NALOXONE VERSUS METOCLOPRAMIDE FOR THE TREATMENT OF ESTABLISHED POSTOPERATIVE NAUSEA AND VOMITING IN PATIENTS FOLLOWING GENERAL ANESTHESIA WITH FENTANYL SUPPLEMENTATION

Postoperative nausea and vomiting (PONV) remains a common adverse event associated with surgery and anesthesia. Despite significant advances in the area of PONV and the introduction of new antiemetic agents, the overall incidence of PONV is currently estimated to be around 20 to 30%. PONV can cause prolonged post anesthesia care unit (PACU) stay and unanticipated admissions following ambulatory surgery, therefore increasing medical costs. Nausea and vomiting are also among the most unpleasant experiences associated with surgery and one of the most common reasons for poor patient satisfaction rating in the postoperative period. Because PONV is multifactorial and several neurotransmitters are involved in the emetic response, effective management remains challenging. Intraoperative opioids are considered one of the anesthesia related factors for PONV. In a review of 27,626 patients admitted to the PACU, administration of opioids during surgery increased the risk of PONV four folds. Roberts et al also confirmed that incidence of nausea and vomiting both increased in a dose dependent manner by the amount of opiate administered postoperatively. Prophylactic administration of an antiemetic had no influence on the risk of PONV in the PACU related to opioids. Low dose naloxone infusion (0.25mcg-1mcg/kg/hr) has been shown to decrease epidural and patient controlled analgesia (PCA) opioid related side effects (nausea, vomiting and pruritis) without affecting pain scores, and hence naloxone administration may also decrease the incidence of PONV following general anesthesia including fentanyl supplementation. Metoclopramide has been used for the treatment of PONV in the PACU, and for breakthrough PONV after prophylaxis. The purpose of this study is to compare the antiemetic effectiveness of bolus intravenous naloxone 0.5mcg/Kg versus metoclopramide 10mg for the treatment of PONV in the PACU, in patients undergoing general anesthesia including fentanyl supplementation.