Abstract

In order to evaluate the hematological and metaholic effects of brief, intense, thermal stress, six clothed human subjects were exposed to thermal transients 20 minutes in duration, wall temperature rising 28°C (50°F)/min to peaks of 205°C (400°F) with subsequent passive wall-cooling. There was no evidence of hemolysis, and blood cellular elements showed only non-specific “stress” and hemoconcentration effects. There were no significant changes in serum electrolytes, blood sugar, total protein or protein electrophoresis. There was an increase in tidal volume without an increase in respiratory rate, an example of heat hyperpnea, causing an increase in blood oxygen and a fall in carbon dioxide values with consequent increase in pH. Lactic acid rose slightly and a small amount of excess lactate was generated. Lactic dehydrogenase activity decreased although there was no demonstrable change in the LDH isozymes.