Effect of preheating on the maintenance of body temperature in surgical patients: a randomized clinical trial.
Cibele Cristina Tramontini Fuganti, Edson Zangiacomi Martinez, Cristina Maria Galvão
PMID 30379244WHAT IT FOUND
In elective gynecologic surgery, 20 minutes of forced-air preheating did not maintain body temperature better than usual cotton sheets and blankets, when all patients also received upper-body forced-air warming, routine cotton covering, and heated liquids.
Key findings
01Across the measured time points, mean tympanic body temperature did not differ significantly between the forced-air preheating group and the usual-care group; the only significant difference was at 150 minutes after the start of surgery (p = 0.01).
02At the end of surgery, mean tympanic body temperature was 36.8°C in both groups.
03Both groups also received routine cotton sheets and blankets, heated liquids, and upper-body forced-air warming at 38°C after anesthetic induction, so the effect of 20-minute preheating cannot be separated from those measures.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The trial was non-blinded because the warming equipment was visible to the team. It was a single-center study of elective gynecologic surgery, so the result may not apply to other surgeries, anesthesia types, or patient groups. Both groups received the same intraoperative forced-air upper-body warming, routine passive covering, and heated liquids, so the study cannot separate the effect of 20-minute preheating from those other measures. Patients began with high mean tympanic temperatures (37.9°C), which may have limited heat transfer from the forced-air blanket. The room temperature where preheating occurred was not measured, and the time between preheating and surgery was 42.9 minutes in the control group and 38.7 minutes in the experimental group. The only significant temperature difference was at T150, and the authors suggested it may have been related to operating room temperature and humidity at that moment.
The easy way to misread this
Do not read the significant difference at T150 as proof that preheating maintains body temperature. The main comparison was null, and both groups also received upper-body forced-air warming during surgery, routine passive covering, and heated liquids.