Influence of glucose kinetics on plasma lactate concentration and energy expenditure in severely burned patients.
BACKGROUND
In critically ill patients, elevation in the plasma lactate concentration has traditionally been interpreted as indicating a deficiency in oxygen availability and is often an impetus to increase oxygen delivery clinically. However, another possible basis for increased lactate concentrations may be simply a mass effect from increased pyruvate availability (i.e., accelerated glycolysis).


METHODS
In six hypermetabolic burned patients, the rates of glucose production and oxidation were quantified using a tracer infusion of 6,6 d2 glucose combined with indirect calorimetry. Measurements were obtained after a 9-hour fast and after a 3-hour infusion of unlabeled glucose at 30 micromol/kg/min. No patient was overtly septic, hypoxic, or hypovolemic.


RESULTS
The infusion of glucose significantly increased the arterial glucose concentration and rate of glucose oxidation, with a corresponding increase in the arterial plasma concentration of lactate and pyruvate. Resting energy expenditure and oxygen consumption were not affected by the infusion of glucose.


CONCLUSIONS
These findings show that elevations in plasma lactate in severely injured patients may, in part, be related to increases in glucose flux and not entirely a reflection of any deficit in oxygen availability. Such findings highlight a potential pitfall for interpreting plasma lactate concentrations as an index of tissue oxygen availability in hypermetabolic patients.
Gore
D C
DC
Department of Surgery, University of Texas Medical Branch, Shriners Hospitals for Children, Galveston 77555-1173, USA. dcgore@utmb.edu
Ferrando
A
A
Barnett
J
J
Wolf
S E
SE
Desai
M
M
Herndon
D N
DN
Goodwin
C
C
Wolfe
R R
RR
D000328:Adult; D001786:Blood Glucose; D002056:Burns / Q000097:blood* / Q000503:physiopathology; D004734:Energy Metabolism; D005947:Glucose / Q000096:biosynthesis / Q000493:pharmacokinetics* / Q000627:therapeutic use; D006019:Glycolysis; D006439:Hemodynamics; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D010101:Oxygen Consumption
D001786:Blood Glucose; D019344:Lactic Acid; D005947:Glucose