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.

First experimental time-of-flight-based proton radiography using low gain avalanche diodes.

Objective.Ion computed tomography (iCT) is an imaging modality for the direct determination of the relative stopping power (RSP) distribution within a patient's body. Usually, this is done by estimating the path and energy loss of ions traversing the scanned volume utilising a tracking system and a separate residual energy detector. This study, on the other hand, introduces the first experimental study of a novel iCT approach based on time-of-flight (TOF) measurements, the so-called Sandwich TOF-iCT concept, which in contrast to any other iCT systems, does not require a residual energy detector for the RSP determination.Approach.A small Sandwich TOF-iCT demonstrator was built based on low gain avalanche diodes (LGADs), which are 4D-tracking detectors that allow to simultaneously measure the particle position and time-of-arrival with a precision better than 100µm and 100 ps, respectively. Using this demonstrator, the material and energy-dependent TOF was measured for several homogeneous PMMA slabs in order to calibrate the acquired TOF against the corresponding water equivalent thickness (WET). With this calibration, two proton radiographs (pRads) of a small aluminium stair phantom were recorded at MedAustron using 83 MeV and 100.4 MeV protons.Main results.Due to the simplified WET calibration models used in this very first experimental study of this novel approach, the difference between the measured and theoretical WET ranged between 37.09% and 51.12%. Nevertheless, the first TOF-based pRad was successfully recorded showing that LGADs are suitable detector candidates for Sandwich TOF-iCT.Significance.While the system parameters and WET estimation algorithms require further optimization, this work was an important first step to realize Sandwich TOF-iCT. Due to its compact and cost-efficient design, Sandwich TOF-iCT has the potential to make iCT more feasible and attractive for clinical application, which, eventually, could enhance the treatment planning quality.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Avalanche-size distribution of Cayley tree.

Attacks on networks is a very important issue in developing strategies of eradicating spreads of malicious phenomena in networks, such as epidemics and fake information. This field of research is referred to as networks immunization. The traditional approach to evaluating the effectiveness of attacks on networks focuses on measuring macro parameters related to the entire attack, such as the critical probability of a percolation occurrence in the network [Formula: see text] and the relative size of the largest component in the network, known as the giant component, but not considering the attack on a micro perspective, which is the analysis of node removals, during an attack, themselves, their characteristics and results. In this paper we present and apply the last method of focusing on the micro scale of an attack. Based on the theory of percolation in networks, we analyze the phenomenon of an avalanche which results due to a single node removal from a network. An avalanche is a state in which a removal of a single node from the giant component of a network leads to the disconnection of additional nodes. This process significantly contributes to the fragmentation (immunization) of the network, comparing to the impact of the initial node removal alone. Specifically, we focus on the size parameter of an avalanche, which is the number of nodes that are disconnected from the giant component due to a single node removal. Relating to a random attack on a network of the type of Cayley tree, we derive analytically the distribution of the sizes of avalanches that occur during the entire attack on it, until the network is dismantled (immunized) and the attack is terminated.

Many-Body Resonances in the Avalanche Instability of Many-Body Localization.

Many-body localized (MBL) systems fail to reach thermal equilibrium under their own dynamics, even though they are interacting, nonintegrable, and in an extensively excited state. One instability toward thermalization of MBL systems is the so-called "avalanche," where a locally thermalizing rare region is able to spread thermalization through the full system. The spreading of the avalanche may be modeled and numerically studied in finite one-dimensional MBL systems by weakly coupling an infinite-temperature bath to one end of the system. We find that the avalanche spreads primarily via strong many-body resonances between rare near-resonant eigenstates of the closed system. Thus we find and explore a detailed connection between many-body resonances and avalanches in MBL systems.

Critically buried avalanche victims can develop severe hypothermia in less than 60 min.

BACKGROUND: A major challenge in the management of avalanche victims in cardiac arrest is differentiating hypothermic from non-hypothermic cardiac arrest, as management and prognosis differ. Duration of burial with a cutoff of 60 min is currently recommended by the resuscitation guidelines as a parameter to aid in this differentiation However, the fastest cooling rate under the snow reported so far is 9.4 °C per hour, suggesting that it would take 45 min to cool below 30 °C, which is the temperature threshold below which a hypothermic cardiac arrest can occur. CASE PRESENTATION: We describe a case with a cooling rate of 14 °C per hour, assessed on site with an oesophageal temperature probe. This is by far the most rapid cooling rate after critical avalanche burial reported in the literature and further challenges the recommended 60 min threshold for triage decisions. The patient was transported under continuous mechanical CPR to an ECLS facility and rewarmed with VA-ECMO, although his HOPE score was 3% only. After three days he developed brain death and became an organ donor. CONCLUSIONS: With this case we would like to underline three important aspects: first, whenever possible, core body temperature should be used instead of burial duration to make triage decisions. Second, the HOPE score, which is not well validated for avalanche victims, had a good discriminatory ability in our case. Third, although extracorporeal rewarming was futile for the patient, he donated his organs. Thus, even if the probability of survival of a hypothermic avalanche patient is low based on the HOPE score, ECLS should not be withheld by default and the possibility of organ donation should be considered.

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.

Comparative Effectiveness of an Artificial Air Pocket Device to Delay Asphyxiation in Supine Individuals Critically Buried in Avalanche Debris.

Importance: Approximately 70% of individuals critically buried in avalanche debris die within 35 minutes as a result of asphyxial cardiac arrest. An artificial air-pocket device (AAPD) that separates inhaled air from exhaled air may delay the onset of severe hypoxemia and eventual asphyxia during snow burial. Objective: To investigate the efficacy of a new AAPD during snow burial in a supine position. Design, Setting, and Participants: This comparative effectiveness trial was performed in winter 2016 with data analysis in November 2016 and November 2022. Each trial used a simulated critical avalanche burial scenario, in which a trough was dug in a snow pile and an additional air pocket of 0.5 L volume was punched into the lateral wall for each control trial. All participants were buried in a supine position. Trials could be voluntarily terminated at any time, with a maximum length of 60 minutes; trials were automatically terminated if the participant's peripheral oxygen saturation (Spo2) dropped to less than 84%. Exposures: Each participant conducted 2 trials, one in which they breathed into the AAPD (intervention trial) and the other in which they breathed into the prepared air pocket (control trial). Main Outcomes and Measures: Measurements included Spo2, cerebral oxygenation, ventilatory parameters, respiratory gas concentrations, and visual-analogue scales. Kaplan-Meier survival curves and rank test for matched survival data were used to analyze the total burial time in each trial. Results: A total of 13 volunteers (9 men; mean [SD] age, 33 [8] years) were exposed to the intervention and control trials. Intervention trials were terminated less often (2 of 13 trials) as a result of hypoxemia than control trials (11 of 12 trials). Similarly, survival curves showed a longer duration of burial in the intervention compared with the control trials for the time to reach an Spo2 less than 84% (rank test for matched survival data: P = .003). The intervention trials, compared with the control trials, also had slower rates of decrease in fraction of inspired oxygen (mean [SD] rate, -0.8 [0.4] %/min vs -2.2 [1.2] %/min) and of increase in fraction of inspired carbon dioxide (mean [SD] rate, 0.5 [0.3] %/min vs 1.4 [0.6] %/min) and expired ventilation per minute (mean [SD] rate, 0.5 [1.0] L/min2 vs 3.9 [2.6] L/min2). Conclusions and Relevance: This comparative effectiveness trial found that the new AAPD was associated with delaying the development of hypoxemia and hypercapnia in supine participants in a critical burial scenario. Use of the AAPD may allow a longer burial time before asphyxial cardiac arrest, which might allow longer times for successful rescue by companions or by prehospital emergency medical services.

Avalanche Airbag Usage and Risk Attitudes of Backcountry Skiers and Snowboarders in the American West.

INTRODUCTION: Backcountry skiers and snowboarders are increasingly using avalanche airbags to improve safety. New safety devices can cause risk compensation, the concept in which users take more risks given the larger safety margin provided by the device. This may limit overall benefits. We sought to elucidate attitudes toward risk-taking behaviors and risk compensation in backcountry users relating to avalanche airbags. METHODS: A convenience sample of 144 backcountry skiers and snowboarders was surveyed after a backcountry tour in the Wasatch Mountains of Utah and the Tetons of Wyoming during the winter 2020-21 season. Demographic and experiential data were compared with risk propensity scores and attitudes toward risk compensation. Respondents were stratified into high-, medium-, and low-risk groupings based on risk propensity scores and whether an airbag was carried. RESULTS: Thirty-two (22%) respondents carried an airbag. Airbag users were more likely to endorse risk compensation behavior, ski terrain over 30 degrees, and fall into the high-risk cohort. The high-risk cohort was also more likely to endorse risk compensation behavior than medium- and low-risk individuals. CONCLUSIONS: Risk compensation was more prevalent in 2 groups: 1) those carrying an airbag and 2) those falling within the high-risk cohort. Given the prevalence of avalanche airbags, risk compensation should be considered alongside other human factors in avalanche safety and education so that users can mitigate these effects. Although risk compensation appears to be occurring, the magnitude of this effect remains unknown and likely does not obviate the safety benefits of the airbag altogether.