Impairment of exogenous lactate clearance in experimental hyperdynamic septic shock is not related to total liver hypoperfusion

Abstract

IntroductionAlthough the prognostic value of persistent hyperlactatemia in septic shock is unequivocal, its physiological determinants are controversial. Particularly, the role of impaired hepatic clearance has been underestimated and is only considered relevant in patients with liver ischemia or cirrhosis. Our objectives were to establish whether endotoxemia impairs whole body net lactate clearance, and to explore a potential role for total liver hypoperfusion during the early phase of septic shock.MethodsAfter anesthesia, 12 sheep were subjected to hemodynamic/perfusion monitoring including hepatic and portal catheterization, and a hepatic ultrasound flow probe. After stabilization (point A), sheep were alternatively assigned to lipopolysaccharide (LPS) (5 mcg/kg bolus followed by 4 mcg/kg/h) or sham for a three-hour study period. After 60 minutes of shock, animals were fluid resuscitated to normalize mean arterial pressure. Repeated series of measurements were performed immediately after fluid resuscitation (point B), and one (point C) and two hours later (point D). Monitoring included systemic and regional hemodynamics, blood gases and lactate measurements, and ex-vivo hepatic mitochondrial respiration at point D. Parallel exogenous lactate and sorbitol clearances were performed at points B and D. Both groups included an intravenous bolus followed by serial blood sampling to draw a curve using the least squares method.ResultsSignificant hyperlactatemia was already present in LPS as compared to sham animals at point B (4.7 (3.1 to 6.7) versus 1.8 (1.5 to 3.7) mmol/L), increasing to 10.2 (7.8 to 12.3) mmol/L at point D. A significant increase in portal and hepatic lactate levels in LPS animals was also observed. No within-group difference in hepatic DO2, VO2 or O2 extraction, total hepatic blood flow (point D: 915 (773 to 1,046) versus 655 (593 to 1,175) ml/min), mitochondrial respiration, liver enzymes or sorbitol clearance was found. However, there was a highly significant decrease in lactate clearance in LPS animals (point B: 46 (30 to 180) versus 1,212 (743 to 2,116) ml/min, P <0.01; point D: 113 (65 to 322) versus 944 (363 to 1,235) ml/min, P <0.01).ConclusionsEndotoxemia induces an early and severe impairment in lactate clearance that is not related to total liver hypoperfusion.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-015-0928-3) contains supplementary material, which is available to authorized users.

Metformin‐associated lactic acidosis (MALA): Moving towards a new paradigm

“…In these experiments, lactate uptake was maintained until the liver's perfusion was decreased by 50% to 70%, even with an acidic extracellular pH . However, sepsis can trigger hyperlactatemia even when perfusion of the heart, liver, mesentery and kidney is normal, or even elevated . Hence, the above‐mentioned findings emphasize the importance of defining the type of shock.…”

Lactate-guided resuscitation saves lives: we are not sure

“…Whereas Levraut et al [4] demonstrated that impaired clearance was a significant cause of mild hyperlactatemia in stable septic patients, Revelly et al [5] demonstrated, with stable isotopes, that lactate clearance was not the main cause of hyperlactatemia. More recently, Tapia et al [6] showed an almost negligible exogenous lactate clearance in early experimental septic shock despite preserved liver perfusion and a concomitant normal clearance of the alcohol sugar sorbitol.…”

The Liver in Critical Illness

“…35 Damm & Kramer Hepatic dysfunction and endotoxemia are both associated with delayed lactate clearance. 36 This alteration is independent of liver hypoperfusion and mitigates the routine use of lactate clearance as an end point of resuscitation in this patient population. Acid-base disturbances are common in critical illness with ALF.…”