HUMAN RESPONSES TO AN ALTERNATING VERSUS A CONTINUOUS PATTERN OF TOTAL BODY COOLING (TEMPERATURE RESPONSE, THERMAL STRESS).
Contributors: University of Washington.
Published: 1993
Number of pages: 173
Subjects: Health Sciences, Nursing.; Biology, Animal Physiology.
Description: Cold application is a therapeutic often used for the treatment of hyperthermia caused by fever or heat stress. However, application of cooling may constitute additional stress for an individual in an already compromised state.

Purpose. The purpose of this study was to evaluate physiological and experiential responses to two patterns of total body cooling in normothermic healthy adult subjects in a laboratory setting.

Methods. Six women and two men (28 to 45 years) after 10 minutes of exposure to water at 35$\sp\circ$C were exposed to continuous cooling (CC) (32.8$\sp\circ$C) and alternating cooling (AC) (33.5$\sp\circ$C to 31.5$\sp\circ$C) in random sequence on two occasions by spraying water over 80% of the subject's body for 70 minutes. Measures included core temperature (Tc) using an esophageal thermistor, cutaneous blood flow (CBF) using venous occlusion plethysmography, oxygen consumption (VO$\sb2)$ using a metabolic cart, cardiovascular responses (systolic blood pressure (SBP), diastolic blood pressured (DBP), mean blood pressure (MBP), and heart rate (HR)) using noninvasive blood pressure monitoring and stress hormone response (epinephrine, norepinephrine, and cortisol). Experiential responses were measured using a thermal comfort visual analog scale with three components, sensation, aversiveness, and shivering.

Results. As an initial compensatory response, Tc rose in 6 of 8 subjects after application of cold. No difference in average drop of Tc over time during continuous compared to alternating cooling occurred (Tc decrease = 0.19$\sp\circ$C for CC; Tc decrease = 0.23$\sp\circ$C for AC). As well, there were no differences in the average CBF, average VO$\sb2,$ average cardiovascular responses, and stress hormone responses. Thermal comfort scale scores were not significantly different between the two patterns of cooling.

Discussion. In looking at this small group of subjects in general, the methods of cooling did not differ in their effects on core temperature, cutaneous blood flow, oxygen consumption, cardiovascular responses and stress hormone responses. Further, as a group, the subjects did not report overall differences in comfort levels during the two patterns of cooling.

The patterns of cooling in this study did provide examples of after-rise and after-drop, phenomena in body temperature responses to cooling and warming. Changes in water temperature were positively correlated with changes in cutaneous blood flow and inversely correlated with core temperature.
Notes: Source: Dissertation Abstracts International, Volume: 54-05, Section: B, page: 2440.

Thesis (PH.D.)--UNIVERSITY OF WASHINGTON, 1993.

School code: 0250.