Convective air warming is more effective than resistive heating in an experimental model with a water dummy.
Trauma patients with accidental hypothermia have adverse outcomes when compared with normothermic patients. Studies with a small number of mild hypothermic volunteers suggested that convective warming is more effective than warming with 12 volt resistive heating blankets. In a laboratory study, we compared the warming effectiveness of two electric blankets and convective air warming. The average speed of convective rewarming during anaesthesia in patients is approximately 0.6 degree C per hour. Accordingly, calibration of the dummy was performed with increasing amounts of water during convective warming until we reached a temperature gain of 0.6 degree C per hour. The following warming experiments were performed: 12 volt electric warming blanket (SH6012, Hella); 12 volt electric warming blanket (Thermamed, whole-body blanket); convective air warming (Warm Touch, Mallinckrodt, whole-body blanket). Each experiment was repeated four times. The temperature development was measured and recorded online. Convective warming increased the dummy temperature 0.6 degree C per hour, Thermamed 0.3 degree C per hour (P<0.001 versus convective warming) and two Hella blankets 0.2 degree C per hour (P<0.001 versus convective warming). Our laboratory investigation confirmed the superiority of convective warming over resistive heating. Efforts should be made to incorporate convective warming into the out-of-hospital treatment of trauma patients.
Ittner
Karl Peter
KP
Department of Anaesthesiology, University of Regensburg, D-93042 Regensburg, Germany. karl-peter.ittner@klinik.uni-regensburg.de
Bachfischer
Markus
M
Zimmermann
Markus
M
Taeger
Kai
K
D001512:Bedding and Linens; D018481:Convection; D004867:Equipment Design; D006358:Hot Temperature / Q000627:therapeutic use*; D006801:Humans; D007035:Hypothermia / Q000628:therapy; D008348:Manikins; D008962:Models, Theoretical; D005791:Patient Care / Q000295:instrumentation*; D013696:Temperature; D016896:Treatment Outcome; D014867:Water
D014867:Water