postoperative nausea and vomiting

Postoperative nausea and vomiting is an unpleasant complication affecting about a third of the 10% of the population undergoing general anaesthesia each year. This equates to about two million people in the United Kingdom annually.

Impact

Although it is very rarely fatal, nausea and vomiting can be extremely distressing for patients. In some patients, for example those with wired jaws after maxillofacial surgery, vomiting can be dangerous. About 1% of patients with planned day surgery require overnight admission because of uncontrolled postoperative nausea and vomiting.

Management

Because no currently available antiemetic is a gold standard good enough for use on its own, and successful control is often elusive, experts recommend a multimodal approach. Anaesthetic strategies to prevent vomiting include using regional anaesthesia wherever possible and avoiding emetogenic drugs. Pharmacological treatment and prevention of postoperative nausea and vomiting is limited by both cost and the adverse effects of drugs. Patients with risk factors probably warrant prophylaxis, whereas a "wait and see" strategy is appropriate for those without risk factors.

Pharmacology

The introduction of the 5HT₃ receptor antagonist, ondansetron, in the early 1990s was a significant breakthrough. Despite the many studies, however, the evidence base to support rational antiemetic treatment remains patchy. Recent research has led to better understanding of some older drugs and has demonstrated that combinations of drugs are often useful. While the efficacy of droperidol is now clear, metoclopramide, a popular antiemetic for decades, has been found to have no worthwhile efficacy. Some older drugs, such as haloperidol and hyoscine remain inadequately studied. Emetogenic drugs commonly used in anaesthesia include nitrous oxide, physostigmine and opioids. The intravenous anaesthetic propofol is currently the least emetogenic general anaesthetic.

Risk factors

Postoperative nausea and vomiting results from anaesthesic, surgical, and patients factors. Gynaecological, urological, or middle ear surgery increases the risk of postoperative nausea and vomiting. Patients that are female or have a past history of postoperative nausea and vomiting are at greater risk. Smoking decreases the risk, but this would never be recommended by any physician.

Reference

Tramr MR. Treatment of postoperative nausea and vomiting. BMJ 2003;327:762-3. Fulltext. PMID 14525850.