CASE STUDY

Case Study

Case Study

Introduction

Postoperative nausea and vomiting is a nuisance. The anesthetist is usually blamed, despite evidence that postoperative nausea and vomiting results from several factors, some related to anesthesia, others to surgery, and some to the patients themselves. The importance of postoperative nausea and vomiting is generally underestimated because it is self limiting, never becomes chronic, and almost never kills. However, its impact on the cost of health care is not negligible. Ten per cent of the population undergoes general anaesthesia every year, and about 30% of them are affected by postoperative nausea and vomiting.

This amounts to about two million people in the United Kingdom every year. About 1% of patients undergoing ambulatory surgery are admitted overnight because of uncontrolled postoperative nausea and vomiting. Surgical patients prefer to suffer pain rather than postoperative nausea and vomiting3 and would be willing to pay considerable amounts of money for an effective antiemetic.4 However, successful control of postoperative nausea and vomiting has proved elusive. A major obstacle to the development of an effective treatment has been the lack of a valid animal model for postoperative nausea and vomiting. New insights into pathways for emesis and efficacy of antiemetics have come from animal research with highly mutagenic chemotherapy. Extrapolation of these data to postoperative nausea and vomiting has been of limited value. Anesthetists therefore have to rely on the results of a myriad of clinical trials, most of small size and some of doubtful validity. Data on an almost infinite number of potentially useful antiemetic interventions have been published during the last 40 years. Despite this large body of literature fundamental data on dose responsiveness or profiles of adverse effects have remained unclear for most antiemetics, and no agreement has been reached on what constitutes a gold standard. As a consequence, anesthetists have been using antiemetics irrationally.

Case Study

The good news is that notable progress towards improved control of postoperative nausea and vomiting has been achieved during recent years. The first landmark was the advent of several sponsored, high quality, dose finding studies of a 5-hydroxytryptamine3 receptor antagonist, ondansetron, in the early 1990s. For the first time in the history of research into postoperative nausea and vomiting, a manufacturer had launched a large scale trial to evaluate an antiemetic. Initial enthusiasm was subsequently tempered because the manufacturer did not prevent authors from flooding the anesthetic literature with covert duplicate reports that led to an overoptimistic view of the drug's efficacy and safety.5 Secondly, large amounts of the literature on postoperative nausea and vomiting have been systematically reviewed, critically appraised, and quantitatively synthesised.2 Today we understand the relative efficacy and harm of most antiemetic interventions. Droperidol, for example, a butyrophenone that has been withdrawn in some countries for reasons of safety, has a pronounced antinausea effect at doses that are so incredibly low that the occurrence of any relevant adverse effect becomes highly unlikely. Ondansetron, which was thought to represent the first universally effective antiemetic for postoperative nausea and vomiting, was shown to ...