Transdermal nitroglycerine potentiates the analgesic effect of patient controlled epidural analgesia after lower abdominal surgery

BackgroundThis study was designed to evaluate the effect of pre-emptive use of transdermal nitroglycerine (NTG) patch as an adjuvant to combined general epidural anesthesia (CGEA) in patients undergoing lower abdominal surgery.MethodForty patients (ASA I or II) were randomly allocated to two equal groups; control group (group C) and nitroglycerine group (group NG). Nitroderm patch, 5 mg, was applied to patients in group NG, 2 h before surgery. All patients received epidural bolus of 18 ml of 0.25% bupivacaine with fentanyl 2 μg/ml followed by continuous infusion at the rate of 5 ml/h combined with general anesthesia. Patients used patient controlled analgesia (PCA) device to receive bolus dose of 5 ml of patient controlled epidural analgesia (PCEA) solution containing bupivacaine 0.125% and fentanyl 2 μg/ml after surgery. Perioperative mean arterial blood pressure (MAP) and heart rate (HR), time to first rescue analgesic, postoperative bupivacaine and fentanyl consumption, and VAS pain scores were measured for 24 h postoperatively. Patient satisfaction score was also recorded.ResultsPostoperative MAP and HR increased significantly to both baseline and the other group at 2 h in group C and at 4 h in group NG (p < 0.05). The time to first rescue analgesic was significantly longer in group NG (238.62 ± 54.3 min) than in group C (126.75 ± 35.1 min) (p < 0.05). Pain scores were significantly higher compared to the other group at 2 h in group C and at 4 h in group NG (p < 0.05). Postoperative bupivacaine and fentanyl consumption were significantly lower in group NG (74.91 ± 26.34 mg and 121.83 ± 32.5 μg, respectively) than in group C (118.68 ± 29.4 mg and 194.21 ± 45.31 μg, respectively). Patient satisfaction was significantly better in group NG than in group C (p < 0.05).ConclusionPre-emptive application of 5 mg transdermal nitroglycerine patch as adjuvant to CGEA provided significant prolongation of the postoperative analgesia and reduction of the postoperative bupivacaine and fentanyl consumption.