Fluid

Question 0

Which fluid compartment is responsible for oedema? (1)

What is the pathophysiology? (2)

Answer 0

Oedema is an increase in interstitial fluid.

Increased hydrostatic pressure
Reduced oncotic pressure
Obstruction to lymphatic flow
Increased permeability of the blood vessel wall

Question 1

What are the three major fluid compartments in the body? (3)

Answer 1

Intracellular
Extracellular (interstitial)
Plasma

Question 2

Name a disadvantage of colloids as fluid replacement. (1)

Answer 2

Hypersensitivity reactions (anaphylactoid)
Transient increase in bleeding time

Question 3

How can a patients fluid balance be assessed clinically? (3)

Answer 3

Fluid balance charts
Daily weights
Urine output
Skin turgor
Capillary refill
JVP
Invasive cardiac monitoring in HDU patients
Pulse
Lying and standing BP

Question 4

Name 3 causes of increased extracellular volume. (3)

Answer 4

Cardiac failure -reduced CO, increased sympathetic activity, ADH release
Cirrhosis -vasodilatation so under perfusion of volume receptors. Also linked to hypoalbuminaemia.
Nephrotic syndrome -increased sodium resorption in collecting tubules, directly induced by disease. Also hypoalbuminaemia.
Sodium retention -renal impairment or drugs: mineralocirticoids, thiazolidinediones, NSAIDs.

Question 5

Name 4 causes of dehydration (extracellular volume depletion). (4)

Answer 5

Haemorrhage
Burns
GI losses - vomiting, diarrhoea, ileostomy losses ileus
Renal losses - diuretics, reflux nephropathy, DM, SCD, analgesic nephropathy

Question 6

Name 3 causes of metabolic acidosis with a normal anion gap. (3)

Answer 6

1. Increased GI HCO3 loss: diarrhoea, ileostomy
2. Increased renal HCO3 loss: hyperparathyroidism, tubular damage
3. Decreased H+ excretion: type 1&4 renal tubular acidosis
4. Increased HCl production

Question 7

Name 3 causes of metabolic acidosis with a high anion gap. (3)

Answer 7

Renal failure
Ketoacidosis- DM, alcohol poisoning, starvation
Lactic acidosis
Salicylate poisoning