Postoperative nausea and vomiting--when will it stop?

E can walk on the moon, and among other scientific miracles, we can perform minimally invasive, keyhole cardiac surgery with "robots". But so far we have not solved the seemingly simple problem of postoperative nausea and vomiting (PONV). It remains one of the final therapeutic challenges and has been a perpetual dilemma since the birth of our specialty. It is the legendary big, "little problem", l Today, as we stretch the limits of ambulatory care, we are magnifying the problem. When post discharge nausea and vomiting persists after surgery, such as laparoscopic cholecystectomy, and patients cannot retain oral analgesics, their suffering is further compounded by unrelieved pain. Now we have a big, "big problem". In the early days of ether anesthesia PONV was severe. Patients can still describe it decades later and in great detail. Ironically, it may not have been perceived as a big problem since patients and surgeons were relieved and grateful to have any anesthesia. Even profound PONV was dwarfed by the bigger problems of life-threatening morbidity and significant mortality. Now, we have the opposite situation. New anesthetic agents have reduced the incidence and severity of PONV. Anesthesia is so safe that the major morbidity and mortality problems are rare and often due to human error. PONV is one of the most common and most important elements in morbidity. Patients assume that anesthesia is safe. and refractory nausea is one of their greatest fears. 2 The prevalence of PONV, coupled with high patient expectations, have made it a big problem, especially since antiemetics are not always effective. The ideal antiemetic does not exist. 3 There is no wonder drug for PONV, there aren't even drugs that come close to being called wonderful. The ideal drug would be cheap, simple, safe and effective; one drug, one dose, and always effective. There is no magic bullet for PONV. The major obstacle in solving this problem has been its multifactorial etiology. The factors involved are so numerous, so diverse and so unavoidable, that to encompass such a broad target may require a pharmacological force field rather than a single bullet. The Achilles heel of antiemetic therapy is efficacy. PONV can be alleviated, but not eliminated. This issue of poor efficacy is unique in anesthesia. Induction agents, muscle relaxants and inhalational anesthetics all produce predictable outcomes. Following the "big syringe, little syringe" routine we expect all, not just some, patients to be anesthetized. But a flip o~" a coin odds at 50% are considered good for prophylactic antiemetics, and rescue antiemetic therapy is like tossing out a floatation device that doesn't always float. Since any single antiemetic drug has been shown to have limited efficacy, multimodal therapy has been proposed. In theory, the combination of several drugs ha small doses should create synergistic beneficial effects, while reducing tmdesirable side effects. This is true when the drugs have different side effects. But many antiemetics share similar side effects sedation. When combining antiemetics their efficacy may remain evasive while synergistic sedation becomes very evident. Luckily, drug induced drowsiness is one of the best ways to relieve PONV. Sedation makes nausea more bearable by allowing the patient to "sleep it off". Is something better than nothing? Is an ounce of prevention worth a pound of cure? Some patients have a history of severe PONV and some surgical procedures almost guarantee PONV. So we feel justified in doing something, even if therapy is not very effective, because to do nothing seems callous, even cruel. On the other hand, it is important to consider that with every drug we give there is an additional small but real risk of