Intrathecal bupivacaine in comparison with a combination of nalbuphine and bupivacaine for subarachnoid block: a randomized prospective double-blind clinical study.

We performed this randomized, prospective double-blind study to evaluate the effects of 2 different doses of intrathecal nalbuphine (a synthetic opioid agonist-antagonist) on the onset, duration of action, side effects, and complication produced by intrathecal hyperbaric 0.5% bupivacaine in lower abdominal, urologic and lower limb surgeries. Seventy-five patients of ASA grades 1 and 2 of either sex in the age group of 20-60 years were randomly allocated to 1 of 3 groups. Group A (n = 25) received 2.5 mL of 0.5% hyperbaric bupivacaine + 1 mL sterile water intrathecally; group B (n = 25) received 2.5 mL of 0.5% hyperbaric bupivacaine + 1 mL (200 μg) nalbuphine intrathecally; group C (n = 25) received 2.5 mL of 0.5% hyperbaric bupivacaine + 1 mL (400 μg) nalbuphine intrathecally. The onsets of sensory and motor blockade, highest level of sensory blockade, 2 segment regression time of sensory blockade, duration of motor blockade and analgesia, visual analog scale score, hemodynamic and respiratory changes, side effects were recorded, tabulated, and analyzed. Onsets of sensory and motor blockade and duration of motor blockade were not affected. Two segment regression time of sensory blockade and duration of analgesia were maximally prolonged in group C (P < 0.05). The visual analog scale scores were in the following order: group A > group B > group C at 90, 120, and 150 minutes after induction (P < 0.05). Hemodynamic and respiratory complications were absent except in 2 patients in groups A and C each, and 1 patient in group B developed bradycardia (P > 0.05). One patient in group A had nausea and vomiting, 2 patients in each group developed shivering (P > 0.05). No other side effect or complication was observed. Nalbuphine hydrochloride (400 μg) significantly prolongs the duration of sensory blockade and postoperative analgesia without any side effect or complication when introduced intrathecally along with hyperbaric bupivacaine.