A study to evaluate the efficacy of transdermal nitroglycerine patch in enhancing analgesia of intrathecal neostigmine following inguinal hernioplasty under bupivacaine subarachnoid block

Abstract

Objectives: We aimed to evaluate and compare the safety and efficacy of combining intrathecal neostigmine with transdermal nitroglycerine patch for pain relief in patients undergoing inguinal hernioplasty under bupivacaine subarachnoid block. And to evaluate the adverse effects of intrathecal neostigmine with transdermal nitroglycerine patch. Methodology: After taking informed consent, 60 patients of ASA Grade I and II were systematically randomized into two groups of 30 each. Patients were infused with Ringer's lactate solution 10ml/kg preoperatively. Group N patients received Intrathecal injection of 15 mg of 0.5% hyperbaric bupivacaine with 10 mcg of neostigmine and transdermal nitroglycerine patch (5 mg/24 hours). Group P patients received Intrathecal injection of 15 mg 0.5% hyperbaric bupivacaine with 10 mcg of neostigmine and transdermal placebo patch. Subarachnoid Block was performed at L3-L4 level, with 25 gauge spinal needle and 3.5 ml of the drug solution was injected intrathecally per the group allocation. Sensory block was assessed by using pin prick method and motor block was checked by using modified Bromage scale. Pulse rate, blood pressure and SpO2 were monitored. Intra-operative complications were noted. Sample size was calculated to be 60 with a total of two groups with a power of 90 % and a alpha of 0.05. Test for analysis among two groups was done by Unpaired t test. A p value less than 0.05 was taken statistically significant. Results: The characteristics of study were comparable among two groups. The mean duration of analgesia in Group N was significantly longer (p < 0.001) than in Group P (367.4 ± 16.7 vs. 218.7 ± 16.8 min respectively). Group P had higher VAS scores and the number of rescue analgesic requirement was significantly more in Group P as compared to Group N. Hemodynamic changes remained insignificant in both groups. Incidences of side effects were not significant in both the groups. Conclusion: We conclude that the nitroglycerin transdermal patch used as an adjuvant to intrathecal neostigmine and bupivacaine prolongs postoperative analgesia.