Nausea & Vomiting

Nausea is an unpleasant feeling that may include dizziness, vague discomfort in the abdomen, an unwillingness to eat, and a sensation of needing to vomit. Vomiting is the forceful contraction of the stomach that propels its contents up the esophagus and out through the mouth. Vomiting serves to empty the stomach of its contents and often makes a person with nausea feel considerably better, at least temporarily. Vomiting is not the same as regurgitation, which is the spitting up of stomach contents without forceful abdominal contractions and nausea.
Vomitus-the material that is vomited up-usually reflects what was recently eaten. Sometimes it contains chunks of food. When blood is vomited, the vomitus is usually bright red (hematemesis) . When bile is present, the vomitus is green.
Even normal vomiting can be violent. A person who is vomiting typically doubles over and makes considerable noise. Severe vomiting can project food many feet (projectile vomiting). Vomiting greatly increases pressure within the esophagus, and severe vomiting can tear or even rupture the lining of the esophagus. People who are unconscious can inhale their vomitus. The acidic nature of the vomitus can severely irritate the lungs. Frequent vomiting can cause dehydration and electrolyte abnormalities; newborns and infants are particularly susceptible to these complications.

Causes
Nausea and vomiting result when the vomiting center in the brain is activated. These symptoms commonly occur with any dysfunction of the digestive tract but are particularly common with gastroenteritis and bowel obstruction. Obstruction of the intestine causes vomiting because food and fluids back up into the stomach from the blockage. The vomiting center also can be activated by certain brain disorders, including infections (such as meningitis and encephalitis) , brain tumors, and migraines. The balance organs of the inner ear (vestibular apparatus) are connected to the vomiting center. This connection is why some people become nauseated by the movement of a boat, car, or airplane and by certain disorders of the inner ear (such as labyrinthitis and positional vertigo). Nausea and vomiting may also occur during pregnancy, particularly during the early weeks and especially in the morning. Many drugs, including opioid analgesics, such as morphine, and chemotherapy drugs, can cause nausea. Psychologic problems also can cause nausea and vomiting (known as functional, or psychogenic, vomiting). Such vomiting may be intentional- for instance, a person who has bulimia vomits to lose weight. Or it may be unintentional- a conditioned response to address psychologic distress, such as to avoid going to school.

Evaluation
Otherwise healthy adults and older children who have only a few episodes of vomiting (with or without diarrhea) and no other symptoms may not require evaluation. Young children and older people, and those in whom vomiting lasts more than 1 day or who have any other symptoms, particularly abdominal pain, headache, weakness, or confusion, are evaluated by the doctor. If the person's symptoms and physical examination show no signs of dehydration or serious underlying illness, doctors may not perform any testing. Women of childbearing age may receive a pregnancy test. In others, blood tests may be obtained to look for signs of dehydration or abnormal electrolyte levels. If bowel obstruction is suspected, x-rays are obtained.

Treatment
Specific conditions are treated. If there is no serious underlying disorder and the person is not dehydrated, small amounts of clear liquids may be given an hour or so after the last bout of vomiting. If these liquids are tolerated, the amounts are increased gradually. When these increases are tolerated, the person may resume eating normal foods. If the person is
dehydrated and can tolerate some liquids by mouth, doctors usually recommend oral rehydration solutions. Those with significant dehydration or electrolyte abnormalities and those who cannot tolerate liquids by mouth usually require intravenous fluids.
For some adults and adolescents, doctors use anti-nausea drugs such as metoclopramide or prochlorperazine. For people whose vomiting is caused by chemotherapy, doctors usually use stronger drugs such as odansetron or granisetron.

[Merck]