Impact of naloxone and droperidol on postoperative epidural morphine analgesia

This study was designed to evaluate the impact of epidural naloxone [N] or droperidol [D] on the outcome of epidural morphine analgesia. The study comprised 60 females assigned to undergo abdominal hysterectomy randomly allocated into three equal groups [n=20], each received medication mixture via infusors; Group M received 3 mg morphine in 100 ml bupivacaine 0.125% at rate of 2 ml/hr; group M+N and M+D received the same mixture, but with the addition of naloxone so as to provide an infusion rate of 0.167 micro g/kg/hr of naloxone in group M+N or droperidol in a dose of 1.25 mg/day continuous infusion in group M+D. Pain sensation was evaluated using 100-mm visual analogue scale, postoperative nausea and vomiting [PONV] was monitored on a four-point scale: 0: no, 1: mild not requiring an antiemetic, 2: moderate requiring an antiemetic and 3: severe nausea/vomiting, resistant to antiemetic. Pruritus was evaluated using a four-point scale: 0=no, 1= mild, 2 moderate and 3= severe itching. Somnolence was graded as follow: 1=clear mentality, 2= good response to verbal command but drowsy and 3= poor response to repeated verbal command. Respiratory depression was assessed as 1= no respiratory depression and 2= respiratory depression exists with a respiratory rate<8 breaths/min. All parameters were assessed at 2, 4, 8, 16, 32, and 48 hr PO. At 8-hrs PO, VAS scores were significantly lower in M+N [P1 =0.017] and M+D [P1 =0.034] groups compared to group M., with a non-significant [P2>0.05] reduction of VAS scores between combination groups but in favor of group M+N. Thereafter, VAS scores were significantly lower in groups M+N and M+D compared to group M with a significant reduction of VAS scores in group M+N compared to group M+D. Epidural naloxone [Group M+N] significantly reduced the frequency and severity of side effects in comparison to group M and significantly reduced the frequency and severity of somnolence and respiratory depression and non-significantly reduced the frequency and severity of PONV in comparison to group M+D. On the other hand, epidural droperidol [Group M+D] significantly reduced the frequency and severity of pruritus and respiratory depression but reduced the frequency of PONV and somnolence non-significantly in comparison to group M. Moreover, epidural droperidol significantly reduced the frequency and severity of pruritus compared to epidural naloxone. It could be concluded that epidural co-administration of morphine and naloxone or morphine and droperidol provided more effective postoperative analgesia with a significant reduction of morphine-induced side effects; however, droperidol appears to be a better alternative when pruritus is taken into consideration, while naloxone is a better alternative when somnolence is taken into consideration