Nausea And Vomiting : Causes, Treatments & Complications

Sunday, April 6th 2014. | Other

Nausea and Vomiting : Causes, Treatments & Complications

Nausea is usually defined as the inclination to vomit or as a feeling in the throat or epigastric region alerting an individual that vomiting is imminent. Vomiting is defined as the ejection or expulsion of gastric contents through the mouth, often requiring a forceful event.
Pathophysiology of NAusea and Vomiting :
  • A variety of other common etiologies have been proposed for the development of nausea and vomiting in cancer patients.
  • The three consecutive phases of emesis include 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 gastrointestinal (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, GI, and abdominal muscles, leading to vomiting.
  • The CTZ, located in the area postrema of the fourth ventricle of the brain, is a major chemosensory organ for emesis and is usually associated with chemically induced vomiting.
  • Numerous neurotransmitter receptors are located in the vomiting center, CTZ, and GI tract. Examples of such receptors include cholinergic and histaminic, dopaminergic, opiate, serotonin, neurokinin, and benzodiazepine receptors. It is theorized that chemotherapeutic agents, their metabolites, or other emetic compounds trigger the process of emesis through stimulation of one or more of these receptors.
Nausea and vomiting may be classified as either simple or complex. The term simple applies to those episodes of nausea and/or vomiting described by one of the following criteria: (1) occur occasionally and are self-limiting or relieved by the minimal use of antiemetic methods or medications; (2) account for slight patient deterioration such as fluid-electrolyte imbalances, pain, or noncompliance with prescribed therapies; or (3) are not related to the administration of or exposure to noxious agents.
The term complex is used when describing a patient’s clinical course as including symptoms that are not adequately or readily relieved by the administration of a single antiemetic method or medication; that lead to progressive patient deterioration secondary to fluid-electrolyte imbalances, pain, or noncompliance with prescribed therapies; or that are caused by noxious agents or psychogenic events.
Nausea and vomiting occur frequently after operative procedures; those of the abdomen, eye, ear, nose, and throat are generally associated with higher incidences of nausea and vomiting than other procedures. Women experience a threefold higher incidence of nausea and vomiting compared to men, independent of the type of operation or anesthetic. Children are about twice as susceptible as adults.
Other risk factors that may be associated with an increase in postoperative symptoms include patient variables such as obesity, increased age, a history of motion sickness or prior postoperative emesis, as well as drug therapy variables such as the choice of premedication or general anesthetic agent.
Treatment of Nausea and Vomiting :
  • Most cases of nausea and vomiting are self-limiting, resolve spontaneously, and require only symptomatic therapy.
  • Antiemetic therapy is indicated in patients with electrolyte disturbances secondary to vomiting, severe anorexia or weight loss, or progression of disease either owing to refusal of continued therapy or poor nutritional status.
  • For patients with simple complaints, perhaps related to food or beverage consumption, avoidance or moderation of dietary intake may be preferable.
  • Nonpharmacologic interventions are classified as behavioral interventions and include relaxation, biofeedback, self-hypnosis, cognitive distraction, guided imagery, and systematic desensitization.
  • Psychogenic vomiting may benefit from psychological interventions.
  • Antiemetic drugs (over-the-counter [OTC] and prescription) are most often recommended to treat nausea and vomiting. Provided that a patient can and will adhere to oral dosing, a suitable and effective agent can often be selected; however, for certain other patients, oral medications may be inappropriate because of their inability to retain any appreciable oral ingestion. In these patients, the rectal or injectable route of administration might be preferred.
  • Information concerning commonly available antiemetic preparations is compiled in Table 26-4.
  • For most conditions, a single-agent antiemetic is preferred; however, for those patients not responding to such therapy and those receiving highly emetogenic chemotherapy, multiple-agent regimens are usually required.
  • The treatment of simple nausea and vomiting usually requires minimal therapy. Both OTC and prescription drugs useful in the treatment of simple nausea and vomiting are usually effective in small, infrequently administered doses.
  • The management of complex nausea and vomiting may require aggressive drug therapy, possibly with more than one antiemetic agent.
Medicine Therapy for Nausea and Vomiting :
  • Antacids : Single or combination OTC antacid products, especially those containing magnesium hydroxide, aluminum hydroxide, and/or calcium carbonate, may provide sufficient relief from simple nausea or vomiting, primarily through gastric acid neutralization.
  • Antihistamines, Anticholinergics : Histamine2 antagonists (cimetidine, famotidine, nizatidine, ranitidine) may be used in low doses to manage simple nausea and vomiting associated with heartburn. Antiemetic drugs from the antihistaminic-anticholinergic category may be appropriate in the treatment of simple symptomology.
  • Phenothiazines : are most useful in patients with simple nausea and vomiting or in those receiving mildly emetogenic doses of chemotherapy. Rectal administration is most preferred when parenteral administration is impractical or oral medications cannot be retained and are therefore ineffective.
  • Corticosteroids : have been used successfully in the management of chemotherapy-induced nausea and vomiting (CINV) and postoperative nausea and vomiting (PONV) with few problems. Reported adverse effects included mood changes ranging from anxiety to euphoria as well as headache, a metallic taste in the mouth, abdominal discomfort, and hyperglycemia.
  • Metoclopramide :  increases lower esophageal sphincter tone, aids gastric emptying, and accelerates transit through the small bowel, possibly through the release of acetylcholine. Because the adverse reactions to metoclopramide include extrapyramidal effects, IV diphenhydramine, 25 to 50 mg, should be administered prophylactically or provided on-call for its anticipated need.
Agents that have commonly been prescribed during pregnancy include phenothiazines (prochlorperazine and promethazine), the antihistaminic-anticholinergic agents (dimenhydrinate, diphenhydramine, meclizine, and scopolamine), metoclopramide, and pyridoxine.
The efficacy of antiemetics has been questioned, while the importance of other management plans (including emphasis on fluid and electrolyte management, vitamin supplements, and efforts aimed at reducing psychosomatic complaints) has been addressed.
Teratogenicity is a major consideration for the use of antiemetic drugs during pregnancy and is the primary factor that dictates the drug of choice. Of the agents commonly used, dimenhydrinate, diphenhydramine, doxylamine, hydroxyzine and meclizine have no human teratogenic potential.
Studies using SSRIs in nausea and vomiting of pregnancy are limited.
The safety and efficacy of SSRIs for the prophylaxis of CINV in children has been established but the best doses or dosing strategy have not been determined.
For nausea and vomiting associated with pediatric gastroenteritis, there is greater emphasis on rehydration measures than on pharmacologic intervention.

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