NAUSEA AND VOMITING

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 and is often a forceful event. Either condition may occur transiently with no other associated signs or symptoms

ETIOLOGY:-

Gastrointestinal Mechanisms Mechanical gastric outlet obstruction Peptic ulcer disease Gastric carcinoma Pancreatic disease Motility disorders Gastroparesis Drug-induced gastric stasis Chronic intestinal pseudo-obstruction Postviral gastroenteritis Irritable bowel syndrome Postgastric surgery Idiopathic gastric stasis Anorexia nervosa Intra-abdominal emergencies Intestinal obstruction Acute pancreatitis Acute pyelonephritis Acute cholecystitis Acute cholangitis Acute viral hepatitis Acute gastroenteritis Viral gastroenteritis Salmonellosis Shigellosis Staphylococcal gastroenteritis (enterotoxins)

Cardiovascular Diseases Acute myocardial infarction Congestive heart failure Shock and circulatory collapse Neurologic Processes Midline cerebellar hemorrhage Increased intracranial pressure Migraine headache Vestibular disorders Head trauma Metabolic Disorders Diabetes mellitus (diabetic ketoacidosis) Addison’s disease Renal disease (uremia) Psychogenic Causes Self-induced Anticipatory Therapy-induced Causes Cytotoxic chemotherapy Radiation therapy Theophylline preparations (intolerance, toxic) Anticonvulsant preparations (toxic) Digitalis preparations (toxic) Opiates Amphotericin B Antibiotics Drug Withdrawal Opiates Benzodiazepines Miscellaneous Causes Pregnancy Any swallowed irritant (foods, drugs) Noxious odors Operative procedures

Pathophysiology:-

The three consecutive phases of emesis include nausea, retching, and vomiting. Nausea, the imminent need to vomit, is associated with gastric stasis and may be considered a separate and singular symptom. 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 caused by GI retroperistalsis. The act of vomiting requires the coordinated contractions of the abdominal muscles, pylorus, and antrum, a raised gastric cardia, diminished lower esophageal sphincter pressure, and esophageal dilatation. Vomiting should not be confused with regurgitation, an act in which the gastric or esophageal contents rise to the pharynx because of pressure differences caused by, for example, an incompetent lower esophageal sphincter. Accompanying autonomic symptoms of pallor, tachycardia, and diaphoresis account for many of the distressing feelings associated with emesis. 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. Because of its location, blood-borne and cerebrospinal fluid toxins have easy access to the CTZ.

Clinical presentation:-

General

Depending on severity of symptoms, patients may present in mild to

severe distress

Symptoms

Simple: Self-limiting, resolves spontaneously and requires only

symptomatic therapy

Complex: Not relieved after administration of antiemetics; progressive

deterioration of patient secondary to fluid-electrolyte imbalances;

usually associated with noxious agents or psychogenic events

Signs

Simple: Patient complaint of queasiness or discomfort

Complex: Weight loss; fever; abdominal pain

Laboratory tests

Simple: None

Complex: Serum electrolyte concentrations; upper/lower Gl evaluation

Other information

Fluid input and output

Medication history

Recent history of behavioral or visual changes, headache, pain, or stress

Family history positive for psychogenic vomiting.

POSTOPERATIVE NAUSEA AND VOMITING

One of the most common complications of surgery is postoperative nausea and vomiting (PONV). Most patients undergoing an operative procedure do not require preoperative prophylactic antiemetic therapy and universal PONV prophylaxis is not cost effective. Consensus therapeutic guidelines for the prophylaxis and treatment of PONV have recently been published. Factors to be considered for PONVprophylaxis and treatment include: risk factors, potential morbidity, potential adverse events associated with various antiemetics, efficacy of antiemetics, and costs.

Risk Factors for PONV

Patient-specific factors

Female gender

Nonsmoking status

History of motion sickness/PONV

Anesthetic risk factors

Use of volatile anesthetics

Nitrous oxide

Use of opioids (intraoperative or postoperative)

Surgical risk factors

Duration of surgery

Operative procedure (intra-abdominal, ear-nose-throat, major

gynecologic, orthopedic, or laparoscopic)

ANTIEMETIC USE DURING PREGNANCY

More than one-half of pregnant women experience nausea and vomiting to some degree during the first trimester of pregnancy (nausea and vomiting of pregnancy; NVP). Teratogenicity is a major consideration for the use of antiemetic drugs during pregnancy and is the primary factor that guides drug selection. A large body of evidence suggests that the histamine1-receptor antagonists (dimenhydrinate, diphenhydramine, doxylamine, hydroxyzine, and meclizine) have no human teratogenic potential and are effective in reducing treatment failure. Whether used alone or in combination with doxylamine, pyridoxine has not been found to be teratogenic and significantly decreases the nausea score. Other commonly prescribed agents that are effective and not teratogenic include the phenothiazines prochlorperazine and promethazine. Studies using the SSRIs in NVP are limited. In a randomized controlled trial of 15 patients exposed during the first trimester to intravenous ondansetron versus promethazine for treatment of severe NVP, ondansetron was no more beneficial than promethazine with respect to the following outcome measures: severity of nausea, daily weight gain, days requiring hospitalization, treatment failures, and voluntary use of the drug. The limited safety data for ondansetron does not allow it to be recommended as first-line therapy. Nonpharmacologic interventions for NVP include ginger and acupuncture, although safety and efficacy trials for acupuncture are lacking.

Treatment :-

Antacids, Antihistaminic-Anticholinergic Agents, Histamine H2 Antagonists, Phenothiazines, Cannabinoids, Butyrophenones, Corticosteroids, Benzodiazepines, Substance P/Neurokinin1 Receptor Inhibitor