The Snow Snorkel: a proof of concept study

Perlite is a suitable model material for experiments investigating breathing in high density snow

Outdoor breathing trials with simulated avalanche snow are fundamental for the research of the gas exchange under avalanche snow, which supports the development of the international resuscitation guidelines. However, these studies have to face numerous problems, including unstable weather and variable snow properties. This pilot study examines a mineral material perlite as a potential snow model for studies of ventilation and gas exchange parameters. Thirteen male subjects underwent three breathing phases—into snow, wet perlite and dry perlite. The resulting trends of gas exchange parameters in all tested materials were similar and when there was a significant difference observed, the trends in the parameters for high density snow used in the study lay in between the trends in dry and wet perlite. These findings, together with its stability and accessibility year-round, make perlite a potential avalanche snow model material. Perlite seems suitable especially for simulation and preparation of breathing trials assessing gas exchange under avalanche snow, and potentially for testing of new avalanche safety equipment before their validation in real snow.

The study was registered in ClinicalTrials.gov on January 22, 2018; the registration number is NCT03413878.

Recreational Sporting Activity Vehicle-Related Deaths

Deaths occurring in the setting of nonprofessional, vehicle-related, recreational sporting activities occurring on land or in water during warm or winter months represent a diverse group of cases. These deaths tend to involve scenarios where the participants are purposefully attempting to enjoy themselves prior to experiencing sudden, catastrophic accidents resulting in lethal outcomes. Ultimately, many of the deaths are related to the high speed at which these vehicle-related activities normally occur. Three broad categories of factors may play contributory roles in death: human factors, vehicle factors, and environmental factors. A series of selected cases are presented, representing examples of varying activity types, involving motorized and nonmotorized vehicles, land and water activities, and warm weather and cold weather environments. For each case, the various human, vehicle and environmental factors believed to be contributory to the accident are considered, and strategies for prevention of these and similar deaths involving recreational sporting vehicles are presented.

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

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