Adding low dose meperidine to spinal lidocaine prolongs postoperative analgesia.

PURPOSE: To investigate the effects of the addition of low dose meperidine to spinal lidocaine on the sensory and motor blockade profile, and the quality and duration of postoperative analgesia.

METHODS: In a randomized double blind prospective dose finding study 40 patients undergoing transurethral prostatectomy with spinal anesthetic were allocated to receive 75 mg lidocaine 5% intrathecally as the sole agent (group A), or co-administered with 0.15 mg x kg(-1) meperidine (group B) or 0.30 mg x kg(-1) meperidine (group C). Sensory and motor blockade profiles were documented. Postoperatively, the amount of analgesics required, time to first analgesic, visual analogue scores and adverse events were recorded.

RESULTS: Sensory blocks at or above T10 was maintained for 128, 156 and 145 minutes in groups A, B and C respectively. There was no difference in the latency or duration of the motor block among the three groups. Patients in group C had lower visual analogue pain scores (VAPS) over time than did those in groups A and B (P < 0.05). Time to first analgesia was longer (429 +/- 197 minutes) in group C than in group A (254 +/- 157 minutes) (P < 0.05). Fewer patients in group C required parenteral opioid postoperatively than in group A (P < 0.05). The incidence of bradycardia was higher in the groups receiving meperidine. No symptoms of transient radicular irritation (TRI) were reported in the groups receiving meperidine.

CONCLUSION: The addition of 0.3 mg x kg(-1) of meperidine to spinal lidocaine prolongs postoperative analgesia without delaying discharge from post anesthetic care unit (Table II) and reduces the requirement for parenteral analgesics (Table III).