Perioperative Train-of-Four Monitoring And Residual Curarization: Pancuronium Versus Vecuronium

Objective: To observe the incidence of postoperative residual curarization (PORC) following the use of pancuronium and vecuronium, and to discuss the feasibility of decreasing the incidence of PORC by using perioperative train-of-four (TOP) monitoring. Methods: Eighty one adult patients, ASA I ?II, scheduled for elective surgery under general anesthesia, were randomly divided into 4 groups: vecuronium with TOP monitoring(group V+M, n=21), vecuronium without TOP monitoring(group V, n=23), pancuronium with TOP monitoring (group P+M, n=19) and pancuronium without TOP monitoring(group P, n=18). Tracheal intubation was induced with propofol 2-2.5mg ?kg', vecuronium or pancuronium 0.8-1.2mg ?kg"1. Anesthesia was maintained with inhalation of 50%N2O plus isoflurane and fentanyl supplementation as needed. Neuromuscular blockade was assessed with TOP-GUARD accelerometer. In group V+M and P+M, as soon as a second twitch was palpable, 0.04mg ?kg"1 neostigmine plus 0.02mg ?kg"1 atropine were administered intravenously. In group V and P, the timing and dose of administration of reversal drugs were chosen by the participating anesthetists. The total dose of neuromuscular relaxant and neostigmine, and when the patients arrived at the ICU, the incidence and duration of PORC were observed. The time from the beginning of reversal to 0.70 and 0.90 of TOFr in group V+M and group P+M, and the TOFr which each patient could sustain 5-s head lift and perform the tongue depressor test wererecorded respectively. Results: The recovery time (time to reach a TOFr of 0.70 or 0.90) was significantly longer in group P+M than in group V+M (P<0.01). The incidence of PORC (TOP ratio<0.70) was greater in group V (39.13%) and P (83.33%) than in group V+M (23.8%) and P+M (42.11%) respectively (PO.05). The duration of PORC was longer in group V(30.00?15.12 min) than in group V+M (11.00 + 5.48 min) and in group P (44.87 + 31.39 mm) than in group P+M (21.15 + 11.62 min) respectively (PO.05). The total dose of pancuronium and vecuronium was significantly higher in group V and group P than in group V+M and group P+M. The mean value of TOFr which all patients could sustain 5-s head lift and perform the tongue depressor test were 0.55 + 0.11 and 0.65 + 0.10 respectively (P<0.01), and the difference has no relationship with the kinds of neuromuscular relaxant. Conclusions: (1) Perioperative TOP monitoring decreased the incidence and the degree of PORC following the use of non-depolarizing neuromuscular relaxants. (2) The incidence and duration of PORC after using pancuronium was significantly higher than using vecuronium. (3) It is necessary to antagonize residual block produced by non-depolarizing neuromuscular relaxants routinely. (4) The tongue depressor test is more sensitive than the 5-s head-lift test for assessment of neuromuscular recovery.