Accidental hypothermia is an unintentional drop in core body temperature below 35 °C. It can occur at any time of year and in any climate, and can affect all age groups. The epidemiology of accidental hypothermia reflects the interaction between biological susceptibility, social conditions and exposure to environmental factors. As core temperature falls and thermoregulation mechanisms become insufficient, the metabolism slows, consciousness deteriorates and the hypothermic myocardium becomes increasingly prone to arrhythmias and cardiac arrest. The prognosis is variable, and treatment outcomes are dependent on multiple factors, with cardiac arrest being the decisive determinant, carrying an in-hospital mortality rate of up to 50%. Diagnosis relies on accurate core temperature measurement whenever possible, together with clinical staging when measurement is unavailable. The management of accidental hypothermia should follow the hypothermic chain of survival: prevent further cooling, handle the patient gently, provide airway, breathing and circulatory support, choose the correct destination hospital, and rewarm the patient using passive, active external, active internal or extracorporeal techniques according to severity. Extracorporeal life support is crucial for patients with hypothermic cardiac arrest. Most survivors of hypothermic cardiac arrest have excellent neurological outcomes. Effective prevention and education, together with well-organized regional pathways of care and personalized strategies to prevent cardiac arrest, are needed to improve outcomes. Accidental hypothermia, in particular its moderate and severe forms, is a medical emergency owing to the associated risks of arrhythmias, organ dysfunction and cardiac arrest. In this Primer, Darocha et al. describe the epidemiology and mechanisms of this condition, and discuss its diagnosis, management and effects on quality of life, and future research directions.

Accidental hypothermia is an unintentional drop in core body temperature below 35 °C. It can occur at any time of year and in any climate, and can affect all age groups. The epidemiology of accidental hypothermia reflects the interaction between biological susceptibility, social conditions and exposure to environmental factors. As core temperature falls and thermoregulation mechanisms become insufficient, the metabolism slows, consciousness deteriorates and the hypothermic myocardium becomes increasingly prone to arrhythmias and cardiac arrest. The prognosis is variable, and treatment outcomes are dependent on multiple factors, with cardiac arrest being the decisive determinant, carrying an in-hospital mortality rate of up to 50%. Diagnosis relies on accurate core temperature measurement whenever possible, together with clinical staging when measurement is unavailable. The management of accidental hypothermia should follow the hypothermic chain of survival: prevent further cooling, handle the patient gently, provide airway, breathing and circulatory support, choose the correct destination hospital, and rewarm the patient using passive, active external, active internal or extracorporeal techniques according to severity. Extracorporeal life support is crucial for patients with hypothermic cardiac arrest. Most survivors of hypothermic cardiac arrest have excellent neurological outcomes. Effective prevention and education, together with well-organized regional pathways of care and personalized strategies to prevent cardiac arrest, are needed to improve outcomes.

Avalanches claim the lives of around 160 winter recreationists and workers in hazardous snow-covered mountain regions worldwide. These fatalities result from asphyxia, trauma, and hypothermia. Survival for critically buried subjects relies on the speed of extrication, absence of trauma, presence of a patent airway and air pocket, immediate field treatment, and rapid transport to the most appropriate hospital by organized search and rescue (SAR) and emergency medical services (EMS). Survival may be improved with helicopter EMS, advancements in safety and rescue equipment technology, early deployment of professional SAR teams with checklists and standard operating procedures (SOPs), and the use of drones. Prehospital and in-hospital care of an avalanche accident requires medical, technical, logistical, and organizational competencies. This narrative review of historic and updated survival curves, professional society guidelines, and snow burial studies, discusses the best practices for prehospital care, triage, transport, and in-hospital management of avalanche patients.

Background:The main causes of death in avalanche victims are asphyxia, trauma, and hypothermia. However, most evidence is based on epidemiological studies with inconsistent forensic data. We aimed to integrate current evidence on causes of death and types of injuries in avalanche victims undergoing postmortem examination. Methods:We conducted a scoping review of studies reporting forensic data on avalanche-related deaths. Eligible studies included victims who underwent postmortem examination, excluding those buried in buildings or vehicles. Extracted data included study and population characteristics, postmortem investigation (external examination, autopsy, histopathology, toxicology, and imaging), and results (causes of death, types of injuries). Results:We included 38 studies, of which 31 reported original data involving 1543 fatalities. Of these, 862 (56 %) underwent postmortem examination, with 442 (51 %) receiving autopsies. Among 387 autopsied cases with reported causes of death, asphyxia accounted for 72 %, trauma 18 %, hypothermia 2 %, and combined causes 8 %. Asphyxia-related findings included pulmonary edema, organ congestion, and petechiae. Trauma-related deaths involved head, neck, and thoracic injuries. Hypothermia findings included Wischnewski spots and frostbite. Histopathology (n = 48) revealed asphyxia-related lesions in all victims, while hypothermia findings were infrequent. Postmortem imaging (n = 12) showed pulmonary edema. Toxicology detected ethanol in 4 %, cannabinoids in 11 % and cocaine in 1 % of cases tested. Conclusion:Our review aligns with previous studies, confirming asphyxia as the leading cause of death, followed by trauma and hypothermia. Gaps in knowledge remain on autopsy-confirmed causes of death and related injuries. Standardized forensic protocols could improve death classification accuracy, particularly in cases with combined causes.

In critically ill patients, tracheal intubation may be required in the prehospital setting, where airway management presents unique technical and logistical challenges. While videolaryngoscopy has emerged as a potential alternative to direct laryngoscopy by providing a better and easier visualization of the glottis, the improved view of anatomical structures does not necessarily correlate with successful tracheal tube placement. Intubation may be harder because novice providers performing videolaryngoscopy may only look at the screen and only obtain a two-dimensional representation of the patient’s airways. By directly visualizing the airways, these providers may obtain a better 3D apprehension and an improved mental visualization of the patient’s anatomy. We compared the impact of an unrestricted videolaryngoscopy use with a sequence consisting in direct visualization of the airway followed by videolaryngoscopy (“Direct Laryngoscopy-to-VideoLaryngoscopy sequence” or “DL-VL sequence”) on time to intubation among novice providers. This was a parallel group simulated randomized controlled superiority trial. Participants were medical students or junior residents with an experience of less than 10 intubations. After a presentation and workshop on direct laryngoscopy and videolaryngoscopy, participants were randomized in two groups. In the control group, participants were free to use of the videolaryngoscope as they intended. In the other group (DL-VL sequence), participants were told to perform an initial direct laryngoscopy without looking at the video screen until they reached the epiglottis. All intubations were conducted in a simulated prehospital environment, with a high-fidelity manikin placed supine on the floor. Each participant performed three intubations of increasing levels of difficulty. The primary outcome was the time to intubation. Secondary outcomes included first-pass success, time to ventilation, and number of intubation attempts. The chi-squared test was used to compare categorical variables while the t-test was used to compare continuous variables. Time to intubation was shorter in the control group (22±8 s vs. 27±11 s, p < 0.001). This difference was consistent in all levels of difficulties. First-pass success rates were similar (99/111, 89

We studied adult hypothermic cardiac arrest (CA) patients admitted to a University Hospital (UH) and a Regional Hospital (RH) for whom Extracorporeal Life Support (ECLS) was implemented. We used the HOPE score to estimate individual survival probabilities and to compare overall results between hospitals. We included hypothermic CA patients who underwent ECLS between 2000 and 2022. We assessed the predicted survival probabilities by calculating the HOPE scores, both at individual and hospital levels. We assessed the performance of a HOPE score cutoff of 10% in predicting survival to hospital discharge, as ECLS rewarming is currently recommended when the HOPE is ≥ 10%. We also assessed the utility of the HOPE score in evaluating and comparing patient management within and between two hospitals. In the 46 patients with successful ECLS implementation, a HOPE score < 10% would have contraindicated and therefore prevented futile ECLS rewarming procedures for 17 patients (37%) who did not survive, while finding that ECLS was indicated for 100% of survivors. The observed survival rate was 24% (UH: 35%, RH: 11%) whereas the HOPE score predicted a survival rate of 35% (UH: 41%, RH: 26%), suggesting underperformance of ECLS rewarming among both hospitals. The difference of survival between the two hospitals was not statistically significant. This study confirmed the utility of the HOPE score in estimating individual survival probabilities. The HOPE score may also be used to estimate the overall survival rate in a patient cohort, enabling internal quality-control and outcome results comparisons between different settings.

AIM OF THE STUDY:Artificial intelligence (AI) such as large language models (LLMs) tools are potential sources of information on hypothermic cardiac arrest (HCA). The aim of our study was to determine whether, for patients with HCA, LLMs provide information consistent with expert consensus on criteria that would usually contraindicate extracorporeal cardiopulmonary resuscitation (eCRP) in patients with normothermic cardiac arrest (NCA), but not HCA. METHODS:Based on Extracorporeal Life Support Organization guidelines, selected factors were identified that may be contraindications to eCPR in NCA but not in HCA. Four questions were created and entered into AI software (GPT-3.5 turbo, GPT-4o, GPT-4o-mini, Claude 3.5 Sonnet, Claude 3 Haiku, Mistral Large, Mistral Small, Gemini Pro and Gemini Flash). The responses obtained and citations returned were assessed by an international panel of experts for consistency with current knowledge. RESULTS:Complete agreement of responses with expert consensus was obtained for 5/10 AI tools. In total, all AI tools presented 101 items in the literature. No reference was rated as "correct"; 45 citations (45%) "existed but did not answer the question"; and 56 citations (55%) were considered "hallucinatory". CONCLUSION:Use of artificial intelligence in decision-making for extracorporeal cardiopulmonary resuscitation in patients with hypothermic cardiac arrest risks unjustifiably withdrawing treatment from patients who have a chance of survival with a good neurological outcome. Large language models should not be used as the only tool for decision-making.

The aim of this study was to develop a scoring tool to estimate the probability of survival following extracorporeal rewarming in patients suffering hypothermic cardiac arrest. This is a multicenter retrospective study based on registry data. We included adult patients with hypothermic cardiac arrest not associated with asphyxia, with a core temperature of ≤28°C, who underwent extracorporeal rewarming. A multivariable logistic regression model was developed to serve as the predictive tool. Internal validation with bootstrap resampling was performed to adjust model parameters and reduce model optimism. Our study population included 141 patients. The survival rate was 46% (65/141). A total of 88% of the survivors (57/65) had a favorable neurological outcome (Cerebral Performance Category 1–2). The predictive model includes four variables. Outdoor occurrence of hypothermia and a higher hemoglobin level raise survival odds while higher concentrations of potassium and lactate reduce survival odds. The area under the receiver operating characteristic (ROC) curve was 0.812 and p value of the Hosmer-Lemeshow test was 0.8. We developed a prognostic model to estimate the probability of survival in adult patients with non–asphyxia-related hypothermic cardiac arrest. This model may aid in identifying candidates suitable for extracorporeal rewarming, though it should not be used as the sole deciding factor.

OBJECTIVE:Prolonged hypoglycemia can cause irreversible brain damage. Clinicians may thus be reluctant to initiate extracorporeal cardiopulmonary resuscitation in hypothermic cardiac arrest patients with severe hypoglycemia. The aim of this study was to evaluate the survival rate with good neurologic outcomes of patients with hypothermic cardiac arrest and severe hypoglycemia. DESIGN:Retrospective study. SETTING:Multicenter study based on data from the HELP Registry. PARTICIPANTS:Adult victims of accidental hypothermia with a core temperature ≤28°C and cardiac arrest who had undergone extracorporeal rewarming between January 2014 and June 2024 were included in the study. INTERVENTIONS:Patients with initial blood glucose concentration <3 mmol/L (<54 mg/dL) (severe hypoglycemia) were compared with those with glucose level ≥3 mmol/L (≥54 mg/dL). Survival to hospital discharge with favorable neurologic outcome was considered the primary outcome. MEASUREMENTS AND MAIN RESULTS:The study population consisted of 127 patients, of whom 21 (17%) presented with glucose concentration <3 mmol/L (<54 mg/dL) on admission to the hospital. By hospital discharge, 8 of 21 patients (38%) with severe hypoglycemia had survived in good neurologic condition. The lowest blood glucose level in a patient who survived without neurologic deficit was 0.9 mmol/L (16 mg/dL). There was no statistically significant difference in survival rates between patients with and without severe hypoglycemia (38% v 43%, p = 0.7). CONCLUSIONS:In patients with hypothermic cardiac arrest, severe hypoglycemia on admission to the hospital does not rule out survival with good neurologic outcomes after extracorporeal rewarming.

Aim:Our aim is to evaluate the management and outcome of avalanche victims in cardiac arrest (CA), focusing on the adherence to international management guidelines and to identify ways to improve the future care of avalanche victims through retrospective evaluation of the missions. Methods:We analysed a retrospective cohort of all avalanche victims in CA treated by Swiss Air-Rescue Rega between 2010 and 2024. Data regarding the avalanche burial (type of burial, burial duration, presence of a patent airway) were evaluated, as were helicopter operational data, data on prehospital medical care [cardiopulmonary resuscitation (CPR) efforts, airway management, core temperature], transport destination, data from further in-hospital treatment if applicable [core temperature, type of rewarming, serum potassium levels, extracorporeal life support (ECLS)] as well as patient outcome. Results:147 patients could be evaluated. 50 (34%) were declared dead without CPR efforts. CPR was started in 97 patients (66%), of whom 19 achieved ROSC (13%). Only 4 of these patients survived to hospital discharge (3%), 3 of whom had a good neurological outcome (2%). 34 patients (23%) were transported to hospital while CPR was ongoing, of whom in 11 (7%) ECLS was tried to initiate. None of these patients survived to hospital discharge. 27 patients (18%) were not treated in accordance with the guidelines. 22 of these (15%) were (potentially) undertreated (mainly in the sense of transport to a non-ECLS centre, although an ECLS centre would have been correct), 5 (3%) were overtreated (mainly in the sense of transport under ongoing CPR, although not indicated). 61% were tracheally intubated. On admission, core temperature was 1.9 °C (95% confidence interval 1.1-2.7) lower than the temperature measured on scene. Conclusions:Patients who suffer a CA in avalanche accidents have a very poor outcome. A high proportion of patients were not tracheally intubated during transport, cooled down further during resuscitation and transport or were not transported to ECLS centres although indicated. On the other hand, the outcome of ECLS patients is extremely poor.

DISCLAIMER:These guidelines on extracorporeal membrane oxygenation (ECMO) are intended for educational use to build the knowledge of physicians and other health professionals in assessing the conditions and managing the treatment of patients undergoing ECMO and describe what are believed to be useful and safe practices for ECMO. Guidelines aim to help clinicians make informed decisions about their patients. However, adherence to a guideline does not guarantee a successful outcome. Healthcare professionals must make their own treatment decisions about care on a case-by-case basis, after consultation with their patients, using their clinical judgment, knowledge, and expertise. These guidelines do not take the place of the physicians' and other health professionals' judgment in the diagnosis and treatment of ECMO patients. These guidelines are not intended to and should not be interpreted as setting a standard of care or being deemed inclusive of all proper methods of care, nor exclusive of other methods of care directed at obtaining the same results. The ultimate judgment must be made by the physician, other health professionals, and the patient/patient family, considering all the circumstances presented by the individual patient, and the known variability and biologic behavior of the clinical condition. These guidelines reflect the data at the time the guidelines were prepared. The results of subsequent studies or other information may lead to revisions of the recommendations in these guidelines. In no event will ELSO be liable for any decision made or action taken in reliance upon the information provided through these guidelines.

Background Tranexamic acid (TXA) decreases mortality in injured patients and should be administered as soon as possible. Despite international guidelines recommending TXA in the prehospital setting, its use remains low. The aim of this study was to assess the prehospital administration of TXA for injured patients in a Swiss region. Methods We conducted a retrospective observational study in Switzerland between 2018 and 2021. Inclusion criteria were injured patients ≥18 years for whom an ambulance or helicopter was dispatched. The exclusion criterion was minor injury defined by a National Advisory Committee for Aeronautics score <3. The primary outcome was the proportion of patients treated with TXA according to guidelines. The European guidelines were represented by the risk of death from bleeding (calculated retrospectively using the Bleeding Audit for Trauma and Triage (BATT) score). Factors impacting the likelihood of receiving TXA were assessed by multivariate analysis. Results Of 13 944 patients included in the study, 2401 (17.2%) were considered at risk of death from bleeding. Among these, 257 (11%) received prehospital TXA. This represented 38% of those meeting US guidelines. For European guidelines, the treatment rate increased with the risk of death from bleeding: 6% (95% CI 4.4% to 7.0%) for low risk (BATT score 3–4); 13% (95% CI 11.1% to 15.9%) for intermediate risk (BATT score 5–7); and 21% (95% CI 17.6% to 25.6%) for high risk (BATT score ≥8) (p<0.01). Women and the elderly were treated less often than men and younger patients, irrespective of the risk of death from bleeding and the mechanism of injury. Conclusion The proportion of injured patients receiving TXA in the prehospital setting of the State of Vaud in Switzerland was low, with even lower rates for women and older patients. The reasons for this undertreatment are probably multifactorial and would require specific studies to clarify and correct them.