Expansion
Type A from hypoperfusion, type B without hypoxia
Expansion
Type A: tissue hypoxia
- Shock of any cause, cardiac arrest
- Severe hypoxaemia, severe anaemia, carbon monoxide poisoning
- Regional ischaemia such as mesenteric ischaemia or a compartment syndrome
Type B: no tissue hypoxia
- B1 underlying disease: liver failure (impaired clearance), malignancy, sepsis, thiamine deficiency, diabetes
- B2 drugs and toxins: metformin, adrenaline and salbutamol (through beta-2 stimulated glycolysis), alcohol, antiretrovirals, propofol infusion syndrome, cyanide
- B3 inborn errors of metabolism
Lactate is cleared mainly by the liver (about 70 per cent) and kidney, so impaired clearance raises it as readily as increased production.
Clinically, lactate clearance is a better prognostic marker than a single value, and it is important not to assume hypoperfusion in a patient who is warm and well perfused but on high-dose salbutamol or adrenaline.