Utility of lactate, central venous oxygen saturation, and the difference in venous and arterial CO2 partial pressures (delta pCO2) levels in quantifying microcirculatory failure: A single-center prospective observational study

Background: The aim of the study was to evaluate the utility of lactate, central venous oxygen saturation (ScvO2), and the difference in venous and arterial CO2 partial pressures (delta pCO2) levels and their relationship with the prognosis of critically ill children with circulatory failure in the pediatric intensive care unit (PICU). Subjects and Methods: Thirty children with circulatory failure who were admitted to the PICU of a tertiary university hospital between January 15 and November 1, 2020, were evaluated in this prospective observational study. Lactate levels, ScVO2, and delta pCO2 levels were evaluated on admission and at hours 4, 12, and 24 (T0, T4, T12, T24) in the PICU. Results: The mortality of the children with circulatory failure was 30% (n = 9). Arterial and venous lactate levels were highly correlated at T0, T4, T12, T24 (P < 0.001; P < 0.001; P < 0.001; P < 0.001, respectively). Nonsurvivors had always higher arterial lactate levels (T0, T4, T12, T24) (P = 0.019, P = 0.007, P = 0.002, P = 0.0003, respectively) and higher delta pCO2 at T0 (P = 0.039) when compared with survivors. Receiver operating characteristic analysis showed that T0 arterial lactate levels (area under the curve [AUC] 0.788, P = 0.019), T24 arterial lactate (AUC 0.918, P < 0,001), and T0 delta pCO2 levels (AUC 0,741, P = 0.039) and were predictive of mortality. Conclusions: Lactate remains the most important marker of microcirculatory dysfunction in critically ill children with circulatory failure. Delta pCO2 may be an additional marker of microcirculatory dysfunction in critically ill children.