Intrathecal atropine versus preoperative intravenous ondasetron for prevention of postoperative nausea and vomiting due to intrathecal morphine in perineal surgery

Background Opioids are frequently added to neuroaxial local anesthetics (LAs). Intrathecal (IT) opioid is not devoid of adverse effects such as postoperative nausea and vomiting (PONV), respiratory depression, and pruritis. IT atropine also carries a significant antiemetic effect, and this can be a valuable modality for the prevention of IT opioid-related PONV. The antagonist of 5-HT3 receptors such as ondasetron which is usually used to decrease the incidence of nausea and vomiting was considered for the prevention and treatment of neuroaxial opioid-induced (PONV). Method 100 cases of ASA I-II aged 18 and 45 who planned to do elective perineal surgery, and receiving bupivacaine spinal anesthesia were randomly divided into two equal groups. Group (A) cases received IT hyperbaric bupivacaine (10 mg 0.5%) in combination with morphine 250 μg and atropine sulphate 100 μg. Before anesthesia, group (B) participants received IT hyperbaric bupivacaine (10 mg 0.5%) and 250 μg of morphine and 4 mg IV ondansetron. Follow-up for PONV attacks, vital signs, and side effects in the two groups. Results The occurrence of postoperative nausea were 4 and 18% in group A and B, respectively (P value=0.049) while postoperative vomiting was 0 and 12% in group A and B, respectively (P value=0.027). The occurrence of sedation, mouth dryness, headache, and drowsiness were more in group A compared with group B. Conclusion IT atropine is more effective than IV ondasetron preoperative in relieving PONV related to IT morphine, sedation is the frequent side effect occurred in IT atropine, headache is the frequent side effect occurred in the ondasetron group