Early reduction of forced-air warming temperature can reduce energy consumption during craniotomy: a prospective randomized trial

Despite their well-known efficacy, forced-air warming during operations has its drawbacks, mainly high energy consumption and risk of hyperthermia. We therefore investigated two warming strategies in a prospective randomized study with the aim of reducing the incidence of hyperthermia without increasing the risk of intraoperative hypothermia. In the standard of care group temperature of the forced-air warmer was reduced to 32 °C when core temperature reached 37.3 °C. In the modified warming group this reduction was performed when core temperature reached 36.5 °C. The difference in the duration of normothermia between standard of care and the modified warming strategy was estimated to be 3.9% (90%-CI: 0.8% to 7.1%) and was within the predefined equivalence bounds of ± 20% ( p < 0.001). In both treatment groups no intraoperative hyperthermia ocurred. Average energy consumption per hour was significantly higher in the standard-of-care group (0.51 kWh/h; 95%-CI: 0.47–0.56) compared with the modified warming strategy (0.40 kWh/h; 95%-CI: 0.35–0.46; p = 0.002). By strictly limiting the heat supply, intraoperative hyperthermia can be safely prevented during craniotomies. A lower threshold value of 36.5 °C allows for a meaningful reduction in energy consumption.