___________________________________________ Palliative Care and Pain Management at the End of Life
The causes also differ according to the pathway stimulated ( Table 14 ) [328; 329]. Most often the cause is multifactorial, but sometimes no cause can be determined. Prevention The prevention of nausea and vomiting has focused on pro- phylactic treatment for patients receiving chemotherapy or radiation therapy for cancer. Although most patients at the end of life do not receive anticancer treatment, chemotherapy may be given as part of palliative care. ASCO classifies chemo- therapy drugs according to their emetogenic potential: high (>90% incidence of emesis without an antiemetic), moder- ate (30% to 90% incidence), low (10% to 30% incidence), and minimal (<10% incidence) [330]. According to ASCO guidelines, a 5-hydroxytryptamine type 3 (5-HT3) antagonist, dexamethasone (Decadron), and a neurokinin 1 (NK1) recep- tor antagonist (such as aprepitant [Emend]) should be used as prophylaxis for a highly emetic chemotherapy agent or combi- nation (such as an anthracycline and cyclophosphamide) [330]. Palonosetron (Aloxi), in combination with dexamethasone or netupitant, is recommended for chemotherapy agents with moderate emetic risk, and dexamethasone is recommended before the first dose of chemotherapy with a low emetic risk. A 5-mg dose of olanzapine has been shown to be safe and effective when used in combination with a 5-HT3 receptor antagonist, an NK1 receptor antagonist, and dexamethasone in patients with high emetic risk [330]. For nausea and vomiting not related to chemotherapy, treatment with regular dosing of an antiemetic will help prevent subsequent episodes of the symptoms. Assessment A detailed history, physical examination, and review of the medication list are essential for planning effective manage- ment of nausea and vomiting. In talking with the patient, the clinician should ensure that the patient is actually expe- riencing nausea, as patients have used the term nausea to describe other feelings, such as pain, distention, abdominal
discomfort, and early satiety [67; 331]. The clinician should ask about the onset of the nausea, how frequently it occurs, if there are precipitating factors, and if there is a relationship to food intake. It may be helpful to ask the patient to rate the intensity of nausea on a scale similar to a pain scale (a 10-point numerical scale). Because the cause of nausea and vomiting is often multifactorial, a multidimensional assessment is benefi- cial, with particular attention paid to such other symptoms as pain, appetite, fatigue, depression, and anxiety. The physical examination should include evaluation for signs of cachexia or malnutrition, assessment of the abdomen for evidence of bowel obstruction, increased bowel sounds, and abdominal distention. A plain x-ray of the abdomen (e.g., kidney, ureters, bladder) may distinguish constipation with stool seen in the bowel from malignant bowel obstruction [331]. In addition, a neurologic examination should be done to determine if there are signs of increased intracranial pressure, papilledema, or autonomic insufficiency [67; 331]. Diagnostic testing may include laboratory studies to rule out metabolic disorders, renal impairment, or liver failure, or radiographs of the abdomen to determine if there is obstruction. Nausea and vomiting assessment often leads to no clear etiology or several possible causes [331]. Nausea is often not reported; patients should be asked if they have experienced nausea even if they have not vomited [246]. Management Evidence-based guidelines for the management of nausea and vomiting unrelated to chemotherapy and radiation are lacking [332]. In addition, most studies of these symptoms and recom- mendations are related to the cancer setting. In general, experts have recommended that antiemetics be selected on the basis of the emetic pathway and the etiology of the nausea and/or vomiting, but systematic reviews have found that the evidence for recommendations is weak to moderate at best [206; 328; 329; 332; 333; 334]. One systematic review found no evidence that the choice of antiemetic according to etiology or multiple antiemetics was better than a single antiemetic [332].
CAUSES OF NAUSEA AND VOMITING ACCORDING TO PATHWAY STIMULATED AND CLASS OF ANTIEMETICS Pathway Stimulated Causes Class of Antiemetics Chemoreceptor trigger zone Dopamine antagonists
Metabolic disorders (hypercalcemia, hyponatremia, hepatic/renal failure)
Opioids
Prokinetic agent, dopamine antagonists Prokinetic agent, dopamine antagonists, corticosteroids
Malignant bowel obstruction
Cortex of brain
Increased intracranial pressure, anxiety, five senses
Corticosteroids, anxiolytics
Peripheral pathways (gastrointestinal tract)
Gastroparesis
Prokinetic agent
Vestibular system
Motion
Muscarinic acetylcholine receptor, antihistamine
Source: [206; 328]
Table 14
41
MDCA1525
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