Postoperative nausea and vomiting
Postoperative nausea and vomiting (PONV) is the most frequent side effect that occurs after exposure to anesthetic agents, occurring in 20% to 30% of the general surgical population and up to 80% in high-risk patients. Although PONV is self-limiting, it increases patients’ dissatisfaction and can be associated with significant morbidity (Box 109-1). PONV also results in higher costs from treatment, delayed discharge from the postanesthesia care unit or the hospital, and unplanned hospitalization.
Physiology
The vomiting center of the brain, in the reticular formation, receives input from the chemotactic trigger zone, gastrointestinal tract, vestibular portion of the eighth cranial nerve, and pharynx. Important neurotransmitter receptor sites documented, or suspected, to be associated with PONV include serotonin, dopamine, histamine, neurokinin-1, opioid, acetylcholine, and muscarinic receptor sites (see Chapter 98).
Risk factors
Identification of independent risk factors for PONV is complicated because of limitations in study designs and the wide array of variables influencing PONV, including patient-related, surgery-related, and anesthesia-related factors. Some risk factors appear to be well established (Box 109-2
