Adding low dose meperidine to spinal lidocaine prolongs postoperative analgesia

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.

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.

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.

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).