Patterns of death among avalanche fatalities: a 21-year review

Hemorrhage at high altitude: impact of sustained hypobaric hypoxia on cerebral blood flow, tissue oxygenation, and tolerance to simulated hemorrhage in humans

With ascent to high altitude (HA), compensatory increases in cerebral blood flow and oxygen delivery must occur to preserve cerebral metabolism and consciousness. We hypothesized that this compensation in cerebral blood flow and oxygen delivery preserves tolerance to simulated hemorrhage (via lower body negative pressure, LBNP), such that tolerance is similar during sustained exposure to HA vs. low altitude (LA). Healthy humans (4F/4 M) participated in LBNP protocols to presyncope at LA (1130 m) and 5-7 days following ascent to HA (3800 m). Internal carotid artery (ICA) blood flow, cerebral delivery of oxygen (CDO2) through the ICA, and cerebral tissue oxygen saturation (ScO2) were determined. LBNP tolerance was similar between conditions (LA: 1276 ± 304 s vs. HA: 1208 ± 306 s; P = 0.58). Overall, ICA blood flow and CDO2 were elevated at HA vs. LA (P ≤ 0.01) and decreased with LBNP under both conditions (P < 0.0001), but there was no effect of altitude on ScO2 responses (P = 0.59). Thus, sustained exposure to hypobaric hypoxia did not negatively impact tolerance to simulated hemorrhage. These data demonstrate the robustness of compensatory physiological mechanisms that preserve human cerebral blood flow and oxygen delivery during sustained hypoxia, ensuring cerebral tissue metabolism and neuronal function is maintained.

Wilderness Medical Society Clinical Practice Guidelines for Prevention and Management of Avalanche and Nonavalanche Snow Burial Accidents: 2024 Update

To provide guidance to the general public, clinicians, and avalanche professionals about best practices, the Wilderness Medical Society convened an expert panel to revise the evidence-based guidelines for the prevention, rescue, and resuscitation of avalanche and nonavalanche snow burial victims. The original panel authored the Wilderness Medical Society Practice Guidelines for Prevention and Management of Avalanche and Nonavalanche Snow Burial Accidents in 2017. A second panel was convened to update these guidelines and make recommendations based on quality of supporting evidence.

National Association of Medical Examiners Position Paper: Recommendations for the Documentation and Certification of Disaster-Related Deaths

ABSTRACT

Collecting and reporting accurate disaster mortality data are critical to informing disaster response and recovery efforts. The National Association of Medical Examiners convened an ad hoc committee to provide recommendations for the documentation and certification of disaster-related deaths. This article provides definitions for disasters and direct, indirect, and partially attributable disaster-related deaths; discusses jurisdiction for disaster-related deaths; offers recommendations for medical examiners/coroners (ME/Cs) for indicating the involvement of the disaster on the death certificate; discusses the role of the ME/C and non-ME/C in documenting and certifying disaster-related deaths; identifies existing systems for helping to identify the role of disaster on the death certificate; and describes disaster-related deaths that may require amendments of death certificates. The recommendations provided in this article seek to increase ME/C's understanding of disaster-related deaths and promote uniformity in how to document these deaths on the death certificate.

On-site treatment of avalanche victims: Scoping review and 2023 recommendations of the international commission for mountain emergency medicine (ICAR MedCom)

INTRODUCTION

The International Commission for Mountain Emergency Medicine (ICAR MedCom) developed updated recommendations for the management of avalanche victims.

METHODS

ICAR MedCom created Population Intervention Comparator Outcome (PICO) questions and conducted a scoping review of the literature. We evaluated and graded the evidence using the American College of Chest Physicians system.

RESULTS

We included 120 studies including original data in the qualitative synthesis. There were 45 retrospective studies (38%), 44 case reports or case series (37%), and 18 prospective studies on volunteers (15%). The main cause of death from avalanche burial was asphyxia (range of all studies 65-100%). Trauma was the second most common cause of death (5-29%). Hypothermia accounted for few deaths (0-4%).

CONCLUSIONS AND RECOMMENDATIONS

For a victim with a burial time ≤ 60 minutes without signs of life, presume asphyxia and provide rescue breaths as soon as possible, regardless of airway patency. For a victim with a burial time > 60 minutes, no signs of life but a patent airway or airway with unknown patency, presume that a primary hypothermic CA has occurred and initiate cardiopulmonary resuscitation (CPR) unless temperature can be measured to rule out hypothermic cardiac arrest. For a victim buried > 60 minutes without signs of life and with an obstructed airway, if core temperature cannot be measured, rescuers can presume asphyxia-induced CA, and should not initiate CPR. If core temperature can be measured, for a victim without signs of life, with a patent airway, and with a core temperature < 30 °C attempt resuscitation, regardless of burial duration.

Accidental Hypothermia in a Swiss Alpine Trauma Centre-Not an Alpine Problem

BACKGROUND

Research in accidental hypothermia focuses on trauma patients, patients exposed to cold environments or patients after drowning but rarely on hypothermia in combination with intoxications or on medical or neurological issues. The aim of this retrospective single-centre cohort study was to define the aetiologies, severity and relative incidences of accidental hypothermia, methods of measuring temperature and in-hospital mortality.

METHODS

The study included patients ≥18 years with a documented body temperature ≤35 °C who were admitted to the emergency department (ED) of the University Hospital in Bern between 2000 and 2019.

RESULTS

439 cases were included, corresponding to 0.32 per 1000 ED visits. Median age was 55 years (IQR 39-70). A total of 167 patients (38.0%) were female. Furthermore, 63.3% of the patients suffered from mild, 24.8% from moderate and 11.9% from severe hypothermia. Exposure as a single cause for accidental hypothermia accounted for 12 cases. The majority were combinations of hypothermia with trauma (32.6%), medical conditions (34.2%), neurological conditions (5.2%), intoxications (20.3%) or drowning (12.0%). Overall mortality was 22.3% and depended on the underlying causes, severity of hypothermia, age and sex.

Avalanche Preparedness and Accident Analysis Among Backcountry Skier, Sidecountry, and Snowmobile Fatalities in the United States: 2009 to 2019

INTRODUCTION

While avalanche fatalities have remained relatively steady per year, data suggest a possible increase in sidecountry use and snowmobile fatalities. Limited information is known regarding the accident details and preparedness among different groups of backcountry users including snowmobiles, sidecountry, and backcountry skiers, and what specific factors could contribute to their fatalities.

METHODS

Avalanche fatality reports covering all US states posted by the Colorado Avalanche Information Center available online for 10 seasons (2009-2010 through 2018-2019 seasons) were analyzed for group size, specific equipment carried, burial depth, burial time, and other details. Only reports in the 3 following categories were included in the analysis: backcountry ski/snowboard, sidecountry ski/snowboard, and snowmobile/snowbike. These aspects were compared among the 3 tourer types using statistical analyses (ANOVA).

RESULTS

Two hundred and five fatalities were analyzed (n=32 sidecountry, n=91 skier/snowboard, n=82 snowmobile/snowbike). Using 2 preparedness scores, the ski/snowboard group had the greatest distribution of high scores when evaluated by equipment carried and group size, with significant differences per group (P<0.01). Of the fatalities that were buried, burial time was related to the tourer group (P=0.04), with the ski/snowboard group having the highest proportion of burials <15 min. Burial depth was significantly different among the 3 tourer groups, with snowmobiles buried the deepest on average (P<0.01).

CONCLUSIONS

Despite limited data available on fatalities, an analysis of preparedness suggests that backcountry skiers and snowboarders are more prepared for avalanche accidents compared to snowmobiles and sidecountry users when evaluated by equipment carried and group size.

Safety Measures and Risk Analysis for Outdoor Recreation Technicians and Practitioners: A Systematic Review

There is no expectation to suppress all accidents in the outdoor recreation sector; nevertheless, it is expected that all possible safety measures are taken in order to minimize the risk of accidents. The objective of this study was to systematize the knowledge regarding recommended and used safety measures and risk assessments for technicians and outdoor recreation practitioners. We conducted a systematic review on PubMed, BVS, SciELO, Science Direct, ABI/INFORM, Spinger, Web of Knowledge, and Esmerald full text databases, up to February 2021. The eligible criteria followed the PICOS strategy; the included risk assessment studies on outdoor recreation (according to its definition) had methodological quality, were indexed, and peer reviewed. Ten studies, from ten countries, fulfilled these specifications, which focused on different approaches. Five studies focused on risk perception, four studies focused on safety practices, injuries, and risk assessment; three studies addressed safe behaviors; two studies addressed equipment- and risk matrix-related themes. We concluded that there was a concern for this topic, and the 28 mentioned measures could provide important information regarding health and prevention. These measures could be used to develop safety strategies and risk reduction, aimed at reducing accidents in outdoor recreation activities. In order to evaluate the pertinence and importance of the mentioned measures, namely risk perception, safe practices, sport injuries, risk analysis, safe behaviors, as well as equipment and risk assessment matrices, further investigation is needed using experimental or observational designs. These strategies and procedures can contribute to enhanced interventions by technicians with higher security and quality, and therefore, improved well-being and satisfaction of practitioners.

Solid Organ Donation From Brain-dead Donors With Cardiorespiratory Arrest After Snow Avalanche Burial: A Retrospective Single-center Study

BACKGROUND

Complete snow avalanche burial is associated with high mortality. The aim of this study was to assess the feasibility and incidence of organ retrieval in brain-dead donors following cardiorespiratory arrest due to avalanche burial and to evaluate the function of transplanted organs.

METHODS

The transplant registry of the Medical University of Innsbruck was searched for organ donors with a history of avalanche burial, and the function and survival of transplanted organs were assessed.

RESULTS

Thirty-three organs were procured from eight donors and 31 organs (13 kidneys, 6 livers, 3 pancreases, 5 hearts, and 4 lungs) were ultimately transplanted. Allograft and recipient 1-y survival were 100% and both initial and long-term graft function were good. Only one-third of all avalanche victims who died in the intensive care unit with signs of irreversible hypoxic brain injury became organ donors.

CONCLUSIONS

Initial experience from this retrospective study suggests that organs from brain-dead avalanche victims can be transplanted with good results. Starting a Donation after Circulatory Determination of Death program might be an option for increasing the number of organ donations from avalanche victims with irreversible hypoxic brain injury.

Quality Indicators for Avalanche Victim Management and Rescue

Decisions in the management and rescue of avalanche victims are complex and must be made in difficult, sometimes dangerous, environments. Our goal was to identify indicators for quality measurement in the management and rescue of avalanche victims. The International Commission for Mountain Emergency Medicine (ICAR MedCom) convened a group of internal and external experts. We used brainstorming and a five-round modified nominal group technique to identify the most relevant quality indicators (QIs) according to the National Quality Forum Measure Evaluation Criteria. Using a consensus process, we identified a set of 23 QIs to measure the quality of the management and rescue of avalanche victims. These QIs may be a valuable tool for continuous quality improvement. They allow objective feedback to rescuers regarding clinical performance and identify areas that should be the foci of further quality improvement efforts in avalanche rescue.

Survival probability in avalanche victims with long burial (≥60 min): A retrospective study

BACKGROUND

The survival of completely buried victims in an avalanche mainly depends on burial duration. Knowledge is limited about survival probability after 60 min of complete burial.

AIM

We aimed to study the survival probability and prehospital characteristics of avalanche victims with long burial durations.

METHODS

We retrospectively included all completely buried avalanche victims with a burial duration of ≥60 min between 1997 and 2018 in Switzerland. Data were extracted from the registry of the Swiss Institute for Snow and Avalanche Research and the prehospital medical records of the physician-staffed helicopter emergency medical services. Avalanche victims buried for ≥24 h or with an unknown survival status were excluded. Survival probability was estimated by using the non-parametric Ayer-Turnbull method and logistic regression. The primary outcome was survival probability.

RESULTS

We identified 140 avalanche victims with a burial duration of ≥60 min, of whom 27 (19%) survived. Survival probability shows a slight decrease with increasing burial duration (23% after 60 min, to <6% after 1400 min, p = 0.13). Burial depth was deeper for those who died (100 cm vs 70 cm, p = 0.008). None of the survivors sustained CA during the prehospital phase.

CONCLUSIONS

The overall survival rate of 19% for completely buried avalanche victims with a long burial duration illustrates the importance of continuing rescue efforts. Avalanche victims in CA after long burial duration without obstructed airway, frozen body or obvious lethal trauma should be considered to be in hypothermic CA, with initiation of cardiopulmonary resuscitation and an evaluation for rewarming with extracorporeal life support.

Effects of Climate Change on Avalanche Accidents and Survival

Avalanches are major natural hazards in snow-covered mountains, threatening people and infrastructure. With ongoing climate change, the frequency and types of snow avalanches may change, affecting the rates of avalanche burial and survival. With a wetter and warmer snow climate, consequences of burial may become more severe. In this review, we assess the potential effects of climate change on the frequency and characteristics of avalanches. We then discuss how these changes might affect the survival rates of subjects buried by avalanches and might influence the responses of search and rescue (SAR) teams and health care providers. While climate change is inevitable, the effects on avalanches remain elusive. The frequency of human triggered avalanches may not change, because this depends largely on the number and behavior of winter recreationists. Blunt trauma and secondary injuries will likely become more frequent as terrain roughness is expected to rise and snow cover to become thinner. Higher snow densities in avalanche debris will likely interfere with the respiration of completely buried victims. Asphyxia and trauma, as causes of avalanche death, may increase. It is unlikely that SAR and health care providers involved in avalanche rescue will have to change their strategies in areas where they are already established. The effects of climate change might foster the expansion of mitigation strategies and the establishment of mountain rescue services in areas subject to increased avalanche hazards caused by changes in snow cover and land use.

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.

Cardiac Arrest Secondary to Accidental Hypothermia: Who Should We Resuscitate?

Cardiac arrest with a degree of concurrent hypothermia is not a rare presentation. This presentation, often in remote areas, poses a challenge for the prehospital physician because the cause of the arrest will significantly alter decision making and prognostication. Survival from cardiac arrest secondary to accidental hypothermia is significantly greater than that of normothermic arrests when appropriate triage and management decisions are made. The complexity of this decision benefits from a specific algorithm to follow in the event of such a casualty presenting. This article systematically reviews the literature on cardiac arrest secondary to accidental hypothermia and provides recommendations in addition to a novel algorithm to aid the responding prehospital clinician in deciding if a hypothermic resuscitation standard operating procedure should be implemented.

Mortality in Different Mountain Sports Activities Primarily Practiced in the Winter Season-A Narrative Review

Annually, millions of people engage in mountain sports activities all over the world. These activities are associated with health benefits, but concurrently with a risk for injury and death. Knowledge on death rates is considered important for the categorization of high-risk sports in literature and for the development of effective preventive measures. The death risk has been reported to vary across different mountain sports primarily practiced in the summer season. To complete the spectrum, the aim of the present review is to compare mortality rates across different mountain sports activities primarily practiced in winter. A comprehensive literature search was performed on the death risk (mortality) during such activities, i.e., alpine (downhill) skiing, snowboarding, cross-country skiing, ski touring, and sledging. With the exception of ski touring (4.4 deaths per 1 million exposure days), the mortality risk was low across different winter sports, with small activity-specific variation (0.3–0.8 deaths per 1 million exposure days). Traumatic (e.g., falls) and non-traumatic (e.g., cardiac death) incidents and avalanche burial in ski tourers were the predominant causes of death. Preventive measures include the improvement of sport-specific skills and fitness, the use of protective gear, well-targeted and intensive training programs concerning avalanche hazards, and sports-medical counseling for elderly and those with pre-existing diseases.

Common Skiing and Snowboarding Injuries

Participation in skiing, and especially snowboarding, continues to rise. As participation and level of competition in these winter sports increases, the number of injuries increases as well. Upper-extremity injuries are more common in snowboarding, whereas lower-extremity injuries are more common in skiing. Head injuries, particularly concussions, are common in both sports. Special consideration in these sports should be given to environmental conditions, such as high altitude and ultraviolet radiation. The purpose of this review is to discuss the most common musculoskeletal injuries seen in skiing and snowboarding, as well as considerations for initial assessment of these injuries and triage to the appropriate level of care. It is important for sports medicine physicians covering these sports to understand initial assessment and treatment of these injuries. Due to the potential for severe injuries in these sports, it is important to be able to quickly recognize an injury that needs to be assessed and treated urgently or emergently. With the increased participation and number of injuries in these sports, it also is important to consider prevention strategies that may minimize risk of injury.

Cut-off values of serum potassium and core temperature at hospital admission for extracorporeal rewarming of avalanche victims in cardiac arrest: A retrospective multi-centre study

AIM

Evidence of existing guidelines for the on-site triage of avalanche victims is limited and adherence suboptimal. This study attempted to find reliable cut-off values for the identification of hypothermic avalanche victims with reversible out-of-hospital cardiac arrest (OHCA) at hospital admission. This may enable hospitals to allocate extracorporeal life support (ECLS) resources more appropriately while increasing the proportion of survivors among rewarmed victims.

METHODS

All avalanche victims with OHCA admitted to seven centres in Europe capable of ECLS from 1995 to 2016 were included. Optimal cut-off values, for parameters identified by logistic regression, were determined by means of bootstrapping and exact binomial distribution and served to calculate sensitivity, rate of overtriage, positive and negative predictive values, and receiver operating curves.

RESULTS

In total, 103 avalanche victims with OHCA were included. Of the 103 patients 61 (58%) were rewarmed by ECLS. Six (10%) of the rewarmed patients survived whilst 55 (90%) died. We obtained optimal cut-off values of 7 mmol/L for serum potassium and 30 °C for core temperature.

CONCLUSION

For in-hospital triage of avalanche victims admitted with OHCA, serum potassium accurately predicts survival. The combination of the cut-offs 7 mmol/L for serum potassium and 30 °C for core temperature achieved the lowest overtriage rate (47%) and the highest positive predictive value (19%), with a sensitivity of 100% for survivors. The presence of vital signs at extrication is strongly associated with survival. For further optimisation of in-hospital triage, larger datasets are needed to include additional parameters.

Cause of Death in Utah Avalanche Fatalities, 2006-2007 through 2017-2018 Winter Seasons

INTRODUCTION

Understanding patterns of avalanche fatalities can aid prevention and rescue strategies. In 2007, we published a report reviewing avalanche deaths in Utah between the 1989-1990 and 2005-2006 winter seasons. In the current report, we discuss Utah avalanche fatalities from the 2006-2007 to 2017-2018 seasons.

METHODS

Avalanche fatality data were obtained from the Utah Avalanche Center and Utah State Office of the Medical Examiner. Autopsy reports were reviewed to determine demographic information, type of autopsy (external vs internal), injuries, and cause of death.

RESULTS

Thirty-two avalanche deaths occurred in Utah during the study period. The mean (±SD) age of victims was 32±13 (8-54) y. Thirty victims (94%) were male and 2 (6%) were female. Seventy-two percent of deaths were from asphyxiation, 19% from trauma alone, and 9% from a combination of asphyxiation and trauma. Snowmobilers accounted for the largest percentage of avalanche fatalities (15 victims; 47%) during the 2007-2018 period.

CONCLUSIONS

Asphyxia continues to be the most prevalent killer in avalanche burial. Patterns of ongoing avalanche deaths continue to suggest that rapid recovery and techniques that prolong survival while buried may decrease fatality rates. Trauma is a significant factor in many avalanche fatalities. Education and technologies focused on reducing traumatic injuries such as improved education in techniques for avalanche risk avoidance and/or use of avalanche airbags may further decrease fatality rates. Snowmobilers represent an increasing percentage of Utah avalanche deaths and now make up the majority of victims; increased education targeting this demographic in the basics of avalanche rescue gear and avalanche rescue may also reduce fatalities.

Patient and rescuer safety: recommendations for dispatch and prioritization of rescue resources based on a retrospective study of Norwegian avalanche incidents 1996-2017

BACKGROUND

Avalanche emergency response should address current accident scenarios to optimize survival chances of victims and to keep rescuers safe. The purpose of this article is to present a basis for evaluation and necessary adjustments in dispatch, prioritization, and management of Norwegian avalanche rescue operations.

METHODS

This is the first peer-reviewed retrospective study of all Norwegian avalanche incidents registered by the two Joint Rescue Co-ordination Centers (JRCCs) in the period 1996-2017 that describes the characteristics and trends of rescue missions and victims.

RESULTS

The Norwegian JRCCs have registered 720 snow avalanche events, with a total of 568 avalanche victims, of which 120 (21%) died. Including those fatally injured, a total of 313 avalanche victims in 209 accidents were treated as patients (55%), and we saw > 1 patient in 24% of these operations. Norwegian avalanche victims were partially or completely recovered prior to the arrival of rescuers in 75% (n = 117) of all rescue operations. In the remaining 25% of cases, the rescue service located 62% (n = 55) of the avalanche victims visually or electronically. In 50% of the 720 incidents, rescuers spent time searching in avalanches with no victims.

CONCLUSIONS

This survey indicates that we have experienced a shift in Norwegian avalanche rescue: from search for missing persons in the avalanche debris to immediate medical care of already-located patients. The findings suggest that a stronger focus on both patient and rescuer safety is necessary. The patients must be ensured the right treatment at the right place at the right time and the allocation of rescue resources must reflect a need to reduce exposure in avalanche terrain, especially in cases with no affirmed victims. We present a flowchart with a recommended rescue response to avalanche accidents in Norway.

Accidental hypothermia in recreational activities in the mountains: A narrative review

The popularity of recreational activities in the mountains worldwide has led to an increase in the total number of persons exposed to cold and extreme environments through recreation. There is little conclusive evidence about the risk of hypothermia for specific activities or populations, nor is it clear which activities are represented in the literature. This is a non-systematic review of accidental hypothermia in different recreational activities in the mountains, with a specific focus on outdoor or winter activities that potentially involve cold exposure. Cases of hypothermia have been reported in the literature in mountaineering, trekking, hiking, skiing, activities performed in the backcountry, ultra-endurance events, and databases from search and rescue services that include various types of recreation. Of these activities, hypothermia as a primary illness occurs most commonly during mountaineering in the highest elevation areas in the world and during recreation practiced in more northern or remote areas. Hypothermia in skiers, snowboarders, and glacier-based activities is most often associated with accidents occurring off-piste or in the backcountry (crevasse, avalanche). Organizers of outdoor events also have a role in reducing the incidence of hypothermia through medical screening and other preparedness measures. More complete collection and reporting of data on mild hypothermia and temperature measurement would improve our understanding of the incidence of hypothermia in outdoor recreation in future.

Avalanche Safety Practices Among Backcountry Skiers and Snowboarders in Jackson Hole in 2016

INTRODUCTION

Carrying standard safety gear (beacon, probe, and shovel), planning a route of descent, and recreating with companions can help to mitigate the risk of injury or death resulting from avalanches in the backcountry. The goal of this study was to identify factors associated with performance of these safety practices.

METHODS

A convenience sample of backcountry skiers and snowboarders was surveyed in 2016 at the backcountry gates of Jackson Hole Mountain Resort. Each participant was surveyed on characteristics including skill level, sex, age, prior avalanche education, and residency in the Jackson Hole area. Safety practices were also measured against avalanche hazard forecasts. Correlations were assessed using Fisher's exact testing.

RESULTS

A total of 334 participants were surveyed. Factors associated with carrying avalanche safety gear included higher expertise, being a resident of the Jackson Hole area, and prior avalanche education. Factors associated with having a planned route of descent included higher expertise and being a resident of the Jackson Hole area. Factors associated with recreating with companions included younger age and lower expertise. Sex had no association with any of the surveyed safety practices. Participants were less likely to carry avalanche safety gear on low avalanche hazard days.

CONCLUSIONS

Certain individual characteristics of backcountry skiers and snowboarders are associated with increased frequency of adherence to recommended safety practices. These findings suggest that particular categories of backcountry recreationists may benefit from further avalanche safety education. The results of this study could help direct future educational efforts among backcountry recreationists.

On-Site Treatment of Snow Avalanche Victims: From Bench to Mountainside

The number of avalanche accidents involving winter recreationists has notably increased in recent decades due to the increasing popularity of outdoor winter activities. The International Liaison Committee on Cardiopulmonary Resuscitation, the International Commission for Mountain Emergency Medicine (ICAR Medcom), and the Wilderness Medical Society have recently published evidenced-based recommendations for the on-site treatment of snow avalanche victims. Despite these recommendations, recent studies found poor knowledge and compliance by both healthcare providers and laypersons. The aim of this nonsystematic review is to provide an updated overview of avalanche accident epidemiology, to present recent advances in snow avalanche pathophysiology, and to discuss recent advancements in on-site treatment of snow avalanche victims.

Causes of Death Among Avalanche Fatalities in Colorado: A 21-Year Review

INTRODUCTION

A better understanding of the nature of morbidity and mortality in avalanche accidents helps direct both rescue efforts as well as preventive strategies to reduce fatalities.

METHODS

We reviewed all avalanche fatalities from the avalanche years beginning in 1994 to 2015 in the state of Colorado, United States, using the database maintained by the Colorado Avalanche Information Center. For each fatality, we obtained the coroner's official determination of cause of death, and autopsy records if one was performed. We used these records to determine cause of death. Injury severity scores (0-75 scale) were calculated for those victims who underwent autopsy.

RESULTS

Mortality information was available for 110 fatalities occurring during the 21-year study period. Of these, 64 underwent autopsy. Asphyxia was the cause of death in 65% of fatalities (72/110). Trauma was the cause of death in 29% of the fatalities (32/110). Of these, the primary cause was multiple system trauma in 38% (12/32), head trauma in 31% (10/32), and spinal injuries in 19% (6/32). Of the victims who died of asphyxia and had autopsy, only 10% (4/42) also had significant trauma, defined as an injury severity score greater than 15. There were 6 fatalities from other causes, including hypothermia, drowning, and primary cardiac arrest. There was no correlation between trauma and mode of travel, avalanche type, or starting zone elevation.

CONCLUSIONS

Asphyxia was the primary cause of death in avalanche fatalities in Colorado during our study period. The incidence of fatal trauma was 29% and did not correlate with user group demographics or avalanche characteristics.

Fall-related accidents among hikers in the Austrian Alps: a 9-year retrospective study

Objective

To analyse the circumstances of fatal and non-fatal mountain hiking accidents caused by falls.

Methods

The study was designed as a retrospective analysis. Mountain hiking accidents caused by falls were documented during a 9-year period (2006–2014). After screening of all data for potential exclusion criteria the final sample size of 5368 accidents and 5665 victims was included into the analyses. Main outcome measures were details about accidents, victims, type of trail and surface.

Results

The annual number of accidents showed a continuous increase from 467 in 2006 to 700 in 2014. In total, 5.8% of all victims died during the 9-year period. 75.3% of the hikers fell during descent and 80.9% of the victims had their accident on a marked hiking trail or small path. The sex ratio for non-fatal accidents was 55% female and 45% male; for fatal accidents the female-to-male ratio was 28%:72%. Mean age of all victims was 52.5±17.5 years and victims of fatalities were about 5 years older compared with victims of non-fatal accidents (57.5±16.5 vs 52.2±17.5 years, P<0.01).

Conclusion

Descent is the most risky part for accidents caused by falls during mountain hiking. Male hikers are at greater risk for fatalities independent of age and this is associated with accidents occurring in pathless terrain. The death rate from falls was 6%. We recommend a critical self-assessment of the individual capabilities and mountain hiking skills and adequate planning of the hiking tours for mountain hikers.

Color stability of dental restorative materials submitted to cold temperatures for forensic purposes

In the post-mortem examination of the dental arches of accident victims in cold locations, dental restorative materials can be found. Cold temperatures can be capable of causing color changes of aesthetic materials, such as composite resin (CR) and glass ionomer cement (GIC). The aim of this study was to evaluate the effect of the cold action on the color stability of CR and GIC restorations, in order to discriminate them and enable the adequate comparison between antemortem and post-mortem data. Sixty bovine teeth (30 CR and 30 GIC) were prepared (6 × 6 × 2 mm) and separated into groups (n = 10). The color readouts were taken by a portable spectrophotometer, before and after of cold action (2.5 °C, -20 °C, -80 °C) inside of freezers. There were color alterations in the coordinates (ΔE, ΔL^∗, Δa^∗ e Δb^∗) for both materials. The authors concluded that cold was capable of producing changes in color in the two esthetic materials, with similar intensities between the two, at all the temperatures studied, when analyzed at 7 days. After being submitted to cold for 30 days, the changes were more significant for CR, allowing it to be differentiated from GIC after 30 days, at all the temperatures tested. Therefore, the test proposed in the study was shown to be practical, feasible and capable of helping Forensic Odontology with the identification of victims.

Does Avalanche Shovel Shape Affect Excavation Time: A Pilot Study

In Europe and North America, approximately 150 fatalities occur as a result of avalanches every year. However, it is unclear whether certain shovel shapes are more effective than others in snow removal during avalanche victim recovery. The objective was to determine the performance parameters with a developed standardized test using different shovel shapes and to determine sex-specific differences. Hence, several parameters were determined for clearing the snow from a snow filled box (15 men, 14 women). A flat (F) and a deep (D) shovel blade with the shaft connected straight (S) or in clearing mode (C) were used for the investigation of the shovel shapes FS, DC and the subsequent use of DC&DS. Mean snow mass shifted per unit time increased significantly from 1.50 kg/s with FS to 1.71 kg/s (14%) with DS and further to 1.79 kg/s (4%) with DC&DS for all participants. Snow mass shifted per unit time was 44% higher (p < 0.05) for men than for women. In excavation operations, the sex-specific physical performance should be taken into account. The results were limited to barely binding snow, because only with this snow did the tests show a high reliability.

Wilderness Medical Society Practice Guidelines for Prevention and Management of Avalanche and Nonavalanche Snow Burial Accidents

To provide guidance to clinicians and avalanche professionals about best practices, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for the prevention, rescue, and medical management of avalanche and nonavalanche snow burial victims. Recommendations are graded on the basis of quality of supporting evidence according to the classification scheme of the American College of Chest Physicians.

Results of a Prospective Observational Study on Mountaineering Emergencies in Western Alps: Mind Your Head

Brustia, Raffaele, Giulia Enrione, Bruna Catuzzo, Luca Cavoretto, Massimo Pesenti Compagnoni, Enrico Visetti, Emmanuel Cauchy, Stefanie Ziegler, and Guido Giardini. Results of a prospective observational study on mountaineering emergencies in Western Alps: mind your head. High Alt Med Biol. 17:116-121, 2016.-

BACKGROUND

In the northern Italian district Valle d'Aosta district during winter and summer season the population can increase up to 170% of the resident population. A prospective monocentric observational registry was held to obtain a precise picture of seasonal mountain-related medical and traumatic major events.

METHODS

From 1st January 2012 to 31st December 2013 all patients admitted to the Aosta Regional Hospital Emergency Room for any event occurred above 2500 m were screened: all those affected by High Altitude Illness, Acute Illness in High Altitude, Trauma, or Cold disease were prospectively included. Activity incidence rate is expressed as the occurrence of mountain-related events per 1000 hours of mountain activity. Event Incidence rate is expressed as the occurrence of new cases per 1000 hours of mountain activity.

RESULTS

Two hundred two patients were included during the study period. Trauma (65.1% vs. 24.6%, p < 0.001) and head commotive injury (48.1% vs. 15.1%, p < 0.001) were more frequent during winter compared to the summer season. High altitude illness (36.9% vs. 9.3%, p < 0.001) and cold pathologies (15.1% vs. 0.1%, p < 0.001) occurred more frequently in summer than in winter. Patients (51.4%) were immediately discharged from emergency room, 8.4% after a 24-hour observation period, and 30.6% required hospitalization. During summer, the event risk is 0.013 per person and 1000 hours of mountain activity, while in winter, event risk amounts to 0.005 per person and 1000 hours of mountain activity.

COMMENTS

High altitude medical events or trauma represent <1% of pathologies observed in the emergency room department of a mountain district in the western Alps. Head commotive injury is the most observed mountain-related event in high altitude, in winter and during ski practice. High altitude illness and cold injuries are observed more frequently in summer, during trekking or climbing activities.

Serum potassium concentration predicts brain hypoxia on CT after avalanche-induced cardiac arrest

BACKGROUND

Brain anoxia after complete avalanche burial and cardiac arrest (CA) may occur despite adequate on-site triage.

PURPOSE

To investigate clinical and biological parameters associated with brain hypoxia in a cohort of avalanche victims with whole body computed tomographic (CT) scan.

METHODS

Retrospective study of patients with CA and whole body CT scan following complete avalanche burial admitted in a level-I trauma center.

MAIN FINDINGS

Out of 19 buried patients with whole body CT scan, eight patients had refractory CA and 11 patients had pre-hospital return of spontaneous circulation. Six patients survived at hospital discharge and only two had good neurologic outcome. Twelve patients had signs of brain hypoxia on initial CT scan, defined as brain edema, loss of gray/white matter differentiation and/or hypodensity of basal ganglia. No clinical pre-hospital parameter was associated with brain anoxia. Serum potassium concentration at admission was higher in patients with brain anoxia as compared to patients with normal CT scan: 5.5 (4.1-7.2) mmol/L versus 3.3 (3.0-4.2) mmol/L, respectively (P<.01). A threshold of 4.35 mmol/L serum potassium had 100% specificity to predict brain anoxia on brain CT scan.

CONCLUSIONS

Serum potassium concentration had good predictive value for brain anoxia after complete avalanche burial. This finding further supports the use of serum potassium concentration for extracorporeal life support insertion at hospital admission in this context.

Work of Breathing into Snow in the Presence versus Absence of an Artificial Air Pocket Affects Hypoxia and Hypercapnia of a Victim Covered with Avalanche Snow: A Randomized Double Blind Crossover Study

Presence of an air pocket and its size play an important role in survival of victims buried in the avalanche snow. Even small air pockets facilitate breathing. We hypothesize that the size of the air pocket significantly affects the airflow resistance and work of breathing. The aims of the study are (1) to investigate the effect of the presence of an air pocket on gas exchange and work of breathing in subjects breathing into the simulated avalanche snow and (2) to test whether it is possible to breathe with no air pocket. The prospective interventional double-blinded study involved 12 male volunteers, from which 10 completed the whole protocol. Each volunteer underwent two phases of the experiment in a random order: phase “AP”—breathing into the snow with a one-liter air pocket, and phase “NP”—breathing into the snow with no air pocket. Physiological parameters, fractions of oxygen and carbon dioxide in the airways and work of breathing expressed as pressure-time product were recorded continuously. The main finding of the study is that it is possible to breath in the avalanche snow even with no air pocket (0 L volume), but breathing under this condition is associated with significantly increased work of breathing. The significant differences were initially observed for end-tidal values of the respiratory gases (EtO₂ and EtCO₂) and peripheral oxygen saturation (SpO₂) between AP and NP phases, whereas significant differences in inspiratory fractions occurred much later (for F_IO₂) or never (for F_ICO₂). The limiting factor in no air pocket conditions is excessive increase in work of breathing that induces increase in metabolism accompanied by higher oxygen consumption and carbon dioxide production. The presence of even a small air pocket reduces significantly the work of breathing.

The prehospital management of avalanche victims

Avalanche accidents are frequently lethal events with an overall mortality of 23%. Mortality increases dramatically to 50% in instances of complete burial. With modern day dense networks of ambulance services and rescue helicopters, health workers often become involved during the early stages of avalanche rescue. Historically, some of the most devastating avalanche accidents have involved military personnel. Armed forces are frequently deployed to mountain regions in order to train for mountain warfare or as part of ongoing conflicts. Furthermore, military units are frequently called to assist civilian organised rescue in avalanche rescue operations. It is therefore important that clinicians associated with units operating in mountain regions have an understanding of, the medical management of avalanche victims, and of the preceding rescue phase. The ensuing review of the available literature aims to describe the pathophysiology particular to avalanche victims and to outline a structured approach to the search, rescue and prehospital medical management.

Outcome of avalanche victims with out-of-hospital cardiac arrest

STUDY BACKGROUND

Previous studies focused on the outcome of avalanche victims with out-of-hospital cardiac arrest (OHCA) after long duration of burial (>35min); the outcome of victims with short duration (≤35min) remains obscure.

AIM OF THE STUDY

To investigate outcome of avalanche victims with OHCA.

METHODS

Retrospective analysis of avalanche victims with OHCA between 2008 and 2013 in the Tyrolean Alps.

RESULTS

55 avalanche victims were identified, 32 of whom were declared dead after extrication without cardiopulmonary resuscitation (CPR), all with long duration of burial. In the remaining 23 CPR was initiated at scene; three were partially and 20 completely buried, nine of whom suffered short and 11 long duration of burial. All nine victims with short duration of burial underwent restoration of spontaneous circulation (ROSC) at scene, four of them after bystander CPR, five after advanced life support by the emergency physician. Two patients with ROSC after short duration of burial and bystander CPR survived to hospital discharge with cerebral performance category 1. None of the 11 victims with long duration of burial survived to hospital discharge, although six were transported to hospital with ongoing CPR and three were supported with extracorporeal circulation.

CONCLUSIONS

In this case series survival with favourable neurological outcome was observed in avalanche victims with short duration of burial only if bystander CPR was immediately performed and ROSC achieved. Strategies for reducing avalanche mortality should focus on prompt extrication from the snow and immediate bystander CPR by uninjured companions.

Effect of head and face insulation on cooling rate during snow burial

OBJECTIVES

Avalanche victims are subjected to a number of physiological stressors during burial. We simulated avalanche burial to monitor physiological data and determine whether wearing head and face insulation slows cooling rate during snow burial. In addition, we sought to compare 3 different types of temperature measurement methods.

METHODS

Nine subjects underwent 2 burials each, 1 with head and face insulation and 1 without. Burials consisted of a 60-minute burial phase followed by a 60-minute rewarming phase. Temperature was measured via 3 methods: esophageal probe, ingestible capsule, and rectal probe.

RESULTS

Cooling and rewarming rates were not statistically different between the 2 testing conditions when measured by the 3 measurement methods. All temperature measurement methods correlated significantly.

CONCLUSIONS

Head and face insulation did not protect the simulated avalanche victim from faster cooling or rewarming. Because the 3 temperature measurement methods correlated, the ingestible capsule may provide an advantageous noninvasive method for snow burial and future hypothermia studies if interruptions in data transmission can be minimized.

Survival after avalanche-induced cardiac arrest

AIM

Criteria to prolong resuscitation after cardiac arrest (CA) induced by complete avalanche burial are critical since profound hypothermia could be involved. We sought parameters associated with survival in a cohort of victims of complete avalanche burial.

METHODS

Retrospective observational study of patients suffering CA on-scene after avalanche burial in the Northern French Alps between 1994 and 2013. Criteria associated with survival at discharge from the intensive care unit (ICU) were collected on scene and upon admission to Level-1 trauma center. Neurological outcome was assessed at 3 months using cerebral performance category score.

RESULTS

Forty-eight patients were studied. They were buried for a median time of 43 min (25-76 min; 25-75th percentiles) and had a pre-hospital body core temperature of 28.0°C (26.0-30.7). Eighteen patients (37.5%) had pre-hospital return of spontaneous circulation and 30 had refractory CA. Rewarming of 21 patients (43.7%) was performed using extracorporeal life support. Eight patients (16.7%) survived and were discharged from the ICU, three (6.3%) had favorable neurological outcome at 3 months. Pre-hospital parameters associated with survival were the presence of an air pocket and rescue collapse. On admission, survivors had lower serum potassium concentrations than non-survivors: 3.2 mmol/L (2.7-4.0) versus 5.6 mmol/L (4.2-8.0), respectively (P<0.01). They also had normal values for prothrombin and activated partial thromboplastin compared to non-survivors.

CONCLUSIONS

Our findings indicate that survival after avalanche burial and on-scene CA is rarely associated with favorable neurological outcome. Among criteria associated with survival, normal blood coagulation on admission warrants further investigation.

The effectiveness of avalanche airbags

AIM

Asphyxia is the primary cause of death among avalanche victims. Avalanche airbags can lower mortality by directly reducing grade of burial, the single most important factor for survival. This study aims to provide an updated perspective on the effectiveness of this safety device.

METHODS

A retrospective analysis of avalanche accidents involving at least one airbag user between 1994 and 2012 in Austria, Canada, France, Norway, Slovakia, Switzerland and the United States. A multivariate analysis was used to calculate adjusted absolute risk reduction and estimate the effectiveness of airbags on grade of burial and mortality. A univariate analysis was used to examine causes of non-deployment.

RESULTS

Binomial linear regression models showed main effects for airbag use, avalanche size and injuries on critical burial, and for grade of burial, injuries and avalanche size on mortality. The adjusted risk of critical burial is 47% with non-inflated airbags and 20% with inflated airbags. The adjusted mortality is 44% for critically buried victims and 3% for non-critically buried victims. The adjusted absolute mortality reduction for inflated airbags is -11 percentage points (22% to 11%; 95% confidence interval: -4 to -18 percentage points) and adjusted risk ratio is 0.51 (95% confidence interval: 0.29 to 0.72). Overall non-inflation rate is 20%, 60% of which is attributed to deployment failure by the user.

CONCLUSION

Although the impact on survival is smaller than previously reported, these results confirm the effectiveness of airbags. Non-deployment remains the most considerable limitation to effectiveness. Development of standardized data collection protocols is encouraged to facilitate further research.

High-altitude mountaineering made safer

Mountains all over the world are attracting a steadily growing number of visitors due to the increasing number of cheap flights; the construction of new roads, railways, and cable cars; and commercial offers of trekking tours and expeditions to attempt even the world's highest peaks. However, one must not forget that mountains are typically inhospitable areas characterised by cold and hypoxic environments and rapidly changing weather and track conditions associated with a relatively high risk of accidents and emergencies. Beside the objective hazards, subjective hazards, for example physical fitness and health status, mountaineering skills, and equipment, contribute substantially to the risk. Whereas in some regions, for example the Alps, rescue operations and medical emergency interventions can be performed rapidly and effectively, this is absolutely not the case in most of the very remote areas and on very high mountains. Therefore, the understanding of the risk associated with the various modes of mountaineering as well as knowledge about how to optimise prevention is of the utmost importance. Ultimately, it is the informed mountaineer who has to decide whether the risks are acceptable or not. Continuing joint efforts of scientists, medical and alpine institutions, expedition organisers, and mountaineers will help to make high-altitude mountaineering safer.

Wilderness medicine

BACKGROUND

Human activity in wilderness areas has increased globally in recent decades, leading to increased risk of injury and illness. Wilderness medicine has developed in response to both need and interest.

METHODS

The field of wilderness medicine encompasses many areas of interest. Some focus on special circumstances (such as avalanches) while others have a broader scope (such as trauma care). Several core areas of key interest within wilderness medicine are discussed in this study.

RESULTS

Wilderness medicine is characterized by remote and improvised care of patients with routine or exotic illnesses or trauma, limited resources and manpower, and delayed evacuation to definitive care. Wilderness medicine is developing rapidly and draws from the breadth of medical and surgical subspecialties as well as the technical fields of mountaineering, climbing, and diving. Research, epidemiology, and evidence-based guidelines are evolving. A hallmark of this field is injury prevention and risk mitigation. The range of topics encompasses high-altitude cerebral edema, decompression sickness, snake envenomation, lightning injury, extremity trauma, and gastroenteritis. Several professional societies, academic fellowships, and training organizations offer education and resources for laypeople and health care professionals.

CONCLUSIONS

THE FUTURE OF WILDERNESS MEDICINE IS UNFOLDING ON MULTIPLE FRONTS: education, research, training, technology, communications, and environment. Although wilderness medicine research is technically difficult to perform, it is essential to deepening our understanding of the contribution of specific techniques in achieving improvements in clinical outcomes.

Fatalities Among Iranian High-altitude Outdoor Enthusiasts: Causes and Mechanisms

Purpose

This study was performed to determine the possible causes and mechanisms of fatalities among Iranian mountaineers during climbing.

Methods

By contacting several sources, deceased mountaineers were identified. Data about the causes and mechanism of death was retrospectively obtained using a standard questionnaire for each case.

Results

A total of 29 deaths were identified from March 2006 to June 2010. Deceased subjects had a mean age of 39 years (SD: 12.8, Range: 20-67). Falling was the most common accident leading to death of outdoor enthusiasts (n = 14, 48%). Asphyxia (n = 6, 24%) was the most common cause of death among the subjects, followed by heart attack, internal bleeding, cerebral hemorrhage and hypothermia (17%, 17%, 17% and 10%, respectively).

Conclusions

Our findings suggest that education of medical service providers of the climbing groups on facing victims in high altitude areas, where they have limited resources, can be particularly helpful. In addition, a national program to educate mountaineers might help to reduce fatalities.