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 & X
List some causes of nausea and vomiting for each of the four mechanisms below: Vestibular system CNS Chemoreceptor Trigger Zone (CTZ) Cranial Nerves IX & X
- Vestibular System - vertigo BPPV Meniere’s disease Labyrinthitis Motion sickness - CNS – brain problems Pain Anxiety Raised ICP Meningitis/Encephalitis - CTZ – chemicals in the blood Alcohol Drugs Toxins Electrolytes Hormones - CN IX & X – abdomen and heart problems GI obstruction GI infection Inflammation of the diaphragm Infection/Inflammation of organs (e.g. hepatitis, pancreatitis)
List some key features of the history of presenting complain 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
List some important associated symptoms to ask about.
Fever
Headache, visual disturbance, focal neurological deficits
Vertigo
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)
Industrial chemicals (e.g. arsenic, organophosphates)
Alcohol and drugs
Why is it important to enquire about previous abdominal surgery?
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
List some particularly worrying signs that are associated with nausea and vomiting.
Peritonitis (guarding, motionless, rigid abdomen, absent bowel sounds) Signs of bowel obstruction High fever (infection) Signs of raised ICP Signs of MI Signs of meningitis Reduced consciousness Haematemesis
List some signs of meningitis.
Photophobia
Neck stiffness
Headache
Kernig’s sign (when the hip is flexed, there is resistance against knee extension)
Brudzinski’s sign (flexion of the neck causes flexion of the hip)
List some key features of inspection when performing an abdominal examination on a patient presenting with nausea and vomiting.
Hydration status (vomiting can lead to dehydration) Abdominal distension Scars Hernias Jaundice
List two important signs that may be picked up on auscultation of the abdomen.
Absent bowel sounds –> ileus
Tinkling bowel sounds –> obstruction
List some blood tests that would be undertaken in a patient presenting with nausea and vomiting and explain why they would be performed.
FBC and CRP – high WCC and CRP in infection
U&Es – vomiting can cause derangement of electrolyte levels
LFTs – check for hepatobiliary cause of nausea/vomiting
VBG – check lactate and pH to get an idea of how sick the patient is
Amylase – rule out pancreatitis
Group and save
List two forms of imaging that may be useful in patients with nausea and vomiting.
AXR
Erect CXR
How are the small and large bowel differentiated on an AXR?
Small bowel – valvulae conniventes, 3 cm diameter
Large bowel – haustra, 6 cm diameter
Which test is important to consider in young female patients presenting with nausea and vomiting?
Pregnancy test
Outline the management of a patient with acute abdomen.
Nil-by-mouth
Drip and suck
Analgesia
Anti-emetics
Which anti-emetic must you take caution with when using in a patient with acute abdomen?
Metoclopramide – it has a prokinetic effect on the GI tract
Which form of imaging is useful in a patient with suspected bowel obstruction?
CT scan – allows localisation of the obstruction and identification of a cause
Under what circumstances is surgery indicated in patients with bowel obstruction?
Signs of strangulation or peritonism
After 48 hrs if it hasn’t resolved
No history of previous abdominal surgery – this suggests that there may be a more sinister cause (not adhesions)
Describe the typical presentation of gastroenteritis.
Nausea, vomiting, diarrhoea, fever and abdominal pain
Last a matter of days and resolves by itself
What does ketonuria in a patient without diabetes suggest?
Starvation
How can food poisoning be differentiated from gastroenteritis?
Food poisoning is caused by bacterial toxins
Symptoms don’t tend to persist longer than 24 hrs
Describe the typical presentation of DKA.
Drowsy Polyuria/Polydipsia Abdominal pain Nausea and vomiting If severe: Kussmaul breathing, reduced consciousness
Outline the management of DKA.
IV fluids to rehydrate
IV insulin (sliding scale)
Monitor capillary ketones and serum K+ concentration
Switch to subcutaneous insulin once pH and capillary ketones have normalised
When does morning sickness typically affect pregnant women?
First trimester
Outline the management of morning sickness.
Advise dietary changes (e.g. avoiding spicy food)
Anti-emetics (e.g. promethazine)
Electrolyte replacement
Thiamine supplementation
What term is used to describe severe morning sickness?
Hyperemesis gravidarum
List some strong anti-emetics that may be used in such cases of severe morning sickness.
Prochlorperazine
Chlorpromazine
Ondansteron
Metoclopramide
Describe the distinguishing clinical features of raised ICP.
Early morning nausea and vomiting
Headaches worse when lying down
Which cranial nerve palsy is most commonly involved in raised ICP and why?
CN VI – it has the longest intracranial course
