Is there thermal benefit from preoperative warming in children?
OBJECTIVE
We aimed to quantify the impact of a raised preoperative ambient temperature (T(ambient)) on core temperature (T(core)) after induction of anesthesia in children.


BACKGROUND
It has been suggested that prewarming of patients before anesthesia induction reduces postinduction drop in T(core). Neither the prewarming temperature nor its duration is established for adults or children. Nevertheless, it remains common practice to either warm the operating theatre and induction room or employ radiant heaters prior to induction of anesthesia, particularly for infants and neonates. We aimed to quantify the benefit, if any, of this warming practice.


METHODS
We conducted a prospective clinical study to assess T(core) behavior in children randomized to either raised or standard ambient temperature as a prewarming technique prior to induction and until the operation commenced. We have called this 'preoperative' warming. Well, children scheduled for elective surgery where presurgical anesthetic duration exceeded 20 min were randomized to a T(ambient) of either 26 or 21 degrees C. Esophageal temperature was monitored continuously until the operative procedure commenced.


RESULTS
There were 30 children in each group. Those in the warmed group (26 degrees C) had a statistically significant higher initial T(core) (0.4 degrees C warmer) and less drop in their T(core) (0.18 degrees C benefit at 20 min). Although younger/lighter/shorter individuals were more likely to drop their T(core), a warmer T(ambient) had only 0.1 degrees C thermal benefit irrespective of age.


CONCLUSIONS
There are statistically significant thermal advantages to preoperative environmental warming. This study provides data to assist the anesthetist in deciding when these are likely to be clinically relevant.
Cassey
John G
JG
Pediatric Surgeon, John Hunter Hospital, Newcastle, Australia. jcpaed@iinet.net.au
King
Robert A R
RA
Armstrong
Peter
P
D000293:Adolescent; D000758:Anesthesia; D000763:Anesthesia, Caudal; D001831:Body Temperature / Q000502:physiology*; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D023381:Endpoint Determination; D004947:Esophagus / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D016014:Linear Models; D008297:Male; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D012727:Sex Characteristics; D013696:Temperature; D014432:Tympanic Membrane / Q000502:physiology