Time-pattern of lactate and lactate to pyruvate ratio in the first 24 hours of intensive care emergency admissions

Blood lactate elevation in critically ill patients commonly is taken as a s ign of impaired tissue perfusion. Simultaneous elevation of lactate to pyru vate ratio (L/P ratio) may be helpful in discriminating between different m echanisms of hyperlactatemia and thus in determining the relevance of the f inding, We studied prospectively the prevalence and the time pattern of hyp erlactatemia and simultaneous L/P ratio elevation in 98 consecutive emergen cy admission patients in a 23-bed surgical-medical University Hospital inte nsive care unit. Blood lactate, L/P ratio, and blood gases were measured at 2-h intervals during the initial 24 h of intensive care unit admission. Hy perlactatemia (blood lactate over 2 mmol/L) was found in 48 (49%) patients, and the median peak value of the non-survivors was higher than that of the survivors [5.3 (interquartile range 1.9-7.5) vs. 1.9 (1.3-2.9) mmol/L, res pectively, p = 0.003]. Hyperlactatemia at admission (n = 31) was associated with a higher hospital mortality than hyperlactatemia developing later (n = 17) (29.0% vs. 5.9%, P = 0.003). Sustained admission hyperlactatemia (>6 h) was associated with higher mortality than short-lasting hyperlactatemia (36.8% vs. 0%, P = 0.008). Simultaneously elevated L/P ratio (L/P ratio > 1 8; n = 16) was associated with higher mortality than hyperlactatemia with n ormal L/P ratio (n = 32; 37.5% vs. 12.5%, respectively, P = 0.03) and was f ound mainly in patients who had severe circulatory failure, The hyperlactat emia of patients with sepsis was not associated with L/P ratio elevation. W e conclude that hyperlactatemia is common in emergency admission patients. Hyperlactatemia with L/P ratio elevation and lactic acidosis is likely to b e associated with inadequate tissue perfusion. Hyperlactatemia persisting m ore than 6 h and simultaneous elevation of L/P ratio are associated with in creased mortality.