There are many reasons why nausea and vomiting may occur, which can make it difficult to achieve complete control.
The mechanism of vomiting
The vomiting centre is situated in the brainstem and controls and coordinates vomiting. It responds to stimuli from:
The chemoreceptor trigger zone – situated in the area postrema in the fourth ventricle. Stimulated by:
- Blood toxins
- Biochemical abnormalities, e.g. hypercalcaemia, uraemia
- Drugs, e.g. NSAIDs, opioids
Area neurotransmitters – serotonin and dopamine.
The vestibular nerve – stimulated by:
- Middle ear disease
- Motion sickness
Area neurotransmitters – acetylcholine and histamine.
The cerebral cortex – stimulated by:
- Anxiety
- Thoughts
- Tastes and smells
- Anticipation of past remembered stimulus, e.g. chemotherapy
Area neurotransmitters – acetylcholine and histamine.
The vagus nerve – stimulated by:
- Gastric stasis
- Constipation
- Gastrointestinal obstruction
- Gastric distension
- Stretched liver capsule
- Cough/excessive sputum
Area neurotransmitters – acetylcholine and serotonin.
Direct stimulation:
- Radiotherapy
- Raised intracranial pressure
Management of nausea and vomiting
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