Snow avalanches are a primary climate-linked driver of mountain ungulate populations

Snow is a major, climate-sensitive feature of the Earth's surface and catalyst of fundamentally important ecosystem processes. Understanding how snow influences sentinel species in rapidly changing mountain ecosystems is particularly critical. Whereas effects of snow on food availability, energy expenditure, and predation are well documented, we report how avalanches exert major impacts on an ecologically significant mountain ungulate - the coastal Alaskan mountain goat (Oreamnos americanus). Using long-term GPS data and field observations across four populations (421 individuals over 17 years), we show that avalanches caused 23-65% of all mortality, depending on area. Deaths varied seasonally and were directly linked to spatial movement patterns and avalanche terrain use. Population-level avalanche mortality, 61% of which comprised reproductively important prime-aged individuals, averaged 8% annually and exceeded 22% when avalanche conditions were severe. Our findings reveal a widespread but previously undescribed pathway by which snow can elicit major population-level impacts and shape demographic characteristics of slow-growing populations of mountain-adapted animals.

Prevalence of airway patency and air pocket in critically buried avalanche victims - a scoping review

INTRODUCTION

Survival of critically buried avalanche victims is directly dependent on the patency of the airway and the victims' ability to breathe. While guidelines and avalanche research have consistently emphasized on the importance of airway patency, there is a notable lack of evidence regarding its prevalence.

OBJECTIVE

The aim of this review is to provide insight into the prevalence of airway patency and air pocket in critically buried avalanche victims.

METHODS

A scoping review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline extension for scoping reviews. MEDLINE and Cochrane databases, as well as additional manual searching was performed to identify literature reporting data on airway patency and the presence of an air pocket in critically buried avalanche victims. After eliminating duplicates, we screened abstracts and main texts to identify eligible studies.

RESULTS

Of 4,109 studies identified 154 were eligible for further screening. Twenty-four publications and three additional data sources with a total number of 566 cases were included in this review. The proportion of short-term (< 35 min) to long-term burial (≥ 35 min) in the analysed studies was 19% and 66%, respectively. The burial duration remained unknown in 12% of cases. The prevalence of airway patency in critically buried avalanche victims was 41% while that of airway obstruction was 12%, with an overall rate of reporting as low as 50%. An air pocket was present in 19% of cases, absent in 46% and unknown in 35% of the cases.

CONCLUSION

The present study found that in critically buried avalanche victims patent airways were more than three times more prevalent than obstructed, with the airway status reported only in half of the cases. This high rate of airway patency supports the ongoing development and the effectiveness of avalanche rescue systems which oppose asphyxiation in critically buried avalanche victims. Further effort should be done to improve the documentation of airway patency and the presence of an air pocket in avalanche victims and to identify factors affecting the rate of airway obstruction.

Quality of Cardiopulmonary Resuscitation in Avalanche Victims with a Single Rescuer: A Prospective, Crossover, Manikin Pilot Study

Tanaka, Shota, Koshi Nakagawa, Yosuke Kanagawa, Takashi Katsurahara, Kazuki Kozakai, Ken Tsuhako, Fumitaka Yoshikawa, Soh Gotoh, Kensuke Osanai, Madoka Sono, Hironori Inoue, Shuji Sakanashi, Hiroyuki Takahashi, and Hideharu Tanaka. Quality of cardiopulmonary resuscitation in avalanche victims with a single rescuer: a prospective, crossover, manikin pilot study. High Alt Med Biol. 25:60-67, 2024. Background: Winter outdoor recreational activities such as off-piste skiing have gained popularity and, as a result, the number of avalanche-related deaths has increased. However, the quality of cardiopulmonary resuscitation (CPR) at avalanche sites remains unclear. Our study compared the quality of CPR performed in a simulated avalanche burial on a snowy mountain with that performed indoors. Methods: Ten prehospital health care providers participated in the crossover pilot study. Various methods, including over-the-head CPR (OTH-CPR) and standard CPR, were used to perform avalanche resuscitation, with five rescue breaths, followed by 30 chest compressions and two breaths. The quality CPR was judged by four variables of chest compression and ventilation. Results: The OTH-CPR performed indoors was better in quality: 5.33% [95% confidence interval (CI) -14.2 to 3.5] higher in adequate compression depth (94.3 ± 10.6% on the snow vs. 99.3 ± 1.1% indoors), 3.4% [95% CI -16.1 to 22.9] higher in adequate compression rate (70.4 ± 38.0% vs. 76.1 ± 35.7%), and 2.3% [95% CI -6.4 to 1.72] higher in adequate recoil (96.9 ± 4.8% vs. 99.2 ± 1.6%) than OTH-CPR on the snow. In terms of ventilation quality, OTH-CPR performed indoors had a 50% higher ventilation score [95% CI -73.0 to -27.0] than OTH-CPR on the snow (1.4 ± 4.3% vs. 45.9 ± 32.6%, Cohen's d = -1.81). Conclusions: Chest compression quality was slightly impaired in the avalanche scenarios on the snow than in indoor settings. Asphyxiation is the main cause of avalanche-related deaths; however, low ventilation quality was observed on snow compared with the indoor setting.

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.

Surviving 20 Hours of Critical Avalanche Burial and a Core Temperature of 22.5 °C

A 24-year-old male snowboarder was buried in an avalanche for 20 h and rescued on the next day at a depth of 2.3 m below the snow surface. A large air pocket was noted in front of his mouth and nose. He was responsive but moved restlessly and uncoordinatedly. The epitympanic temperature was 22.5 °C. He was bradycardic (35/min), and a right bundle branch block with Osborn waves was noted. Rewarming (1 °C/h) was initiated with continuous hemodialysis; core temperature raised to 29.8 °C within 4 h. At 30 °C he became conscious. With rewarming, the heart rate increased to 90 beats per minute and the ECG changes disappeared; nonfreezing cold injuries were noted. On the next day, his pulmonary function deteriorated-fluid overload of 9 L since admission was diagnosed. With spontaneous diuresis, the situation improved. On Day 4, the neurologist reported subtle polyneuropathy in both legs secondary to hypothermia, without tendency to regress. This case occurred more than 20 years ago but has not been reported yet. To this day, this is the third-longest critical avalanche burial ever reported. We discuss the circumstances of this accident, the clinical course, and how treatment has changed since 2000.

Prolonged critical avalanche burial for nearly 23 h with severe hypothermia and severe frostbite with good recovery: a case report

BACKGROUND

Accidental hypothermia with severe frostbite is a rare combination of injuries with a high risk for long-term sequelae. There are widely accepted recommendations for the management of avalanche victims and for frostbite treatment, but no recommendation exists for the treatment of frostbite in severe hypothermic patients, specifically for the management of hypothermic avalanche victims presenting with frostbite.

CASE PRESENTATION

We present a case of a previously healthy, 53-year-old male skier who was critically buried by an avalanche at 2300 m of altitude at an ambient temperature of - 8 °C for nearly 23 h. The victim was found with the right hand out of the snow and an air connection to outside. He was somnolent with Glasgow Coma Scale 11 (Eye 4, Verbal 2, Motor 5) and spontaneously breathing, in a severely hypothermic state with an initial core temperature of 23.1 °C and signs of cold injuries in all four extremities. After rescue and active external forced air rewarming in the intensive care unit, the clinical signs of first-degree frostbite on both feet and the left hand vanished, while third- to fourth-degree frostbite injuries became apparent on all fingers of the right hand. After reaching a core body temperature of approximately 36 °C, aggressive frostbite treatment was started with peripheral arterial catheter-directed thrombolysis with alteplase, intravenous iloprost, ibuprofen, dexamethasone and regional sympathicolysis with a right-sided continuous axillary block. After ten months, the patient had no tissue loss but needed neuropathic pain treatment with pregabalin.

CONCLUSION

The combination of severe accidental hypothermia and severe frostbite is rare and challenging, as drug metabolism is unpredictable in a hypothermic patient and no recommendations for combined treatment exist. There is general agreement to give hypothermia treatment the priority and to begin frostbite treatment as early as possible after full rewarming of the patient. More evidence is needed to identify the optimal dosage and time point to initiate treatment of frostbite in severely hypothermic patients. This should be taken into consideration by future treatment recommendations.

History of Avalanches in the Eastern Spanish Pyrenees

Avalanches have caused injuries and deaths in mountain areas throughout history. We have examined the historical effects of avalanches on communities in the eastern Spanish Pyrenees. Surviving written records began in the year 1444 when an avalanche destroyed the village of Gessa. Many other avalanches since then have destroyed houses and other buildings and have caused injuries and deaths. In the 20th and 21st centuries, many villages evolved from agrarian areas to destinations for winter sports. The first known deaths during winter recreation likely occurred in 1930. Because of avalanche mitigation efforts, including relocating settlements, physical barriers, avalanche control measures, efforts to increase avalanche awareness, and avalanche warnings, avalanches now seldom affect inhabited areas in the eastern Spanish Pyrenees. Avalanche injuries and fatalities are now mainly limited to backcountry skiers and others traveling out of bounds near avalanche-controlled ski resorts.

Avalanche Education Is Associated with Increased Avalanche Safety Practices in the New Hampshire Backcountry

INTRODUCTION

Avalanche risk can be mitigated by adhering to certain safety practices. Previous studies of these practices have focused on western United States and European cohorts. We conducted a survey of backcountry users in the White Mountains of New Hampshire to determine local adherence to 5 previously studied avalanche safety practices. We assessed whether participants were carrying transceiver, probe, and shovel (TPS); had formal avalanche education; had awareness of the day's avalanche danger level; had a route plan; and were traveling in a group.

METHODS

Backcountry users in the White Mountains were directed to an online survey from December 2020 to June 2021. The survey was completed individually and queried demographics and avalanche safety practices.

RESULTS

A total of 133 users participated. Not all surveyed participants answered all questions. Avalanche training was reported by 87% of users, 86% checked the avalanche forecast prior to recreating, 93% had a travel plan, 87% traveled in a group, and 59% carried TPS. All 3 items were carried by all group members only 48% of the time. Only 28% of users met all 5 safety practices.

CONCLUSIONS

White Mountains backcountry users are less likely to meet avalanche safety practices than users in previous studies. There is an association between meeting these defined safety practices and formal avalanche education.

Chirality-induced avalanche magnetization of magnetite by an RNA precursor

Homochirality is a hallmark of life on Earth. To achieve and maintain homochirality within a prebiotic network, the presence of an environmental factor acting as a chiral agent and providing a persistent chiral bias to prebiotic chemistry is highly advantageous. Magnetized surfaces are prebiotically plausible chiral agents due to the chiral-induced spin selectivity (CISS) effect, and they were utilized to attain homochiral ribose-aminooxazoline (RAO), an RNA precursor. However, natural magnetic minerals are typically weakly magnetized, necessitating mechanisms to enhance their magnetization for their use as effective chiral agents. Here, we report the magnetization of magnetic surfaces by crystallizing enantiopure RAO, whereby chiral molecules induce a uniform surface magnetization due to the CISS effect, which spreads across the magnetic surface akin to an avalanche. Chirality-induced avalanche magnetization enables a feedback between chiral molecules and magnetic surfaces, which can amplify a weak magnetization and allow for highly efficient spin-selective processes on magnetic minerals.

Stuck in an Avalanche-A Graphic Story

This Arts and Medicine feature tells the story of a patient with undiagnosed illness caught in the futile administrative cycles of the US health care system.

Debris flow simulation and modeling of the 2021 flash flood hazard caused by a rock-ice avalanche in the Rishiganga River valley of Uttarakhand

The high mountain ecosystem of the Indian Himalayas has frequently been experiencing primary hazards (like earthquakes, avalanches, and landslides). Often, these events are followed by the triggering of secondary hazards (like landslide dams, debris flows, and flooding), thereby posing massive risks to infrastructure and residents in the region. This study was taken up to understand the dynamics of an extraordinary debris flood disaster in the Rishiganga River valley, Chamoli district of Uttarakhand on 7th February 2021. Rapid mass movements (RAMMS)-debris flow software was employed to recreate the entire sequence of the hazard consisting of a rock-ice slide, mass deposition and erosion along the channel, and subsequent debris flood. Forty-nine scenarios were analyzed for accurate calibration of dry-Coulomb type friction coefficient (µ) and viscous-turbulent friction coefficient (ξ). Consequently, the geomorphologic characteristics of the debris flow were validated using high-resolution satellite image interpretation and field photographs. The volume of detached rock-ice mass was estimated to be 26.42 × 106 m3. At the same time, the RAMMS-derived model outputs for velocity, flow depth, and momentum were found in good agreement with the extent and height of actual debris on the ground. The study highlights an urgent need to identify the glaciers with a high risk of ice avalanches in the Indian Himalayas. The presented modeling approach may be applied in dynamic mountain ecosystems to simulate potential flash floods due to avalanches. Moreover, the information reported in this study can be vital input for improving the district-level disaster management plan.

Productivity Decline or Administrative Avalanche? Examining Factors That Shape Changing Workloads in Primary Care

Background

In Canada, family physicians (FPs) per capita have increased but so have access challenges. We explored changes in population characteristics, service delivery and FP practice that may help understand these trends.

Methods

We used linked administrative data in British Columbia to describe changes in patient ages and comorbidities, hospitalizations and receipt of services that may require FP coordination, review and/or follow-up: prescriptions dispensed, laboratory tests, diagnostic imaging (radiology and ultrasound), specialist visits and emergency department visits. We estimate the number of FPs delivering community-based comprehensive care and report changes in service volume per community-based FP visit.

Results

Between 1999/2000 and 2017/2018, people experienced fewer days in hospital, but the number of treated comorbidities, day surgeries and other services requiring FP coordination increased over and above the expected levels attributed to population aging. While the total number of FPs per capita have increased, numbers in community-based care have not and visits per physician have fallen. Increases in services that may involve FP coordination per community-based FP visit ranged from 32.2% for diagnostic radiology to 122.1% for lab tests.

Conclusion

Findings suggest substantially increased coordination workload per FP visit. Ongoing impacts of population aging and changing service delivery on primary care workload require further examination.

Takotsubo Cardiomyopathy Following Complete Avalanche Burial: A Case Report

Libersa, Marie, Louis Marxer, Ken Zafren, Stephane Oggier, Lorenzo Pucci, and Mathieu Pasquier. Takotsubo cardiomyopathy following complete avalanche burial: a case report. High Alt Med Biol. 24:149-151, 2023.-Takotsubo cardiomyopathy is a transient left ventricular dyskinesia triggered by a stressful physical or emotional event. We report a case of mid-ventricular Takotsubo stress cardiomyopathy in an avalanche victim. The patient was a 41-year-old woman who was completely buried under 1.2 m of snow for 30 minutes. On arrival at the hospital, she was conscious and hypothermic (core temperature 33.7°C). Her ECG showed rapid atrial fibrillation (142 beats/min) that converted to sinus rhythm after rewarming and administration of crystalloids. Echocardiography showed akinesia of the left mid-ventricle with a left ventricular ejection fraction of 41%. At 48-hour follow-up, echocardiography showed an almost complete recovery. During her hospital stay the patient was diagnosed with an acute stress disorder with symptoms of dissociation. She was discharged home after 5 days. At 2-week follow-up echocardiography was normal. Psychological follow-up was normal at 7 months. The physical and psychological stress of the avalanche, as well as hypothermia, were all possible triggers of Takotsubo cardiomyopathy.

Towards a holistic paradigm for long-term snow avalanche risk assessment and mitigation

In mountain territories, snow avalanches are a prevalent threat. Long-term risk management involves defining meaningful compromises between protection and overall sustainability of communities and their environment. Methods able to (i) consider all sources of losses, (ii) account for the high uncertainty levels that affect all components of the risk and (iii) cope for marked non-stationarities should be employed. Yet, on the basis of a literature review and an analysis of relations to Sustainable Development Goals (SDGs), it is established that snow avalanche risk assessment and mitigation remain dominated by approaches that can be summed up as deterministic, hazard oriented, stationary and not holistic enough. A more comprehensive paradigm relying on formal statistical modelling is then proposed and first ideas to put it to work are formulated. Application to different mountain environments and broader risk problems is discussed.

Survival in a Collapsed Stable for 37 Days After Avalanche Burial in 1755

In 1755 in Bergemoletto, Italy, an avalanche buried 4 people (2 women, a girl, and a boy) and several animals in a stable. After 37 d in a pitch-dark confined space, 3 of the 4 people were rescued alive. The 3 survivors had only goat milk, a few chestnuts, a few kg of raw kid meat, and meltwater for nutrition. We describe the longest-known survival in an avalanche burial and discuss the medical and psychological problems of the survivors. The boy died. When they were extricated, all 3 survivors were exhausted, cachectic, and unable to stand or walk. They were severely malnourished and were experiencing tingling, tremors, and weakness in the legs; constipation; changes in taste; and amenorrhea. One of the women had persistent eye problems and developed symptoms consistent with post-traumatic stress disorder. The survivors were given slow refeeding. It took from 1 to 6 wk before they could walk. We compare this case to other long-duration burials, especially mining accidents, and describe the rescue and patient care after long-duration burials. This case demonstrates that people can overcome extremely adverse conditions and survive.

Occasional but severe: Past debris flows and snow avalanches in the Helmos Mts. (Greece) reconstructed from tree-ring records

The eastern Mediterranean is a hotspot in terms of geomorphic hazards, but the activity of gravitational processes in mountainous areas is largely unexplored. We carried out dendrogeomorphic research in the Helmos Mountains (Northern Peloponnese, Greece) to determine the timing, spatial extent, and hydrometeorological triggers of debris flows and snow avalanches. Specifically, we sampled increment cores from 123 injured Greek firs (Abies cephalonica L.) growing on a debris flow cone and growing along a snow avalanche track. Tree rings were counted and cross-dated with the reference chronology using CooRecorder and CDendro software and the event years were determined on the basis of the location of scars and traumatic resin ducts. We compiled an 118-year chronology (1904-2021) with seven debris flow event years and only one severe debris flow occurring in the 1970/1971 dormant period (W_It = 148.0), followed by spatially limited records for 1986/1987 (W_It = 3.8) and 1993/1994 (W_It = 2.5). Similarly, seven snow avalanche event years were identified in the period 1854-2021, with one major event in 1997/1998 (W_It = 304.5) followed by the 1998/1999 event (W_It = 6.3). Extremely wet conditions in February-March 1971 followed by rain-on-snow precipitation were considered as the most likely trigger of the analysed debris flow event using data from nearby meteorological stations and the ERA5 reanalysis. The snow avalanche event was deciphered in the spring of 1998, when heavy snowfall over three days (62 cm) was followed by rapid snowmelt due to high average temperatures (6-11 °C). We conclude that the abundance of snow is a crucial factor in the geomorphic activity in the study region and that the temperature fluctuations and rain-to-snow transitions are the leading factors for the debris flows or snow avalanches to occur. Furthermore, the dendrogeomorphic approach used can be useful to clearly identify large-scale geomorphic events and excludes potential geomorphic noise caused by other ecological stresses.

Imminent threat of rock-ice avalanches in High Mountain Asia

Upsurge of glacier-related hazards in High Mountain Asia (HMA) has been evident in recent years due to global warming. While many glacial-related hazards are instantaneous, some large landslides were preceded by slow gravitational deformation, which can be predicted to evade catastrophes. Here, we present robust evidence of historical deformation in 2021 Chamoli rock-ice avalanche of Himalaya using space imaging techniques. Multi-temporal satellite data provide evidence of a precursor event in 2016 and expansion of a linear fracture along joint planes, indicating 2021 rock-ice avalanche is a retrogressive wedge failure. The deformation history shows that the fracture propagated at a velocity of ~0.07 m day^-1 until September 2020, and with an accelerated velocity (~0.14 m day^-1 on average) lately. Analysis of recent similar cases in HMA supported our inference on global warming-induced glacier retreat and thermomechanical effects in enhancing the weakening of fractured rock masses in tectonically active mountain belts. Recent advances in Earth observation and seismic monitoring system can offer clues to the location and timing of impending catastrophic failures in high mountain regions.

Temporal evolution of failure avalanches of the fiber bundle model on complex networks

We investigate how the interplay of the topology of the network of load transmitting connections and the amount of disorder of the strength of the connected elements determines the temporal evolution of failure cascades driven by the redistribution of load following local failure events. We use the fiber bundle model of materials' breakdown assigning fibers to the sites of a square lattice, which is then randomly rewired using the Watts-Strogatz technique. Gradually increasing the rewiring probability, we demonstrate that the bundle undergoes a transition from the localized to the mean field universality class of breakdown phenomena. Computer simulations revealed that both the size and the duration of failure cascades are power law distributed on all network topologies with a crossover between two regimes of different exponents. The temporal evolution of cascades is described by a parabolic profile with a right handed asymmetry, which implies that cascades start slowly, then accelerate, and eventually stop suddenly. The degree of asymmetry proved to be characteristic of the network topology gradually decreasing with increasing rewiring probability. Reducing the variance of fibers' strength, the exponents of the size and the duration distribution of cascades increase in the localized regime of the failure process, while the localized to mean field transition becomes more abrupt. The consistency of the results is supported by a scaling analysis relating the characteristic exponents of the statistics and dynamics of cascades.

AvaLife-A New Multi-Disciplinary Approach Supported by Accident and Field Test Data to Optimize Survival Chances in Rescue and First Aid of Avalanche Patients

Snow sports in the backcountry have seen a steep increase in popularity, and therefore preparedness for efficient companion and organized rescue is important. While technical rescue skills are widely taught, there is a lack of knowledge regarding first aid for avalanche patients. The stressful and time-critical situation for first responders requires a rule-based decision support tool. AvaLife has been designed from scratch, applying mathematical and statistical approaches including Monte Carlo simulations. New analysis of retrospective data and large prospective field test datasets were used to develop evidence-based algorithms exclusively for the avalanche rescue environment. AvaLife differs from other algorithms as it is not just a general-purpose CPR algorithm which has been slightly adapted for the avalanche patient. The sequence of actions, inclusion of the ≥150 cm burial depth triage criterion, advice to limit CPR duration for normothermic patients to 6 min in case of multiple burials and shortage of resources, criteria for using recovered subjects as a resource in the ongoing rescue, the adapted definition of "injuries incompatible with life", reasoning behind the utmost importance of rescue breaths, as well as the updated BLS-iCPR algorithm make AvaLife useful in single and multiple burial rescue. AvaLife is available as a companion rescue basic life support (BLS) version for the recreational user and an advanced companion and organized rescue BLS version for guides, ski patrols and mountain rescuers. AvaLife allows seamless interoperability with advanced life support (ALS) qualified medical personnel arriving on site.

Avalanches during epithelial tissue growth; Uniform Growth and a drosophila eye disc model

Epithelial tissues constitute an exotic type of active matter with non-linear properties reminiscent of amorphous materials. In the context of a proliferating epithelium, modeled by the quasistatic vertex model, we identify novel discrete tissue scale rearrangements, i.e. cellular rearrangement avalanches, which are a form of collective cell movement. During the avalanches, the vast majority of cells retain their neighbors, and the resulting cellular trajectories are radial in the periphery, a vortex in the core. After the onset of these avalanches, the epithelial area grows discontinuously. The avalanches are found to be stochastic, and their strength is correlated with the density of cells in the tissue. Overall, avalanches redistribute accumulated local spatial pressure along the tissue. Furthermore, the distribution of avalanche magnitudes is found to obey a power law, with an exponent consistent with sheer induced avalanches in amorphous materials. To understand the role of avalanches in organ development, we simulate epithelial growth of the Drosophila eye disc during the third instar using a computational model, which includes both chemical and mechanistic signaling. During the third instar, the morphogenetic furrow (MF), a ~10 cell wide wave of apical area constriction propagates through the epithelium. These simulations are used to understand the details of the growth process, the effect of the MF on the growth dynamics on the tissue scale, and to make predictions for experimental observations. The avalanches are found to depend on the strength of the apical constriction of cells in the MF, with a stronger apical constriction leading to less frequent and more pronounced avalanches. The results herein highlight the dependence of simulated tissue growth dynamics on relaxation timescales, and serve as a guide for in vitro experiments.

Numerical investigation of the effect of cohesion and ground friction on snow avalanches flow regimes

With ongoing global warming, snow avalanche dynamics may change as snow cohesion and friction strongly depend on temperature. In the field, a diversity of avalanche flow regimes has been reported including fast, sheared flows and slow plugs. While the significant role of cohesion and friction has been recognized, it is unclear how these mechanical properties affect avalanche flow regimes. Here, we model granular avalanches on a periodic inclined plane, using the distinct element method to better understand and quantify how inter-particle cohesion and ground friction influences avalanche velocity profiles. The cohesion between particles is modeled through bonds that can subsequently break and form, thus representing fragmentation and aggregation potentials, respectively. The implemented model shows a good ability to reproduce the various flow regimes and transitions as observed in nature: for low cohesion, highly sheared and fast flows are obtained while slow plugs form above a critical cohesion value and for lower ground frictions. Simulated velocity profiles are successfully compared to experimental measurements from the real-scale test site of Vallée de la Sionne in Switzerland. Even though the model represents a strong simplification of the reality, it offers a solid basis for further investigation of relevant processes happening in snow avalanches, such as segregation, erosion and entrainment, with strong impacts on avalanche dynamics research, especially in a climate change context.

Parameter importance assessment improves efficacy of machine learning methods for predicting snow avalanche sites in Leh-Manali Highway, India

Due to ongoing climate change, water mass redistribution and related hazards are getting stronger and frequent. Therefore, predicting extreme hydrological events and related hazards is one of the highest priorities in geosciences. Machine Learning (ML) methods have shown promising prospects in this venture. Every ML method requires training where we know both the output (extreme event) and input (relevant physical parameters and variables). This step is critical to the efficacy of the ML method. The usual approach is to include a wide variety of hydro-meteorological observations and physical parameters, but recent advances in ML indicate that the efficacy of ML may not improve by increasing the number of input parameters. In fact, including unimportant parameters decreases the efficacy of ML algorithms. Therefore, it is imperative that the most relevant parameters are identified prior to training. In this study, we demonstrate this concept by predicting avalanche susceptibility in Leh-Manali highway (one of the most severely affected regions in India) with and without Parameter Importance Assessment (PIA). The avalanche locations were randomly divided into two groups: 70% for training and 30% for testing. Then, based on temporal and spatial sensor data, eleven avalanche influencing parameters were considered. The Boruta algorithm, an extension of Random Forest (RF) ML method that utilizes the importance measure to rank predictors, was used and it found nine out of eleven parameters to be important. Support Vector Machine (SVM) based ML technique is used for avalanche prediction, and to be comprehensive, four different kernel functions were employed (linear, polynomial, sigmoid, and radial basis function (RBF)). The prediction accuracy for linear, polynomial, sigmoid, and RBF kernels, with all the eleven parameters were found to be 80.4%, 81.7%, 39.2%, and 85.7%, respectively. While, when using selected parameters, the prediction accuracy for linear, polynomial, sigmoid, and RBF kernels were 84.1%, 86.6%, 43.0%, and 87.8%, respectively. We also identified locations where occurrences of avalanches are most likely. We conclude that parameter selection should be considered when applying ML methods in geosciences.

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.

Powder Fever and Its Impact on Decision-Making in Avalanche Terrain

We examined the effect of emotions, associated with "powder fever", on decision-making in avalanche terrain.

BACKGROUND

Skiing in avalanche terrain is a voluntary activity that exposes the participant to potentially fatal risk. Impaired decision-making in this context can therefore have devastating results, often with limited prior corrective feedback and learning opportunities. Previous research has suggested that arousal caused by emotions affects risk assessment and intentions to engage in risky behavior. We propose that powder fever may induce similar responses.

METHODS

We used the following two experimental methods: laboratory studies with visual visceral stimuli (ski movies) and a field study with real stimuli (skiing exciting terrain). We evaluated the effect of emotions on attention, risk assessment, and willingness to expose oneself and others to risk.

RESULTS

Both the laboratory studies and the field study showed that skiing-related stimuli had a relatively strong effect on reported emotions. However, we found very few significant effects on decision-making or assessment of risk.

CONCLUSIONS

Skiing activities make people happier. However, despite the clear parallels to sexual arousal, powder fever does not appear to significantly impair decision-making in our study. More research on the effects of powder fewer on milder forms of risk-taking behavior is needed.

Noise and Breakdown Characterization of SPAD Detectors with Time-Gated Photon-Counting Operation

Being ready-to-detect over a certain portion of time makes the time-gated single-photon avalanche diode (SPAD) an attractive candidate for low-noise photon-counting applications. A careful SPAD noise and performance characterization, however, is critical to avoid time-consuming experimental optimization and redesign iterations for such applications. Here, we present an extensive empirical study of the breakdown voltage, as well as the dark-count and afterpulsing noise mechanisms for a fully integrated time-gated SPAD detector in 0.35-μm CMOS based on experimental data acquired in a dark condition. An "effective" SPAD breakdown voltage is introduced to enable efficient characterization and modeling of the dark-count and afterpulsing probabilities with respect to the excess bias voltage and the gating duration time. The presented breakdown and noise models will allow for accurate modeling and optimization of SPAD-based detector designs, where the SPAD noise can impose severe trade-offs with speed and sensitivity as is shown via an example.

Survivors of avalanche accidents: posttraumatic stress disorder symptoms and quality of life: a multicentre study

BACKGROUND

As any traumatic event, avalanches could trigger psychological disorders on survivors. Our objectives were to determine the prevalence of post-traumatic stress disorder among avalanche survivors and to evaluate post-traumatic stress disorder risks factors as well as the impact on quality of life.

METHODS

A multicentre study was conducted in victims included in the North Alpine Avalanche Registry from 2014 to 2018. Data were collected through a standard questionnaire during semi-directed phone interviews. The primary outcome was the total score on the Impact of Event Scale Revised. Secondary outcomes were the Mental Component Scale and the Physical Component Scale scores of the Short Form 12 questionnaire.

RESULTS

During the study period, 132 of 211 victims survived. Among the 107 victims included, 55 (51.4%) phone interviews were obtained. Six patients (10.9, 95% CI 1.76-20.05) had an Impact of Event Scale Revised score ≥ 33 indicating a strong probability for post-traumatic stress disorder. Median Mental Component Scale score was 39.0 (IQR 30.5-46.3) for post-traumatic stress disorder patients and 40.1 (IQR 36.5-43.4) for non post-traumatic stress disorder (p = 0.76). Median Physical Component Scale score was 39.4 (37.2-44.3) for post-traumatic stress disorder patients and 44.2 (39.1-46.8) for non post-traumatic stress disorder (p = 0.39). No significant difference in the quality of life in both populations was observed, and no independent risk factors of post-traumatic stress disorder was identified.

CONCLUSION

Avalanche accidents may induce post-traumatic stress disorders among survivors in a comparable prevalence to the most traumatic event already studied. Early recognition and preventive measures should be set up in order to reduce the psychological burden in these victims.

TRIAL REGISTRATION

NCT03936738 .

Single Photon Avalanche Diode Arrays for Time-Resolved Raman Spectroscopy

The detection of peaks shifts in Raman spectroscopy enables a fingerprint reconstruction to discriminate among molecules with neither labelling nor sample preparation. Time-resolved Raman spectroscopy is an effective technique to reject the strong fluorescence background that profits from the time scale difference in the two responses: Raman photons are scattered almost instantaneously while fluorescence shows a nanoseconds time constant decay. The combination of short laser pulses with time-gated detectors enables the collection of only those photons synchronous with the pulse, thus rejecting fluorescent ones. This review addresses time-gating issues from the sensor standpoint and identifies single photon avalanche diode (SPAD) arrays as the most suitable single-photon detectors to be rapidly and precisely time-gated without bulky, complex, or expensive setups. At first, we discuss the requirements for ideal Raman SPAD arrays, particularly focusing on the design guidelines for optimized on-chip processing electronics. Then we present some existing SPAD-based architectures, featuring specific operation modes which can be usefully exploited for Raman spectroscopy. Finally, we highlight key aspects for future ultrafast Raman platforms and highly integrated sensors capable of undistorted identification of Raman peaks across many pixels.

An Ultrafast Active Quenching Active Reset Circuit with 50% SPAD Afterpulsing Reduction in a 28 nm FD-SOI CMOS Technology Using Body Biasing Technique

An ultrafast Active Quenching-Active Reset (AQAR) circuit is presented for the afterpulsing reduction in a Single Photon Avalanche Diode (SPAD). The proposed circuit is designed in a 28 nm Fully Depleted Silicon On Insulator (FD-SOI) CMOS technology. By exploiting the body biasing technique, the avalanche is detected very quickly and, consequently, is quenched very fast. The fast quenching decreases the avalanche charges, therefore resulting in the afterpulsing reduction. Both post-layout and experimental results are presented and are highly in accordance with each other. It is shown that the proposed AQAR circuit is able to detect the avalanche in less than 40 ps and reduce the avalanche charge and the afterpulsing up to 50%.

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.

From a first person perspective: Soldiers' experiences three decades after an avalanche - A qualitative interview study

STUDY OBJECTIVES

The aim of this study was to explore indirectly exposed soldiers' subjective experiences following an avalanche. Three decades after the trauma, this study describes the perceived impact of the disaster by peers of those who survived or died in the avalanche.

METHOD

A qualitative, cross-sectional, study based on 17 individual interviews with persons indirectly exposed to an avalanche. Data was analysed according to qualitative content analysis.

FINDINGS

The findings revealed 'being a significant first person' as the main theme. Two categories were developed: 1) Experience of closeness to the victims 2) Experience of distance post-disaster. The categories elaborated two subcategories each: 1) Could have been me 2) Sadness, grief, shame and guilt over losing friends and 1) Unorganized military service post-disaster 2) Anger towards the system.

CONCLUSION

The soldiers indirectly exposed to the avalanche need to be seen both as a person and as a group. Both immediately following and decades after the disaster, the informants wanted the military to offer adequate follow-up.

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.

Snow avalanche deaths in Switzerland from 1995 to 2014-Results of a nation-wide linkage study

Objectives

More than 20 people die each year in snow avalanches in Switzerland. Previous studies have primarily described these victims, but were not population based. We investigated sociodemographic factors for avalanche mortality between 1995 and 2014 in the entire Swiss resident population.

Design and methods

Within the Swiss National Cohort we ascertained avalanche deaths by anonymous data linkage with the avalanche accident database at the Swiss WSL Institute of Snow and Avalanche Research SLF. We calculated incidence rates, by dividing the number of deaths from avalanches by the number of person-years, and hazard ratios (HRs) for sociodemographic and economic characteristics using Cox proportional hazard models.

Results

The data linkage yielded 250 deaths from avalanche within the SNC population for the 20 years 1995 to 2014. The median distance between the place of residence and the place of the event (avalanche) was 61.1 km. Male gender, younger age (15–45 years), Swiss nationality, living in the Alpine regions, higher education, living in the highest socioeconomic quintile of neighbourhoods, being single, and living in a household with one or more children were associated with higher avalanche mortality rates. Furthermore, for younger persons (<40 years) the hazard of dying in an avalanche between 2005 and 2014 was significantly lower than in the years 1995 to 2004 (HR = 0.56, 95%-CI: 0.36–0.85).

Conclusion

Over a 20-year period in Switzerland, higher rates of dying in an avalanche were observed in men, in younger age groups, and persons with tertiary education, living in the highest socioeconomic quintile of neighbourhoods, and living in an Alpine region. For younger persons (<40 years), the hazard declined during the study period.

The experiences of dealing with consequences of an avalanche - surviving soldiers' perspectives

Purpose: The aim of the study was to explore and describe experiences of daily life after having experienced an avalanche three decades ago.Method: This paper presents a qualitative study of 12 male survivors of an avalanche during their military service, interviewed 30 years post-disaster.Findings: A comprehensive understanding of the categories led to the latent theme "Finding my own way of managing and dealing with life". Findings revealed three categories describing experiences of daily living: (i) A comfortable life; (ii) A challenging, yet accomplished life; (iii) A demanding life. The first category represents a greater degree of using adaptive coping strategies for managing everyday life compared to the other two categories. The third category represents the group having the most challenging consequences. Among the three, the latter category conveys the most maladaptive coping strategies.Conclusions:The participants had different experiences with regards to their health and how they coped with their everyday life after the avalanche disaster. Insights into coping strategies may provide a guide for appropriate interventions for survivors dealing with traumatic events.

Management of accidental hypothermia: A narrative review

A narrative review is presented on the diagnosis, treatment and management of accidental hypothermia. Although all these processes form a continuum, for descriptive purposes in this manuscript the recommendations are organized into the prehospital and in-hospital settings. At prehospital level, it is advised to: a) perform high-quality cardiopulmonary resuscitation for cardiac arrest patients, regardless of body temperature; b) establish measures to minimize further cooling; c) initiate rewarming; d) prevent rescue collapse and continued cooling (afterdrop); and (e) select the appropriate hospital based on the clinical and hemodynamic situation of the patient. Extracorporeal life support has revolutionized rewarming of the hemodynamically unstable victim or patients suffering cardiac arrest, with survival rates of up to 100%. The new evidences indicate that the management of accidental hypothermia has evolved favorably, with substantial improvement of the final outcomes.

Identification of the technical and medical requirements for HEMS avalanche rescue missions through a 15-year retrospective analysis in a HEMS in Switzerland: a necessary step for quality improvement

BACKGROUND

Avalanche rescues mostly rely on helicopter emergency medical services (HEMS) and include technical rescue and complex medical situations under difficult conditions. The adequacy of avalanche victim management has been shown to be unexpectedly low, suggesting the need for quality improvement. We analyse the technical rescue and medical competency requirements of HEMS crewmembers for avalanche rescue missions, as well as their clinical exposure. The study aims to identify areas that should be the focus of future quality improvement efforts.

METHODS

This 15-year retrospective study of avalanche rescue by the Swiss HEMS Rega includes all missions where at least one patient had been caught by an avalanche, found within 24 h of the alarm being raised, and transported.

RESULTS

Our analyses included 422 missions (596 patients). Crews were frequently confronted with technical rescue aspects, including winching (29%) and patient location and extrication (48%), as well as multiple casualty accidents (32%). Forty-seven percent of the patients suffered potential or overt vital threat; 29% were in cardiac arrest. The on-site medical management of the victims required a large array of basic and advanced medical skills. Clinical exposure was low, as 56% of the physicians were involved in only one avalanche rescue mission over the study period.

CONCLUSIONS

Our data provide a solid baseline measure and valuable starting point for improving our understanding of the challenges encountered during avalanche rescue missions. We further suggest QI interventions, that might be immediately useful for HEMS operating under similar settings. A coordinated approach using a consensus process to determine quality indicators and a minimal dataset for the specific setting of avalanche rescue would be the logical next step.

Application of Ultraviolet Light in Dental Identification of Avalanche Victims

In any disaster, it becomes important to identify the deceased for ethical, social and legal causes.Out of the numerous methods of identification, dental comparison is considered to be one of the scientific methods in a Disaster Victim Identification process. The two victims of avalanche in Nepal were identified using dental comparison. The two bodies brought for examination were unidentifiable visually. To aid identification of tooth coloured restorations, ultraviolet light was used. The ultraviolet light made the tooth coloured restorations appear distinct from the adjacent tooth structure in one of the cases. This helped in post-mortem charting of dental examination with greater accuracy. When the ante-mortem dental records and the post-mortem dental findings were compared, positive identification was made for both the cases. The bodies were then handed over to their respective kin. These cases highlighted the importance of ultraviolet light in post-mortem dental examination and the significance of forensic dentistry in identification process.

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.

[Mountain medicine - an introduction. I]

Tourism to high-altitude areas is increasingly popular even from low-lying regions such as Denmark. Mountain sports include skiing, mountaineering, and ski touring. The young, elderly and at-risk individuals with pre-existing illnesses engage in recreational mountain activities. Thus, risk assessment and counselling regarding altitude exposure is increasingly relevant to all healthcare providers. In this first article of two in a review series, we summarize the state of the art of altitude physiology, alpine dangers and avalanches, and medical aspects of the increased UV-exposure at altitude.

[Death by avalanche in the minor mountain range]

On 30 Jan 2015, two avalanche accidents happened in the Black Forest (at the foot of the 1493 m high Feldberg and the Herzogenhorn situated next to it), in which experienced ski tourers--a 58-year-old woman and a 20-year-old man--were completely buried by snow masses. Both victims were recovered dead after nearly 2 hours under the snow. The avalanches were promoted by strong snowfalls, snowdrift by the wind and steep downwind slopes. One of the victims, the 20-year-old man, underwent a forensic autopsy. The findings suggested death by protracted asphyxiation with agonal hypothermia. A mechanical traumatization with internal injuries suspected by the emergency doctor at the scene could not be confirmed at autopsy. The possible causes of death in the avalanche are discussed using the reported case as an example and in reference to the relevant literature.

Posttraumatic stress and other health consequences of catastrophic avalanches: A 16-year follow-up of survivors

To date, no study has investigated the effects of avalanches on survivor's health beyond the first years. The aim of this study was to examine long-term health status 16 years after exposure to avalanches using a matched cohort design. Mental health, sleep quality and somatic symptoms among avalanche survivors (n=286) and non-exposed controls (n=357) were examined. Results showed that 16% of survivors currently experience avalanche-specific PTSD symptoms (PDS score>14). In addition, survivors presented with increased risk of PTSD hyperarousal symptoms (>85th percentile) (aRR=1.83; 98.3% CI [1.23-2.74]); sleep-related problems (PSQI score>5) (aRR=1.34; 95% CI [1.05-1.70]); PTSD-related sleep disturbances (PSQI-A score≥4) (aRR=1.86; 95% CI [1.30-2.67]); musculoskeletal and nervous system problems (aRR 1.43; 99% CI 1.06-1.93) and gastrointestinal problems (aRR 2.16; 99% CI 1.21-3.86) compared to the unexposed group. Results highlight the need for treatment for long-term PTSD symptoms and sleep disruption in disaster communities.

[Special challenges in the highest-elevation acute-care hospital in Europe]

Oberengadin Hospital in Samedan is faced with particular challenges, as the highest-elevation acute-care hospital in Europe (1750 m = 5,740 ft above sea level). The factors responsible for this are elevation-related and meteorological/climatic influences, as well as seasonal variations in Südbünden's demographic structure due to tourism.