Exercise After Atropine and Pralidoxime Increases the Rational Effective Temperature,

The purpose of the study was to determine the effect of antidotal treatment for organophosphate poisoning on heat exchange in four men during exercise at 55 peak aerobic power in a warm environment T sub a 30.2 or - 0.5 C T sub g 30.3 or - 0.5 C P sub w 0.97 or - 0.08 kPa. Each subject performed four experiments with the control treatment being an intramuscular i.m. injection of saline SAL which was compared to atropine ATR 2 mg i.m., pralidoxime 2-PAM 600 mg i.m. and atropine plus pralidoxime CMB treatment. Partitional calorimetric analysis was done at 25 min of exercise. Mean skin temperature, rectal temperature T sub re and esophageal temperature T sub es were measured twice each min. Evaporative heat loss was calculated from changes in body weight. The displacement by heat storage of a theoretical temperature which is determined by heat exchange due to exercise and drug treatment, was calculated. A rational effective temperature ET was derived using a psychrometric format and was used to assess the relative thermoregulatory strain for each treatment. ATR and 2-PAM treatment resulted in greater heat storage than SAL. Heat storage, when calculated from T sub re was greater CMB than with either drug alone. The ET was approximately 2 C higher with ATR or 2-PAM than with SAL, while CMB resulted in an increase of 4.1 C in ET above SAL. When heat storage was calculated from changes in T sub es rather than T sub re, the EI was increased by approximately 4C, but was not as prominent as T sub re in demonstrating differences between drugs.