MAINTENANCE OF BODY-TEMPERATURE IN ELDERLY PATIENTS WHO HAVE JOINT REPLACEMENT SURGERY - A COMPARISON BETWEEN THE HEAT AND MOISTURE EXCHANGER AND HEATED HUMIDIFIER

The effect of a heat and moisture exchanger on intra‐operative aural canal (core) and mean skin temperatures was investigated in elderly patients who had elective total hip arthroplasty under general anaesthesia with artificial ventilation of the lungs. Group 1 (n = 20) did not receive any form of artificial humidification while in group 2 (n = 20) a heat and moisture exchanger was inserted in the breathing system and in group 3 (n = 20) the inspired gases were humidified and warmed at 40°C by means of a heated humidifier. Time of surgery, intravenous fluid administration and operating theatre temperature were standardised. Mean (SD) aural canal (core) temperature decreased significantly in groups 1 and 2 (p < 0.001), while there was a fall of 0.3°C(0.6) in group 3, which was not significant. Mean skin temperature decreased during anaesthesia and surgery in both groups 1 and 2 (p < 0.05), while it increased in group 3. There was a significantly greater loss of body heat in groups 1 and 2 compared with group 3 intra‐operatively (p < 0.001). We conclude that a heat and moisture exchanger did not prevent the decrease in intra‐operative body temperature in elderly patients. Copyright © 1990, Wiley Blackwell. All rights reserved