Vomiting anticipatory

Motion sickness is caused by stimulation of the vestibular system. This area contains many histaminic (Hj) and muscarinic cholinergic receptors. The higher brain (i.e., cerebral cortex) is affected by sensory input such as sights, smells, or emotions that can lead to vomiting. This area is involved in anticipatory nausea and vomiting associated with chemotherapy. 

The central nervous system plays a role in vomiting due to psychiatric disorders, stress, and anticipatory vomiting prior to cancer chemotherapy. 

Benzodiazepines such as lorazepam or diazepam are used before the initiation of chemotherapy to reduce anticipatory vomiting or vomiting caused by anxiety. The pharmacology of these agents is presented in Chapter 22. 

Lorazepam (Ativan, and others) is used as an adjunct to antiemetic regimens, particularly in patients with anticipatory vomiting. Alprazolam (Xanax) has also been used as an adjunct. Benzodiazepines can cause somnolence and amnesia lasting for several hours, which may be beneficial. 

Benzodiazepines The antiemetic potency of lorazepam and alprazolam (see p. 89) is low. Their beneficial effects may be due to their sedative, anxiolytic and amnesic properties. These same properties make benzodiazepines useful in treating anticipatory vomiting. 

Nausea and vomiting are common adverse effects of cytostatic drugs (48). They can be acute (occurring within 24 hours of therapy), delayed (persisting for 6-7 days after therapy), or anticipatory (occurring before chemotherapy) (49). Their treatment has been reviewed (50,51). 

HT3 antagonists are effective for acute nausea, but are not effective for anticipatory nausea, and efficacy is low for delayed nausea. Lorazepam is very effective for anticipatory nausea. Other agents used in chemotherapy-induced emesis are dopamine antagonists, scopolamine, and dronabinol. Antihistamines are generally less effective for chemotherapy-induced nausea and vomiting. 

E Lorazepam is most effective for anticipatory nausea and vomiting, or emesis that oaurs prior to chemotherapy administration. The antiemetic effects may be related to the sedative and anxiolytic properties of lorazepam. 5-HT3 antagonists and dopamine antagonists are poor choices because efficacy has not been shown in anticipatory nausea and vomiting. 

Optimal control of acute nausea and vomiting positively impacts the incidence and control of delayed and anticipatory nausea and vomiting. 

Nausea and vomiting that occurs within 24 hours of chemotherapy administration is defined as acute, whereas when it starts more than 24 hours after chemotherapy administration, it is defined as delayed. The primary goal with CINV is to prevent nausea and/or vomiting optimal control of acute nausea and vomiting positively impacts the incidence and control of delayed and anticipatory nausea and vomiting. Clinical practice guidelines for the use of antiemetics in CINV have been published. Despite the availability of nationally recommended guidelines, individual practice varies from one institution to the next. Product availability and recommended doses are institution-specific and may vary considerably from the doses listed in Table 35-5. 

Morrow GR, Morrell C. Behavioral treatment for the anticipatory nausea and vomiting induced by cancer chemotherapy. N Engl J Med 1982 307 1476-1480. 

Parker, L.A. and Kemp, S.W. (2001) Tetrahydrocaimabinol (THC) interferes with conditioned retching in Suncus murinus an animal model of anticipatory nausea and vomiting (ANV), Neuroreport 12 749-751. 

Anticipatory nausea and vomiting are very difficult to control. It is important for the nurse to medicate the cKent to prevent the nausea from occurring. This client should be medicated first. 

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