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
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
Nausea and Vomitting may be caused by peritonitis. List some other signs of peritonitis
- Motionless patient
- Rigid abdomen
- Absent bowel sounds
Nausea and Vomitting may be caused by bowel obstruction what are some other signs of bowel ostruction
- Faeculant vomitting
- Absolute constipation
- Distended abdomen
- Abdominal pain
Nausea and Vomitting may be caused by RICP list some other signs of RICP
- Early morning vomiting
- Headache worse on lying down
- Nerve VI palsy
List some conditions which may lead to reduced consciousness post vomitting
- DKA
- Meningitis
- RICP
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= can be obstruction or 6 Fs (fat, faeces, foetus, flatus, fluid, fatal growth-neoplasm)
- Scars
- Hernias
- Jaundice
What might be seen on palpation of the abdomen
- Tenderness= inflammation
- Signs of dehydration= cold peripheries, delayed cap refill
- Masses= cause obstruction
- Guarding and rigidity= peritonitis
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: can look for pneumoperitoneum or Rigler’s sign (air in and out of bowel) indicating bowel perforation
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? Which hormone in pregnancy is thought to be associated with nausea and vomitting and causes hyperemesis
Pregnancy test-, B-HCG
List some other potential investigation other than bloods and CXR/ Abdo XR that you might conduct on someone with nausea and vomitting
- Pregnancy test
- Toxicology screen
- Contrast studies- barium swallow
- Abdo CT
- Head CT
Outline the management of a patient with acute abdomen.
- Nil-by-mouth - to prevent aspiration when under anaesthesia
- Drip and suck- IC fluids + gastic decompression
- Analgesia
- Anti-emetics
Which anti-emetic must you take caution with when using in a patient with acute abdomen? Which anti-emetics could you use instead?
Metoclopramide – it has a prokinetic effect on the GI tract. Cyclizine or ondansterone
Which form of imaging is useful in a patient with suspected bowel obstruction?
CT scan – allows localisation of the obstruction and identify whether there’s closed loop obstruction, ischaemic bowel and to identify cause
Under what three 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, contact hx
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, ketotic breath, reduced consciousness
Outline the management of DKA.
- IV fluids to rehydrate
- IV insulin + K+ therapy (because insulin in means potassium out of cells) until no ketones in blood
- 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, small meals)
- Anti-histamines (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- during sleep we hypoventilate –> rise in pCO2 –> cerebral vasculature dilatation –> increased ICP –> worse symptoms on waking
- 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
Interpreting a VBG. What is considered to be an acidic blood pH? What is considered to be low HCO3-? and What does the presence of a positive anion gap indicate?
- pH<7.35
- HCO3- < 22mM= metabolic acidosis
- Positive anion gap indicates there are more positive ions in plasma (acidic)
List what these scars are from 1–>8
- Kocher’s (or subcostal) incision: cholecystectomy
- Rooftop incision: Whipple’s surgery, gastric surgery
- Tansverse abdominal incision for nephrectomy
- Midline incision: laparotomy e.g. exploratory, bowel obstruction, gynaecological
- Paramedian incision: same as midline
- McBurney’s incision/ Gridiron: appendicectomy
- Lanz incision: appendicectomy
- Pfannensteil incision: C-section, gynae
NOTE: look for porthole scars (inc one in the umbilicus) for laparoscopic surgery
Describe the three mechanisms of action of metaclopromide… and when is it contraindicated?
- Agonist at 5HT4R (in CTZ)
- D2R antagonist (in CTZ)
- Prokinetic in stomach
Parkinson patients (D2 antagonist) and Bowel Obstruction (because pro-kinetic)
