The effects of peripheral hypothermia on monitoring the recovery from deep neuromuscular blockade with rocuronium

ABSTRACT

BACKGROUND: The skin temperature is often decreased during anesthesia because of a cool ambient temperature in the operating room. Contractility of the muscles may be affected by lowering the muscle temperature. This study was designed to verify that efforts to maintain normothermia on the monitored arm can make recovery from deep neuromuscular blockade more reliable. METHODS: A total of 60 patients were enrolled in this study. Each patient was randomly assigned to group 1 (the monitored arm was shielded with a passive warming protector) or group 2 (the monitored arm was was exposed to the ambient operating room temperature). Conventional inhalation anesthesia was induced with propofol and alfentanil, and this was maintained with O2, N2O and isoflurane. The twitch response of the adductor pollicis muscle was recorded. After calibration of the TOF watch(R), 0.6 mg/kg of rocuronium was injected. During anesthesia, the post tetanic count (PTC) was checked every 5 to 6 minutes until the first response to a train-of-four (TOF) stimulations appeared. The ambient operating room temperature, the core temperature and the skin temperature were checked simultaneously. RESULTS: The skin temperature of group 2 was lower than that of group 1 (33.89 +/- 0.81 degreesC and 35.41 +/- 0.45 degreesC, respectively, P < 0.05). When the data was plotted with the equation y=be(-ax), this equation well represented the data of group 1 (R2 = 0.82), but it did not well represent the data of group 2 (R2 = 0.54). CONCLUSIONS: During recovery from deep neuromuscular blockade with using rocuronium, it may be desirable to maintain normothermia at the thenar area for a better recovery time from a given PTC.