Acidosis and Alkalosis
Metabolic acidosis
Metabolic alkalosis
Respiratory acidosis
Respiratory alkalosis
normal anion gap (hypercholaemic metabolic acidosis)
anion gap normal range = 10-18mmol/L
gastro intestinal bicarbonate loss
prolonged diarrhoea, may also result in hypokalaemia
ureterosigmoidoscopy
fistula
renal tubular acidosis
drugs
acetazolamide
ammonium chloride injection
Addison's diseaser
raised anion gap
lactate
shock
sepsis
hypoxia
ketones
diabetic acidosis
alcohol
urate
renal failure
acid poisoning
salicylates
methanol
type A: sepsis, shock, hypoxia, burns
type B: metformin
COPD
decompensation in other resp conditions
life threatening asthma
pulmonary oedema
neuromuscular disease
obesity hypoventilation syndrome
sedative drugs
benzodiazepenes
opiate overdose
mechanism
vomiting / aspiration
loss of hydrogen ions or gain of bicarb
mostly kidney or GI problems
activation of RAAS is key
aldosterone causes reabsorption of Na+ in exchange for H+ in DCT
extracellular fluid depletion (vomiting, diuretics) --> Na+ and Cl- loss --> RAAS activated --> raised aldosterone levels
in hypokalaemia, K+ shift from cell --> ECF, alkalosis is caused by shift of H+ into cells to maintain neutrality
e.g. peptic ulcer leading to pyloric stenos, nasogastric suction
vomiting may also lead to hypokalaemia
diuretics
liquirice, carbenoxolone
hypokaemaemia
primary hypoaldosteronism
Cushing's syndrome
Bartter's syndrome
anxiety leading to hyperventilation
pulmonary embolism
salicylate poisoning
initially resp alkalosis bc of early stimulation of respiratory centre
then met alkalosis bc of direct effects of salicylates and acute renal failure
CNS disorders
stroke
subarachnoid haemorrhage
encephalitis
pregnancy
salicylate poisoning
initially resp alkalosis bc of early stimulation of respiratory centre
then met alkalosis bc of direct effects of salicylates and acute renal failure
Sammer Sheikh
(Na+ + K+) - (Cl- + HCO-3)