Prevention and control of nausea and vomiting (emesis) (N&V) are paramount in the treatment of cancer patients. N&V can result in serious metabolic derangements, nutritional depletion and anorexia, deterioration of patients' physical and mental status, esophageal tears, fractures, wound dehiscence, withdrawal from potentially useful and curative antineoplastic treatment, and degeneration of self-care and functional ability. (See Table 1 for criteria on grading severity.) Despite advances in pharmacologic and nonpharmacologic management, N&V remain two of the more distressing and feared side effects to cancer patients and their families, and incidence may be underestimated by physicians and nurses.[1,2,3,4,5]
In this summary, unless otherwise stated, evidence and practice issues as they relate to adults are discussed. The evidence and application to practice related to children may differ significantly from information related to adults. When specific information about the care of children is available, it is summarized under its own heading.
Nausea is a subjective phenomenon of an unpleasant, wavelike sensation experienced in the back of the throat and/or the epigastrium that may culminate in vomiting (emesis). Vomiting is the forceful expulsion of the contents of the stomach, duodenum, or jejunum through the oral cavity. Retching is gastric and esophageal movements of vomiting without expulsion of vomitus and is also referred to as dry heaves.
Various classifications of N&V have been used,[1,6] including acute, delayed, late or persistent, chronic, anticipatory, breakthrough, or refractory, as well as distinctions related to type of treatment (e.g., chemotherapy induced or radiation induced) and clinical course of disease (e.g., advanced or terminal disease).[7,8] Despite this variety, the most commonly described types of N&V are acute, delayed, and anticipatory chemotherapy-induced N&V and chronic N&V in advanced cancer patients. Although there are no standard definitions, the following are commonly used to classify the different types.
- Acute N&V: N&V experienced during the first 24-hour period after chemotherapy administration is considered acute N&V.
- Delayed (or late) N&V: N&V that occurs more than 24 hours after chemotherapy administration is considered delayed, or late, N&V. Delayed N&V is associated with cisplatin, cyclophosphamide, and other drugs (e.g., doxorubicin and ifosfamide) given at high doses or on 2 or more consecutive days.
- Anticipatory nausea and vomiting (ANV): ANV is nausea and/or vomiting that occurs prior to the beginning of a new cycle of chemotherapy in response to conditioned stimuli such as the smells, sights, and sounds of the treatment room. ANV is a classically conditioned response that typically occurs after three or four prior chemotherapy treatments, following which the person experienced acute or delayed N&V.
- Chronic N&V in advanced cancer patients: Chronic N&V in the advanced cancer patient is N&V associated with a variety of potential etiologies. A definitive understanding of cause is neither well known nor well researched, but potential causal factors include gastrointestinal, cranial, metabolic, drug-induced (e.g., morphine), cytotoxic chemotherapy, and radiation-induced mechanisms.