Nausea and vomiting

Chapter 5 NAUSEA AND VOMITING




KEY POINTS



• Nausea and vomiting are most often secondary to extra-gastrointestinal processes.

• A systematic approach to diagnosis and management is imperative given the multitude of causes.

• Review all medications and consider their side effects.

• The metabolic consequences and complications of vomiting should be an integral part of patient assessment.

• A therapeutic trial of antiemetics and/or prokinetics is a reasonable approach if a specific cause is not found after appropriate investigations.

• Chronic unexplained nausea and vomiting may respond to tricyclic antidepressant therapy.


INTRODUCTION


Nausea and vomiting are common symptoms with a wide array of possible causes. Nausea describes the unpleasant subjective sensations that precede vomiting. During nausea, reflux of duodenal contents into the stomach is frequent, possibly due to increased tone of the duodenum and proximal jejunum, although this is not always present. Concurrently, gastric tone is reduced and gastric peristalsis is diminished or absent. It is important to distinguish between four distinct symptoms, namely retching, vomiting, regurgitation and rumination, that superficially may appear similar (Table 5.1). In particular, vomiting involves expulsion of gastric contents through the mouth via forceful, sustained contraction of the abdominal muscles and diaphragm when the pylorus is contracted. Occasionally, vomiting is associated with hypersalivation and defecation; cardiac dysrhythmias may rarely occur.


TABLE 5.1 Definitions of terminology associated with nausea and vomiting



















Nausea: The unpleasant sensation of the imminent need to vomit, usually referred to the throat or epigastrium; a sensation that may or may not ultimately lead to the act of vomiting.
Retching: Spasmodic respiratory movements against a closed glottis with contractions of the abdominal musculature without expulsion of any gastric contents, referred to as ‘dry heaves’.
Vomiting: Forceful oral expulsion of gastric contents associated with contraction of the abdominal and chest wall musculature.
Regurgitation: The act by which food is brought back into the mouth without the abdominal and diaphragmatic muscular activity that characterises vomiting.
Rumination: Chewing and swallowing of regurgitated food that has come back into the mouth through an unconscious voluntary increase in abdominal pressure within minutes of eating or during eating.
Anorexia: Loss of desire to eat, that is, a true loss of appetite.
Sitophobia: Fear of eating because of subsequent or associated discomfort.
Early satiety: The feeling of being full after eating an unusually small quantity of food.

Adapted from Quigley EM, Hasler WL, Parkman HP. AGA technical review on nausea and vomiting. Gastroenterology 2001; 120:263–86.



PATHOGENESIS


Emetic stimuli are recognised in the vomiting centre in the dorsal medulla, which is linked to other centres controlling respiration and salivation. This area is innervated by vagal and sympathetic afferents from the gastrointestinal tract, the pharynx, vestibular system, heart, peritoneum and higher central nervous system centres such as the thalamus, hypothalamus and cerebral cortex. A second area in the brain, the area postrema, is home to the chemoreceptor trigger zone (CTZ). The blood–brain barrier is essentially absent in this location, permitting substances in the circulation to stimulate the CTZ, which in turn induces vomiting, probably via the vomiting centre.


Neurotransmission in the vomiting centre and CTZ appears to be mediated via dopaminergic, serotonergic, muscarinic and histaminergic receptors, and pharmacological therapies have been developed targeting each of these (see later).



CLINICAL CONSIDERATIONS


The differential diagnosis of nausea and/or vomiting is extensive and is presented in Table 5.2. The major causes include infection, medications (particularly chemotherapeutic agents) and toxins, central nervous system pathology, organic gastrointestinal disorders, endocrine and metabolic disorders including pregnancy, systemic illnesses, psychiatric disease, postoperatively and functional gastrointestinal disorders including the cyclical vomiting syndrome.


TABLE 5.2 Causes of nausea and/or vomiting



















Medications and toxic aetiology
• Cancer chemotherapy
– Severe: cisplatin, dacarbazine, nitrogen mustard

– Moderate: etoposide, methotrexate, cytarabine

– Mild: fluorouracil, vinblastine, tamoxifen

• Analgesics
– Aspirin or non-steroidal antiinflammatory drugs (NSAIDs)

– Gold

– Antigout drugs

• Cardiovascular medications
– Digoxin

– Antiarrhythmics

– Antihypertensives

– Beta-blockers

– Calcium channel blockers

– Diuretics

• Hormonal preparations/therapies
– Oral hypoglycaemic agents

– Oral contraceptives
• Antibiotics/antivirals
– Erythromycin

– Tetracycline

– Sulfonamides

– Antituberculous drugs

– Aciclovir

• Gastrointestinal medications
– Sulfasalazine

– Azathioprine

• Central nervous system (CNS) active
– Nicotine

– Narcotics

– Antiparkinsonian drugs

– Anticonvulsants

• Theophylline

• Ethanol abuse

• Marijuana toxicity
Disorders of the gut and peritoneum

• Organic gastrointestinal disorders
– Pancreatic adenocarcinoma

– Inflammatory intraperitoneal disease

– Peptic ulcer disease

– Cholecystitis

– Pancreatitis

– Hepatitis

– Crohn’s disease

– Mesenteric ischaemia

– Retroperitoneal fibrosis

– Mucosal metastases
• Functional gastrointestinal disorders
– Functional nausea and vomiting disorders

– Cyclic vomiting syndrome

– Irritable bowel syndrome

• Mechanical obstruction
– Gastric outlet obstruction

– Small bowel obstruction

– Gastroparesis

– Chronic intestinal pseudo-obstruction
Endocrine and metabolic causes
• Pregnancy

• Other endocrine and metabolic
– Uraemia

– Diabetic ketoacidosis

– Hyperparathyroidism

– Hypoparathyroidism
– Hyperthyroidism

– Addison’s disease

– Acute intermittent porphyria
Infectious causes
• Gastroenteritis
– Viral e.g. Norwalk, rotavirus, adenoviruses

– Bacterial e.g. Staphylococcus aureus, Salmonella, Bacillus cereus, Clostridium perfringens
• Non-gastrointestinal infections
– Otitis media

– Urinary tract infection

– Jamaican vomiting sickness
CNS causes
• Migraine

• Increased intracranial pressure
– Malignancy

– Haemorrhage

– Infarction

– Abscess

– Meningitis

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Cancer of the pancreas and pancreatic cystic lesions Faecal incontinence Inflammatory bowel disease Suspected iron overload or high serum ferritin Pregnancy and liver disease Obesity surgery

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Mar 29, 2017 | Posted by in GASTROENTEROLOGY | Comments Off on Nausea and vomiting

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