Avalanche Accident Research Articles

Sequential Chimeric Osteocutaneous DCIA-Perforator-SIEA Flap to Reconstruct an Osteocutaneous Defect in the Lower Extremity and the Importance of Preserving the Ascending Branch - A Case Report

The deep circumflex iliac artery (DCIA) perforator flap is an established method to reconstruct osteocutaneous defects. However, the cutaneous perforators come with a great anatomic variability. To deal with this problem, we used a sequential chimeric osteocutaneous free flap for reconstruction. A 58-year-old man presented with an open tibial fracture after an avalanche accident resulting in an extended osteocutaneous defect in the lower extremity. The injury required osteocutaneous free flap coverage. We reconstructed the defect with a sequential chimeric osteocutaneous DCIA-perforator-SIEA flap. The preservation of the ascending branch of the deep circumflex iliac vessels offered us the possibility to effectively cover an extended osteocutaneous defect in the lower extremity with a sequential chimeric osteocutaneous DCIA-perforator-SIEA flap. In our patient, the sequential chimeric osteocutaneous DCIA-perforator-SIEA flap healed without complications. A small hernia developed at the inguinal donor site area, but it healed without further complications after surgical treatment. The patient regained an adequate function and returned to daily life and physical exercise. While preparing the DCIA-perforator free flap, it is important to preserve the ascending branch of the deep circumflex iliac vessels and the vessels needed to harvest either a SIEA or SCIP flap.

Simulation and Analysis of a Snow Avalanche Accident in Lower Western Himalaya, India

In Western Himalaya, an average 49 person die every year due to snow avalanche activities and this death rate is very high as compared to other Asian countries. A snow avalanche accident was observed on 5 January 2018 on Chowkibal–Tangdhar (CT) road axis at avalanche site number CT-8 located near Chowkibal village in Kupwara district, union territory Jammu and Kashmir, India. In the present paper, we discuss snow avalanche simulation, the climatic condition, avalanche debris height and length, and suggested solutions to handle avalanche situations. Rapid Mass MovementS numerical model in combination with digital elevation model and potential release area has been used to simulate avalanche accident occurred on 5 January 2018 at CT-8. The analysis demonstrates maximum snow avalanche velocity, impact of pressure and height of flow to be ~ 25 ms−1, ~ 9.39 × 104 kgm−1 s−2, and ~ 3.0 m respectively on 5 January 2018 at CT-8. Further simulated avalanche debris height and length form road has been validated with ground observed data. Ground reconnaissance of the location was conducted by a team of Snow and Avalanche Study Establishment, Chandigarh and it has been observed that lack of ‘avalanche awareness and Standard Operating Procedures during movement in avalanche prone areas’ among the travellers on the road cause accident . The present paper seems to be first to investigate snow avalanche accident in Western Himalaya and recommend that proper campaigning of avalanche awareness among the people residing in avalanche prone areas of Himalaya could reduce such accidents significantly.

Do avalanche airbags lead to riskier choices among backcountry and out-of-bounds skiers?

Abstract While the effectiveness of airbags for reducing mortality in avalanche involvements has been examined in various studies, the question of whether the added safety benefit might lead to increased risk-taking – a phenomenon referred to as risk compensation or risk homeostasis – has only been tackled by a few researchers. Building on the existing research on airbags, risk compensation, and stated terrain preferences in winter backcountry recreation, we conducted an extensive online survey including a discrete choice experiment to approach the topic of avalanche airbags and risk compensation from multiple perspectives. Our study sample consists of 163 airbag owners and 243 non-owners mainly from Switzerland, Germany, and Austria. The analyses of the survey responses provide both indirect and direct evidence that risk compensation in response to avalanche airbags is likely within at least certain segments of the recreational backcountry and out-of-bounds skiing population. Initial indirect evidence on risk compensation is provided by examining participants’ responses to airbag attitude and use questions using the framework of Hedlund (2000). The stated terrain preferences in our discrete choice experiment with and without airbags indicate that non-owners of airbags might make more aggressive terrain choices when they are given an airbag, whereas the preference patterns of owners did not change when the airbag was taken away from them. Finally, our analysis of avalanche involvement rates with and without airbags offers the most direct evidence that more thrill-seeking backcountry users are taking higher risks when equipped with airbags. The paper concludes with a discussion that highlights that the potential for risk compensation is not a strong argument against the use of avalanche airbags. Management implications • If properly used, avalanche airbags are an effective avalanche safety device for reducing the risk of critical burials and death. • Considerable indirect and direct evidence exists that highlights that avalanche airbags likely lead to risk compensation within at least some segments of the recreational backcountry and out-of- bounds skiing population. • Risk-taking in the backcountry is a personal choice, but recreationalists should have the necessary information about the direct and potential indirect effects of safety devices to make informed decisions. • The topic of risk compensation should be included in avalanche awareness courses and discussed in avalanche airbag support documentation and user manuals to increase the awareness of the potential among users. • Additional avalanche accident research should be conducted to better understand the circumstances when the effectiveness of airbags is limited.

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

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. 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. 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). 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.

Special Issue on NIED Frontier Research on Science and Technology for Disaster Risk Reduction and Resilience 2019

The National Research Institute for Earth Science and Disaster Resilience (NIED) is working on three tasks: predicting disasters, preventing damage, and realizing speedy reconstruction and recovery efforts in the event of natural disasters such as earthquakes, tsunamis, volcanic eruptions, landslides, torrential rains, blizzards, and ice storms. In the last three years of the NIED’s fourth mid/long term plan period, which began in 2016, natural disasters have occurred every year, including earthquake disasters such as the 2016 Kumamoto earthquake (M7.3) and the 2018 Iburi, Hokkaido, earthquake (M7.1). Disasters of the rainfall include the heavy rainfall in the northern Kyushu (Fukuoka and Oita) in July 2017, the heavy rain event in southwestern Japan in July 2018, the rainfall in northern Kyushu (Saga) in August 2019, and the heavy rainfall in Kanto and Tohoku in October 2019. There were also other disasters: an avalanche accident on Nasudake in 2017 and a phreatic eruption of Kusatsu-Shiranesan in 2018. Due to the above-mentioned very frequent occurrence of such natural disasters on the Japanese islands, our institute has conducted several research projects to mitigate the damage from such disasters and to accelerate the recovery from them. As the third NIED special issue in the Journal of Disaster Research, several related research results were presented such as those on seismic disasters (Wakai et al., Nakazawa et al., and Ohsumi et al.), those on climatic disasters (Nakamura, and Ishizawa and Danjo), and those of their integrated researches for disaster risk reduction (Cui et al. and Nakajima et al.). Although the achievements detailed in these papers are the results of individual research, the NIED hopes that these results as a whole will be fully utilized to promote science and technology for disaster risk reduction and resilience. The NIED hopes that this special issue awakens the readers’ interest in new research and, of course, creates an opportunity for further collaborative works with us.

Special Issue on NIED Frontier Research on Science and Technology for Disaster Risk Reduction and Resilience 2018

The National Research Institute for Earth Science and Disaster Resilience (NIED) is working on three tasks: predicting disasters, preventing damage, and realizing speedy reconstruction and recovery efforts in the event of natural disasters such as earthquakes, tsunamis, volcanic eruptions, landslides, torrential rains, blizzards, and ice storms. In the last two years of the NIED’s fourth mid/long term plan period, which began in 2016, the 2016 Kumamoto earthquake (M6.5 and M7.3), the heavy rainfall in the Northern Kyushu District in July 2017, and the heavy rain event of July 2018 are listed as “named” disasters, named by Japan Meteorological Agency. In addition, there were other disasters: an avalanche accident on Nasudake in 2017, an earthquake (M6.1) with its epicenter in northern Osaka, an eruption of Kirishimayama (Shinmoedake and Ioyama) and a phreatic eruption of Kusatsu-Shiranesan in 2018. The results of research done on the above-mentioned disasters and the latest results of ongoing projects in each research division and center were compiled as the second NIED special issue of the Journal of Disaster Research (JDR). In this special issue, we are delighted to present ten papers on three topics: climatic disasters, seismic disasters, and integrated research on disaster risk reduction. In particular, this special issue contains three papers on the above-mentioned heavy rainfall in the Northern Kyushu District in July 2017 and two papers related to the Kumamoto earthquake. Although the achievements detailed in these papers are the results of individual research, the NIED hopes that these results as a whole will be fully utilized to promote science and technology for disaster risk reduction and resilience. The NIED hopes that this special issue awakens the readers’ interest in new research and, of course, creates an opportunity for further collaborative works with us.

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.

Study of a Snow Avalanche Accident Along Chowkibal–Tangdhar Road in Kupwara District, Jammu and Kashmir, India

Study of a Snow Avalanche Accident Along Chowkibal–Tangdhar Road in Kupwara District, Jammu and Kashmir, India

Overconfident people are more exposed to “black swan” events: a case study of avalanche risk

Overconfidence is a well-established bias in which someone's subjective confidence in their own judgments is systematically greater than their objective accuracy. There is abundant anecdotal evidence that overconfident people increase their exposure to risk. In this paper, we test whether overconfident people underestimate the probability of incurring an avalanche accident. An avalanche accident is a typical event because it has a low probability of occurring but has potential dramatic consequences. To test whether the overconfidence bias affects the decision of backcountry skiers to go on a ski trip under different levels of avalanche risk, we measured individual cognitive traits and then used a random effect logit model to measure their effects on the probability to take the tour, by controlling for other observable characteristics of the respondent. We show that 1) overconfidence is widespread even in our sample and 2) practitioners who are more prone to overestimate their knowledge are also more likely to take the risk associated with a ski trip exposed to avalanche danger. This suggests that overconfident people are more exposed to black swan events.

A concept for optimizing avalanche rescue strategies using a Monte Carlo simulation approach.

Recent technical and strategical developments have increased the survival chances for avalanche victims. Still hundreds of people, primarily recreationists, get caught and buried by snow avalanches every year. About 100 die each year in the European Alps–and many more worldwide. Refining concepts for avalanche rescue means to optimize the procedures such that the survival chances are maximized in order to save the greatest possible number of lives. Avalanche rescue includes several parameters related to terrain, natural hazards, the people affected by the event, the rescuers, and the applied search and rescue equipment. The numerous parameters and their complex interaction make it unrealistic for a rescuer to take, in the urgency of the situation, the best possible decisions without clearly structured, easily applicable decision support systems. In order to analyse which measures lead to the best possible survival outcome in the complex environment of an avalanche accident, we present a numerical approach, namely a Monte Carlo simulation. We demonstrate the application of Monte Carlo simulations for two typical, yet tricky questions in avalanche rescue: (1) calculating how deep one should probe in the first passage of a probe line depending on search area, and (2) determining for how long resuscitation should be performed on a specific patient while others are still buried. In both cases, we demonstrate that optimized strategies can be calculated with the Monte Carlo method, provided that the necessary input data are available. Our Monte Carlo simulations also suggest that with a strict focus on the "greatest good for the greatest number", today's rescue strategies can be further optimized in the best interest of patients involved in an avalanche accident.

Avalanche fatalities in the European Alps: long-term trends and statistics

Abstract. Avalanche accidents, particularly those resulting in fatalities, attract substantial attention from policy makers and organizations, as well as from the media and the public. Placing fatal accidents in a wider context requires long-term and robust statistics. However, avalanche accident statistics, like most other accident statistics, often rely on relatively small sample sizes, with single multi-fatality events and random effects having a potentially large influence on summary and trend statistics. Additionally, trend interpretation is challenging because statistics are generally explored at a national level, and studies vary in both the period covered and the methods. Here, we addressed these issues by combining the avalanche fatality data from the European Alps (Austria, France, Germany, Liechtenstein, Italy, Slovenia, and Switzerland) for three different periods between 1937 and 2015 and applying the same data analysis methodology. During the last four decades, about 100 people lost their lives each year in the Alps. Despite considerable inter-annual variation, this number has remained relatively constant in the last decades. However, exploring fatality numbers by the location of the victims at the time of the avalanche revealed two partly opposing trends. The number of fatalities in controlled terrain (settlements and transportation corridors) has decreased significantly since the 1970s. In contrast to this development, the number of fatalities in uncontrolled terrain (mostly recreational accidents) almost doubled between the 1960s and 1980s and has remained relatively stable since then, despite a strong increase in the number of winter backcountry recreationists. Corresponding to these trends, the proportion of fatalities in uncontrolled terrain increased from 72 to 97 %. These long-term trends were evident in most national statistics. Further, the temporal correlation between subsets of the Alpine fatality data, and between some of the national statistics, suggests that time series covering a longer period may be used as an indicator for missing years in shorter-duration datasets. Finally, statistics from countries with very few incidents should be compared to, or analysed together with, those from neighbouring countries exhibiting similar economical and structural developments and characteristics.

Avalanche Fatalities in the United States: A Change in Demographics

To describe demographic patterns in avalanche fatalities in the United States during the past 6 decades according to geographic location and preavalanche activity. The Colorado Avalanche Information Center currently manages the National Avalanche Accident Dataset. This dataset describes deidentified avalanche fatalities beginning in 1951. Covariates included age, sex, month, state of occurrence, and preavalanche activity. Both absolute and proportional avalanche fatalities were calculated by year and by each covariate. A linear regression model was used to trend the proportion of avalanche fatalities stratified by covariate. There were 925 recorded avalanche fatalities in the United States between 1951 and 2013. There were an average of 15 ± 11 fatalities/y (mean ± SD; range, 0 to 40 fatalities/y). The mean (+/- SD) age was 29 ± 6.6 years (range, 6-67 years), and 86% were men. Total avalanche fatalities have increased linearly (R(2) = 0.68). Despite the highest number of total deaths in Colorado (n = 253), the proportion of avalanche fatalities in Colorado decreased (-5% deaths/decade; P = .01). Snowmobilers are now the largest group among fatalities and accounted for 23% of deaths (n = 213). The proportion of snowmobile fatalities has increased (+7% deaths/decade; P < .01), as has the proportion of snowboarder fatalities (+2% deaths/decade; P < .01). Avalanche fatalities have increased. This is most likely related to an overall rise in backcountry utilization. Fatalities have increased among snowmobilers and snowboarders. Despite a rise in backcountry utilization, avalanche fatalities in Colorado are decreasing. A strategy of focused training and education aimed toward at-risk groups could result in lower avalanche fatalities.

Risk of Avalanche Involvement in Winter Backcountry Recreation: The Advantage of Small Groups

Avalanches are the primary hazard for winter backcountry recreationists and cause numerous deaths and injuries annually. Although recreationists usually travel in groups, there is little empirical knowledge on group-related risk factors. This study aims to explore the relative risk of avalanche accidents with respect to group size and to discuss underlying reasons for different risk levels. We compared backcountry usage data in regions in Switzerland and Italy with avalanche accident data in these regions. We found higher avalanche risk for groups of 4 or more people and lower risk for people traveling alone and in groups of 2. The relative risk of group size 4, 5, and 6 was higher compared with the reference group size of 2 in the Swiss and Italian dataset. The relative risk for people traveling alone was not significantly different compared with the reference group size of 2 in the Italian dataset but was lower in the Swiss dataset. These findings are in accordance with avalanche safety recommendations regarding the higher risk of large groups but not regarding lower risks of people traveling alone in avalanche terrain, which is not recommended and requires great caution. Further studies on backcountry usage are necessary to improve our understanding of human behavior and risk factors. New techniques (eg, video monitoring) may be useful for acquiring reliable data on backcountry usage.

Analysis of avalanche risk factors in backcountry terrain based on usage frequency and accident data in Switzerland

Abstract. Recreational activities in snow-covered mountainous terrain in the backcountry account for the vast majority of avalanche accidents. Studies analyzing avalanche risk mostly rely on accident statistics without considering exposure (or the elements at risk), i.e., how many, when and where people are recreating, as data on recreational activity in the winter mountains are scarce. To fill this gap, we explored volunteered geographic information on two social media mountaineering websites – bergportal.ch and camptocamp.org. Based on these data, we present a spatiotemporal pattern of winter backcountry touring activity in the Swiss Alps and compare this with accident statistics. Geographically, activity was concentrated in Alpine regions relatively close to the main Swiss population centers in the west and north. In contrast, accidents occurred equally often in the less-frequented inner-alpine regions. Weekends, weather and avalanche conditions influenced the number of recreationists, while the odds to be involved in a severe avalanche accident did not depend on weekends or weather conditions. However, the likelihood of being involved in an accident increased with increasing avalanche danger level, but also with a more unfavorable snowpack containing persistent weak layers (also referred to as an old snow problem). In fact, the most critical situation for backcountry recreationists and professionals occurred on days and in regions when both the avalanche danger was critical and when the snowpack contained persistent weak layers. The frequently occurring geographical pattern of a more unfavorable snowpack structure also explains the relatively high proportion of accidents in the less-frequented inner-alpine regions. These results have practical implications: avalanche forecasters should clearly communicate the avalanche danger and the avalanche problem to the backcountry user, particularly if persistent weak layers are of concern. Professionals and recreationists, on the other hand, require the expertise to adjust the planning of a tour and their backcountry travel behavior depending on the avalanche danger and the avalanche problem.

Overconfident People are More Exposed to 'Black Swan' Events: A Case Study of Avalanche Risk

Overconfidence is a well-established bias in which someone's subjective confidence in their own judgments is systematically greater than their objective accuracy. There is abundant anecdotal evidence that overconfident people increase their exposure to risk. In this paper, we test whether overconfident people underestimate the probability of incurring an avalanche accident. An avalanche accident is a typical event because it has a low probability of occurring but has potential dramatic consequences. To test whether the overconfidence bias affects the decision of backcountry skiers to go on a ski trip under different levels of avalanche risk, we measured individual cognitive traits and then used a random effect logit model to measure their effects on the probability to take the tour, by controlling for other observable characteristics of the respondent. We show that 1) overconfidence is widespread even in our sample and 2) practitioners who are more prone to overestimate their knowledge are also more likely to take the risk associated with a ski trip exposed to avalanche danger. This suggests that overconfident people are more exposed to black swan events.

Formation and persistence of snow instabilityassociated with precipitationinduced weak layer that caused Mumeizawa avalanche accident

2009年1月25日に八方尾根無名沢においてスノーボーダー1名が重傷を負う雪崩事故が発生した．破断面における観測結果と周辺の積雪・雪崩に関する記録，同時期に広域で行った積雪観測データ等を基に雪崩発生の原因となった積雪不安定性とその形成過程および空間的な分布について検討した．雪崩の原因となった積雪不安定性をもたらしたのは厚さ約40cmの新雪-しまり雪によって構成されたスラブと雲粒の付着のない大型の板状結晶からなる厚さ2cmの降雪結晶弱層の組み合わせから成る積雪構造であった．弱層は22〜23日にかけての低気圧に伴う降雪によって広域に形成されたが，弱層形成後に晴れ間があり日射の影響を受ける斜面では弱層の強度が増加した．また，スラブは冬型降雪によって形成されており日本海側に限定されて形成された．このため，この不安定性は日本海側山岳地の高標高域で，尚且つ日射の影響を受けにくい斜面に限定的に存在したと推定された．また，他の弱層の観測事例から得られたデータも合わせて検討したところ，大型で雲粒の付着のない板状結晶によって形成された層においては，他の新雪層よりも長期間脆弱な状態が持続すると考えられた．

The Sand and Stone Avalanche Accident which Occurred in Hiroshima-shi August, 2014

The Sand and Stone Avalanche Accident which Occurred in Hiroshima-shi August, 2014

A deep insight into avalanche transceivers for optimizing rescue

It is well known that in order to increase the chances of survival after an avalanche accident, the rescue time has to be minimized. Therefore, the accurate and prompt location of an avalanche victim is of vital importance. Nowadays, searching with avalanche transceivers is the only reliable method for locating a completely buried victim immediately after an accident. The present work is firstly focused on the magnetic field pattern generated by an avalanche transceiver and how it is perceived depending on the number of receiving antennas. The influence of the snow and soil media is theoretically studied. The computations show that the magnetic field is notably distorted by the soil at distances from the transmitter that can take place during the signal and coarse search. The location of the victim is usually directly inferred from the maximum signal position. However, the computations clearly show that this can be wrong. There is a location error limited to 50% of the burial depth for one and two-antenna receivers whereas for three-antenna transceivers, assuming location takes place within the third antenna range, this figure is reduced to 25% of the burial depth. Furthermore, real tests show that the cross-like search method using three-antenna receivers can be inefficient depending on the algorithm used for the distance calculation for burial depths greater than 1.5m. As a result, a new search technique, called the bisector method, is proposed and experimentally validated. In addition, a new transmission mode mainly directed to minimize the location error is suggested. This is a vertical transmission that can optimize the search. The present theoretical and experimental outcomes will contribute to further progress in rescue operations conducted with avalanche transceivers.

Is extracorporeal rewarming indicated in avalanche victims with unwitnessed hypothermic cardiorespiratory arrest?

International guidelines recommend using extracorporeal rewarming in all hypothermic avalanche victims with prolonged cardiac arrest if they have patent airways and a plasma potassium level≤12 mmol/L. The aim of this study was to evaluate outcome data to determine if available experience with extracorporeal rewarming of avalanche victims supports this recommendation. At Innsbruck Medical University Hospital, 28 patients with hypothermic cardiac arrest following an avalanche accident were resuscitated using extracorporeal circulation. Of these patients, 25 were extricated from the snow masses with no vital signs and did not survive to hospital discharge. Three patients had witnessed cardiac arrest after extrication and a core temperature of 21.7°C, 22°C, and 24.0°C, two of whom survived long-term with full neurological recovery. A search of the literature revealed only one asystolic avalanche victim with unwitnessed hypothermic cardiac arrest (core temperature 19°C) surviving long-term. All other avalanche victims in the medical literature surviving prolonged hypothermic cardiac arrest suffered witnessed arrest after extrication with a core temperature below 24°C. Our results suggest that prognosis of hypothermic avalanche victims with unwitnessed asystolic cardiac arrest and a core temperature>24°C is extremely poor. Available outcome data do not support the use of extracorporeal rewarming in these patients.

Lebensrettender luftgestützter Lawineneinsatz bei Nacht im hochalpinen Gelände

This is a case report about a helicopter emergency medical service (HEMS) operation during the night in response to an avalanche accident with two completely buried victims. One of the victims was rescued alive after 9.2 h presenting with a patent airway and an air pocket and was successfully rewarmed with forced air from 23°C core temperature without any neurological deficits. After the rescue the patient developed lung edema which resolved spontaneously within 2 days. The second victim was found dead presenting with an air pocket but solid frozen thorax. The special circumstances of the rescue operation and treatment are presented and discussed. The impact of a frozen chest on resuscitation decisions is presented and discussed with an emphasis on the triage of multiple victims.