Article

Lactate and glucose metabolism in severe sepsis and cardiogenic shock. Crit Care Med

Surgical Intensive Care Unit, University Hospital, Lausanne, Switzerland.
Critical Care Medicine (Impact Factor: 6.15). 10/2005; 33(10):2235-40. DOI: 10.1097/01.CCM.0000181525.99295.8F
Source: PubMed

ABSTRACT To evaluate the relative importance of increased lactate production as opposed to decreased utilization in hyperlactatemic patients, as well as their relation to glucose metabolism.
Prospective observational study.
Surgical intensive care unit of a university hospital.
Seven patients with severe sepsis or septic shock, seven patients with cardiogenic shock, and seven healthy volunteers.
C-labeled sodium lactate was infused at 10 micromol/kg/min and then at 20 micromol/kg/min over 120 mins each. H-labeled glucose was infused throughout.
Baseline arterial lactate was higher in septic (3.2 +/- 2.6) and cardiogenic shock patients (2.8 +/- 0.4) than in healthy volunteers (0.9 +/- 0.20 mmol/L, p < .05). Lactate clearance, computed using pharmacokinetic calculations, was similar in septic, cardiogenic shock, and controls, respectively: 10.8 +/- 5.4, 9.6 +/- 2.1, and 12.0 +/- 2.6 mL/kg/min. Endogenous lactate production was determined as the initial lactate concentration multiplied by lactate clearance. It was markedly enhanced in the patients (septic 26.2 +/- 10.5; cardiogenic shock 26.6 +/- 5.1) compared with controls (11.2 +/- 2.7 micromol/kg/min, p < .01). C-lactate oxidation (septic 54 +/- 25; cardiogenic shock 43 +/- 16; controls 65 +/- 15% of a lactate load of 10 micromol/kg/min) and transformation of C-lactate into C-glucose were not different (respectively, 15 +/- 15, 9 +/- 18, and 10 +/- 7%). Endogenous glucose production was markedly increased in the patients (septic 14.8 +/- 1.8; cardiogenic shock 15.0 +/- 1.5) compared with controls (7.2 +/- 1.1 micromol/kg/min, p < .01) and was not influenced by lactate infusion.
In patients suffering from septic or cardiogenic shock, hyperlactatemia was mainly related to increased production, whereas lactate clearance was similar to healthy subjects. Increased lactate production was concomitant to hyperglycemia and increased glucose turnover, suggesting that the latter substantially influences lactate metabolism during critical illness.

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    • "During shock the heart undergoes a major shift in substrate utilization such that it oxidizes lactate for the majority of its energy needs [98]. Revelly and coworkers demonstrated that an infusion of sodium lactate increased cardiac performance in patients with both cardiogenic and septic shock [99]. Similarly, during increased demand on brain metabolism, lactate is increasingly utilized as an energy substrate [100]–[102]. "
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    • "Blood acidification may be achieved by infusion of other metabolizable acids, such as citric or acetic acid; however, their anions are difficult to measure in the clinical setting. Moreover, their clearance is less predictable than that of lactate, at least for citric acid [19]. Furthermore, oxidation of equal caloric amounts of these acids produces more CO2 than lactic acid (see Table 2). "
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