Early Central Venous-to-Pa co2 Difference and Subsequent Lactate Clearance in Shock: Prospective Pediatric Cohort, 2021-2022.

OBJECTIVES

To evaluate early central venous-to-Pa co2 difference (∆P co2 ) and its correlation with later lactate concentration in pediatric patients with shock.

DESIGN

Prospective observational study.

SETTING

Two medical-surgical PICUs in a tertiary-care university hospital.

PATIENTS: Children younger than 18 years old with septic or cardiogenic shock admitted to the PICUs (March 2021 to December 2022).

INTERVENTIONS: None.

MEASUREMENTS AND MAIN

RESULTS

Demographic, clinical, and outcome data were collected from medical records. Arterial and central venous blood samples were collected simultaneously at PICU admission and 6, 24, and 48 hours after admission to determine ∆P co2 , arterial lactate concentration, lactate clearance, and central venous oxygen-hemoglobin saturation (Scv o2 ). Left ventricle ejection fraction (LVEF) was estimated by echocardiography. Fifty-four patients 1.1 to 203.1 months old (median, 25.2 mo old) were included: (43/54 [79.6%] had septic shock and 11/54 [20.4%] had cardiogenic shock). Patients were divided into two groups according to ∆P co2 at 6 hours (24 ≤ 6 mm Hg and 30 > 6 mm Hg). The group with ∆P co2 greater than 6 mm Hg, compared with the group less than or equal to 6 mm Hg, had a higher Vasoactive-Inotropic Score and Pediatric Logistic Organ Dysfunction score, and there was a higher proportion of patients with low LVEF, elevated lactate concentrations, reduced lactate clearance, and Scv o2 less than 70%. ∆P co2 positively correlated with lactate concentrations and negatively correlated with lactate clearance and Scv o2 . The ∆P co2 cutoff of 7.5 mm Hg at 6 hours had sensitivity of 0.70, specificity of 0.76, positive predictive value of 0.87, and negative predictive value of 0.54 for predicting lactate clearance less than 10% at 24 hours (area under the receiver operating characteristic curve, 0.81 [95% CI, 0.69-0.91]). There were no differences in clinical outcomes between the groups.

CONCLUSIONS

In pediatric shock, ∆P co2 measured 6 hours after presentation is correlated with subsequent lactate clearance at 24 hours and may serve as an early resuscitation and severity stratification metric.