Time course of action and pharmacokinetics of ropivacaine in adult and elderly patients following combined lumbar plexus-sciatic nerve block.

摘要

OBJECTIVE: Large doses of local anesthetics are needed in combined lumbar plexus-sciatic nerve block. The safety of local anesthetics is important among elderly patients. This study investigates the pharmacokinetics of ropivacaine in elderly patients with combined lumbar plexus-sciatic nerve block. METHODS: Ropivacaine pharmacokinetics and the time of onset, duration of sensory and motor block were studied in adult patients (18 - 60 y) and elderly patients (>= 60 y). Combined lumbar plexus-sciatic nerve block was performed using a nerve stimulator. 0.375% ropivacaine was injected in patients. Plasma concentration of ropivacaine was determined by high performance liquid chromatography. RESULTS: There was no significant difference in onset time and time to peak (tmax1, tmax2) between elderly patients and adult patients. Half-life time (t1/2alpha, t1/2beta) and the duration of sensory and motor block were longer in elderly patients (p < 0.05). While the peak plasma concentrations of (double peaks, Cmax1, Cmax2) wer lower in elderly patients than that in adult patients. CONCLUSIONS: Age does not affect the onset time of ropivacaine after combined lumbar plexus-sciatic nerve block but can influence the motor and sensory recovery. Local absorption of ropivacaine is slower in elderly patients compared to adults.