Prewarming for Prevention of Hypothermia in Older Patients Undergoing Hand Surgery Under Brachial Plexus Block

Older patients are more vulnerable to inadvertent perioperative hypothermia. Prewarming contributes to the prevention of inadvertent perioperative hypothermia in patients under general or neuraxial anesthesia. However, the effects of brachial plexus block (BPB) on thermoregulation and the efficacy of prewarming in the prevention of hypothermia in older patients undergoing surgery with BPB remain unclear. This study evaluated the effects of BPB on thermoregulation and the efficacy of prewarming during BPB in older patients.

Patients aged ≥65 years were randomly allocated to receive either standard preoperative insulation (control group, n=20) or preanesthetic forced-air warming for 20 minutes before BPB (prewarming group, n=20). During the perioperative period, tympanic temperatures were measured. Thermal comfort scores and shivering grades were also obtained.

The tympanic temperatures at the end of surgery did not differ between the groups (36.9°C±0.5°C and 37.0°C±0.4°C in the control and prewarming groups, respectively; p=0.252). The maximum temperature change was significantly lower in the prewarming group compared to the control group (0.36°C±0.4°C and 0.65°C±0.3°C, respectively; p=0.013). The hypothermia incidence and severity, thermal comfort scores, and shivering grades did not differ between the groups.

Regardless of the application of prewarming, BPB did not cause a clinically significant impairment of thermoregulation. Moreover, the efficacy of prewarming appeared to be low; thus, it may not be routinely required in patients undergoing orthopedic hand surgery under BPB.