Nausea and Vomiting Flashcards
Where is the vomiting centre located?
Medulla oblongata
What are the two main types of receptors found within the vomiting centre?
Histamine receptors Acetylcholine receptors
What are the four main inputs to the vomiting centre?
Vestibular system CNS Chemoreceptor Trigger Zone (CTZ) Cranial Nerves IX & amp; X
List some causes of nausea and vomiting for the Vestibular system and state which recpetors they act on in the Vomiting centre
Vestibular System: “vertigo”
- BPPV
- Meniere’s disease
- Labyrinthitis
- Motion sickness
=> 5-HT receptors and ACh receptors
List some causes of vomitting for the CNS
CNS – “brain problems”
- Pain
- Anxiety
- Raised ICP
- Meningitis/Encephalitis
List some causes of vomitting for the Chemoreceptor Trigger Zone (CTZ) and state which recpetors they act on in the Vomiting centre
CTZ “chemicals in the blood”
- Alcohol
- Drugs
- Toxins
- Electrolytes
- Hormones
=>Dopamine Receptors
List some causes of vomitting for the Cranial Nerves IX & X
CN IX & X “abdomen and heart problems”
- GI obstruction
- GI infection
- Inflammation of the diaphragm
- Infection/Inflammation of organs (e.g. hepatitis, pancreatitis)
=> 5-HT receptors and ACh
List some key features of the history of presenting complain (Vomit) that you should ask about.
- Contents
- Timing
- Association with eating
- Pain
Describe different types of vomit and how they relate to their aetiology.
- Undigested – the food hasn’t reached the stomach, probably an oesophageal problem
- Partially digested – gastric outlet obstruction, gastroparesis
- Bile – SBO distal to ampulla of Vater
- Faeculent – distal intestinal or colonic obstruction
- Blood/coffee-ground – haematemesis causes
Which causes of nausea and vomiting are associated with early-morning vomiting?
- Raised ICP
- Pregnancy
Explain how the association between the nausea/vomiting and eating helps narrow down the differential diagnosis.
- Within 1 hr of eating = high GI obstruction (proximal to gastric outlet)
- Longer, post-prandial delay = lower GI obstruction
- Early satiety, post-prandial bloating and abdominal discomfort = gastroparesis or outlet obstruction
If there is relief of pain/ discomfort after vomiting what is this indicative of?
Obstruction causing vomiting
If a patient complains of vomiting within an hour of eating probably due to obstruction high up in the GIT which condition should you consider and enquire about and why
PUD- it can cause scarring and pyloric stenosis
List some important associated symptoms to ask about.
- Fever= inflammatory/ infectious causes
- Headache, visual disturbance, focal neurological deficits= meningitis, encephalitis, RICP, migraine
- Vertigo= labrynthitis, meniere’s BPPV
Explain how asking about the patient’s bowel movements can help narrow the differential diagnosis.
- Absolute constipation – bowel obstruction
- Diarrhoea – suggests gastroenteritis
List some risk factors for infectious diarrhoea.
- Close contacts with similar symptoms
- Living in close quarters
- Unusual meals
- Recent travel
List some drugs/toxins that are associated with causing nausea and vomiting.
- Medications (e.g. opiates, chemotherapy, anti-convulsants, antiniotics)
- Industrial chemicals (e.g. arsenic, organophosphates)
- Alcohol and illicit drugs
Why is it important to enquire about previous abdominal surgery in patients presenting with nausea and vomitting?
Previous abdominal surgery increases the risk of forming adhesions, which can lead to bowel obstruction
How can the causes of chronic nausea and vomiting be subdivided?
- Weight loss-Upper GI obstruction (e.g. cancer) Functional dysphagia (e.g. achalasia) Coeliac disease
- No weight loss- Oesophagitis Pharyngeal pouch
List some causes of nausea and vomiting that are associated with:
- Abdominal Pain
- Headache
- Vertigo
- Onset shortly after eating food
- None of the above
- Abdominal Pain With fever: infection (e.g. gastroenteritis), inflammation (e.g. appendicitis, cholecystitis) Without fever: DKA, SBO, drug side-effects, toxins - Headache Meningitis Raised ICP Migraine - Vertigo Labyrinthitis Meniere’s disease BPPV Motion sickness - Onset shortly after eating food Gastric outlet obstruction - None of the above Drug side-effect Psychogenic Hyperthyroid Renal failure + uraemia