MATERIALS SUITABLE TO SIMULATE SNOW DURING BREATHING EXPERIMENTS FOR AVALANCHE SURVIVAL RESEARCH

Terrain experiments for avalanche survival research require appropriate snow conditions, which may not be available year round. To prepare these experiments and test the protocol, it might be advantageous to test them in a laboratory with a snow model. The aim of the study was to find a material that can be used to simulate avalanche snow for studying gas exchange of a person covered with avalanche snow. Three loose porous materials (perlite, wood shavings and polystyrene) were tested in two forms—dry and moisturized. Each volunteer underwent six phases of the experiment in random order (three materials each dry or moisturized) during experimental breathing into the tested materials. Physiological parameters and fractions of oxygen and carbon dioxide in the airways were recorded continuously. All the materials selected as possible models of the avalanche snow negatively affected gas exchange during the breathing of the volunteers in a very similar extent. The time courses of the recorded parameters were very similar and were bordered from one side by the wet perlite and from the other side by the dry perlite. Therefore, other tested materials may be substituted with perlite with and appropriate water content. From all the tested materials, perlite is the best to simulate avalanche snow because of its homogeneity, reproducibility and easy manipulation

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 FIO2) or never (for FICO2). 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

Measuring carbon fiber aging on orbit

This paper describes the outcome of internship at the faculty of science and engineering, Hosei University in summer 2014. The goal of the project is to design a measuring system of aging properties of a carbon fiber reinforced composite in space. The project is a part of the nano-satellite project at Czech Technical University in Prague, scheduled to be launched in 2016. The measurement environment In space is different from the standard measurements performed on the ground in laboratory. The system design specification has a large constraint in size, weight and power consumption by the limit of space probes. To meet these requirement, the basic measuring system of the mechanical damping characteristics of the carbon fiber composite is designed in this internship project. A damping oscillator to simulate the response of the target material has been assembled and measuring parameters arc optimized. The optimized algorithm has been implemented in the chip to be launched on the space orbit

Scheme of the breathing circuit and its installation in the snow.

<p>(Illustration: B. Kracmar).</p

Inspiratory (F_IO₂) and end-tidal (EtO₂) fractions of oxygen in the breathing gas during NP and AP phases.

<p>The symbol * represents statistically significant differences in F_IO₂ between NP and AP groups; the symbol # represents statistically significant differences in EtO₂ between NP and AP phases; p ≤ 0.05.</p

The courses of inspiratory (F_ICO₂) and end-tidal (EtCO₂) fractions of carbon dioxide in the breathing gas during NP and AP phases.

<p>The symbol * represents statistically significant differences in EtCO₂ between the NP and AP groups; p ≤ 0.05.</p

Flow diagram of the study with enrollment, allocation and analysis of the participants.

<p>Flow diagram of the study with enrollment, allocation and analysis of the participants.</p