Does postoperative pain induce emesis

Objective: The aim of this prospective, controlled study was to evaluate the risk factors for postoperative emesis in patients undergoing gynecologic surgery and receiving patient-controlled analgesia for three days. Methods: Six hundred twenty-five gynecologic patients with an American Society of Anesthesiologists physical status of I to III undergoing lower-abdominal surgeries were enrolled. A standard, general anesthetic technique was used. Postoperative pain was treated by a patient-controlled analgesia device with bolus intravenous doses of 1 mg morphine. For 3 days after surgery patients were assessed for occurrence of emesis, sedation, and pain intensity when at rest and during movement. Results: The incidence of emesis was 26% on postoperative day 1, 13% on day 2, and 4% on day 3. On all 3 days, patients' pain scores when at rest and when coughing were higher for those with emesis than for those without. During the first 2 postoperative days the patients with and those without emesis consumed similar amounts of morphine daily, but on the third day the patients with emesis consumed significantly more morphine than did those without emesis (p <0.05). Further logistic regression analysis showed that incident pain was the main risk factor for postoperative emesis on all 3 days. Conclusions: The results suggested that postoperative pain was an associative risk factor to increase the incidence of emesis in these female patients.