Increased lactate/pyruvate ratio with normal b-hydroxybutyrate/acetoacetate ratio and lack of oxygen supply dependency in a patient with fatal septic shock

Abstract

We report a case of fatal septic shock, with hyperlactatemia and blood cultures positive for Streptococcus pneumoniae, in a 70-year-old patient. On two occasions (5 days, and 2 days before the patient‘s death), the relationship between oxygen delivery (D˙O₂) and consumption (V˙O₂) was examined in conjunction with two presumed markers of tissue oxygenation: the lactate/pyruvate ratio (L/P), and the β-hydroxybutyrate acetoacetate ratio (βOHB/AcAc). Increasing D˙O₂ by about 30% (“oxygen flux test”) failed to increase V˙O₂. The βOHB/AcAc ratio remained within normal limits, thus suggesting uncompromised tissue oxygenation at the hepatic level. The L/P ratio remained persistently above normal limits, thus suggesting actual organ or regional hypoxia. This case shows that during an overwhelming septic shock, the “oxygen flux test” can be negative, despite the presence of hyperlactatemia and of an increased L/P ratio suggestive of impaired tissue oxygenation.