Reduction of postoperative residual muscle relaxation : using a peripheral nerve stimulator or a newer relaxant?

Abstract

The objectives of this research were: 1. To study whether using a peripheral nerve stimulator (PNS) to guide muscle relaxant administration instead of giving muscle relaxant at fixed time interval will reduce the prevalence of residual relaxation. 2. To study whether using a newer relaxant instead of an older relaxant will reduce the prevalence of residual relaxation. One hundred and eighty patients were randomly allocated into 4 groups according to a factorial design. Group I and II patients received pancuronium at fixed time interval or guided by PNS while group III and IV patients received vecuronium at fixed time interval or guided by PNS respectively. All patients were scheduled for lower abdominal, gynecological operations and all of them did not have any serious systemic diseases. The mean ages were 40.6 ± 6.9, 39.7 ± 7.1, 38.9 ± 8.8 and 39.4 ± 6.3 years respectively. Residual relaxation was assessed at 30 min post reversal by using an accelograph. The % T4/T1 ratio were 54.3 ± 26.0%, 61.3 ± 24.2%, 75.4 ± 20.3% and 88.2 ± 23.1% respectively. Using the T4/T1 ratio of 70% as the cut-off point, there were 26, 24, 12 and 8 cases of residual relaxation resulting in prevalance rates of 57.8%, 53.3%, 26.7% and 17.8% respectively. There were statistically significant difference (p < 0.001 and 0.00007 respectively). The differences were explained by types of relaxants, but not by whether the PNS was used or the interaction between these 2 factors. In this study, the use of newer relaxant was shown to significantly reduce the prevalence of residual relaxation, while the use of the PNS was not. From the health care provider viewpoint, the cost-effectiveness ratio of using vecuronium instead of pancuronium in 100 cases equaled 88.59 baht/ hr/case reduction.