N. Patel et al., HEAT CONSERVATION VS CONVECTIVE WARMING IN ADULTS UNDERGOING ELECTIVESURGERY, Canadian journal of anaesthesia, 44(6), 1997, pp. 669-673
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.