Blood pH level modulates organ metabolism of lactate in septic shock in dogs.

OBJECTIVE: Lactic acidosis is an important complication of septic shock. Alkali treatment such as sodium bicarbonate is often used to treat the low pH level that develops in sepsis. The effect of this treatment on lactate (Lac) clearance is not clear. In the present study, the objective was to examine whether blood pH level alters Lac metabolism in sepsis. Measurements were determined in a canine model of Escherichia coli sepsis after bolus infusion (5 mmol/kg) of either lactic acid (LA) or sodium lactate (NaL). In one preparation, Lac uptake by the splanchnic organs (SP), liver, lung, kidneys (Kid), and soft tissues of the lower extremity (SOL) was primarily determined, whereas in another preparation, Lac uptake by the head and neck region and lung was obtained.

METHODS: The dogs were studied while anesthetized and ventilated. After 4 hours of sepsis, either LA or NaL was given through a catheter positioned in the abdominal aorta in respective sepsis (SepLA, SepNaL) and nonsepsis groups (ConLA, ConNaL) (n approximately equal to 6 in each preparation). Catheters and flow probes were used to measure organ Lac uptake. Measurements were obtained at end infusion and at 15-minute intervals after infusion until 75 minutes after infusion.

RESULTS: Arterial clearance of Lac in the sepsis groups was slower as compared with the nonsepsis groups. In the liver, sepsis inhibited the uptake of LA as compared with the nonseptic group. In SP, both sepsis and pH affected Lac uptake in which an increase in uptake was found only after NaL infusion in the nonseptic group. In the head and neck region, Lac uptake was pH-level dependent and was found after LA infusion in the sepsis and nonsepsis groups. In the lung, Lac was produced after either LA or NaL infusion in all groups. Neither Kid nor SOL contributed to Lac uptake in any of the groups.

CONCLUSION: Lactate clearance was reduced in sepsis. Both effects of pH level and sepsis modulated the organ uptake of Lac in septic shock. Only a small amount of the total Lac infused could be accounted for by the organs measured in the present study. This suggests that additional organs may account for lactate removal in sepsis.