BODY HEAT-TRANSFER DURING HIP-SURGERY USING ACTIVE CORE WARMING

The purpose of this study was to evaluate the effect of core warming o n heal redistribution from the core to the periphery as manifested by changes in core, mean skin temperature and mean body heat, investigate d in a group of 30 patients undergoing total hip replacement. The cont rol group (n = 10) had no active warming. Core warming was achieved in the humidifier group (n = 10) by using humidified and warmed gases at 40 degrees C, whilst in the oesophageal group (n = 10), an oesophagea l heat exchanger was used to achieve active warming. Operating room te mperature and relative humidity was standardised. Aural canal and skin temperatures (15 sites) were measured before induction of anaesthesia , at the end of surgery and one hour of recovery after anaesthesia. Me an skin temperatures were calculated for a weighted four and unweighte d 15 points, and mean body heat were calculated to quantify the distri bution of body heal. Core temperature decreased in the control and the oesophageal groups, but not in the humidifier group at the end of sur gery; by mean values +/-SD of 1.9 degrees C +/-0.6, 1.2 degrees C +/-0 .6 and 0.4 degrees C +/-0.2, respectively (P < 0.01). Mean skin temper ature (MST(15) decreased in the control group by 1.0 degrees C +/-1.0, but not in the actively warmed groups where the mean increased by 0.1 degrees C +/-1.4 and 0.2 degrees C +/-0.2 in the oesophageal and humi difier groups, respectively (P < 0.05). Mean body heat decreased in th e control and the oesphageal groups by 350.2 +/- 155.9 and 201 +/- 184 .2, in contrast to the humidifier group, 43.5 +/- 28.4 kJ (P < 0.01). Thus this study shows the effect of efficient core warming on total bo dy heat and in ensuring adequate heat content to compensate for heat l oss from the periphery.