Acid base disorders

Question 1

what are causes of a metabolic acidosis with a raised anion gap?

Answer 1

lactate: sepsis, shock, hypovolaemia, metformin
uraemia: renal failure
ketones: DKA, alcohol
acid poisoning: salicylates

Question 2

what acid base disorder does aspirin overdose cause?

Answer 2

(salicylate poisoning)
metabolic acidosis (raised anion gap) + respiratory alkalosis

Question 3

what are causes of a metabolic acidosis with a normal anion gap?

Answer 3

GI bicarbonate loss: diarrhoea, fistula
renal tubular acidosis
drugs e.g. acetazolamide 
ammonium chloride injections 
addison's disease

Question 4

what is the normal anion gap?

how do you work it out?

Answer 4

anion gap = (Na + K) - (Cl + HC02)

normal range = 10-18 mmol/L

Question 5

what are causes of a metabolic alkalosis?

Answer 5

vomiting / aspiration 
diuretics 
liquorice / carbenoxolone
cushings syndrome
berters syndrome 
congenital adrenal hyperplasia

Question 6

what are causes of a respiratory alkalosis?

Answer 6

anxiety 
PE
altitude
pregnancy
salicylate poisoning
CNS disorders e.g. stroke, SAH, encephalitis

Question 7

what are causes of a respiratory acidosis?

Answer 7

COPD
asthma attack, PE
sedatives e.g. benzodiazepines, opiate overdose