a higher serum potassium, creatinine, serum sodium or lactate level as well as more severe coagulation disorders., Conclusion: Cardiac arrest related to rescue collapse was associated with favorable outcome. On-scene rescue collapse should prompt prolonged resuscitation and ECLS rewarming in all CA patients with deep hypothermia. Conversely, unwitnessed cardiac arrest was associated with unfavorable outcome and will likely not benefit from ECLS., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Introduction: Cardiac arrest (CA) in patients with severe accidental hypothermia (core temperature <28 °C) differs from CA in normothermic patients. Maintaining CPR throughout the prehospital period may be impossible, particularly during difficult evacuations. We have developed guidelines for rescuers who are evacuating and treating severely hypothermic CA patients., Methods: A literature search was performed. The authors used the findings to develop guidelines., Results: Full neurological recovery is possible even with prolonged CA if the brain was already severely hypothermic before CA occurred. Data from surgery during deep hypothermic CA and prehospital case reports underline the feasibility of delayed and intermittent CPR in patients who have arrested due to severe hypothermia., Conclusions: Continuous CPR is recommended for CA due to primary severe hypothermia. Mechanical chest-compression devices should be used when available and CPR-interruptions avoided. Only if this is not possible should CPR be delayed or performed intermittently. Based on the available data, a patient with a core temperature <28 °C or unknown with unequivocal hypothermic CA, evidence supports alternating 5 min CPR and ≤5 min without CPR. With core temperature <20 °C, evidence supports alternating 5 min CPR and ≤10 min without CPR., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Hypothermic cardiac arrest has high mortality and few known prognostic factors. We studied retrospectively 34 victims of accidental hypothermia with cardiac arrest admitted to The University Hospital of North Norway during 1985-2013 who were resuscitated and rewarmed by extracorporeal circulation. No patient survived prior to 1999, while nine out of 24 (37.5%) survived hypothermic cardiac arrest from 1999 to 2013. The lowest measured core temperature among survivors was 13.7°C; the longest time from cardiac arrest to return of spontaneous circulation was 6 h and 52 min. The only predictor of survival identified was lower blood potassium concentration in the nine survivors compared with the non-survivors. Submersion was not associated with reduced survival. Non-survivors consumed modest hospital resources. Most survivors had a favourable neurological outcome., (Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

Background: Accidental hypothermic cardiac arrest is associated with unfortunate prognosis and large studies are rare. We therefore have performed an outcome analysis in patients that were admitted to Vienna University Hospital with the diagnosis of accidental hypothermic cardiac arrest., Methods: This study employed a retrospective outcome analysis of prospectively collected data in a selected cohort of hypothermic cardiac arrest patients. We screened 3800 cardiac arrest patients, treated at our department between 1991 and 2010, for eligibility. Inclusion criteria were cardiac arrest with a body core temperature ≤28 °C and return of spontaneous circulation., Results: A total of 18 patients who achieved return of spontaneous circulation were analysed. Nine patients (50%) achieved survival in good neurologic condition (defined as cerebral performance category CPC 1 or 2). Accidental hypothermia with consecutive cardiac arrest was caused by intoxication in most cases (67%). These patients had a better outcome than patients with other causes of accidental hypothermic cardiac arrest (OR=28; 95%KI 2-37.9; p<0.01). Hypothermia associated typical ECG changes after return of spontaneous circulation (Osborne waves) were more frequent in the surviving population (OR 16; 95%KI 1.3-19.5; p=0.05)., Conclusions: Accidental hypothermic cardiac arrest in a central European urban area is rare. Prognosis was excellent in patients where hypothermic cardiac arrest was caused by intoxication., (Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

Background: Resuscitation guidelines for the treatment of accidental hypothermia are based primarily on isolated cases. Mortality rates are high despite aggressive treatment aimed at restoring spontaneous circulation and normothermia., Methods: The present report is based on a boating accident where 15 healthy subjects (median age 16 (range 15-45) years) were immersed in 2 °C salt water. Seven victims were recovered in circulatory arrest with a median temperature of 18.4 °C (range 15.5-20.2 °C). They were all rewarmed with extracorporeal membrane oxygenation (ECMO) and were subsequently evaluated with advanced neuroradiological and functional testing. The remaining 7 had established spontaneous circulation without the use of ECMO. One victim drowned in the accident., Results: The victims that survived the accident without circulatory arrest were predominantly females with a higher body mass index. Victims with circulatory arrest pH on arrival was a median of 6.61 (range 6.43-6.94), with ECMO being established a median of 226 (178-241)min after the accident. Magnetic resonance spectroscopy showed neuronal dysfunction in five. In five victims initial normal white matter spectra progressed to show evidence of abnormal axonal membranes. Based on the seven-level Functional Independence Measure test functional outcome was good in six circulatory arrest victims and in all without circulatory arrest. Mild to moderate cognitive dysfunction was seen in six and severe dysfunction in one circulatory arrest victim., Conclusion: Seven patients with profound accidental hypothermic circulatory arrest were successfully resuscitated using a management approach that included extracorporeal rewarming, followed by successive periods of therapeutic hypothermia and sedated normothermia and intensive neurorehabilitation. Seven other hypothermic victims (core temperature as low as 23 °C) that did not suffer circulatory arrest also survived the accident., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Aim of the Study: Accidental hypothermia (AH) is a complex and life threatening condition. Knowledge about epidemiology, rewarming treatments, complications and outcome is limited. This study was initiated to obtain data on causes, rewarming treatments and complications., Methods: A retrospective cohort study of all patients with a body temperature ≤ 35°C admitted to the Emergency Department (ED) of the VU university medical centre, Amsterdam, The Netherlands, between January 1, 2000 and August 31, 2008. A predefined set of epidemiological and clinical data was retrieved., Results: Eighty-four patients were included (median age: 47 years). Categories of hypothermia included immersion (18), submersion (29) and exposure to cold (37); concomitant factors were intoxication (26), trauma (40) and homelessness (7). Temperature at admission in the ED was 31.6 ± 2.6°C (mean ± SD), lowest temperature 24.2°C. Fourteen different rewarming treatments were used resulting in a wide range of rewarming speeds. Seventy-nine complications occurred: pulmonary, renal and neurological complications in 20, 17 and 10 patients respectively. Seventeen patients had 2 or more late complications. Twenty-four patients (28.6%) died: 10 during rewarming and 14 after rewarming was completed. Prognosis was poor in older and colder patients and after indoor exposure and submersion., Conclusion: AH is a rare diagnosis in an inhomogeneous population, treated with a large variety of rewarming techniques. Most complications and death occurred late, after rewarming was completed. Because individual teams gain little clinical experiences, we suggest multiple centre data collection as a first step towards an evidence-based standard of care., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Aim of the Study: Recent works demonstrate the benefits of hypothermia when used to preserve brain, cardiac, hepatic, and intestinal function against hypoxic-ischemic injury. However, it is also known that hypothermia affects systemic parameters and also induces the generation of reactive oxygen species in cells and tissues. Here we studied the acid-base related parameters and the antioxidant-oxidant effects of deep hypothermia induction before an acute hypoxic insult in rats., Methods: Acid-base indicators and parameters related to oxidative stress were analyzed in hypothermic rats (21-22 degrees C) breathing room air during 2h (control hypothermia), and hypothermic animals switched to hypoxic air (10% O(2)) during the second hour (hypothermia hypoxia group), and they were compared with corresponding normothermia groups maintained at 37 degrees C (control normothermia and normothermia hypoxia groups)., Results: Mild metabolic acidosis appeared early in arterial blood during hypothermia. After exposure to hypoxia, evidence of tissue injury (plasma transaminases and blood lactate) and oxidative stress (increase in lipid peroxidation, decrease in glutathione levels and in the glutathione reduction potential in liver) was found. In contrast, in the hypothermia hypoxia group, plasmatic parameters remained as the control values, and the hepatic glutathione reduction potential were significantly more negative when compared with the normothermia hypoxia group., Conclusions: We propose that acidosis induced by hypothermia contributes to the maintenance of intracellular reduction potential in liver, regarding the GSSG/2GSH couple and may help to increase plasmatic antioxidant pool. Our findings provide new insights into the protective effects of hypothermia in vivo., (Copyright 2010 Elsevier Ireland Ltd. All rights reserved.)

Objective: To determine the rate of return of spontaneous circulation (ROSC) in animal models performing resuscitation from induced ventricular fibrillation (VF) in severe hypothermia (<30 degrees C)., Materials and Methods: A medical literature database search from 1966 to present was performed identifying placebo controlled trials using anti-arrhythmic or vasopressor medications to treat ventricular fibrillation in the setting of severe hypothermia., Results: 7 controlled studies were identified (n=117) testing 6 combinations of resuscitative medications. ROSC rates for treatment versus control groups were as follows: amiodarone (6% vs. 18%, p=0.6, n=34), bretylium (35% vs. 35%, p=1.0, n=40), intermediate- and high-dose epinephrine (adrenaline) (36% vs. 27%, p=1.0, n=22), vasopressin (60% vs. 0%, p<0.0001, n=39), vasopressin and amiodarone (0% vs. 0%, p=NS, n=11), low-dose epinephrine and amiodarone (91% vs. 30%, p=0.0075, n=21). Cumulatively, among all studies administering vasopressors, the rate of ROSC was 62% in treatment groups contrasted to 17% in control groups (p<0.0001, n=77)., Conclusions: In controlled animal models of severe hypothermia, ROSC rates for induced ventricular fibrillation are higher with utilization of vasopressor medications. Current guidelines which recommend withholding these medications in the setting of hypothermic cardiac arrest should be re-evaluated.

This report describes the case of an 88-year-old non-diabetic female who presented to the emergency department following a presumed hypoglycaemic collapse due to self-neglect. Subsequent rewarming and resuscitation demonstrated a number of the significant consequences of severe hypothermia, including apparent secondary impairment of glycaemic autoregulation. The phenomenon of reversible inhibition of insulin secretion due to severe hypothermia has been documented previously in the field of cardiac surgery. The hyperglycaemia was not treated with any antihyperglycaemic agent, and her recovery was uneventful. Subsequent blood sugar level monitoring was normal. If insulin is administered to the hypothermic patient, intensive monitoring of blood glucose is essential due to the increase in endogenous insulin secretion on rewarming.

Mild hypothermia improves survival and neurological outcome after cardiac arrest, as well as increasing activation of the extracellular-signal-regulated kinase (ERK) in hippocampus. ERK signaling is involved in neuronal growth and survival. We tested the hypothesis that the beneficial effects of hypothermia required ERK activation. ERK activation was measured by immunoblotting with phosphorylation-specific antibodies. Rats (n = 8 per group) underwent 8 min of asphyxial cardiac arrest and were resuscitated with chest compressions, ventilation, epinephrine and bicarbonate. At 30 min after resuscitation, vehicle (50% saline:50% DMSO) or the ERK kinase inhibitor U0126 (100 microg) was infused into the lateral ventricle. Cranial temperature was kept at either 33 degrees C (hypothermia) or 37 degrees C (normothermia) between 1 and 24 h. Neurological function was assessed daily for 14 days. Surviving neurons were counted in the hippocampus. A dose of 100 mug U0126 inhibited ERK bilaterally for 12 to 24 h and decreased phosphorylation of the ERK substrates ATF-2 and CREB. As in previous studies, hypothermia improved survival, neurological and histological outcome after cardiac arrest. However, survival, neurological score and histology did not differ between U0126 and vehicle-treated rats after cardiac arrest. Therefore, a dose of U0126 sufficient to inhibit biochemical markers of ERK signaling in hippocampus does not alter the beneficial effects of hypothermia induced after resuscitation in rats and did not affect recovery of normothermia-treated rats. These results suggest that hypothermia-induced improvement in outcomes does not require ERK activation.

The recommended treatment for severe hypothermia with circulatory collapse is re-warming using cardiopulmonary by-pass. This may require transporting a patient to hospital with on-going cardiopulmonary resuscitation (CPR). Manual CPR during patient transport may result in sub-optimal chest compressions and can be a hazard for the ambulance crew. We report a case of a patient with a core temperature of 22.2 degrees C and crew-witnessed cardiac arrest due to hypothermia. After unsuccessful initial resuscitation he was transported to hospital for re-warming with cardiopulmonary by-pass. CPR was continued during transport using a mechanical active compression-decompression device (the LUCAS-device). During cardiopulmonary by-pass ROSC was achieved after 90 min of cardiac arrest. The patient recovered with a cerebral performance category of 3. Using a mechanical device for chest compressions during transport of a hypothermic patient with on-going CPR is feasible, effective and safe.

We report the case of a victim of deep accidental hypothermia who was extracted from the ice and received 1.5 h of mechanical chest compression. This was followed with rapid rewarming on cardiopulmonary bypass and resulted in good physical and mental recovery. This management option should be considered for similar victims.

Background: Accidental hypothermia resulting in cardiac arrest poses numerous therapeutic challenges. Cardiopulmonary bypass (CPB) should be used if feasible since it optimally provides both central rewarming and circulatory support. However, this modality may not be available or is contraindicated in certain cases. Thoracic lavage (TL) provides satisfactory heat transfer and may be performed by a variety of physicians. This paper presents the physiological rationale, technique, and role for TL in accidental hypothermia with cardiac arrest., Methods: A patient with hypothermic cardiac arrest, treated by the author using TL, serves as the basis for this report. A search of the English language literature using PubMed (National Library of Medicine, Bethesda, Maryland) was conducted from 1966 to 2003 and 13 additional patients were identified. Demographic information, lavage method, rewarming rate, complications, and neurological outcome were analysed., Results: There were numerous causes for hypothermia, with drug and alcohol intoxication being the most common (n = 4; 28.6%). Patient age ranged from 8 to 72 years (median = 36 years). Mean core temperature was 24.5+/-0.60 degrees C. Most patients were without blood pressure or pulse upon presentation to the Emergency Department and the predominant cardiac rhythm was ventricular fibrillation (VF) (n = 9; 64.3%). Thoracic lavage was accomplished by thoracotomy in seven patients and tube thoracotomy in the remaining seven. Median rewarming rate was 2.95 degrees C/h. Median time until sinus rhythm was restored was 120 min. Median length of hospital stay was 2 weeks. Four (28.6%) patients died. Complications were seen in 12 (85.7%) patients. Among survivors, neurological outcome was normal in 8 (80%) while two were left with residual impairments., Conclusions: Patients presenting in cardiac arrest from accidental hypothermia may be rewarmed effectively using TL. Among survivors, normal neurological recovery is seen. Thoracic lavage should be strongly considered for these patients if CPB is not available or contraindicated.

Hypothermia < 28 degrees C is rarely compatible with life, with only a few cases described surviving such low temperatures. We present a case of a man who survived with a core body temperature below 21.0 degrees C after spending a night in a snowbank with an ambient temperatures as low as -20.0 degrees C. Prolonged CPR and early initiation of extracorporeal membrane oxygenation enabled survival without neurological deficit at hospital discharge. Frostbite was limited to both hands and all toes only; although the entire upper and lower extremity appeared to be deeply frozen on admission, amputation of both hands was inevitable and resulted in permanent disability.

The aches and pains that accompany fever appear to be mediated, at least in part, by the peripheral release of cytokines such as interleukin-1beta (IL-1beta). The objective of this study was to determine, whether changes in nociceptive sensitivity produced by IL-1beta administration are temporally linked to changes in core body temperature. Experiment 1 examined nociceptive responsiveness for a period of 3 h following systemic administration of IL-1beta (1, 3, 10 and 20 microg/kg). The two highest doses of IL-1beta produced a drop in temperature beginning approximately 60 min after cytokine administration. This hypothermia lasted 90 min and was associated with hyperalgesia. Experiment 2 examined changes in temperature and nociception for 12 h following administration of IL-1beta (10 microg/kg). An early, short-lived hypothermia was followed by a significant hyperthermia from 3.25 to 6.5 h following IL-1beta administration. This late-occurring fever was accompanied by hyperalgesia. Both the hypo- and hyperthermia phases were associated with a reduction in locomotor activity. Given that repeated nociceptive testing may confound assessment of temperature and activity, Experiment 3 examined the effects of IL-1beta (10 microg/kg) administration on temperature and activity in rats that remained in their home cages. The biphasic change in temperature and the reduction in activity were nearly identical to that reported in Experiment 2, indicating that repeated nociceptive testing did not confound these data. The results of this study demonstrate that, two phases of hyperalgesia occur and coincide with the periods of altered thermoregulation produced by systemic administration of IL-1beta.

Snow avalanche case reports have documented the survival of skiers apparently without permanent hypoxic sequelae, after prolonged complete burial despite there being only a small air pocket on extrication. We investigated the underlying pathophysiological changes in a prospective, randomised 2 x 2 crossover study in 12 volunteers (28 tests) breathing into an artificial air pocket (1- or 2-l volume) in snow. Peripheral SpO(2), ETCO(2), arterialised capillary blood variables, air pocket O(2) and CO(2), snow density, and snow conditions at the inner surface of the air pocket were determined. SpO(2) decreased from a median of 99% (93-100%) to 88% (71-94%; P<0.001) within 4 min of breathing into the air pocket; the reduction was greater at 1 l, than 2 l, volume air pocket (P=0.013, intention to treat P=0.003) and correlated to snow density (r=0.50, P=0.021, partial correlation coefficient). ETCO(2) rose simultaneously from median 5.07 kPa (3.47-6.93 kPa) to 6.8 kPa (5.87-8.27 kPa; P<0.001), with consequent respiratory acidosis. Despite premature interruption due to hypoxia (SpO(2)

Accidental hypothermia is a common companion of trauma/haemorrhage, and several clinical studies have identified reduced body temperature as an independent risk predisposing to increased morbidity and mortality. Accordingly, the majority of trauma care guidelines prescribe early and aggressive rewarming of hypothermic patients. Enzyme reactions are generally downregulated at temperatures below 37 degrees C, including most of those responsible for the inflammatory response. The rationale for adhering to these recommendations uncritically may therefore be questioned. In a rat model of mild hypothermia and haemorrhagic shock we wanted to compare the influence of rapid rewarming with persistently reduced temperature on the synthesis of early inflammatory mediators and organ function. Thirty-four male albino Sprague-Dawley rats were studied. Withdrawal of 2.5 ml blood/100 g body weight was performed over 10 min, with simultaneous reduction of body temperature to 32.5-33.5 degrees C. Seventy-five minutes after initiation of bleeding, two-thirds of the shed blood was retransfused. One group (n=17) was rewarmed to normothermia, the other (n=17) was kept hypothermic. The study was terminated after an observation period of 2 h. At the end of the study the rewarmed animals had a significantly lower mean arterial pressure, higher heart rate, higher synthesis of reactive oxygen species from peritoneal phagocytes, increased circulating levels of nitric oxide, and higher values of the organ markers aspartate aminotransferase and urea. The pro-inflammatory cytokines TNF-alpha and IL-6, the anti-inflammatory cytokine IL-10, the organ markers alanine aminotransferase, alpha-glutathione S-transferase and creatinine, as well as organ injury scores were equal in both groups. Three rewarmed rats died prematurely, versus one hypothermic animal. In conclusion, the results suggest that during the early stages after haemorrhagic shock, rapid rewarming from mild hypothermia may have unfavourable effects both on basic haemodynamic variables, and on the internal inflammatory environment of cells and tissues.

Methods of rewarming patients with severe accidental hypothermia remain controversial. This paper reports our experience with the use of forced air rewarming in patients with severe accidental hypothermia and a body core temperature below 30 degrees C. Fifteen hypothermic patients (body core temperature 24-30 degrees C) were successfully treated with forced air rewarming to a body core temperature above 35 degrees C (mean rewarming rate 1.7 degrees C/h, range from 0.7 to 3.4 degrees C/h). An afterdrop phenomenon was not observed in any of the patients. Nine hypothermic patients (group 1) had no prehospital cardiac arrest, all nine were long-term survivors and made a full recovery. Six patients (group 2) had prehospital cardio circulatory arrest with restoration of spontaneous circulation. None of the group 2 patients survived long-term. Group 1 and group 2 patients did not differ in core temperature (26.6+/-1.6 degrees C group 1 and 27.0+/-1.8 degrees C group 2). Group 2 patients needed catecholamine support during rewarming more frequently (83 versus 22%) and had higher lactate levels and lower pH values at all points of observation. In conclusion our preliminary data indicate that forced air rewarming is an efficient and safe method of managing patients with severe accidental hypothermia. The poor outcome of patients with a history of prehospital cardiopulmonary resuscitation is probably due to irreversible ischaemic brain damage in primarily asphyxiated avalanche and near-drowning victims, rather than the consequence of the rewarming method used.

Hypothermia and its management are examined and logical explanations are given for discarding many traditional views. Hypothermia is classified according to physiological changes, and a practical approach is suggested for management.

Asystole in avalanche victims is generally due to asphyxia and not primarily to hypothermia. Hence, on-site establishment of death by asphyxiation would avoid evacuation risks to the rescue party, as well as high costs of transport to, and treatment at, frequently distant specialist centres in cases with a hopeless prognosis. This paper presents a novel differential diagnosis scheme based on burial duration (critical time 45 min) and core temperature (critical level 32 degrees C) of the person on extrication, as well as the presence or absence of an air pocket, facilitating on-site identification of asphyxiated victims. When information regarding an air pocket is uncertain in victims buried longer than 45 min, determination of serum potassium (critical level 10 mmol/l) at the nearest hospital becomes an alternative criterion for triage. The proposed guidelines aim to clarify field decision-making for the emergency doctor with respect to discontinuation of resuscitation and limitation of transferral for cardiopulmonary bypass core rewarming to those patients with presumptive reversible hypothermia.