Nausea and Vomiting

Symptoms of

GI

• Food poisoning
• Gastroenteritis
• GI obstruction
• Appendicitis
• 'Acute abdomen'

CNS

• Raised intracranial pressure
• Motion
• Migraine
• Meniere's Disease
• Labarythitis
• Head Injury
• Cerebellar and Brain stem disease
• Psychiatric disorder

Metabolic

• Uraemia
• Pregnancy
• Drugs/toxins
  • cytotoxics
  • alcohol
  • opiates
  • antibiotics

Complications

• Metabolic alkalaemia
• hyponatraemia
• hypokalaemia
• Mallory-Weiss tears - bleeding

Treatment - antiemetics

Anticholinergic (muscarinic)

• hyoscine (0.3 mg) single dose

Antihistamine (H₁)

• Have additional anticholinergic effects
• Cyclizine
  •  good for motion sickness
  • produces sedation
  • blurred visaion
• Promethazine
  • more sedative than cyclizine
• Bethistine
• Cinnarizine

Dopamine Antagonists

• Metoclopromide(10mg 3-4x/day PO or 1-3x/day IM/IV)
  • Extra-pyramidal side-effects
  • raises threshold of CTZ
  • decreases sensitivity of visceral nerves
  • speeds gastric emptying
  • high doses block 5HT₃ receptors
• Domperidone
  • does not penetrate blood-brain barrier
• Phenothiazines
  • risk of  extrapyramidal side effects, dyskinesia and restlessness
  • chlorpromazine (10-25mg PO or 25mg IM)
  • prochlorperazine (5-25mg PO, 12.5mg IM, 25mg PR)
  • Perphenzine 2-5mg
• Butryophenones
  • droperidol (2.5-10mg)
    • extra-pyramidal and oculogyric crises particular risk

5-HT₃ Receptor antagonists

• New = v. expensive
• Ondansetron (8mg by slow IV + maintenance IV)
  • headache
  • abnormal LFTs

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