Effects of preceding stimulation patterns of muscle relaxant on potency measurement vecuronium
Objective To observe the effects of preceding stimulation patterns of muscle relaxant on potency measurement of vecuronium. Methods Thirty female patients were investigated in this study. Both arms of patients were stimulated using. One of paired arms (Control-Arm) was received 20 min of TOF stimulation with a 5 s, 50 Hz tetanus stimulation before AUTO I calibration . Values of T1 were recorded per minute. T1 at 20 min was compared with previous T1 using a paired student t test. The contralateral arms (Test-Arm) were divided into 3 groups, receiving 20 min (Group1), 1 min ( Group2) and 6min( Group3) of TOF stimulation without tetanus stimulation before calibration, respectively. T1 of Group1 were recorded per minute. T1 at 20 min was compared with previous T1 using a paired student t test. Then potency of vecuronium was estimated on both arms using cumulative dose-response technique. Results With tetanus stimulation, values of T1 keep constant during 20 min of TOF stimulation. Without tetanus stimulation, values of T1 slowly increased during first 6 min, then keep constant. ED50, ED90 and ED95 weren't significantly different between paired arms in Group1 and Group3. However, in Group2, ED50, ED90 and ED95 were underestimated at Test-Arm. Conclusion With tetanus stimulation, T1 immediately reach plateaus after AUTO I calibration., However, without tetanus stimulation, T1 reach plateaus after 6 min of TOF stimulation. Potency of vecuronium isn’t affected by preceding stimulation patterns after T1 reaches plateaus.