Clinical trial NCT03082105: Snow Physical Properties and Human Ventilatory Response
Official title: Evaluation of Air Pocket Factors That Contribute to the Development of Hypoxia and Hypercapnia
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Hypoxic Respiratory Failure
Hypercapnic Respiratory Failure
Avalanche Burial
Snow Physical Properties
Lead sponsor: Institute of Mountain Emergency Medicine
Sponsor class: OTHER
Collaborators: name: Medical University Innsbruck
First posted: 2017-03-17
Enrollment: 12
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

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).


Eligibility criteria: 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.

Primary outcomes:
measure: SpO2 (%)
timeFrame: 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
Secondary outcomes:
measure: EtCO2 (mmHg)
timeFrame: 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
measure: Cause of interruption
timeFrame: Timepoint immediately before interruption of snow-breathing phase (max 30min)
measure: VE (L/min)
timeFrame: 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
measure: rSO2 (%)
timeFrame: 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
Other outcomes:
Locations:
city: Bolzano
country: Italy
facility: Institute of Mountain Emergency Medicine, Eurac Research
state: Bz
Study officials:
affiliation: Eurac Research
name: Giacomo Strapazzon, MD PhD
role: STUDY_DIRECTOR
affiliation: Eurac Research
name: Hermann Brugger, MD
role: STUDY_DIRECTOR
References:
citation: Brugger H, Sumann G, Meister R, Adler-Kastner L, Mair P, Gunga HC, Schobersberger W, Falk M. Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival. Resuscitation. 2003 Jul;58(1):81-8. doi: 10.1016/s0300-9572(03)00113-8.
citation: Haegeli P, Falk M, Brugger H, Etter HJ, Boyd J. Comparison of avalanche survival patterns in Canada and Switzerland. CMAJ. 2011 Apr 19;183(7):789-95. doi: 10.1503/cmaj.101435. Epub 2011 Mar 21.