Metoclopramide and dexamethasone in prevention of postoperative nausea and vomiting after inhalational anaesthesia

Objective: Because of its complex profile of action (binding to dopamine, serotonin and histamine receptors), low rate of adverse effects and low cost as a medicinal preparation, metoclopramide is an interesting substance for the prophylaxis of postoperative nausea and vomiting (PONY). As a single substance its antiemetic effects are slight at the usual dose, so the aim was to test the efficacy of a combination of metoclopramide and dexamethasone for the prevention of PONY on a group of patients with the same operative trauma. Method: All patients (n = 204) were recruited prospectively (January-October 2002) and were to undergo a lumbar disc operation. The anaesthetic was administered according to a standard procedure as a balanced anaesthetic with fentanyl and isoflurane in oxygen/air. 60 min before the end of the operation, all patients were given 10 mg of metoclopramide and 8 mg of dexamethasone intravenously. The Wurzburg-Oulu-Score served as an instrument for comparison, because no placebo group has been included. 24 hours after the operation, all patients were asked to report on nausea and vomiting, stating the time and the degree of discomfort (quantification by means of an analogue numerical scale from 0-10). The influence of age, height, weight, duration of the anaesthetic, operating position and increased dexamethasone dose was analyzed in addition to the risk factors according to the score. The cost analysis was based on the purchase prices of the hospital dispensary. Results: The expected PONV incidence was 35.8%; 10% nausea (average intensity 4.3) and 3% emesis (4.8) was reported for the 24-hour period. The rescue medication (dimenhydrinate) was requested 8 times. Nausea was mainly during the early part of the period (0-6 hours). Of 42 patients with a history of PONV, 71% had no symptoms. The Odds Ratios for female sex (2.9), nonsmoker status (2.0) and post-operative opioid administration (1.9) correspond to the data given in the literature; it was not possible to determine the significance of a history of PONV as an independent risk factor. None of the other factors investigated had a significant influence on PONV. For the chosen combination of antiemetic drugs the number-needed-to-treat is 3.9 (95% CI: 3.3-4.7). The direct costs of the PONY prophylaxis are 0.65 Euro per patient. Conclusions: The metoclopramide/dexamethasone combination proved to be effective and inexpensive, on the basis of these findings it is used prophylactically at our hospital if only one PONY risk factor exists.