P0345 / #1784: EVALUATION OF THE VENOUS TO ARTERIAL CO2 PARTIAL PRESSURE DIFFERENCE AS AN INDIRECT MEASURE OF ADEQUACY OF TISSUE BLOOD FLOW AFTER CONGENITAL HEART DISEASE SURGERY

Abstract

Aims & Objectives: In the postoperative period of cardiac surgery with extracorporeal circulation, the occurrence of low cardiac output is common, especially in neonates and infants under one year old. The venous to arterial CO2 partial pressure difference (VACO2) may be an indirect measure of cardiac output, and, in normal conditions, varies between 2 and 6 mmHg. Higher values of VACO2 may indicate insufficient cardiac output or inadequate microcirculatory blood flow. To evaluate the value of VACO2 as an indirect measure of adequacy of tissue blood flow and cardiac output in children after cardiac surgery and verify its association with outcome. Methods: Prospective observational cohort study involving patients between 0 and 18 years old admitted to the pediatric intensive care unit (PICU) after cardiac surgery with extracorporeal circulation at HCFMRP-USP. In the first 48 postoperative hours, laboratory tests, clinical data, illness severity scores and vasoactive inotropic score were registered. VACO2 and lactate clearance was calculated every 6h. Clinical outcome and the length of stay in the hospital and in PICU were evaluated. Patients were divided in two groups according to the values of VACO2 at 24h after PICU admission (≥ 6 and < 6 mmHg) and were compared by Mann-Whitney U test. Results: Values of VACO2 ≥ 6mmHg were more frequent in younger patients, with lower weight. They were also associated with greater length of stay in hospital and in PICU. There was no correlation with lactate clearance. Conclusions: High VACO2 values at 24h following cardiac surgery for congenital heart disease were associated with worse postoperative outcomes.