Author: Harriet W. Hopf, M.D.
Published in The Journal of the American Society of Anesthesiologists 2 2015, Vol.122, 229-230. doi:10.1097/ALN.0000000000000552
When I started anesthesia residency in 1988, patients undergoing major surgery routinely arrived in the postanesthesia care unit (PACU) with a core temperature of 34.5° to 35°C. We did not fully understand how anesthesia causes hypothermia; we did not have practical, effective means of warming patients; and we did not have evidence of harm—although the shivering patients in the PACU probably had a different perspective. All this changed during my first decade in practice; by 1999, maintenance of perioperative normothermia had been incorporated into practice guidelines.1 The most common definition of perioperative normothermia is core temperature at least 36.0°C on arrival in the PACU. This number was extrapolated from studies that compared outcomes between patients with relatively large differences in core temperature (1° to 2°C) on arrival in the PACU. Sun et al.2 in this issue, using innovative analyses of a large patient dataset, demonstrate that, although most patients meet criteria for normothermia on arrival in the PACU, intraoperativehypothermia (35° to 36°C) is common. Moreover, longer duration of hypothermia is associated with a significant increase in transfusion requirement and a small but statistically significant increase in hospital length of stay. These results suggest the need for a more comprehensive definition of perioperative normothermia and more aggressive efforts to prevent intraoperative hypothermia.