Lactate and Perfusion Trending

Blood lactate is a warning signal that oxygen delivery, cellular metabolism, or lactate clearance may be abnormal. In health it is roughly 0.5-2.0 mmol/L; a value above 2 mmol/L is conventionally called hyperlactatemia. Even a mild elevation around 1.4-2.0 mmol/L has been associated with increased mortality in critically ill patients, so a “normal-ish” result should not overrule a concerning bedside picture. A lactate result does not directly measure tissue perfusion and does not, by itself, diagnose sepsis, hypovolemia, or a need for more fluid. Interpret it beside MAP and blood pressure, mental status, capillary refill, skin temperature and colour, pulse quality, urine output, oxygenation, and the response to treatment. The useful question is not “How do I normalize this number?” but “Why is it elevated, is perfusion improving, and what requires action now?”