Transdermal nitroglycerine enhances spinal sufentanil postoperative analgesia following orthopedic surgery

BACKGROUND: Sufentanil is a potent but short-acting spinal analgesic used to manage perioperative pain. This study evaluated the influence of transdermal nitroglycerine on the analgesic action of spinal sufentanil in patients undergoing orthopedic surgery. METHODS: Fifty-six patients were randomized to one of four groups. Patients were premedicated with 0.05-0.1 mg/kg intravenous midazolam and received 15 mg bupivacaine plus 2 ml of the test drug intrathecally (saline or 10 microg sufentanil). Twenty to 30 min after the spinal puncture, a transdermal patch of either 5 mg nitroglycerin or placebo was applied. The control group received spinal saline and transdermal placebo. The sufentanil group received spinal sufentanil and transdermal placebo. The nitroglycerin group received spinal saline and transdermal nitroglycerine patch. Finally, the sufentanil-nitroglycerin group received spinal sufentanil and transdermal nitroglycerine. Pain and adverse effects were evaluated using a 10-cm visual analog scale. RESULTS: The time to first rescue analgesic medication was longer for the sufentanil-nitroglycerin group (785+/-483 min) compared with the other groups (P<0.005). The time to first rescue analgesics was also longer for the sufentanil group compared with the control group (P<0.05). The sufentanil-nitroglycerin group group required less rescue analgesics in 24 h compared with the other groups (P<0.02) and had lesser 24-h pain visual analog scale scores compared with the control group (P<0.005), although these scores were similar to the sufentanil and nitroglycerin groups (P>0.05). The incidence of perioperative adverse effects was similar among groups (P>0.05). CONCLUSIONS: Transdermal nitroglycerine alone (5 mg/day), a nitric oxide generator, did not result in postoperative analgesia itself, but it prolonged the analgesic effect of spinal sufentanil (10 microg) and provided 13 h of effective postoperative analgesia after knee surgery.