Decreases in myocardial glucose and increases in pyruvate but not ischaemia are observed during porcine endotoxaemia

Background: Myocardial dysfunction occurs commonly in septic shock. It is not known whether this is due to local ischaemia and metabolic disturbances. Our hypothesis was that endotoxaemic myocardial dysfunction may be associated with interstitial ischaemic and metabolic changes, measured using interstitial microdialysis (MD). Methods: Eighteen pigs were randomized to control (n=6) or endotoxin infusion (n=12). MD catheters were inserted into the myocardium for measurement of interstitial glucose, pyruvate and lactate concentrations. Plasma glucose and lactate concentrations and systemic haemodynamic parameters were measured simultaneously. Results: Compared with the control group, the endotoxaemic animals had significantly decreased left ventricular stroke work and venous oxygen saturation (SvO2), and increased mean pulmonary artery pressure and plasma lactate. In the endotoxaemic group, decreases in interstitial glucose were observed, occurring simultaneously with increases in interstitial pruvate. Interstitial lactate : pyruvate ratios decreased with time in all animals. Conclusions: Despite severe systemic and pulmonary haemodynamic changes, interstitial MD measurements revealed no evidence of anaerobic metabolism in the myocardium of endotoxaemic pigs. There were, however, changes in glucose and pyruvate concentrations, suggesting local energy metabolic disturbances.