HEMODYNAMIC AND THERMAL RESPONSES TO HEAD AND NECK COOLING IN MEN ANDWOMEN

Personal cooling systems are used to alleviate symptoms of multiple sc lerosis and to prevent increased core temperature during daily activit ies. The objective of this study was to determine the operating charac teristics and the physiologic changes produced by short term use of on e commercially available thermal control system. A Life Support System s, Inc. Mark VII portable cooling system and a liquid cooling helmet w ere used to cool the head and neck regions of 12 female and 12 male su bjects (25-55 yr) in this study. The healthy subjects, seated in an up right position at normal room temperature (similar to 21 degrees C), w ere tested for 30 min with the liquid cooling garment operated at its maximum cooling capacity. Electrocardiograms and scalp and intracrania l blood flows were recorded periodically during each test sequence. Sc alp, right and left ear, and oral temperatures and cooling system para meters were logged every 5 min. Scalp, right and left ear canal, and o ral temperatures were all significantly (P < 0.05) reduced by 30 min o f head and neck cooling. Oral temperatures decreased approximately 0.2 -0.6 degrees C after 30 min and continued to decrease further (similar to 0.1-0.2 degrees C) for a period of similar to 10 min after removal of the cooling helmet. Intracranial blood flow decreased significantl y (P < 0.05) during the first 10 min of the cooling period, Both right and left ear temperatures in the women were significantly lower than those of the men during the cooling period. These data indicate that h ead and neck cooling may be used to reduce core temperature to that ne eded for symptomatic relief of both male and female multiple sclerosis patients. This study quantifies the operating characteristics of one liquid cooling garment as an example of the information needed to comp are the efficiency of other garments operated under different test con ditions.