Snow Physical Properties and Human Ventilatory Response

Not Applicable

Completed

• Conditions: Avalanche Burial; Hypercapnic Respiratory Failure; Hypoxic Respiratory Failure; Snow Physical Properties
• Interventions: Other: Breathing in snow

• Registration Number: NCT03082105
• Lead Sponsor: Institute of Mountain Emergency Medicine

Brief Summary

Sufficient oxygenation is critical for completely buried avalanche victims to avoid life-threatening consequences during hypoxic exposure. Snow contains a remarkable capacity to maintain air availability; it was suspected that the snow physical properties affect the development of hypoxia and hypercapnia. The aim of this study was to evaluate the influence of different snow physical properties on the development of hypoxia and hypercapnia in subjects breathing into an artificial air pocket in snow. Twelve male healthy subjects breathed through an airtight face-mask and 40cm tube into an artificial air pocket of 4L. Every subject performed three tests on different days with varying snow characteristics. Symptoms, gas and cardiovascular parameters were monitored up to 30min. Tests were interrupted at SpO2 \<75% (primary endpoint); or due to subjective symptoms like dyspnea, dizziness, and headache (i.e. related to hypercapnia). Snow density was assessed via standard methods and micro-computed tomography (CT) analysis, and permeability and penetration with the snow micro-penetrometer (SMP).

Detailed Description

Not available

Study Timeline

• Study Start: 2013-12-01
• Primary Completion: 2014-03-09
• Study Completion: 2014-03-09
• Status Verified: 2017-03
• Study First Submitted: 2017-03-08
• Study First Submitted QC: 2017-03-10
• Last Update Submitted: 2017-03-10
• Study First Posted: 2017-03-17
• Last Update Posted: 2017-03-17

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 12

Inclusion Criteria

• Healthy volunteers with an age above 18yr-old, physically active.
• Volunteers have been informed and have signed consent.

Exclusion Criteria

• Lack of consent.
• Chronic previous illness of the respiratory tract or of the cardiovascular system.
• Acute disease at or immediately prior to the test (eg, flu-like infection, fever of unknown origin).
• Eurac employees.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Intermediate snow	Breathing in snow	Second test series breathing in dry/wet snow in intermediate season
Winter snow	Breathing in snow	First test series breathing in dry snow in winter
Spring snow	Breathing in snow	Third test series breathing in very wet snow in spring

Primary Outcome Measures

Name	Time	Method
SpO2 (%)	Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase	Continuous monitoring

Secondary Outcome Measures

Name	Time	Method
VE (L/min)	Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase	Continuous monitoring
EtCO2 (mmHg)	Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase	Continuous monitoring
Cause of interruption	Timepoint immediately before interruption of snow-breathing phase (max 30min)	SpO2 \<75% or subjectives symptoms due to hypercapnia (like dyspnea, dizziness, and headache)
rSO2 (%)	Changes from baseline (measurement at 0min) -> snow-breathing phase (5min, 15min, and timepoint immediately before interruption of snow-breathing phase [max 30min]) -> 2.5min and 5min after snow-breathing phase	Continuous monitoring

Trial Locations

Locations (1)

Institute of Mountain Emergency Medicine, Eurac Research; 🇮🇹 Bolzano, Bz, Italy