Does Perioperative Monitoring of the Train-of-Four Response Influence the Frequency of Postoperative Residual Curarization in Propofol Anesthesia?

Abstract

Background : Sometimes hypoxemia occurs in the postoperative recovery room because of post- operative residual curarization (PORC). Some reports show that postoperative residual curarization is common. FORC occurs after the use of the long-acting muscle relaxants. It has been recommended to use intermediate-acting muscle relaxants and a TOF monitor to decrease PORC. The purpose of this study was to examine whether the use of the TOF monitor during propofol anesthesia affects the incidence of postoperative residual curarization. Methods : 38 ASA I or II patients were divided randomly into two groups of 19 each. They received propofol-fentanyl-nitrous oxide for anesthesia. Pancuronium (80 ― 100 μg/kg) was used to facilitate tracheal intubation and additional doses were used to maintain surgical relaxation. The requirement for incremental doses of pancuronium and adequacy of recovery following reversal were assessed, either with (control group: n = 19) or without (experimental group: n = 19) TOF monitoring. Fifteen minutes after the arrival at the recovery room, neuromuscular function was assessed clinically and by using TOF. Results : There were no statistical differences in body weight, age, or duration of operation between the two groups. There was no statistical difference in the total dose of pancuronium and total dose of pancuronium relative to body weight and duration of operation. There were statistical differences in TOF ratio in the recovery room (0.73 vs. 0.86). The incidence of PORC was 47% in the control group and 5% in the experimental group. Conclusions : Though the monitoring of TOF did not effect the dose of muscle relaxant, it may have reduced the incidence of PORC. However, the PORC had no clinical significance because the mean TOF ratio in the two groups was over 0.7 and there were no clinical signs of residual muscle weakness. (Korean J Anesthesiol 2000; 38: 783-788)