Guidelines Target Postoperative Nausea, Vomiting

By Sherry Boschert

CHICAGO -- New guidelines for the prevention and management of postoperative nausea should help control an underappreciated problem that affects 30% of adults and half of children undergoing surgery, Dr. Tong J. Gan said at the annual meeting of the American Society of Anesthesiologists.

The presence of risk factors for postoperative nausea and vomiting increases the incidence to 60%-70% in high-risk adults. In children, the incidence increases gradually up to age 4 or 5 and then holds steady at 40%-50% (or higher if risk factors are present) up to age 14 or older, said Dr. Gan, professor of anesthesiology at Duke University, Durham, N.C.

The guidelines, which will update recommendations published by the Society of Ambulatory Anesthesia in 2003, are in the final stages of completion by a panel of experts (Anesth. Anal. 2003;97:62-71).

Dr. Gan is head of the panel, which includes anesthesiologists, surgeons, pharmacists, nurse-anesthetists, and biostatisticians.

In adults, being female triples the risk for postoperative nausea and vomiting, compared with men. Other factors that increase risk in adults include a history of motion sickness or postoperative nausea and vomiting from general anesthesia, being a nonsmoker, and undergoing procedures such as laparoscopy, laparotomy, ENT surgery, neurosurgery, plastic surgery, or surgery for strabismus.

After breast reconstruction surgery, 50%-70% of women will have postoperative nausea and vomiting.

The risk is greater with inhalational anesthesia than with intravenous agents, and the use of nitrous oxide raises the risk by about 10%-15%.

Use of opioids after surgery also increases risk. "Many patients do well, and when they go home and start taking their first Percocet or Vicodin, they develop symptoms" of nausea or vomiting, Dr. Gan said.

Nearly 65% of patients with postoperative nausea and vomiting don't develop symptoms until after they leave the recovery room.

ADULT WOMEN HAVE A 3X HIGHER RISK; OTHER RISKS INCLUDE MOTION SICKNESS, NAUSEA FROM GENERAL ANESTHESIA, AND NONSMOKING.

Patients detest the experience, he added. Dr. Gan and associates surveyed adults after surgery and asked how much they would be willing to pay out of pocket for an effective antiemetic if they needed surgery again. Patients without these symptoms said $60. Those who developed nausea said $70, and patients who vomited in the recovery room said $112, according to Dr. Gan, who has received research funding from multiple companies that make antiemetic medications.

Using more than one class of antiemetics increases effectiveness with each agent added, he said. A multimodal approach using both intravenous and inhaled antiemetics works better than using one approach or the other.

The guidelines discuss the available antiemetics, the best timing for administration, and nonpharmacologic strategies like acupuncture. Compared with the antiemetic ondansetron, acupuncture has been shown to be equally effective in preventing postoperative vomiting and more effective in preventing nausea, he said. Something as simple as adequate hydration during surgery can reduce the risk of postoperative nausea and vomiting for 48 hours.

Other studies show that giving prophylactic antiemetics is cost effective in moderate- and high-risk patients because it shortens hospitalization stays.

First, however, consider other strategies to reduce risk, such as doing the surgery with regional rather than inhaled anesthesia, Dr. Gan suggested.

If you use general anesthesia, try to minimize the dosage of opioids by choosing nonsteroidal anti-inflammatory drugs, for example. Avoid nitrous oxide if you can. Provide adequate hydration. Incorporate propofol into intravenous anesthesia because it has antiemetic properties, he added.

If you think the patient still will be at considerable risk for postoperative nausea and vomiting, consider giving prophylactic antiemetics. If symptoms develop despite these efforts, rule out other medications or mechanical causes before treating with an antiemetic, he said.