Comparison of peripheral and core temperatures in anesthetized horses

Abstract

Objective - To examine temporal patterns of rectal, nasal, groin, and skin temperatures measured in adult horses undergoing general anesthesia and to determine accuracy and precision of temperatures at these sites, compared with core temperature. Animals - 5 healthy adult horses. Procedure - Induction, maintenance of, and recovery from general anesthesia were performed in an air-conditioned surgical suite. Room temperature and relative humidity were approximately 21 C and 40%, respectively. Anesthesia was maintained for 2.5 hours, and body temperatures were measured and recorded every 5 minutes. Mean values were compared by use of ANOVA for repeated measures. Correlation coefficients for linear regressions of site temperature versus core temperature at 30-minute intervals were used to evaluate precision. Results - Rectal temperature decreased in a linear manner, similar to core temperature. Nasal, groin, and skin temperatures followed a biphasic pattern; they sharply increased initially, peaked, then decreased at a rate similar to that of core temperatures. Rectal temperature always accurately reflected core temperature. Initial significant differences between core temperature and nasal, groin, or skin temperature disappeared as peripheral site temperatures approached peak values. Precision of core temperature estimation was generally poor for rectal, groin, and skin temperatures but was high (r > 0.90) after the first hour of anesthesia. Conclusion - Anesthesia-induced core heat redistribution develops with minimal effect on core temperature. Rectal temperature can accurately reflect core temperature.