Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

Resuscitation from severe accidental hypothermia by active core rewarming via an indwelling peritoneal dialysis catheter

Accidental hypothermia is a life-threatening medical condition, which requires the appropriate rewarming strategy with careful monitoring. Active core rewarming is often necessary in the management of severe hypothermia. However, especially in the emergent clinical setting, immediate establishment of a reliable route for active core rewarming is difficult. Severe accidental hypothermia in patients dependent on peritoneal dialysis or combination of hemodialysis with peritoneal dialysis is extremely rare, and the ideal rewarming procedure for these patients is unclear. To our knowledge, this is the first case report illustrating the application of an indwelling peritoneal dialysis catheter to active core rewarming in the management of severe accidental hypothermia. A 64-year-old female with type 1 diabetes and end-stage renal disease (ESRD) on combination of hemodialysis with peritoneal dialysis was delivered to our hospital due to severe accidental hypothermia. On presentation, she was unresponsive and her core temperature was 22.8 °C. Since rewarming by an electric blanket and warmed saline infusion was ineffective, infusion of warmed peritoneal dialysis solution via an indwelling peritoneal dialysis catheter was performed in the emergency room. In the next few hours, her body temperature recovered to normal level, and she regained consciousness. During resuscitation, complications related to rewarming, such as arrhythmia or hypotension, were not observed. She was discharged without any sequelae. Indwelling peritoneal dialysis catheters, if available, could be utilized as the safe and reliable route for active core rewarming in ESRD patients.

Accidental Hypothermia: 2021 Update

Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousands die of primary hypothermia and an unknown number die of secondary hypothermia worldwide. Hypothermia can be expected in emergency patients in the prehospital phase. Injured and intoxicated patients cool quickly even in subtropical regions. Preventive measures are important to avoid hypothermia or cooling in ill or injured patients. Diagnosis and assessment of the risk of cardiac arrest are based on clinical signs and core temperature measurement when available. Hypothermic patients with risk factors for imminent cardiac arrest (temperature < 30 °C in young and healthy patients and <32 °C in elderly persons, or patients with multiple comorbidities), ventricular dysrhythmias, or systolic blood pressure < 90 mmHg) and hypothermic patients who are already in cardiac arrest, should be transferred directly to an extracorporeal life support (ECLS) centre. If a hypothermic patient arrests, continuous cardiopulmonary resuscitation (CPR) should be performed. In hypothermic patients, the chances of survival and good neurological outcome are higher than for normothermic patients for witnessed, unwitnessed and asystolic cardiac arrest. Mechanical CPR devices should be used for prolonged rescue, if available. In severely hypothermic patients in cardiac arrest, if continuous or mechanical CPR is not possible, intermittent CPR should be used. Rewarming can be accomplished by passive and active techniques. Most often, passive and active external techniques are used. Only in patients with refractory hypothermia or cardiac arrest are internal rewarming techniques required. ECLS rewarming should be performed with extracorporeal membrane oxygenation (ECMO). A post-resuscitation care bundle should complement treatment.

Cardiac arrest in special circumstances

PURPOSE OF REVIEW

European Resuscitation Council Guidelines for Cardiopulmonary Resuscitation prioritize treatments like chest compression and defibrillation, known to be highly effective for cardiac arrest from cardiac origin. This review highlights the need to modify this approach in special circumstances.

RECENT FINDINGS

Potentially reversible causes of cardiac arrest are clustered into four Hs and four Ts (Hypoxia, Hypovolaemia, Hyperkalaemia/other electrolyte disorders, Hypothermia, Thrombosis, Tamponade, Tension pneumothorax, Toxic agents). Point-of-care ultrasound has its role in identification of the cause and targeting treatment. Time-critical interventions may even prevent cardiac arrest if applied early. The extracorporeal CPR (eCPR) or mechanical CPR should be considered for bridging the period needed to reverse the precipitating cause(s). There is low quality of evidence available to guide the treatment in the majority of situations. Some topics (pulmonary embolism, eCPR, drowning, pregnancy and opioid toxicity) were included in recent ILCOR reviews and evidence updates but majority of recommendations is based on individual systematic reviews, scoping reviews, evidence updates and expert consensus.

SUMMARY

Cardiac arrests from reversible causes happen with lower incidence. Return of spontaneous circulation and neurologically intact survival can hardly be achieved without a modified approach focusing on immediate treatment of the underlying cause(s) of cardiac arrest.

Use of Extracorporeal Membrane Oxygenation in Patients with Refractory Cardiac Arrest due to Severe Persistent Hypothermia: About 2 Case Reports and a Review of the Literature

We report the cases of two patients experiencing persistent severe hypothermia. They were 45 and 30 years old and had a witnessed cardiac arrest managed with mechanized cardiopulmonary resuscitation (CPR) for 4 and 2.5 hours, respectively. Extracorporeal membrane oxygenation was used in both patients who fully recovered without any neurological sequelae. These two cases illustrate the important role of extracorporeal CPR (eCPR) in persistent severe hypothermia leading to cardiac arrest.

ACSM Expert Consensus Statement: Injury Prevention and Exercise Performance during Cold-Weather Exercise

ABSTRACT

Cold injury can result from exercising at low temperatures and can impair exercise performance or cause lifelong debility or death. This consensus statement provides up-to-date information on the pathogenesis, nature, impacts, prevention, and treatment of the most common cold injuries.

Pediatric Hypothermia: An Ambiguous Issue

Hypothermia in pediatrics is mainly about small body size. The key thermal factor here is the large surface-to-volume ratio. Although small mammals, including human infants and children, are adapted to higher heat losses through their elevated metabolic rate and thermogenic capacity, they are still at risk of hypothermia because of a small regulatory range and an impending metabolic exhaustion. However, some small mammalian species (hibernators) use reduced metabolic rates and lowered body temperatures as adaptations to impaired energy supply. Similar to nature, hypothermia has contradictory effects in clinical pediatrics as well: In neonates, it is a serious risk factor affecting respiratory adaptation in term and developmental outcome in preterm infants. On the other hand, it is an important self-protective response to neonatal hypoxia and an evidence-based treatment option for asphyxiated babies. In children, hypothermia first enabled the surgical repair of congenital heart defects and promotes favorable outcome after ice water drowning. Yet, it is also a major threat in various prehospital and clinical settings and has no proven therapeutic benefit in pediatric critical care. All in all, pediatric hypothermia is an ambiguous issue whose harmful or beneficial effects strongly depend on the particular circumstances.

Successful Non-Extracorporeal Rewarming from Hypothermic Cardiac Arrest: 2 Cases

Accidental hypothermia (core temperature <35°C) is a complication in persons who have fallen into crevasses; hypothermic cardiac arrest is the most serious complication. Extracorporeal life support (ECLS) is the optimal method for rewarming hypothermic cardiac arrest patients, but it may not be readily available and non-ECLS rewarming may be required. We report the medical course of 2 patients with hypothermic cardiac arrest, each of whom had fallen into a crevasse. They were treated successfully with non-ECLS rewarming using peritoneal and thoracic lavage. We discuss non-ECLS treatment options for hypothermic cardiac arrest and describe successful non-ECLS rewarming in an outlying hospital without ECLS rewarming capability in the Grossglockner region of Austria in 1990 and 2003. Both patients survived neurologically intact. Non-ECLS rewarming in a trauma center without ECLS capabilities is feasible and can result in a good outcome when ECLS is not available. The best non-ECLS rewarming method for hypothermic cardiac arrest patients has not yet been established. Non-ECLS rewarming should be adapted to local capabilities. To obtain more robust evidence, it seems reasonable to pool data on the treatment and outcome of non-ECLS rewarming in hypothermic cardiac arrest patients.

Core Temperature Measurement-Principles of Correct Measurement, Problems, and Complications

Core temperature reflects the temperature of the internal organs. Proper temperature measurement is essential to diagnose and treat temperature impairment in patients. However, an accurate approach has yet to be established. Depending on the method used, the obtained values may vary and differ from the actual core temperature. There is an ongoing debate regarding the most appropriate anatomical site for core temperature measurement. Although the measurement of body core temperature through a pulmonary artery catheter is commonly cited as the gold standard, the esophageal temperature measurement appears to be a reasonable and functional alternative in the clinical setting. This article provides an integrative review of invasive and noninvasive body temperature measurements and their relations to core temperature.

Cardiopulmonary resuscitation in special circumstances

Cardiopulmonary resuscitation prioritises treatment for cardiac arrests from a primary cardiac cause, which make up the majority of treated cardiac arrests. Early chest compressions and, when indicated, a defibrillation shock from a bystander give the best chance of survival with a good neurological status. Cardiac arrest can also be caused by special circumstances, such as asphyxia, trauma, pulmonary embolism, accidental hypothermia, anaphylaxis, or COVID-19, and during pregnancy or perioperatively. Cardiac arrests in these circumstances represent an increasing proportion of all treated cardiac arrests, often have a preventable cause, and require additional interventions to correct a reversible cause during resuscitation. The evidence for treating these conditions is mostly of low or very low certainty and further studies are needed. Irrespective of the cause, treatments for cardiac arrest are time sensitive and most effective when given early-every minute counts.

On-Site Medical Management of Avalanche Victims-A Narrative Review

Avalanche accidents are common in mountain regions and approximately 100 fatalities are counted in Europe each year. The average mortality rate is about 25% and survival chances are mainly determined by the degree and duration of avalanche burial, the patency of the airway, the presence of an air pocket, snow characteristics, and the severity of traumatic injuries. The most common cause of death in completely buried avalanche victims is asphyxia followed by trauma. Hypothermia accounts for a minority of deaths; however, hypothermic cardiac arrest has a favorable prognosis and prolonged resuscitation and extracorporeal rewarming are indicated. In this article, we give an overview on the pathophysiology and on-site management of avalanche victims.

The Effect of Cold Exposure on Cognitive Performance in Healthy Adults: A Systematic Review

Several aspects of cognition can be affected after cold exposure, but contradictory results have been reported regarding affected cognitive domains. The aim of the current systematic review was to evaluate the effects of specific cold exposure on cognitive performance in healthy subjects. A systematic search was performed using MEDLINE (through PubMed), EMBASE (Scopus) and PsycINFO databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria were healthy subjects exposed to a cold environment (either simulated or not) and cognitive performance related to cold exposure with an experimental design. The literature search identified 18 studies, eight studies investigated the effect of cold air exposure and ten the effect of cold water immersion on cognitive performance of healthy subjects. There were several differences among the studies (environmental temperature reached, time of exposure, timing, and type of cognitive test administration). Cold exposure induced in most of the experimental settings (15 of 18) an impairment of CP even before accidental hypothermia was established. The most investigated and affected cognitive domains were attention and processing speed, executive function, and memory. Gender differences and effects of repeated exposure and possible acclimation on cognitive performance need further studies to be confirmed.

The Efficacy of Renal Replacement Therapy for Rewarming of Patients in Severe Accidental Hypothermia-Systematic Review of the Literature

Background: Renal replacement therapy (RRT) can be used to rewarm patients in deep hypothermia. However, there is still no clear evidence for the effectiveness of RRT in this group of patients. This systematic review aims to summarize the rewarming rates during RRT in patients in severe hypothermia, below or equal to 32 °C. Methods: This systematic review was registered in the PROSPERO International Prospective Register of Systematic Reviews (identifier CRD42021232821). We searched Embase, Medline, and Cochrane databases using the keywords hypothermia, renal replacement therapy, hemodialysis, hemofiltration, hemodiafiltration, and their abbreviations. The search included only articles in English with no time limit, up until 30 June 2021. Results: From the 795 revised articles, 18 studies including 21 patients, were selected for the final assessment and data extraction. The mean rate of rewarming calculated for all studies combined was 1.9 °C/h (95% CI 1.5–2.3) and did not differ between continuous (2.0 °C/h; 95% CI 0.9–3.0) and intermittent (1.9 °C/h; 95% CI 1.5–2.3) methods (p > 0.9). Conclusions: Based on the reviewed literature, it is currently not possible to provide high-quality recommendations for RRT use in specific groups of patients in accidental hypothermia. While RRT appears to be a viable rewarming strategy, the choice of rewarming method should always be determined by the specific clinical circumstances, the available resources, and the current resuscitation guidelines.

Trauma Prehospital Hypothermia Prevention and Treatment: An Observational Study

BACKGROUND

Hypothermia in trauma patients causes increased morbidity and mortality. Swift recognition and treatment are important to prevent any further heat loss. In addition, patient discomfort from cold decreases satisfaction with care. The administration of active and passive rewarming measures is important in the prevention and treatment of hypothermia, but their use in prehospital trauma patients in Portugal has not been previously reported.

OBJECTIVE

To assess the prevalence of hypothermia, the impact of rewarming measures, and the management of the discomfort caused by cold.

METHODS

This is a prospective cohort study conducted in Immediate Life Support Ambulances in Portugal between March 1, 2019, and April 30, 2020.

RESULTS

This study included records of 586 trauma patients; of whom, 66.2% were men. Cranioencephalic trauma was the most common trauma observed, followed by lower limb and thoracic traumas. Mean body temperature increased 0.12 °C between the first and last assessments (p < .05). Most patients experiencing a level of discomfort of 5 or more on a 0-10 scale reported improvement (from 17.2% to 2.4% after nurses' intervention). Warmed intravenous fluids proved to be effective (p < .05) in increasing body temperature, and passive rewarming measures were effective in preventing hypothermia.

CONCLUSIONS

Hypothermia management has to consider the initial temperature, the season, the available rewarming measures, and the objectives to be achieved. The optimization of resources for the monitoring and treatment of hypothermia should be a priority in prehospital assistance. The implementation of rewarming measures improves patients' outcomes and decreases the discomfort caused by cold in prehospital care.

Management of hypothermic submersion associated cardiac arrest in a 5-year-old child: A case report

We report a case of severe accidental hypothermia (core body temperature of 26.8 °C) in a five-year-old boy due to submersion in freezing lake water. The child was brought to the hospital intubated, in cardiac arrest rhythm of pulseless electrical activity and with dilated and nonreactive pupils. We continued with cardiopulmonary resuscitation and administrated adrenaline in boluses (10 μg/kg) and infusion (0.2 μg/kg/min). Spontaneous circulation returned after 50 minutes. Rewarming was performed with minimally invasive techniques. Post resuscitation he was admitted to the intensive care unit, where he required venovenous extracorporeal membrane oxygenation due to respiratory failure. He was discharged from the hospital neurologically intact and without organ damage on day 17 post arrest.

Hypothermic Cardiac Arrest - Retrospective cohort study from the International Hypothermia Registry

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.

Hypothermia in Trauma

Hypothermia in trauma patients is a common condition. It is aggravated by traumatic hemorrhage, which leads to hypovolemic shock. This hypovolemic shock results in a lethal triad of hypothermia, coagulopathy, and acidosis, leading to ongoing bleeding. Additionally, hypothermia in trauma patients can deepen through environmental exposure on the scene or during transport and medical procedures such as infusions and airway management. This vicious circle has a detrimental effect on the outcome of major trauma patients. This narrative review describes the main factors to consider in the co-existing condition of trauma and hypothermia from a prehospital and emergency medical perspective. Early prehospital recognition and staging of hypothermia are crucial to triage to proper care to improve survival. Treatment of hypothermia should start in an early stage, especially the prevention of further cooling in the prehospital setting and during the primary assessment. On the one hand, active rewarming is the treatment of choice of hypothermia-induced coagulation disorder in trauma patients; on the other hand, accidental or clinically induced hypothermia might improve outcomes by protecting against the effects of hypoperfusion and hypoxic injury in selected cases such as patients suffering from traumatic brain injury (TBI) or traumatic cardiac arrest.

Treatment of Cardiovascular Dysfunction With PDE5-Inhibitors - Temperature Dependent Effects on Transport and Metabolism of cAMP and cGMP

Introduction

Cardiovascular dysfunction is a potentially lethal complication of hypothermia. Due to a knowledge gap, pharmacological interventions are not recommended at core temperatures below 30°C. Yet, further cooling is induced in surgical procedures and survival of accidental hypothermia is reported after rewarming from below 15°C, advocating a need for evidence-based treatment guidelines. In vivo studies have proposed vasodilation and afterload reduction through arteriole smooth muscle cGMP-elevation as a favorable strategy to prevent cardiovascular dysfunction in hypothermia. Further development of treatment guidelines demand information about temperature-dependent changes in pharmacological effects of clinically relevant vasodilators.

Materials and Methods

Human phosphodiesterase-enzymes and inverted erythrocytes were utilized to evaluate how vasodilators sildenafil and vardenafil affected cellular efflux and enzymatic breakdown of cAMP and cGMP, at 37°C, 34°C, 32°C, 28°C, 24°C, and 20°C. The ability of both drugs to reach their cytosolic site of action was assessed at the same temperatures. IC₅₀- and K_i-values were calculated from dose–response curves at all temperatures, to evaluate temperature-dependent effects of both drugs.

Results

Both drugs were able to reach the intracellular space at all hypothermic temperatures, with no reduction compared to normothermia. Sildenafil IC₅₀ and K_i-values increased during hypothermia for enzymatic breakdown of both cAMP (IC₅₀: 122 ± 18.9 μM at 37°C vs. 269 ± 14.7 μM at 20°C, p < 0.05) and cGMP (IC₅₀: 0.009 ± 0.000 μM at 37°C vs. 0.024 ± 0.004 μM at 32°C, p < 0.05), while no significant changes were detected for vardenafil. Neither of the drugs showed significant hypothermia-induced changes in IC₅₀ and K_i–values for inhibition of cellular cAMP and cGMP efflux.

Conclusion

Sildenafil and particularly vardenafil were ableto inhibit elimination of cGMP down to 20°C. As the cellular effects of these drugs can cause afterload reduction, they show potential in treating cardiovascular dysfunction during hypothermia. As in normothermia, both drugs showed higher selectivity for inhibition of cGMP-elimination than cAMP-elimination at low core temperatures, indicating that risk for cardiotoxic side effects is not increased by hypothermia.

Bradycardia in a newborn with accidental severe hypothermia: treat or don't touch? A case report

Background

Hypothermia significantly affects mortality and morbidity of newborns. Literature about severe accidental hypothermia in neonates is limited. We report a case of a neonate suffering from severe accidental hypothermia. An understanding of the physiology of neonatal thermoregulation and hypothermia is important to decide on treatment.

Case presentation

A low-birth-weight newborn was found with severe accidental hypothermia (rectal temperature 25.7 °C) due to prolonged exposure to low ambient temperature. The newborn presented bradycardic, bradypnoeic, lethargic, pale and cold. Bradycardia, bradypnea and impaired consciousness were interpreted in the context of the measured body temperature. Therefore, no reanimation or intubation was initiated. The newborn was closely monitored and successfully treated only with active and passive rewarming.

Conclusion

Clinical parameters such as heart frequency, blood pressure, respiration and consciousness must be interpreted in light of the measured body temperature. Medical treatment should be adapted to the clinical presentation. External rewarming can be a safe and effective measure in neonatal patients.

The efficiency of continuous renal replacement therapy for rewarming of patients in accidental hypothermia--An experimental study

Severe accidental hypothermia carries high mortality and morbidity and is often treated with invasive extracorporeal methods. Continuous veno-venous hemodiafiltration (CVVHDF) is widely available in intensive care units. We sought to provide theoretical basis for CVVHDF use in rewarming of hypothermic patients. CVVHDF system was used in the laboratory setting. Heat balance and transferred heat units were evaluated for the system without using blood. We used 5L of crystalloid solution at the temperature of approximately 25°C, placed in a thermally insulated tank (representing the "central compartment" of a hypothermic patient). Time of warming the central compartment from 24.9 to 30.0°C was assessed with different flow combinations: "blood" (central compartment fluid) 50 or 100 or 150 mL/min, dialysate solution 100 or 1500 mL/h, and substitution fluid 0 or 500 mL/h. The total circulation time was 1535 minutes. There were no differences between heat gain values on the filter depending on blood flow (P = .53) or dialysate flow (P = .2). The mean heating time for "blood" flow rates 50, 100, and 150 mL/min was 113.7 minutes (95% CI, 104.9-122.6 minutes), 83.3 minutes (95% CI, 76.2-90.3 minutes), and 74.7 minutes (95% CI, 62.6-86.9 minutes), respectively (P < .01). The respective median rewarming rate for different "blood" flows was 3.6°C/h (IQR, 3.0-4.2°C/h), 4.8 (IQR, 4.2-5.4°C/h), and 5.4 (IQR, 4.8-6.0°C/h), respectively (P < .01). The dialysate flow did not affect the warming rate. Based on our experimental model, CVVHDF may be used for extracorporeal rewarming, with the rewarming rates increasing achieved with higher blood flow rates.

Hypothermia causes platelet activation in the human spleen

BACKGROUND

Accidental hypothermia results in various dysfunctions in the human body. Additionally, coagulation disorder can lead to a life-threatening condition. We previously demonstrated that platelets stored in the spleen were activated and thus triggered coagulation disorder in a mouse model of hypothermia. In the present study, we wanted to investigate if this phenomenon in mice also occurs in humans as a reaction to hypothermia.

METHODS

We analyzed splenic tissue collected from 22 deceased subjects who have died from hypothermia. These samples were compared with 22 control cases not exposed to cold environment. We performed immunohistochemical staining for CD61 (a marker of all platelets) and CD62P (a marker of activated platelets). We also evaluated the morphology of platelets in the spleen with scanning electron microscopy.

RESULTS

Immunohistochemical analysis revealed no significant changes in the amounts of CD61-positive platelets between the hypothermia and control cases. However, the hypothermia cases contained abundant CD62P-positive platelets compared with those of the control cases. Immunohistochemical analysis also revealed that the activated platelets formed aggregates and adhered to splenic sinusoidal endothelial cells in the hypothermia cases. However, we observed no significant fibrin formation around the activated platelets.

CONCLUSIONS

Hypothermia resulted in splenic platelet activation, which may be used as a postmortem marker of hypothermia. The release of activated platelets from the spleen into to circulation upon rewarming may promote coagulation disturbances.

Case Report: Left Ventricular Unloading Using a Mechanical CPR Device in a Prolonged Accidental Hypothermic Cardiac Arrest Treated by VA-ECMO - a Novel Approach

We recently treated a 36-year-old previously healthy male with a prolonged hypothermic (lowest temperature 22.3°C) cardiac arrest after an alcohol intoxication with a return of spontaneous circulation after 230min of mechanical cardiopulmonary resuscitation and rewarming by veno-arterial ECMO with femoral cannulation and retrograde perfusion of the aortic arch. Despite functional veno-arterial ECMO, we continued mechanical cardiopulmonary resuscitation (Auto Pulse™ device, ZOLL Medical Corporation, Chelmsford, USA) until return of spontaneous circulation to prevent left ventricular distention from persistent ventricular fibrillation. The case was further complicated by extensive trauma caused by mechanical cardiopulmonary resuscitation (multiple rib fractures, significant hemothorax, and a liver laceration requiring massive transfusion), lung failure necessitating a secondary switch to veno-venous ECMO, and acute kidney injury with the need for renal replacement therapy. Shortly after return of spontaneous circulation, the patient was already following commands and could be discharged 3 weeks later without neurologic, cardiac, or renal sequelae and being entirely well. Prolonged accidental hypothermic cardiac arrest might present with excellent outcomes when supported with veno-arterial ECMO. Until return of spontaneous circulation, one might consider continuing with mechanical cardiopulmonary resuscitation in addition to ECMO to allow some left ventricular unloading. However, the clinician should keep in mind that prolonged mechanical cardiopulmonary resuscitation may cause severe injuries.

[Cardiac arrest under special circumstances]

These guidelines of the European Resuscitation Council (ERC) Cardiac Arrest under Special Circumstances are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required for basic and advanced life support for the prevention and treatment of cardiac arrest under special circumstances; in particular, specific causes (hypoxia, trauma, anaphylaxis, sepsis, hypo-/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), specific settings (operating room, cardiac surgery, cardiac catheterization laboratory, dialysis unit, dental clinics, transportation [in-flight, cruise ships], sport, drowning, mass casualty incidents), and specific patient groups (asthma and chronic obstructive pulmonary disease, neurological disease, morbid obesity, pregnancy).

[Paediatric Life Support]

The European Resuscitation Council (ERC) Paediatric Life Support (PLS) guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations of the International Liaison Committee on Resuscitation (ILCOR). This section provides guidelines on the management of critically ill or injured infants, children and adolescents before, during and after respiratory/cardiac arrest.

Guidelines for Mountain Rescue During the COVID-19 Pandemic: Official Guidelines of the International Commission for Alpine Rescue

Roy, Steven, Inigo Soteras, Alison Sheets, Richard Price, Kazue Oshiro, Simon Rauch, Don McPhalen, Maria Antonia Nerin, Giacomo Strapazzon, Myron Allen, Alistair Read, and Peter Paal. Guidelines for mountain rescue during the COVID-19 pandemic: official guidelines of the International Commission for Alpine Rescue. High Alt Med Biol. 22: 128-141, 2021. Background: In mountain rescue, uncertainty exists on the best practice to prevent coronavirus disease 2019 (COVID-19) transmission. The aim of this work was to provide a state-of-the-art overview of the challenges caused by the COVID-19 pandemic in mountain rescue. Methods: Original articles or reviews, published until December 27, 2020 in Cochrane COVID-19 Study Register, EMBASE, PubMed, and Google Scholar were included. Articles were limited to English, French, German, or Spanish with the article topic COVID-19 or other epidemics, addressing transmission, transport, rescue, or cardiopulmonary resuscitation. Results: The literature search yielded 6,190 articles. A total of 952 were duplicates and 5,238 were unique results. After exclusion of duplicates and studies that were not relevant to this work, 249 articles were considered for this work. Finally, 72 articles and other sources were included. Conclusions: Recommendations are provided for protection of the rescuer (including screening, personal protective equipment [PPE], and vaccination), protection of the patient (including general masking if low risk, specific PPE if high risk), equipment hygiene (including disinfection after every mission), use of single-use products, training and medical measures under COVID-19 precautions, and psychological wellbeing of rescuers during the COVID-19 pandemic. Adapted COVID-19 precautions for low-and-medium-income countries are also discussed.

Temperature loss by ventilation in a calorimetric bench model

In intensive care medicine heat moisture exchangers are standard tools to warm and humidify ventilation gases in order to prevent temperature loss of patients or airway epithelia damage. Despite being at risk of hypothermia especially after trauma, intubated emergency medicine patients are often ventilated with dry and in winter probably cold ventilation gases. We tried to assess the amount of temperature-loss due to ventilation with cold, dry medical oxygen in comparison to ventilation with warm and humidified oxygen. We ventilated a 50-kg water-dummy representing the calorimetric capacity of a 60-kg patient over a period of 2 hours (tidal volume 6.6 mL/kg = 400 mL; respiratory rate 13/min). Our formal null-hypothesis was that there would be no differences in temperature loss in a 50 kg water-dummy between ventilation with dry oxygen at 10°C vs. ventilation with humidified oxygen at 43°C. After 2 hours the temperature in the water-dummy using cold and dry oxygen was 29.7 ± 0.1°C compared to 30.4 ± 0.1°C using warm and humidified oxygen. This difference in cooling rates between both ventilation attempts of 0.7 ± 0.1°C after 2 hours represents an increased cooling rate of ~0.35°C per hour. Ventilation with cool, dry oxygen using an automated transport ventilator resulted in a 0.35°C faster cooling rate per hour than ventilation with warm humidified oxygen in a bench model simulating calorimetric features of a 60-kg human body.

The use of minimal invasive extracorporeal circulation for rewarming after accidental hypothermia and circulatory arrest

BACKGROUND

Extracorporeal cardiopulmonary resuscitation has become a recommended treatment option for patients with severe hypothermia with cardiac arrest. Minimal invasive extracorporeal circulation (MiECC) may offer advantages over the current standard extracorporeal membrane oxygenation (ECMO).

METHODS

Retrospective cohort analysis of hospital database for patients with accidental hypothermia and extracorporeal rewarming with MiECC admitted between 2010 and 2019.

RESULTS

Overall, six of 17 patients survived to hospital discharge. Eleven patients suffered accidental hypothermia in an alpine and six in an urban setting. Sixteen patients arrived at the hospital under ongoing cardiopulmonary resuscitation (CPR). CPR time was 90 minutes (0-150). Four patients survived from an alpine setting and two from an urban setting with CPR duration of 90 minutes (0-150) and 85 minutes (25-100), respectively. Asphyctic patients tended to have lower survival (one of seven patients). Two patients of six with major trauma survived.

CONCLUSION

MiECC for extracorporeal rewarming from severe accidental hypothermia is a feasible alternative to ECMO, with comparable survival rates.

Maintaining intravenous volume mitigates hypothermia-induced myocardial dysfunction and accumulation of intracellular Ca2

NEW FINDINGS

What is the central question of this study? Detailed guidelines for volume replacement to counteract hypothermia-induced intravascular fluid loss are lacking. Evidence suggests colloids might have beneficial effects compared to crystalloids. Are central haemodynamic function and level of hypothermia-induced calcium overload, as a marker of cardiac injury, restored by fluid substitution during rewarming, and are colloids favourable to crystalloids? What is the main finding and its importance? Infusion with crystalloid or dextran during rewarming abolished post-hypothermic cardiac dysfunction, and partially mitigated myocardial calcium overload. The effects of volume replacement to support haemodynamic function are comparable to those using potent cardio-active drugs. These findings underline the importance of applying intravascular volume replacement to maintain euvolaemia during rewarming.

ABSTRACT

Previous research exploring pathophysiological mechanisms underlying circulatory collapse after rewarming victims of severe accidental hypothermia has documented post-hypothermic cardiac dysfunction and hypothermia-induced elevation of intracellular Ca²⁺ concentration ([Ca²⁺ ]_i ) in myocardial cells. The aim of the present study was to examine if maintaining euvolaemia during rewarming mitigates cardiac dysfunction and/or normalizes elevated myocardial [Ca²⁺ ]_i . A total of 21 male Wistar rats (300 g) were surface cooled to 15°C, then maintained at 15°C for 4 h, and subsequently rewarmed to 37°C. The rats were randomly assigned to one of three groups: (1) non-intervention control (n = 7), (2) dextran treated (i.v. 12 ml/kg dextran 70; n = 7), or (3) crystalloid treated (24 ml/kg 0.9% i.v. saline; n = 7). Infusions occurred during the first 30 min of rewarming. Arterial blood pressure, stroke volume (SV), cardiac output (CO), contractility (dP/dt_max ) and blood gas changes were measured. Post-hypothermic changes in [Ca²⁺ ]_i were measured using the method of radiolabelled Ca²⁺ (⁴⁵ Ca²⁺ ). Untreated controls displayed post-hypothermic cardiac dysfunction with significantly reduced CO, SV and dP/dt_max . In contrast, rats receiving crystalloid or dextran treatment showed a return to pre-hypothermic control levels of CO and SV after rewarming, with the dextran group displaying significantly better amelioration of post-hypothermic cardiac dysfunction than the crystalloid group. Compared to the post-hypothermic increase in myocardial [Ca²⁺ ]_i in non-treated controls, [Ca²⁺ ]_i values with crystalloid and dextran did not increase to the same extent after rewarming. Volume replacement with crystalloid or dextran during rewarming abolishes post-hypothermic cardiac dysfunction, and partially mitigates the hypothermia-induced elevation of [Ca²⁺ ]_i .

Extreme Cooling Rates in Avalanche Victims: Case Report and Narrative Review

Mittermair, Christof, Eva Foidl, Bernd Wallner, Hermann Brugger, and Peter Paal. Extreme cooling rates in avalanche victims: case report and narrative review. High Alt Med Biol. 22: 235-240, 2021. Background: We report a 25-year-old female backcountry skier who was buried by an avalanche during ascent. A cooling rate of 8.5°C/h from burial to hospital is the fastest reported in a person with persistent circulation. Methods: A case report according to the CARE guidelines is presented. A literature search with the keywords "avalanche" AND "hypothermia" was performed and yielded 96 results, and the last update was on October 25, 2020. A narrative review complements this work. Results: A literature search revealed four avalanche patients with extreme cooling rates (>5°/h). References of included articles were searched for further relevant studies. Nineteen additional pertinent articles were included. Overall, 32 studies were included in this work. Discussion: An avalanche patient cools in different phases, and every phase may have different cooling rates: (1) during burial, (2) with postburial exposure on-site, and (3) during transport. It is important to measure the core temperature correctly, ideally with an esophageal probe. Contributing factors to fast cooling are sweating, impaired consciousness, no shivering, wearing thin monolayer clothing and head and hands uncovered, an air pocket, and development of hypercapnia, being slender. Conclusions: Rescuers should be prepared to encounter severely hypothermic subjects (<30°C) even after burials of <60 minutes. Subjects rescued from an avalanche may cool extremely fast the more contributing factors for rapid cooling exist. After avalanche burial (≥60 minutes) and unwitnessed cardiac arrest, chances of neurologically intact survival are small and depend on rapid cooling and onset of severe hypothermia (<30°C) before hypoxia-induced cardiac arrest.

European Resuscitation Council Guidelines 2021: Paediatric Life Support

These European Resuscitation Council Paediatric Life Support (PLS) guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the management of critically ill infants and children, before, during and after cardiac arrest.

European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances

These European Resuscitation Council (ERC) Cardiac Arrest in Special Circumstances guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required to basic and advanced life support for the prevention and treatment of cardiac arrest in special circumstances; specifically special causes (hypoxia, trauma, anaphylaxis, sepsis, hypo/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), special settings (operating room, cardiac surgery, catheter laboratory, dialysis unit, dental clinics, transportation (in-flight, cruise ships), sport, drowning, mass casualty incidents), and special patient groups (asthma and COPD, neurological disease, obesity, pregnancy).

Clinical staging of accidental hypothermia: The Revised Swiss System: Recommendation of the International Commission for Mountain Emergency Medicine (ICAR MedCom)

Clinical staging of accidental hypothermia is used to guide out-of-hospital treatment and transport decisions. Most clinical systems utilize core temperature, by measurement or estimation, to stage hypothermia, despite the challenge of obtaining accurate field measurements. Recent studies have demonstrated that field estimation of core temperature is imprecise. We propose a revision of the original Swiss Staging system. The revised system uses the risk of cardiac arrest, instead of core temperature, to determine the staging level. Our revised system simplifies assessment by using the level of responsiveness, based on the AVPU scale, and by removing shivering as a stage-defining sign.

ECMO in Cardiac Arrest: A Narrative Review of the Literature

Cardiac arrest (CA) is a frequent cause of death and a major public health issue. To date, conventional cardiopulmonary resuscitation (CPR) is the only efficient method of resuscitation available that positively impacts prognosis. Extracorporeal membrane oxygenation (ECMO) is a complex and costly technique that requires technical expertise. It is not considered standard of care in all hospitals and should be applied only in high-volume facilities. ECMO combined with CPR is known as ECPR (extracorporeal cardiopulmonary resuscitation) and permits hemodynamic and respiratory stabilization of patients with CA refractory to conventional CPR. This technique allows the parallel treatment of the underlying etiology of CA while maintaining organ perfusion. However, current evidence does not support the routine use of ECPR in all patients with refractory CA. Therefore, an appropriate selection of patients who may benefit from this procedure is key. Reducing the duration of low blood flow by means of performing high-quality CPR and promoting access to ECPR, may improve the survival rate of the patients presenting with refractory CA. Indeed, patients who benefit from ECPR seem to carry better neurological outcomes. The aim of this present narrative review is to present the most recent literature available on ECPR and to clarify its potential therapeutic role, as well as to provide an in-depth explanation of equipment and its set up, the patient selection process, and the patient management post-ECPR.

Witnessed Cardiac Arrest in a Hypothermic Avalanche Victim Completely Buried for 2 Hours

A 34-y-old skier triggered a wind slab avalanche and was completely buried for over 2 h. After extrication by rescuers, the victim was breathing and conscious. Despite directions from the rescuers against standing up, the victim struggled to free himself and ultimately stood upright before collapsing in cardiac arrest. The rescuers performed cardiopulmonary resuscitation during transport to a nearby trailhead, where a helicopter emergency medical services crew found that the victim was in ventricular fibrillation. After further resuscitative efforts, including advanced life support, the victim was declared dead at the scene. Afterdrop and circumrescue collapse were the most likely triggers of cardiac arrest. This case highlights a need for rescuers, emergency medical services, and hospitals to be prepared to care for victims with hypothermia. To prevent circumrescue collapse, victims with hypothermia should be extricated gently, should not be allowed to stand, and should be placed flat. This may be difficult or impossible, as in this case. Hypothermic victims in cardiac arrest may require prolonged cardiopulmonary resuscitation, preferably with mechanical compressions, during transport to a hospital that has protocols for rewarming using extracorporeal life support. Resuscitation from hypothermic cardiac arrest should not be terminated before the victim has been rewarmed.

J-wave change during rewarming therapy for accidental hypothermia

Background

J waves are abnormal electrocardiogram findings that indicate an elevation at the junction between the QRS complex and the ST segment. Hypothermia is associated with fetal arrhythmia, along with the increase of J‐wave manifestation.

Case Presentation

A 68‐year‐old woman with a medical history of old cerebral infarction and dementia was admitted to the emergency department with accidental hypothermia. An admission, electrocardiogram (ECG) showed prominent J waves with the highest amplitude recorded in limb and precordial leads. Continuous ECG monitoring was recorded during the rewarming therapy. As the body temperature increased, the amplitude of J waves became lower and disappeared. This case clearly showed that the degree of core body temperature is related to the height of the J‐wave amplitude. There was no fatal arrhythmia during rewarming therapy.

Conclusion

This case describes serial changes in the J‐wave amplitude and morphology during rewarming therapy. Continuous ECG monitoring is important in a patient with severe hypothermia.

Vital Signs in Accidental Hypothermia

Pasquier, Mathieu, Evelien Cools, Ken Zafren, Pierre-Nicolas Carron, Vincent Frochaux, and Valentin Rousson. Vital signs in accidental hypothermia. High Alt Med Biol. 22: 142-147, 2021. Background: Clinical indicators are used to stage hypothermia and to guide management of hypothermic patients. We sought to better characterize the influence of hypothermia on vital signs, including level of consciousness, by studying cases of patients suffering from accidental hypothermia. Materials and Methods: We retrospectively included patients aged ≥18 years admitted to the hospital with a core temperature below 35°C. We identified the cases from a literature review and from a retrospective case series of hypothermic patients admitted to the hospital between 1994 and 2016. Patients who experienced cardiac arrest, as well as those with potential confounders such as concomitant diseases or intoxications, were excluded. Relationships between core temperature and heart rate, systolic blood pressure, respiratory rate, and level of consciousness were explored via correlations and regression. Results: Of the 305 cases reviewed, 216 met the criteria for inclusion. The mean temperature was 29.7°C ± 4.2°C (range 19.3°C-34.9°C). The relationships between temperature and each of the four vital signs were generally linear and significantly positive, with Spearman correlations for respiratory rate, heart rate, systolic blood pressure, and Glasgow Coma Score (GCS) of 0.29 (p = 0.024), 0.44 (p < 0.001), 0.47 (p < 0.001), and 0.78 (p < 0.001), respectively. Based on linear regression, the mean decrease of a vital sign associated with a 1°C decrease of temperature was estimated to be 0.50 minute^-1 for respiratory rate, 2.54 minutes^-1 for heart rate, 4.36 mmHg for systolic blood pressure, and 0.88 for GCS. Conclusions: There is a significant positive correlation between core temperature and heart rate, systolic blood pressure, respiratory rate, and GCS. The relationship between vital signs and temperature is generally linear. This knowledge might help clinicians make appropriate decisions when determining whether the clinical condition of a patient should be attributed to hypothermia. This could enhance clinical care and help to guide future research.

Efficacy of warming systems in mountain rescue: an experimental manikin study

Mountain accident casualties are often exposed to cold and windy weather. This may induce post-traumatic hypothermia which increases mortality. The aim of this study was to assess the ability of warming systems to compensate for the victim's estimated heat loss in a simulated mountain rescue operation. We used thermal manikins and developed a thermodynamic model of a virtual patient. Manikins were placed on a mountain rescue stretcher and exposed to wind chill indices of 0 °C and - 20 °C in a climatic chamber. We calculated the heat balance for two simulated clinical scenarios with both a shivering and non-shivering victim and measured the heat gain from gel, electrical, and chemical warming systems for 3.5 h. The heat balance in the simulated shivering patient was positive. In the non-shivering patient, we found a negative heat balance for both simulated weather conditions (- 429.53 kJ at 0 °C and - 1469.78 kJ at - 20 °C). Each warming system delivered about 300 kJ. The efficacy of the gel and electrical systems was higher within the first hour than later (p < 0.001). We conclude that none of the tested warming systems is able to compensate for heat loss in a simulated model of a non-shivering patient whose physiological heat production is impaired during a prolonged mountain evacuation. Additional thermal insulation seems to be required in these settings.

Case of Severe Accidental Hypothermia Cardiac Arrest in a Subtropical Climate and Review of Management

A patient was brought to the hospital with severe accidental hypothermia due to cold exposure associated with acute alcohol intoxication. Initial bladder core temperature was 21°C (70°F). The patient was agitated and combative with altered mental status and suffered rescue collapse during transport. Initial rhythm was ventricular fibrillation and we initiated a standard advanced cardiac life support (ACLS) protocol with rewarming measures. The patient received 28 mg of epinephrine and 13 shocks. Active and passive rewarming were initiated without extracorporeal rewarming. The patient achieved return of spontaneous circulation (ROSC) at a core temperature of 23.8°C (74.8°F). Patient was discharged 15 days later neurologically intact with no organ damage. The clinical management and implications for further research in severe accidental hypothermia management are discussed. In patients with severe accidental hypothermia (defined as <30°C or <86°F) in cardiac arrest, the optimal rewarming technique, use of epinephrine, and time when defibrillation should be attempted remain controversial. In our patient, the patient achieved ROSC in less than 2 hours with standard ACLS procedures despite a minimal increase in core temperature (21°C to 23.8°C or 70°F to 73.9°F).

[Emergency medicine in the German Maritime Search and Rescue Service-Evaluation of medical emergencies in the North Sea and Baltic Sea over 2 years]

Hintergrund

Die logistischen Besonderheiten eines maritimen Notfallortes und die häufig zusätzlich drohende akzidentelle Hypothermie machen die Versorgung medizinischer Notfälle auf dem Meer besonders anspruchsvoll. In dieser Arbeit sollen die Charakteristika notfallmedizinischer Einsätze der Deutschen Gesellschaft zur Rettung Schiffbrüchiger (DGzRS) als Hauptträgerin der nichthelikopterbasierten medizinischen Seenotrettung auf den Meeren vor der deutschen Küste beschrieben werden.

Material und Methoden

Es erfolgte eine retrospektive Analyse aller Einsätze der DGzRS der Jahre 2017 und 2018. Die Einsatzdaten und –zeiten sowie die Erkrankungsschwere der Patienten (graduiert mittels NACA-Score) wurden ausgewertet und exemplarisch mit denen eines NEF der Hansestadt Lübeck verglichen.

Ergebnisse

Bei insgesamt 182 medizinischen Einsätzen wurden 224 Patienten behandelt. Die Einsatzeinheiten der DGzRS benötigten im Mittel 30 ± 21 min bis zur Ankunft und 43 ± 30 min für Rettung, Behandlung und Transport. Bei 63 Einsätzen wurden die Patienten durch einen Notarzt betreut, der bei 44 Einsätzen durch die Landrettung herangeführt wurde. Durch die Wartezeit auf bordfremdes Personal wurde bei 26 Einsätzen die Abfahrt um im Mittel 18 ± 7 min verzögert.

Die durchschnittliche Erkrankungsschwere in der Seenotrettung war signifikant höher als im Lübecker Notarztdienst; es gab vergleichbar häufig Reanimationen und Todesfälle.

Schlussfolgerung

Trotz der hohen Krankheitsschwere medizinischer Notfälle auf den Meeren vor Deutschlands Küste treffen Notärzte dort häufig mit erheblicher Verzögerung ein. Es gibt den dringenden Bedarf effektiverer Unterstützung der DGzRS durch für den maritimen Einsatz ausgebildetes ärztliches Personal.

Anesthetic Management of Successful Extracorporeal Resuscitation After Six Hours of Cardiac Arrest Due to Severe Accidental Hypothermia

Accidental hypothermia (AH) in Mediterranean countries often is underestimated. AH should be suspected in patients also in moderate climates throughout all seasons. Compared with other countries, the mortality rate due to AH in Spain is low, and hypothermia rarely is recognized and treated. The case of a patient who experienced cardiac arrest due to severe AH and was resuscitated for more than six hours using extracorporeal life support recently was published. Herein that case is reviewed, with the anesthetic management during cannulation detailed. In addition, the authors highlight how the application of extracorporeal cardiopulmonary resuscitation guidelines is different in AH patients, how in-hospital (HOPE score) triage criteria should be applied, and how the establishment of clear standard operating procedures and education strategies should be promoted.

Effects of hypothermia, hypoxia, and hypercapnia on brain oxygenation and hemodynamic parameters during simulated avalanche burial: a porcine study

Avalanche patients who are completely buried but still able to breathe are exposed to hypothermia, hypoxia, and hypercapnia (triple H syndrome). Little is known about how these pathological changes affect brain physiology. The study aim was to investigate the effect of hypothermia, hypoxia, and hypercapnia on brain oxygenation and systemic and cerebral hemodynamics. Anesthetized pigs were surface cooled to 28°C. Fraction of inspiratory oxygen ([Formula: see text]) was reduced to 17% and hypercapnia induced. Hemodynamic parameters and blood gas values were monitored. Cerebral measurements included cerebral perfusion pressure (CPP), brain tissue oxygen tension ([Formula: see text]), cerebral venous oxygen saturation ([Formula: see text]), and regional cerebral oxygen saturation (rSo₂). Tests were interrupted when hemodynamic instability occurred or 60 min after hypercapnia induction. ANOVA for repeated measures was used to compare values across phases. There was no clinically relevant reduction in cerebral oxygenation ([Formula: see text], [Formula: see text], rSo₂) during hypothermia and initial [Formula: see text] reduction. Hypercapnia was associated with an increase in pulmonary resistance followed by a decrease in cardiac output and CPP, resulting in hemodynamic instability and cerebral desaturation (decrease in [Formula: see text], [Formula: see text], rSo₂). Hypercapnia may be the main cause of cardiovascular instability, which seems to be the major trigger for a decrease in cerebral oxygenation in triple H syndrome despite severe hypothermia.NEW & NOTEWORTHY Avalanche patients who are completely buried but still able to breathe are exposed to hypothermia, hypoxia, and hypercapnia (triple H syndrome). In a porcine model, there was no clinically relevant reduction in cerebral oxygenation during hypothermia and initial reduction of fraction of inspiratory oxygen ([Formula: see text]), as observed during hypercapnia. Hypercapnia may be the main cause of cardiovascular instability, which seems to be the major trigger for a decrease in cerebral oxygenation in triple H syndrome despite severe hypothermia.

Determination of Death in Mountain Rescue: Recommendations of the International Commission for Mountain Emergency Medicine (ICAR MedCom)

Determination of death requires specific knowledge, training, and experience in most cases. It can be particularly difficult when external conditions, such as objective hazards in mountains, prevent close physical examination of an apparently lifeless person, or when examination cannot be accomplished by an authorized person. Guidelines exist, but proper use can be difficult. In addition to the absence of vital signs, definitive signs of death must be present. Recognition of definitive signs of death can be problematic due to the variability in time course and the possibility of mimics. Only clear criteria such as decapitation or detruncation should be used to determine death from a distance or by laypersons who are not medically trained. To present criteria that allow for accurate determination of death in mountain rescue situations, the International Commission for Mountain Emergency Medicine convened a panel of mountain rescue doctors and a forensic pathologist. These recommendations are based on a nonsystematic review of the literature including articles on determination of death and related topics.

Management for the Drowning Patient

Drowning is "the process of experiencing respiratory impairment from submersion or immersion in liquid." According to the World Health Organization, drowning claims the lives of > 40 people every hour of every day. Drowning involves some physiological principles and medical interventions that are unique. It occurs in a deceptively hostile environment that involves an underestimation of the dangers or an overestimation of water competency. It has been estimated that > 90% of drownings are preventable. When water is aspirated into the airways, coughing is the initial reflex response. The acute lung injury alters the exchange of oxygen in different proportions. The combined effects of fluid in the lungs, loss of surfactant, and increased capillary-alveolar permeability result in decreased lung compliance, increased right-to-left shunting in the lungs, atelectasis, and alveolitis, a noncardiogenic pulmonary edema. Salt and fresh water aspirations cause similar pathology. If the person is not rescued, aspiration continues, and hypoxemia leads to loss of consciousness and apnea in seconds to minutes. As a consequence, hypoxic cardiac arrest occurs. The decision to admit to an ICU should consider the patient's drowning severity and comorbid or premorbid conditions. Ventilation therapy should achieve an intrapulmonary shunt ≤ 20% or Pao₂:Fio₂ ≥ 250. Premature ventilatory weaning may cause the return of pulmonary edema with the need for re-intubation and an anticipation of prolonged hospital stays and further morbidity. This review includes all the essential steps from the first call to action until the best practice at the prehospital, ED, and hospitalization.

Pediatric hypothermic submersion incident - should we do chest compressions on a beating heart?

Background

Drowning is the third leading cause of unintentional injury death worldwide, with the highest rates of fatality among young children. To decide how to treat these patients prehospitally could be challenging in certain situations when uncertain about the adequacy of the patent’s circulation.

Methods/case report

We describe a 2 year old boy surviving a 15 min hypothermic submersion in a cold river. In spite of the presence of some vital signs, we decided to do full cardiopulmonary resuscitation to the hospital. The main reason was that we were uncertain about the adequacy of the spontaneous circulation, and the transport to hospital was fairly long. The patient suffered no obvious harm and the outcome was good.

Discussion

What is regarded as adequate circulation when accidentally hypothermic between 24 and 25⁰ C? A weak pulse was felt in the femoral artery with a rate of about 40–50 per minute. There were shallow, but regular respiration, and point of care ultrasound revealed a slightly dilated left ventricle and weak, but organised cardiac contractions. Despite these findings a decision was made to continue ventilations and chest compressions during helicopter transport to the University hospital.

Conclusion

In an accidentally hypothermic pediatric submersion incident we decided to do full cardiopulmonary resuscitation to the hospital despite there were signs of circulation. We did no harm to the patient. Future guideline revisions should try to clarify how to handle situations with severly accidentally hypothermic patients like this, so the good outcome that is often seen in these patients could be even better.

Is prehospital use of active external warming dangerous for patients with accidental hypothermia: a systematic review

BACKGROUND

Optimal prehospital management and treatment of patients with accidental hypothermia is a matter of frequent debate, with controversies usually revolving around the subject of rewarming. The rule of thumb in primary emergency care and first aid for patients with accidental hypothermia has traditionally been to be refrain from prehospital active rewarming and to focus on preventing further heat loss. The potential danger of active external rewarming in a prehospital setting has previously been generally accepted among the emergency medicine community based on a fear of potential complications, such as "afterdrop", "rewarming syndrome", and "circum-rescue collapse". This has led to a reluctancy from health care providers to provide patients with active external rewarming outside the hospital. Different theories and hypotheses exist for these physiological phenomena, but the scientific evidence is limited. The research question is whether the prehospital use of active external rewarming is dangerous for patients with accidental hypothermia. This systematic review intends to describe the acute unfavourable adverse effects of active external rewarming on patients with accidental hypothermia.

METHODS

A literature search of the Cochrane Library, MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL], and SveMed+ was carried out, and all articles were screened for eligibility. All article formats were included.

RESULTS

Two thousand three hundred two articles were screened, and eight articles met our search criteria. Three articles were case reports or case series, one was a prospective study, two were retrospective studies, one article was a literature review, and one article was a war report from the Napoleonic Wars.

CONCLUSIONS

One of the main findings in this article was the poor scientific quality and the low number of articles meeting our inclusion criteria. When conducting this review, we found no scientific evidence of acceptable quality to prove that the use of active external rewarming is dangerous for patients with accidental hypothermia in a prehospital setting. We found several articles claiming that active external rewarming is dangerous, but most of them do not cite references or provide evidence.

Severe Hypothermia and Frostbite Requiring ECMO and Four Limb Amputations

Severe hypothermia and frostbite can result in significant morbidity and mortality. We present a case of a patient with severe hypothermia and frostbite due to cold exposure after a snowmobile crash. He presented in cardiac arrest with a core temperature of 19°C requiring prolonged cardiopulmonary resuscitation, active internal rewarming, venoarterial extracorporeal membrane oxygenation, and subsequently amputations of all four extremities. Although severe hypothermia and frostbite can be a fatal condition, the quick action of Emergency Medical Services, emergency physicians, trauma surgeons, cardiothoracic surgeons, intensivists, and the burn team contributed to a successful recovery for this patient including a good neurological outcome. This case highlights the importance of a strong interdisciplinary team in treating this condition.