QNA2 Flashcards
Metabolic abnormalities in gastric outlet obstruction
Metabolic alkalosis
Low cl
Low K (excreted as aldosterone tries retain Na)
Differentials for goitre
Benign:
Simple multinodular goitre
Toxic multinodular goitre
Neoplasm:
follicular
papillary
Why high bicarb in gastric outlet obstruction
- pancreatic juices being retained as patient not eating (rich in bicarb)
- bicarb is reabsorbed in renal tubule to replace chloride loss and maintain ionic neutrality
Differentials for goitre
Benign:
Simple multinodular goitre
Toxic multinodular goitre
Neoplasm:
follicular
papillary
Why do patients get an acidic urine in gastric outlet obstruction
Vomiting->loss of Na
Aldosterone -> reabsorbs Na/H2O for K/H+
H+ in urine leads to acidity
What is the pain pathway
C (dull) and Adelta (sharp pain) fibres detect nociception -> synapse in dorsal horn -> decussate at the same level and travel to thalamus via lateral spinothalamic tract
-> enter somatosensory cortex
Side effects of opioids
Resp depression
N+V
Constipation
Itching
Pain mx
- WHO ladder
- PCA/regional anaesthesia/epidural
- ref to acute pain team
How to assess pain severity?
0-10
Verbal rating scale
Visual analogue scale
Functional assessment
What is PCA
Syringe pump attactched to an IV line
Administers boluses of morphine
Safety mechanisms of PCA
- restricted dose
- restricted frequency
- lock out time (ineffective clicking)
- one way valve preventing backflow into infusion chamber
Problems with PCA
- reduced mobility of patient
- cant give to confused patients
- sleep disturbance
- breaks down/runs out of battery
Complications of pain
- resp distress
- CVS: increased sympathetic drive -> risk of MI
- MSK: immobility and risk of DVT
- GI: delayed gastric emptying: paralytic ileus
What is bilirubin conjugated to
Conjugated to glucouronic acid by glucoronyltransferase in liver
Function of bile
Emulsifies fat -> gives it more surface area for lipase from pancrease to metabolise it
Constituents of bile
Water
Cholesterol
Bile pigments (bilirubin and verdin)
How do bile salts emulsify fat
Anions (hydrophilic/hydrophobic sides)
Form around droplets of fat forming micelles
Hydrophillic side (outside) is negatively charged, stops the fat molecules to aggregate into larger fat particles
What happens to conjugated bilirubin
Haem -> biliverdin -> unconjugated bilirubin -> conjugated bilirubin
Step 1: Excreted in bile -> deconjugated by intestinal bacteria -> urobilinogen (colourless)
Step 2a. 10 % of urobilinogen gets reabsorbed into the enterohepatic circulation
Step 2b. Rest is Urobilinogen is oxidised into stercobilinogen -> brown colour of stool
What is enterohepatic circulation
Reabsorption of bile salts from terminal ileum back to liver (not conjugated bilirubin is NOT reabsorbed)
Causes of jaundice
Prehepatic:
- haemolytic anaemia (eg sickle cell)
- Congenital (Gilberts syndrome)
Hepatic:
- viral hepatitis
- drug induced
- wilsons
Post hepatic:
- gallstones
- PSC
- malignancy
How to check cold sensation in theatre
Ethyl chloride spray or ice pack
Causes of perforated viscus
Perforated ulcer
Diverticulum
Ischaemic colitis
Necrotising enterocolitis
Why BP decreasing in pregnant lady in reverse trendelenburg position
(aka head up)
IVC compressed by uterus decreasing preload -> reducing cardiac output
How does body respond to reduced BP
- barroreceptor reflex produce a compensatory tachycardia and vasoconstriction
- Hormones:
Aldosterone (RAAS) increases salt and water retention
Adrenaline/norad increases contractility/
Devices that stop VTE
TEDS
Intermittent pneumatic compression devices
What is TURP syndrome
Dilutional hypotonic hypervolaemia as a result of using glycine rich irrigation solution -> absorption and dilutional hyponatraemia
Why is glycine used instead of saline for irrigation
Isotonic solution limits use of diathermy: dissemination of electric current will be dangerous to both patient and surgeon
