Adding neostigmine to morphine epidurally lessens the incidence of postoperative urine retention: A comparative study

IntroductionPostoperative urine retention is a common problem faced with many epidurally administered drugs to relief pain. Morphine was introduced as a potent epidural analgesic, however; its administration is associated with a high incidence of urine retention. Neostigmine had been proposed as an epidural analgesic that lacks major side effects faced with intrathecal neostigmine. However, the effect of the combined use of both drugs upon lower urinary system has not been discussed.Methods100 Patients allocated into 4 equal groups were subjected to inguinal hernia repair under epidural anesthesia. Group I received bupivacaine 10 ml 0.5%, Group II received bupivacaine/morphine 2 mg, Group III received bupivacaine/morphine 2 mg and 5 μg/kg neostigmine and Group IV received bupivacaine and 5 μg/kg neostigmine. Incidences of postoperative urine retention and patients who needed catheterization in each group were recorded. Mean arterial blood pressure, heart rate and incidence of complication (nausea, vomiting, pruritis, hypotension and bradycardia) were recorded. Time for 1st rescue analgesic drug was recorded.ResultsNo single patient experienced urine retention in Group IV. Whereas one patient in both Groups I and III versus five patients in Group II suffered from urine retention and required urinary catheterization. The hemodynamic parameters were comparable between all groups. Time for 1st rescue analgesic drug was prolonged in Group III more than the other groups followed by Groups II, IV and I, respectively.ConclusionAddition of neostigmine to morphine epidurally lessened the incidence of postoperative urine retention commonly faced when morphine is used alone with local anesthetic and prolonged the duration of analgesia.