Makindo Medical Notes.com

Vomiting, or emesis, is the forceful expulsion of stomach contents through the mouth, often a protective reflex in response to toxins, infection, or other stimuli. It can be acute or chronic and is commonly associated with a wide range of underlying causes.

Stimuli for Vomiting

• Gastrointestinal irritation (e.g., infection, toxins).
• Activation of the chemoreceptor trigger zone (CTZ) by drugs or chemicals.
• Vestibular system input, such as in motion sickness.
• Psychological factors like anxiety or disgust.

The Vomiting Center

• Located in the medulla oblongata, the vomiting center receives inputs from various sources like the GI tract, CTZ, vestibular system, and higher brain centers.
• It processes these signals to coordinate the vomiting reflex.

Mechanism of Vomiting

• The vomiting center sends signals to the diaphragm, abdominal muscles, and oesophageal sphincters.
• This leads to the relaxation of the lower oesophageal sphincter, contraction of the diaphragm, and expulsion of stomach contents.

Phases of Vomiting

• Nausea: An unpleasant feeling that typically precedes vomiting.
• Retching: Strong, involuntary attempts to vomit without actual expulsion.
• Expulsion: Forceful ejection of stomach contents through the mouth.

Causes of Vomiting

• Gastrointestinal Causes:
  • Gastroenteritis (viral or bacterial)
  • Peptic ulcer disease
  • Bowel obstruction (e.g., adhesions, tumours)
  • Appendicitis
  • Pancreatitis
  • Cholecystitis
• Neurological Causes:
  • Migraine
  • Increased intracranial pressure (e.g., tumour, hemorrhage)
  • Vestibular disorders (e.g., labyrinthitis, Ménière’s disease)
• Endocrine/Metabolic Causes:
  • Diabetic ketoacidosis (DKA)
  • Uraemia
  • Hypercalcemia
  • Adrenal insufficiency
• Pregnancy-Related Causes:
  • Morning sickness (first trimester)
  • Hyperemesis gravidarum
• Drug-Induced Causes:
  • Alcohol or drug intoxication (e.g., opioids, chemotherapy)
  • Medication side effects (e.g., antibiotics, NSAIDs)
• Psychogenic Causes:
  • Anxiety
  • Bulimia

Clinical Features

• Nausea and discomfort prior to vomiting
• Abdominal pain or bloating (may indicate gastrointestinal origin)
• Headache or dizziness (suggests neurological causes)
• Dehydration symptoms (e.g., dry mouth, decreased urine output, tachycardia)
• Weight loss in chronic vomiting
• Haematemesis (vomiting blood) in cases of severe gastric irritation or peptic ulcer disease

Diagnostic Tests

• Blood Tests:
  • Complete blood count (CBC) – To check for infection or anaemia
  • Electrolytes – To assess dehydration, metabolic disturbances (e.g., low sodium or potassium)
  • Liver function tests – To evaluate hepatobiliary disease
  • Serum amylase/lipase – To check for pancreatitis
  • Blood glucose – To rule out diabetic ketoacidosis
• Imaging Studies:
  • Abdominal X-ray or CT scan – To detect bowel obstruction, perforation, or other abdominal pathology
  • Ultrasound – Particularly useful in assessing gallbladder disease or pregnancy-related causes
  • Head CT or MRI – If increased intracranial pressure or other neurological conditions are suspected
• Urine Tests:
  • Urinalysis – To check for infection, dehydration, or ketoacidosis
  • Urine pregnancy test – To rule out pregnancy-related vomiting
• Specialized Tests:
  • Endoscopy – To diagnose peptic ulcer disease, gastritis, or malignancy
  • Vestibular function tests – To evaluate vestibular causes of vomiting

Management of Vomiting

• Rehydration: Oral or intravenous fluids to correct dehydration and electrolyte imbalances
• Antiemetics: Medications to control nausea and vomiting, such as:
  • Ondansetron
  • Metoclopramide
  • Promethazine
  • Domperidone
• Identify and Treat the Underlying Cause:
  • Infection – Antibiotics for bacterial infections like gastroenteritis
  • Obstruction – Surgical intervention for bowel obstruction or appendicitis
  • DKA – Insulin therapy and correction of acidosis
  • Pregnancy-related – Supportive care and antiemetics for hyperemesis gravidarum
• Symptomatic Treatment: Treat pain or discomfort with analgesics and manage related symptoms like diarrhea or fever if present.

Chronic or Severe Vomiting

• Nutritional Support: In cases of prolonged vomiting, nasogastric feeding or parenteral nutrition may be needed. Consider Pabrinex as Thiamine deficiency can cause issues.
• Addressing Psychogenic Factors: For psychogenic vomiting, cognitive behavioral therapy or psychiatric support may be indicated.
• Proton Pump Inhibitors (PPIs) or H2 Antagonists: For cases related to acid reflux or peptic ulcers.

When to Refer

• Persistent or severe vomiting that does not improve with initial treatment
• Vomiting associated with red flags such as haematemesis, severe abdominal pain, neurological symptoms, or weight loss
• Suspected structural abnormalities or malignancy requiring specialist evaluation (e.g., gastroenterologist, neurologist)

Prognosis

The prognosis for vomiting depends on the underlying cause. Acute vomiting due to infections or medications is generally self-limiting, while chronic vomiting related to systemic or structural causes may require more intensive treatment and management.