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Revision as of 01:19, 20 January 2009

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Pre-Medical Editor: Leah Biller

Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [2] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.

Overview

Nausea (Latin: Nausea, Greek: Template:Polytonic, "sea-sickness") is the sensation of unease and discomfort in the stomach with an urge to vomit.

Nausea is not a sickness, but rather a symptom of several conditions, many of which are not related to the stomach. Nausea is often indicative of an underlying condition elsewhere in the body. Travel sickness, which is due to confusion between perceived movement and actual movement, is an example. The sense of equilibrium lies in the ear and works together with eyesight. When these two don't "agree" to what extent the body is actually moving the symptom is presented as nausea even though the stomach itself has nothing to do with the situation. Nausea is also an adverse effect of many drugs. Nausea may also be an effect of a large intake of sugary foods.

In medicine, nausea can be a problem during some chemotherapy regimens and following general anaesthesia. Nausea is also a common symptom of pregnancy. Mild nausea experienced during pregnancy can be normal, and should not be considered an immediate cause for alarm.

Vomiting (also throwing up or emesis) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting may result from many causes, ranging from gastritis or poisoning to brain tumors, or elevated intracranial pressure (ICP). The feeling that one is about to vomit is called nausea. It usually precedes, but does not always lead to vomiting. Antiemetics are sometimes necessary to suppress nausea and vomiting, and in severe cases where dehydration develops, intravenous fluid may need to be administered to replace fluid volume.

The medical branch investigating vomiting, emetics and antiemetics is called emetology.

Pathophysiology of nausea and vomiting

Vomiting center

Vomiting is coordinated in the vomiting center in the lateral medullary reticular formation in the pons. Receptors on the floor of the fourth ventricle of the brain represent a chemoreceptor trigger zone, stimulation of which can lead to vomiting. The chemoreceptor zone lies outside the blood-brain barrier, and can therefore be stimulated by blood-borne drugs that can stimulate vomiting, or inhibit it.

There are various sources of input to the vomiting center:

The chemoreceptor trigger zone at the base of the fourth ventricle has numerous dopamine D₂ receptors, serotonin 5-HT₃ receptors, opioid receptors, Acetylcholine receptors, and receptors for substance P. Stimulation of different receptors are involved in different pathways leading to emesis, in the final common pathway substance P appears to be involved.^[1]
The vestibular system which sends information to the brain via cranial nerve VIII (vestibulocochlear nerve). It plays a major role in motion sickness and is rich in muscarinic receptors and histamine H₁ receptors.
Cranial nerve X (vagus nerve), which is activated when the pharynx is irritated, leading to a gag reflex.
Vagal and enteric nervous system inputs that transmit information regarding the state of the gastrointestinal system. Irritation of the GI mucosa by chemotherapy, radiation, distention or acute infectious gastroenteritis activates the 5-HT₃ receptors of these inputs.
The CNS mediates vomiting arising from psychiatric disorders and stress.

Vomiting Act

The vomiting act encompasses three types of outputs initiated by the medulla: Motor, parasympathetic nervous system (PNS) and sympathetic nervous system (SNS). Collectively, they are as follows:

Increased salivation to protect the enamel of teeth from stomach acids (excessive vomiting leads to caries). This is part of the PNS output.
Retroperistalsis, starting from the middle of the small intestine, sweeping up the contents of the digestive tract into the stomach, through the relaxed pyloric sphincter.
A lowering of intrathoracic pressure (by inspiration against a closed glottis), coupled with an increase in abdominal pressure as the abdominal muscles contract, propels stomach contents into the esophagus without involvement of retroperistalsis. The lower esophageal sphincter relaxes. This is part of the motor output, and it is also important to note that the stomach itself does not contract in the process of vomiting.
Vomiting is ordinarily preceded by retching.
Vomiting also initiates a SNS response causing both sweating and increased heart rate.

The neurotransmitters that regulate vomiting are poorly understood, but inhibitors of dopamine, histamine and serotonin are all used to suppress vomiting, suggesting that these play a role in the initiation or maintenance of a vomiting cycle. Vasopressin and neurokinin may also participate.

Content

Since the stomach secretes acid, vomit contains a high concentration of hydronium ions and is thus strongly acidic. Recent food intake will be reflected in the gastric vomit.

The content of the vomitus (vomit) may be of medical interest. Fresh blood in the vomit is termed hematemesis ("blood vomiting"). Old blood bears resemblance to coffee grounds (as the iron in the blood is oxidized), and when this matter is identified the term "coffee ground vomiting" is used. Bile can enter the vomit during subsequent heaves due to duodenal contraction if the vomiting is severe. Fecal vomiting is often a consequence of intestinal obstruction, and is treated as a warning sign of this potentially serious problem ("signum mali ominis"); such vomiting is sometimes called "miserere". If food has recently been consumed, then partly digested food may show up in the vomit.

If the vomiting reflex continues for an extended period of time with no appreciable vomitus, the condition is known as non-productive emesis or dry heaves, which can become both extremely painful and debilitating.

Causes

Complete differential diagnosis of the causes of nausea and vomiting (alphabetical)

Complete Differential Diagnosis of the Causes of nausea and vomiting

(By organ system)

Cardiovascular	No underlying causes
Chemical / poisoning	No underlying causes
Dermatologic	No underlying causes
Drug Side Effect	No underlying causes
Ear Nose Throat	No underlying causes
Endocrine	Addison's Disease, Adrenal failure,
Environmental	No underlying causes
Gastroenterologic	Achalasia, Acute abdomen and/or peritonitis,
Genetic	No underlying causes
Hematologic	No underlying causes
Iatrogenic	No underlying causes
Infectious Disease	Acute infections,
Musculoskeletal / Ortho	No underlying causes
Neurologic	Acoustic neuroma,
Nutritional / Metabolic	No underlying causes
Obstetric/Gynecologic	No underlying causes
Oncologic	Acoustic neuroma,
Opthalmologic	No underlying causes
Overdose / Toxicity	No underlying causes
Psychiatric	No underlying causes
Pulmonary	No underlying causes
Renal / Electrolyte	No underlying causes
Rheum / Immune / Allergy	No underlying causes
Sexual	No underlying causes
Trauma	No underlying causes
Urologic	No underlying causes
Miscellaneous	Acute high altitude sickness,

Diagnosis

Physical Examination

Exams should include:
- Neurologic
- Ear
- Ophthalmagic
- Abdominal

Laboratory Findings

Complete blood count (CBC)
Electrolytes
Liver function tests (LFTs)
Amylase
Lipase
Calcium
Magnesium
Salicylate level
Hepatitis serologies
Cerebrospinal fluid (CSF) analysis
Toxicology screen

Electrolyte and Biomarker Studies

Electrolytes

Electrocardiogram

ECG to rule out an inferior MI or arrhythmia

X Ray

Plain kidney, ureter, bladder (KUB) X-rays

MRI and CT

Abdominal CT scan (with oral and IV contrast)
Head CT scan

Echocardiography or Ultrasound

Abdominal/pelvic ultrasound

Other Diagnostic Studies

Treatment

Fluid resuscitation (due to vomiting-induced dehydration)
Treat underlying disease etiologies

Treatment of Nausea

While short-term nausea and vomiting are generally harmless, they may sometimes indicate a more serious condition, such as Coeliac disease. When associated with prolonged vomiting, it may lead to dehydration and/or dangerous electrolyte imbalances.

Symptomatic treatment for nausea and vomiting may include short-term avoidance of solid food. This is usually easy as nausea is nearly always associated with loss of appetite. Dehydration may require rehydration with oral or intravenous electrolyte solutions. If the cause is by motion sickness, sitting down in a still environment may also help.

There are several types of antiemetics, and researchers continue to look for more effective treatments. The main types used post operatively for surgical patients are ondansetron, dexamethasone, promethazine, diphenhydramine, and in small doses droperidol. Doxylamine is the drug of choice in pregnancy-related nausea. Anecdotally, another remedy used by recovery room nurses is to place an isopropyl alcohol swab under the patient's nose while he or she breathes through the nose. This may abate the nausea until the antiemetic medication takes effect. When ingested or inhaled, the chemical compound tetrahydrocannabinol has been shown to reduce nausea in some users.^[2] Also available are a variety of non-invasive (often untested) mechanical devices used to suppress nausea due to motion sickness.

The spice ginger is also used for centuries as a folk remedy to treat nausea, and recent research has supported this use.^[3]

Treatment of Vomiting

Acute Pharmacotherapies

Antiemetics: An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of some opioid analgesics and chemotherapy directed against cancer. Antiemetics act by inhibiting the receptor sites associated with emesis. Hence, anticholinergics, antihistamines, dopamine antagonists, serotonin antagonists and cannabinoids are used as anti-emetics.
Anticholinergics

Surgery and Device Based Therapy

Colonoscopy/endoscopy may also be used as therapy

Complications of vomiting

Aspiration of vomit

Vomiting can be very dangerous if the gastric content gets into the respiratory tract. Under normal circumstances the gag reflex and coughing will prevent this from occurring, however these protective reflexes are compromised in persons under narcotic influences such as alcohol or anesthesia. The individual may choke and asphyxiate or suffer an aspiration pneumonia.

Dehydration and electrolyte imbalance

Prolonged and excessive vomiting will deplete the body of water (dehydration) and may alter the electrolyte status. The loss of acids leads to metabolic alkalosis (increased blood pH), and the electrolyte imbalance shows hypokalemia (potassium depletion) and hypochloremia (chlorine depletion). The hypokalemia is an indirect result of the kidney compensating for the loss of acid. With the loss of intake of food the individual will become cachectic.

References

↑ Hornby PJ. Central neurocircuitry associated with emesis. Am J Med 2001;111:106S-12S. PMID 11749934.
↑ Drug Policy Alliance (2001). "Medicinal Uses of Marijuana: Nausea, Emesis and Appetite Stimulation". Retrieved 2007-08-02.
↑ University of Maryland Medical Centre (2006). "Ginger". Retrieved 2007-08-02.

External links

Template:SIB Template:Gastroenterology

Template:Skin and subcutaneous tissue symptoms and signs Template:Nervous and musculoskeletal system symptoms and signs Template:Urinary system symptoms and signs Template:Cognition, perception, emotional state and behaviour symptoms and signs Template:Speech and voice symptoms and signs Template:General symptoms and signs

ar:قيء da:Opkast de:Erbrechen eo:Vomado it:Vomito he:הקאה hr:Povraćanje la:Vomitus lt:Vėmimas mk:Повраќање nl:Braken (lichaamsfunctie) no:Oppkast simple:Vomit sk:Zvracanie sr:Повраћање fi:Oksennus sv:Kräkning uk:Блювання wa:Rivômixhaedje da:Kvalme de:Nausea eo:Vomemo fa:تهوع io:Nauzeo it:Nausea he:בחילה lt:Pykinimas nl:Misselijkheid no:Kvalme og brekninger simple:Nausea sk:Nauzea sv:Illamående

Template:WH Template:WS

[1] Hornby PJ. Central neurocircuitry associated with emesis. Am J Med 2001;111:106S-12S. PMID 11749934.

[2] Drug Policy Alliance (2001). "Medicinal Uses of Marijuana: Nausea, Emesis and Appetite Stimulation". Retrieved 2007-08-02.

[3] University of Maryland Medical Centre (2006). "Ginger". Retrieved 2007-08-02.

[1]

[2]

[3]

v t e Symptoms and signs: circulatory (R00–R03, 785)
Cardiovascular	Template:Navbox subgroup
Myeloid/blood	Template:Navbox subgroup

v t e Symptoms and signs: respiratory system (R04–R07, 786)
Hemorrhage	Epistaxis Hemoptysis
Abnormalities of breathing	Respiratory sounds Stridor Wheeze Crackles Rhonchi Hamman's sign Apnea Dyspnea Hyperventilation/Hypoventilation Hyperpnea/Tachypnea/Hypopnea/Bradypnea Orthopnea/Platypnea Trepopnea Biot's respiration Cheyne-Stokes respiration Kussmaul breathing Hiccup Mouth breathing/Snoring Breath-holding
Other	Asphyxia Cough Pleurisy Sputum Respiratory arrest Hypercapnia/Hypocapnia Pectoriloquy: Whispered pectoriloquy Egophony Bronchophony Pleural friction rub Fremitus Silhouette sign
Chest, general	Chest pain Precordial catch syndrome

v t e Symptoms and signs: digestive system and abdomen (R10–R19, 787,789)
GI tract	Template:Navbox subgroup
Accessory	Hepatosplenomegaly/Hepatomegaly Jaundice
Abdominopelvic	Ascites
Abdominal – general	Abdominal pain (Acute abdomen, Colic, Baby colic) Splenomegaly Abdominal guarding · Abdominal mass · Rebound tenderness Shifting dullness · Bulging flanks · Puddle sign · Fluid wave test

v t e Symptoms and signs: Symptoms concerning nutrition, metabolism and development (R62–R64, 783)
Ingestion/Weight	decrease: Anorexia • Weight loss/Cachexia/Underweight increase: Polyphagia • Polydipsia • Orexigenia • Weight gain
Growth	Delayed milestone • Failure to thrive • Short stature (e.g., Idiopathic)