HEAT CONSERVATION VS CONVECTIVE WARMING IN ADULTS UNDERGOING ELECTIVESURGERY

Purpose: To determine the relative efficacy of heat conservation and c onvective warming in maintaining perioperative normothermia, (central temperature greater than or equal to 36 degrees C). Methods: Thirty-se ven patients undergoing elective gynaecological, orthopaedic, or gener al surgery scheduled to last two hours were prospectively studied. Pat ients were randomized to one of two groups. Group I patients received heat conservation with reflective blankets (Thermadrape(TM), Vital Sig ns, Inc., Totowa, NJ) applied preoperatively and warmed iv fluids (Hot line(TM) SIMS level I Technologies, Inc, Rockland, MA). Group 2 patien ts received convective warming (BairHugger, Augustine Medical, Inc., E den Prairie, MN) after induction of anaesthesia and iv fluids at room temperature. All patients received general anaesthesia with isoflurane . Tympanic membrane and forearm-fingertip skin temperature gradients w ere measured perioperatively at 15 min intervals. Results: Central tem perature decreased after induction to a minimum level of 35.9 +/- 0.1 degrees C in group I and 36.0 +/- 0.1 degrees C in group 2 and then in creased towards pre-induction values in group 2, and were higher (P < 0.05) than in group 1:95% group 2 patients had central temperature gre ater than or equal to 36.0 degrees C at the end of surgery (vs 69% of group I, P < 0.05), During the first 30 min in PACU, central temperatu res were higher in group I than in group 2 (36.8 +/- 0.1 degrees C vs 36.2 +/- 0.2 degrees C, P < 0.05). After 60 min, central temperatures were similar (36.8 degrees C). The incidence of shivering and degree o f peripheral cutaneous vasoconstriction were also similar. Conclusion: Patients receiving convective warming were more likely to leave the o perating room normothermic, and had higher central temperatures during the first 30 min in the recovery room. The intergroup temperature dif ferences were small, and by 60 min, had disappeared.