Action Duration of Rocuronium in the Elderly Patients

Background: The effect of a muscle relaxant may differ in the elderly for pharmacokinetic and pharmacodynamic reasons.Rocuronium, a derivative of vecuronium is a non depolarizing neuromuscular blocker with a rapid onset and intermediate duration.The purpose of this study was to compare differences in the onset and duration of rocuronium in young adults and the elderly.Methods: The study was approved by our instituitional review board, and informed consent was obtained from all patients.Twenty two young adults (15-59 yr) and 21 elderly (65-80 yr) patients, ASA physical status 1-2 underwent elective orthopedic surgery under general anesthesia.All were anesthetized with pentothal sodium, nitrous oxide, and isoflurane.Rocuronium (0.6 mg/kg) was given and then intubation was performed after TOF response had totally disappeared.Neuromuscular relaxation was measured by TOF response at the adductor pollicis muscle after a supramaximal stimulation of Train-of-four (TOF, 2 Hz every 12 sec) at the ulnar nerve.Onset (disappearance of T1) and the recovery times of T1, T2, T3 and T4 were recorded.Results: The onset of neuromuscular block was slower in the elderly than the young adults (P ＜ 0.05), and recovery times of T1, T2, T3, and T4 were prolonged in the elderly (P ＜ 0.05).Conclusions: Rocuronium has a slower onset time and a delayed recovery in the elderly.(Korean J Anesthesiol 2005; 48: 29∼32)