Experience with vecuroniurn during long‐lasting surgery

Our knowledge of the possible cumulative properties of vecuronium is limited. Previous studies have shown a tendency towards an increased duration of effect, a slightly prolonged recovery time, as well as an increased variation in duration of effect. We have studied 15 patients scheduled for middle‐ear surgery. During i.v. N2O‐O2 anaesthesia the twitch response of the adductor pollicis muscle was recorded after supramaximal stimulation of the ulnar nerve at the wrist. Prior to tracheal intubation a bolus dose of vecuronium was given (0.08 mg/kg body weight). During surgery supplementary doses of 0.02 mg/kg body weight were given at a train‐of‐four (TOF) ratio of 0.25. The duration of effect (DUR‐IT‐25) and recovery time from a TOF ratio of 0.10 to 0.25 (Recovery‐IT‐10–25) were recorded. When comparing 10 iteration doses, the mean DUR‐IT‐25 in the 15 patients studied showed only minor variations (n.s.). Each patient had a near constant interval between the iteration doses; however, a noteworthy variation between individuals was found. Recovery‐IT‐10–25 was 250 ± 80 (mean · s.d.) 240 ± 80 and 260 ± 80 s comparing the second, sixth and tenth iteration doses, respectively. In conclusion, the duration of effect vaned considerably between patients. Each patient showed, however, a near constant iteration interval and a recovery time with only small variations. This indicates that cumulation is unlikely to exist following repetitive administration of vecuronium of 0.02 mg/kg body weight.