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

Karel Roubik, Karel Sykora, Ladislav Sieger, Vaclav Ort, Lenka Horakova, Simon Walzel, Karel Roubik, Karel Sykora, Ladislav Sieger, Vaclav Ort, Lenka Horakova, Simon Walzel

Abstract

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.

Conflict of interest statement

The authors declare no competing interests.

© 2022. The Author(s).

Figures

Figure 1
Figure 1
Experimental setup (modified from, with permission).
Figure 2
Figure 2
Time to breathing experiment termination for the three different phases: snow (S), dry perlite (PD) and wet perlite (PW). The term “completed” means that the subject terminated the experiment upon his own request, or the experiment was terminated by the supervising physician based on the clinical assessment of the subject. The term “interrupted” means that the experiment was terminated due to accidental disconnection, or detection of N2O in the breathing circuit.
Figure 3
Figure 3
Individual curves of peripheral blood oxygen saturation (SpO2), end-tidal fractions of carbon dioxide (EtCO2) and inspiratory fractions of oxygen (FiO2) of each of the volunteers for all the three experimental phases: snow (S), dry perlite (PD) and wet perlite (PW).
Figure 4
Figure 4
Peripheral blood oxygen saturation (SpO2) of the subjects during the three different phases: snow (S), dry perlite (PD) and wet perlite (PW). The symbol # represents statistically significant differences between snow and wet perlite, the symbol * represents statistically significant differences between dry perlite and wet perlite; p ≤ 0.05.
Figure 5
Figure 5
Inspiratory fractions of oxygen (FiO2) in (a) and end-tidal fractions of oxygen (EtO2) in (b) in the breathing gas during the three different phases: Snow (S), Dry perlite (PD) and Wet perlite (PW). The symbol * represents statistically significant differences between dry perlite and wet perlite, the symbol # represents statistically significant differences between snow and wet perlite, the symbol § represents statistically significant differences between snow and dry perlite; p ≤ 0.05.
Figure 6
Figure 6
Inspiratory fractions of carbon dioxide (FiCO2) in a) and end-tidal fractions of carbon dioxide (EtCO2) in b) in the breathing gas during the three different phases: snow (S), dry perlite (PD) and wet perlite (PW). No statistically significant difference among the breathing phases was found.

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Source: PubMed

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