Radiation-Induced Nausea and Vomiting
6. E.G. is a 54-year-old man with newly diagnosed head and neck cancer who will receive radiation therapy concurrently with chemotherapy containing cisplatin and fluorouracil. His daily (Monday through Friday) radiation treatments will last for 6 weeks. He has a heavy smoking history (35 pack-years) and “quit” last week, although it is not going well. After E.G.'s nausea and vomiting from the chemotherapy subsides, is he at risk for developing radiation-induced nausea and vomiting?
Radiation therapy can cause nausea and vomiting through the same basic pathways that chemotherapy does. Radiation induced nausea and vomiting (RINV) affects 40% to 80% of patients receiving radiation therapy. The risk of RINV depends on several factors, namely the size and area to be irradiated. Patients whose radiation areas >400 cm2 are more likely to have significant RINV symptoms. Total body irradiation (associated with hematopoietic stem cell transplantation) causes RINV in >90% of patients. Patients receiving radiation to the upper abdominal area experience nausea and vomiting about 50% to 80% of the time. Radiation to other areas of the body is less likely to cause nausea and vomiting. E.G is not at high risk for developing RINV, because his radiation site will be in the head and neck region.
Just as with CINV, symptoms caused by radiation can be prevented with serotonin antagonists, corticosteroids, or both. Evidence- and consensus-based recommendations have been published by several multidisciplinary groups and are shown in Table 7-5. High-risk RINV is best treated with a combination of a serotonin antagonist and a corticosteroid.65,66.67 Patients receiving radiotherapy in the moderate risk group can receive either prophylaxis or rescue therapy with a serotonin antagonist. Because E.G. is unlikely to develop radiation-induced symptoms, he does not need prophylaxis with a serotonin antagonist. If he develops symptoms later, rescue therapy with a dopamine antagonist or a serotonin antagonist should be offered.
Postoperative Nausea and Vomiting
7. E.W. is a 48-year-old woman who is scheduled for a laparoscopic cholecystectomy. The scheduled duration of her surgery is less than an hour. Her medical history includes hypertension. She does not have a history of motion sickness and she is a nonsmoker. E.W. has never had surgery before. Her sister-in-law had severe nausea and vomiting after an outpatient surgical procedure last year and E.W. is worried that it might happen to her. What is E.W.'s risk of having postoperative nausea and vomiting? What can be done to reduce her risk and how can symptoms be treated if they occur?
| Table 7-5 Prophylaxis for Radiation-Induced Nausea and Vomiting | ||||||||||||||||||
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Postoperative nausea and vomiting (PONV) is a common complication of surgery, affecting 25% to 30% of all patients, but up to 80% of patients in high risk groups. In surgical patients, PONV can lead to hospitalizations, stress on the surgical closure, hematomas, and aspiration pneumonitis. Patient-related, surgical and anesthetic factors can increase the risk of PONV.68,69 Some of the patient risk factors include female gender, history of motion sickness, nonsmoking status, obesity, and a history of PONV. Some surgical risk factors for PONV include long duration of surgery and type of surgical procedure (e.g., laparoscopy, ear-nose-throat procedures, gynecologic surgeries, and strabismus repair). Anesthetic risk factors include the use of volatile anesthetics or nitrous oxide (as opposed to IV propofol) and the use of intraoperative or postoperative opioids. Children are twice as likely to develop PONV as adults.68,70 The risk increases with the child's age but declines after puberty.68,70
Certain anesthesia practices may reduce the risk of PONV. These include use of regional anesthesia (instead of general anesthesia), use of intraoperative oxygen, hydration and avoidance of nitrous oxide, and volatile anesthesia therapy.68,69,70,72
Several risk factor models have been studied to correlate these factors into recommendations for prevention and therapy. One model is both simple and practical.69,71 This model uses the following risk factors: female gender, history of PONV or motion sickness, nonsmoking status, surgery >60 minutes in duration, and the use of intraoperative opioids. If the patient has none or one risk factor, the risk of PONV is about 10% to 20%; no prophylaxis is necessary unless there is a medical risk for emesis. If the patient has two or more risk factors, the incidence increases to 40% to 80%; prophylaxis with one or two medications is warranted. E.W. has at least two risk factors (female, nonsmoker) and may have more if her surgery lasts longer than expected or if she receives intraoperative or postoperative opioids. She has a moderate to high risk of PONV.
| Table 7-6 Medications for Prevention and Treatment of Postoperative Nausea and Vomiting (PONV) | ||||||||||||||||||||||||||||||||||||
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An optimal prophylactic regimen for PONV matches medication choice with the patient's risk level.68,69,70,72 Appropriate choices for monotherapy include droperidol, a serotonin antagonist, or dexamethasone. Patients at the highest risk for PONV should be given prophylaxis with a combination of two to three antiemetics. Dual therapy choices include a serotonin antagonist plus either droperidol or dexamethasone. Triple therapy would combine a serotonin antagonist plus dexamethasone plus droperidol. Because E.W. has a moderate to high risk for PONV, a combination of a serotonin antagonist and dexamethasone would be a good choice for prophylactic therapy.
The most effective and commonly used medications for the prevention of PONV include serotonin antagonists, dexamethasone, droperidol, and combinations of these agents. No appreciable difference is found in efficacy or adverse effects between the serotonin antagonists; therefore, the costs of the different agents should be taken into consideration when selecting therapy. Droperidol has long been used for PONV, but concerns have been raised about the rare occurrence of QT prolongation and torsades de pointes.72,73 Most clinicians believe droperidol to be a safe, especially when doses are not excessive (up to 1.25 to 2.5 mg/dose for adults and up to 75 mcg/kg/dose for children).68,73,74 The mechanism by which dexamethasone protects against PONV is unclear, but its efficacy has been shown in many trials.68,70,72 Combinations of medications with different mechanisms of action are more effective than monotherapy. Aprepitant, has been studied in the prevention of PONV. Two studies recently compared oral aprepitant 40 mg or 125 mg with IV ondansetron 4 mg.45,74 These trials showed equivalency between the two doses of aprepitant and slight superiority over ondansetron in the proportion of patients without nausea, vomiting, or the use of rescue medications. Aprepitant, however, is significantly more expensive than generic ondansetron or dexamethasone, which is a consideration. Aprepitant's role in PONV has yet to be determined. Dexamethasone and serotonin antagonist combinations have been well studied and are highly effective.68,70,72,74 Dosages for the prophylaxis and treatment of PONV are shown in Table 7-6. 5-HT3 antagonists and droperidol seem to be more effective when given at the end of surgery. Corticosteroids are best given before the induction of anesthesia.68,72
P.7p11
Several methods for nonpharmacologic techniques for the prevention of PONV have been studied and have been shown to be effective, at least in some patient populations. These include acupuncture, transcutaneous nerve stimulation, acupressure at the P6 wrist point, hypnosis, and aroma therapy with isopropyl alcohol. Ginger remedies were not found to be more effective than placebo for PONV.68
Even with appropriate prophylaxis for PONV, some patients will experience breakthrough symptoms and require rescue therapy. Patients who have not received prophylaxis with a serotonin antagonist can be offered a low dose of a serotonin antagonist for rescue. For rescue, only about one-quarter of the prophylaxis dose is needed.68 Serotonin antagonists have a fairly flat dose response and larger doses (ondansetron 4 to 8 mg) have not been found to be more effective for treatment of PONV than lower doses (ondansetron 1 mg).68,74 For all patients who have breakthrough symptoms, it is important to choose an antiemetic from a different pharmacologic class than the agents used for prophylaxis.69,72 Droperidol, promethazine, metoclopramide, and prochlorperazine are commonly used as rescue medications. If E.W. had breakthrough nausea, droperidol would be a good choice for rescue therapy
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