Evaluation of the Res-Q-Air Inhalation Rewarming System on Non-Shivering Hypothermic Subjects.
DEFENCE AND CIVIL INST OF ENVIRONMENTAL MEDICINE DOWNSVIEW (ONTARIO)
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The objective of the present study was to test the efficacy of inhalation rewarming IR in simulated field conditions using a newly developed model of non-shivering hypothermia in humans. Eight subjects 2 of them female were cooled in 8-10 deg C water for 25 min on two occasions. Ten minutes prior to withdrawal from the water, a total of 1.5 mg-kg-1 of Meperidine, a shivering inhibitor, was injected intravenously into the subjects. The subjects were then removed from the water, settled in a sleeping bag and moved to a cold chamber set at -20 deg C for a 2.5 hour rewarming period. In the control trial, no external source of heat was available to the subject while in the IR trial, IR was provided water saturated air at 43 deg C. In both trials, shivering was successfully suppressed since the metabolic rates during the rewarming phases were not different from baseline values. The duration and magnitude of the post-exposure decrease in esophageal temperature afterdrop were not different between the control 78 11 min 1.41 O.1 deg C and the IR trials 76 or - min 1.2 0.2 deg C. The rates of rewarming were not different between the two treatments 0.4 or - 0.1 deg C h-1 for control 0.2 or - O.1 deg C - h 1 for IR. After the 2.5 hr rewarming phase, the esophageal temperature did not return to the pre-immersion level for either treatment 35.791 O.170C for control 35.85 or - O.13 deg C for IR. It was concluded that IR does not decrease the magnitude of the afterdrop and does not enhance rewarming rate in conscious non-shivering hypothermic subjects as compared to no external heat source.
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