| New guidelines for managing postoperative nausea and vomiting (PONV) in both adults and children were recently announced at the 2006 annual meeting of the American Society of Anesthesiologists in Chicago, Illinois, USA.
These guidelines recommend the use of antiemetics, with an emphasis on the use of the 5-HT3-receptor antagonists. They also suggest a potential benefit of combination prophylaxis.
Tong Gan, from Duke University in Durham, North Carolina, USA, who presented the findings on behalf of an international panel of anaesthetists, surgeons, pharmacists, nurse anaesthetists and biostatisticians, reported that new data comparing the efficacy of antiemetics demonstrated that the 5-HT3-receptor antagonists, dexamethasone and droperidol were equally effective and each independently reduced the risk of PONV by about 25%. Acupuncture was also suggested to have benefits for reducing PONV, but there was insufficient evidence for hypnosis in reducing PONV.
Supplemental oxygen appears to have no effect on PONV symptoms, and the role of perioperative hydration is not universally supported.
Other therapies that proved to be ineffective included metoclopramide when used in standard doses of 10 mg, and often when used at higher doses, along with ginger root and cannabinoids.
Overall, the panel recommended "prophylactic therapy with combination, three or more interventions, in patients at high risk for PONV."
Risk factors identified included female gender, not smoking and having a history of PONV or motion sickness. Anaesthesia and surgical-related predictors were general anaesthesia with volatile anaesthetics, nitrous oxide, use of postoperative opioids and duration of surgery.
For children, Gan reported revised PONV guidelines that included a simplified risk score to determine the degree of risk: duration of surgery 30 minutes or longer, age above 3 years, surgery to correct strabismus or crossed eyes, and history of PONV or PONV among relatives.
Gan stated: "If one of these risk factors is present, there is a 10% chance of PONV. Each additional factor adds another 20% chance, meaning that a child with all four would be at a 70% risk".
The antiemetic treatments recommended for children included the 5-HT3 antagonists ondansetron, dolasetron, granisetron, and tropisetron. Other therapies include droperidol, dimenydrinate and perphenazine, with dexamethasone only being used in children for whom other therapies have failed.
A combination of three or more prophylactic drugs was recommended for children as it is for adults.