Alterations in MAST suit pressure with changes in ambient temperature

Area of Science:

• Physiology
• Aerospace Medicine
• Biomedical Engineering

Background:

• The Military Anti-Shock Trouser (MAST) suit is a medical device used to treat hypotension.
• Its effectiveness may be influenced by environmental factors such as temperature, potentially affecting internal pressure.

Purpose of the Study:

• To investigate the relationship between ambient air temperature and MAST suit pressure.
• To determine if the ideal gas law accurately predicts pressure changes in MAST suits with temperature variations.

Main Methods:

• Two types of MAST suits were tested on Resusci-Annie dummies across a temperature range from 4.4°C to 44°C.
• Controlled trials were conducted in a cold room, with subsequent warming.
• Human trials were also performed to compare pressure changes with those observed in dummies.

Main Results:

• A positive linear correlation was observed between ambient temperature and MAST suit pressure in nine trials.
• The rate of pressure increase varied between the two types of MAST suits tested.
• Human trials indicated increased suit pressure with rising temperatures, though at a lower rate than observed with dummies.
• A correlation of 0.5 to 1.0 mm Hg increase in pressure for every 1.0°C rise in ambient temperature was documented.

Conclusions:

• Ambient air temperature significantly impacts MAST suit pressure, consistent with principles of the ideal gas law.
• Understanding this temperature-pressure relationship is crucial for optimizing MAST suit application in diverse environmental conditions.
• Differences in pressure response between suit types and between dummies and humans warrant further investigation.