Vomiting

Encyclopedia of Alternative Medicine, Apr 06, 2001 by Belinda Rowland

Vomiting is the forceful discharge of stomach contents through the mouth.

Vomiting, also called emesis, is a symptomatic response to any number of harmful triggers. Vomiting is a forceful expulsion, and is different from regurgitation--the effortless return of stomach contents to the mouth. Although unpleasant, vomiting is an important function because it rids the body of harmful substances.

Vomiting is a complex process resulting from the coordinated interaction of nerve pathways, the brain, and muscles of the gastrointestinal system. The primary vomiting trigger point in the brain is called the area postrema. This structure is exposed to chemicals in the blood stream and the cerebrospinal fluid (the fluid found in the brain and spinal cord). Scientific studies have shown that stimulation of the area postrema by a wide variety of drugs as well as bacterial toxins, radiation, and physiologic conditions, induces vomiting.

Certain nerve pathways (called afferent neural pathways) induce vomiting when triggered by motion, ear infections or tumors, Méniére's disease (a disease characterized by recurrent vertigo), odors, visual stimulation, pain, and bad tastes. Still other nerve pathways (peripheral afferent neural pathways) induce vomiting in response to stomach irritants, distension of the intestines and bile ducts, abdominal inflammation, and myocardial infarction (heart attack ).

The physical act of vomiting is controlled by multiple sites of the brain stem. When activated, these structures send signals to the throat, diaphragm, and abdominal muscles. This results in the simultaneous contraction of these muscles which brings the stomach contents up through the esophagus (the tube between the stomach and the throat) and out the mouth. During vomiting, breathing is inhibited, except for short breaths between discharges. Bradycardia (decrease in the heart rate) and changes in blood pressure may occur during retching and vomiting.

Vomiting can be caused by many different things. Vomiting that lasts only one or two days is usually caused by infection, medication, a toxin, uremia (accumulation of protein breakdown products in the bloodstream), and diabetic ketoacidosis (accumulation of toxins resulting from uncontrolled diabetes). Vomiting that lasts longer than one week can be caused by a long term medical or psychiatric condition. Causes of vomiting include:

• Medications. Drugs are the most common cause of vomiting, especially during the first days of use. Drugs can induce vomiting by stimulation of the area postrema or by direct stimulation of peripheral nerve pathways. Medications that commonly cause vomiting include cancer drugs, pain relievers, heart medications, diuretics, hormones, antibiotics, antiasthmatics, gastrointestinal drugs, and medications that act on the brain.
• Infections. Infections of the gastrointestinal system or whole body can cause vomiting. Gastrointestinal infections are more common in infants, toddlers, and young adults (20-29 years old) who usually get 1.2 infections each year. Infections that can cause vomiting include bacterial and viral gastrointestinal infections, otitis media (ear infection ), meningitis (infection of the membrane that surrounds the brain and spinal cord), and hepatitis (infection of the liver).
• Gastrointestinal and abdominal disorders. Disorders of the gastrointestinal system that can produce vomiting include blockage of the stomach or small intestine, motility disorders (muscles in the esophagus become discoordinated or weak, causing difficulty swallowing, regurgitation, and sometimes pain), indigestion, radiation therapy-induced changes, Crohn's disease (chronic recurrent inflammation of the intestines), peptic ulcer, or inflammation of the appendix, gall bladder, or pancreas.
• Nervous system disorders. Cancers, infarction (an area of dead tissue caused by an obstruction in the artery supplying the area), bleeding (hemorrhage), birth defects, ear disorders, motion sickness , weightlessness, ear tumors, Meniere's disease, unpleasant memories, psychogenic (caused by mental factors) vomiting, and bad tastes or smells can all cause vomiting.
• Hormones and physiological conditions. Hormonal and metabolic (physical and chemical processes of the body) conditions that can cause vomiting include: parathyroidism, diabetic ketoacidosis, hyperthyroidism (condition caused by excessive ingestion or production of thyroid hormone), Addison's disease, uremia, and pregnancy. Pregnancy is the most common cause of vomiting associated with the hormonal system.
• Postoperation. Anesthesia and pain medications can cause nausea and vomiting, which are complications associated with 17-39% of surgeries.
• Cyclic vomiting. This rare disorder occurs in children usually beginning at age five years. It is characterized by, on average, eight attacks of vomiting lasting for 20 hours each year. Although the exact cause is unknown, there seems to be a relationship between cyclic vomiting and migraine headaches.
• Miscellaneous causes. Excessive alcohol consumption causes vomiting by acting both on the gastrointestinal tract and the brain.