ETIOLOGY AND PATHOPHYSIOLOGY
Specific etiologies associated with nausea and vomiting are presented in Table 27–1.
Table 27–2 presents cytotoxic agents categorized by their emetogenic potential. Although some agents may have greater emetogenic potential than others, combinations of agents, high doses, clinical settings, psychological conditions, prior treatment experiences, and unusual stimuli to sight, smell, or taste may alter a patient’s response to a drug treatment.
The three consecutive phases of emesis are nausea, retching, and vomiting. Nausea, the imminent need to vomit, is associated with gastric stasis. Retching is the labored movement of abdominal and thoracic muscles before vomiting. The final phase of emesis is vomiting, the forceful expulsion of gastric contents due to GI retroperistalsis.
Vomiting is triggered by afferent impulses to the vomiting center, a nucleus of cells in the medulla. Impulses are received from sensory centers, such as the chemoreceptor trigger zone (CTZ), cerebral cortex, and visceral afferents from the pharynx and GI tract. When excited, afferent impulses are integrated by the vomiting center, resulting in efferent impulses to the salivation center, respiratory center, and the pharyngeal, gastrointestinal (GI), and abdominal muscles, leading to vomiting.
TABLE 27–1Specific Etiologies of Nausea and Vomiting |Favorite Table|Download (.pdf) TABLE 27–1 Specific Etiologies of Nausea and Vomiting
Gastric outlet obstruction
Small bowel obstruction
Functional GI disorders
Chronic intestinal pseudoobstruction
Irritable bowel syndrome
Organic GI disorders
Peptic ulcer disease
Acute myocardial infarction
Congestive heart failure
Increased intracranial pressure
Diabetes mellitus (diabetic ketoacidosis)
Renal disease (uremia)
Volatile general anesthetics
TABLE 27–2Emetic Risk of Agents Used in Oncology |Favorite Table|Download (.pdf) TABLE 27–2 Emetic Risk of Agents Used in Oncology
|Emetic Risk (If No Prophylactic Medication Is Administered) ||Cytotoxic Agent (in Alphabetical Order) |
|High (>90%) || |
Combination of either doxorubicin or epirubicin + cyclophosphamide
Cisplatin (>50 mg/m2)
Cyclophosphamide (≥1500 mg/m2)
Ifosfamide (>10 g/m2)
|Moderate (30%–90%) || |
Aldesleukin (>12–15 million units/m2)
Amifostine (>300 mg/m2)
Cisplatin (<50 mg/m2)
Cytarabine (>200 mg/m2)
Cyclophosphamide (<1500 mg/m2)
Interferon alfa (10 million units/m2...
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