Postoperative Nausea and Vomiting Following General Anaesthesia: A Prospective Study on Surgical Patients in the University of Calabar Teaching Hospital, Calabar, Nigeria

Introduction: Postoperative nausea and vomiting remains a significant problem in our clinical setting. This study at the University of Calabar Teaching Hospital, Calabar in Nigeria aims to investigate the incidence of postoperative nausea and vomiting among gynaecological and non-gynaecological patients undergoing surgery under general anaesthesia, compare the incidence as it affects males and females, identify predisposing factors and recommend preventive measures.

Methodology: One hundred and sixty six(166) adult patients aged 18 years and above were recruited prospectively excluding cases of full stomach, patients with nasogastric tubes and those who could not be followed up for 24 hours. The past history of motion sickness and postoperative nausea and vomiting was obtained and documented. General anaesthesia was induced with either sodium thiopentone or ketamine hydrochloride. Maintenance was inhalational with or without a relaxant technique. Intravenous pentazocine and subanaesthetic doses of ketamine were used for intraoperative analgesia. The patients were observed postoperatively and questioned at two hourly intervals for nausea or vomiting and pain was scored using the categorical rating scale. A data sheet was completed at the end of 2 and 24 hours. The data was entered on a microcomputer for analysis with aid of EPI INFO version 6 software. The level of significance was set at 95% confidence interval with P value less than 0.05.

Results: The overall incidence of nausea was 11.45% and vomiting 13.35% in the 166 patients studied. There was no significant difference in incidence between the gynaecological and non gynaecological patients. Female patients experienced more postoperative nausea and vomiting than male patients with 11.4% and 18.42% nausea and vomiting. Sodium thiopentone induction, muscle relaxant use and reversal as well as moderate to severe postoperative pain increased the incidence of PONV

Conclusion: The use of prophylactic “balanced antiemesis” in high risk patients, avoidance of muscle relaxant reversal and adequate postoperative analgesia are recommended as preventive measures.