Vomiting

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🤢💨 Vomiting (Emesis) is the forceful expulsion of gastric contents via a coordinated brainstem reflex. It is primarily a protective mechanism against toxins, infection, and metabolic disturbance. Clinically, vomiting reflects activation of central and peripheral neural pathways and may signal benign illness or life-threatening pathology.

🎯 Stimuli Triggering Vomiting

• 🦠 Gastrointestinal irritation - infection, toxins, gastritis, obstruction
• 🧪 Chemoreceptor Trigger Zone (CTZ) - opioids, chemotherapy, uraemia, DKA
• 🌀 Vestibular system - motion sickness, labyrinthitis
• 🧠 Cortical input - anxiety, fear, disgust
• 💊 Metabolic / hormonal - pregnancy, hypercalcaemia, adrenal failure

🧠 The Vomiting Centre

• 📍 Located in the medulla oblongata (area postrema)
• 🧩 Integrates input from GI tract, CTZ, vestibular system, and cortex
• 🚦 Coordinates autonomic, respiratory, and muscular responses

⚙️ Mechanism of Vomiting

• 🔓 Relaxation of lower oesophageal sphincter
• ⬇️ Descent of diaphragm
• 💪 Powerful abdominal wall contraction
• 🔄 Reverse peristalsis of stomach and oesophagus

⏱️ Phases of Vomiting

• 🤢 Nausea - autonomic activation, pallor, hypersalivation
• 😖 Retching - rhythmic contractions without expulsion
• 💨 Expulsion - forceful ejection of gastric contents

📚 Causes of Vomiting

• 🟢 Gastrointestinal
  • Gastroenteritis
  • Peptic ulcer disease
  • Bowel obstruction
  • Appendicitis
  • Pancreatitis
  • Cholecystitis
• 🔵 Neurological
  • Migraine
  • Raised ICP (tumour, haemorrhage)
  • Vestibular disorders
• 🟠 Endocrine / Metabolic
  • DKA
  • Uraemia
  • Hypercalcaemia
  • Adrenal insufficiency
• 🤰 Pregnancy-related
  • Early pregnancy nausea
  • Hyperemesis gravidarum
• 💊 Drug-induced
  • Opioids, alcohol, chemotherapy
  • NSAIDs, antibiotics
• 🧠 Psychogenic
  • Anxiety disorders
  • Eating disorders

🩺 Clinical Features

• 🤢 Persistent nausea
• 📦 Abdominal pain or distension
• 🌀 Headache or vertigo
• 💧 Dehydration: dry mouth, oliguria, tachycardia
• 📉 Weight loss (chronic)
• 🩸 Haematemesis (red flag)

🧪 Diagnostic Assessment

• 🩸 Bloods
  • FBC, CRP
  • U&Es (Na⁺, K⁺, creatinine)
  • LFTs
  • Amylase/lipase
  • Glucose/ketones
• 🩻 Imaging
  • AXR/CT - obstruction, perforation
  • USS - biliary disease, pregnancy
  • CT/MRI brain - raised ICP
• 🚽 Urine
  • Dipstick - ketones, infection
  • β-hCG - pregnancy test
• 🔬 Specialist Tests
  • OGD - ulcers, malignancy
  • Vestibular testing

💊 Management of Vomiting

• 💧 Rehydration - Oral rehydration or IV fluids with electrolyte correction
• 🚫 Antiemetics
  • Ondansetron (5-HT₃ antagonist)
  • Metoclopramide (prokinetic)
  • Promethazine
  • Domperidone
• 🎯 Treat Underlying Cause
  • Infection → targeted therapy
  • Obstruction → surgical review
  • DKA → insulin + fluids
  • Hyperemesis → MDT management
• 🩹 Symptomatic Care - Analgesia, antipyretics, rest

📈 Chronic or Severe Vomiting

• 🥗 Nutritional support (NG/TPN if needed)
• 💉 Thiamine (Pabrinex) before glucose in malnourished/alcohol-dependent patients
• 🧠 Psychological support where indicated
• 🛡️ PPIs/H₂ blockers for acid-related disease

🚨 When to Refer Urgently

• 🩸 Haematemesis or melaena
• ⚠️ Severe abdominal pain or peritonism
• 🧠 New neurological signs
• 📉 Unintentional weight loss
• 💧 Refractory dehydration
• 🤰 Severe hyperemesis

📊 Prognosis

📈 Prognosis depends on cause. Acute infective or drug-related vomiting is usually self-limiting. Persistent vomiting suggests systemic, structural, or neurological disease and requires specialist management. Early correction of dehydration prevents most serious complications.

🧠 Teaching Pearl
Always think in systems: gut, brain, blood, drugs, and psychology. A vomiting patient with metabolic alkalosis + hypokalaemia has probably been losing gastric acid. Check ketones early - “vomiting + ketones” is DKA until proven otherwise.