Objective The purpose of the study was to determine, and compare, the effectiveness of five heated hypothermia enclosure systems (HES).

Methods This study compared the thermal, physiologic and subjective responses of five subjects (one female) in five HES (with vapor barrier and chemical heat sources) during 60 min of exposure to a −22°C climate. The five systems were: 1) user-assembled (Control); 2) Doctor Down® Rescue Wrap® (DD); 3) Hypothermia Prevention and Management Kit (HPMK®); 4) MARSARS Hypothermia Stabilizer Bag (M); and 5) Wiggy’s Victims Casualty Hypothermia Bag (W). Core temperature, skin heat loss, and metabolic heat production were determined continuously. Subjective responses were also evaluated for: whole body cold discomfort; overall shivering rating; temperature rating; and overall preferential ranking.

Results Total heat loss was higher with HPMK, W and M compared to Control and DD (p<0.05). Net heat gain was higher with the Control and DD compared to W and M (p<0.05). Control, M and DD consistently scored better in the subjective scales.

Conclusions Although all systems provide insulation and heat, the Control (user-assembled), MASARS and Doctor Down systems were more effective, and preferred.

Funding NSERC, Canada.