ΔPCO 2 and ΔPCO 2 /C (a-cv) O 2 Are Not Predictive of Organ Dysfunction After Cardiopulmonary Bypass

Cardiac surgery is associated with a substantial risk of major adverse events. Although carbon dioxide (CO )-derived variables such as venous-to-arterial CO difference (ΔPCO ), and PCO gap to arterial-venous O content difference ratio (ΔPCO /C O ) have been successfully used to predict the prognosis of non-cardiac surgery, their prognostic value after cardiopulmonary bypass (CPB) remains controversial. This hospital-based study explored the relationship between ΔPCO , ΔPCO /C O and organ dysfunction after CPB. We prospectively enrolled 114 intensive care unit patients after elective cardiac surgery with CPB. Patients were divided into the organ dysfunction group (OI) and non-organ dysfunction group (n-OI) depending on whether organ dysfunction occurred or not at 48 h after CPB. ΔPCO was defined as the difference between central venous and arterial CO partial pressure. The OI group has 37 (32.5%) patients, 27 of which (23.7%) had one organ dysfunction and 10 (8.8%) had two or more organ dysfunctions. No statistical significance was found ( = 0.84) for ΔPCO in the n-OI group at intensive care unit (ICU) admission (9.0, 7.0-11.0 mmHg), and at 4 (9.0, 7.0-11.0 mmHg), 8 (9.0, 7.0-11.0 mmHg), and 12 h post admission (9.0, 7.0-11.0 mmHg). In the OI group, ΔPCO also showed the same trend [ICU admission (9.0, 8.0-12.8 mmHg) and 4 (10.0, 7.0-11.0 mmHg), 8 (10.0, 8.5-12.5 mmHg), and 12 h post admission (9.0, 7.3-11.0 mmHg), = 0.37]. No statistical difference was found for ΔPCO /C O in the n-OI group ( = 0.46) and OI group ( = 0.39). No difference was detected in ΔPCO , ΔPCO /C O between groups during the first 12 h after admission ( > 0.05). Subgroup analysis of the patients with two or more failing organs compared to the n-OI group showed that the predictive performance of lactate and Base excess (BE) improved, but not of ΔPCO and ΔPCO /C O . Regression analysis showed that the BE at 8 h after admission (odds ratio = 1.37, 95%CI: 1.08-1.74, = 0.009) was a risk factor for organ dysfunction 48 h after CBP. ΔPCO and ΔPCO /C O cannot be used as reliable indicators to predict the occurrence of organ dysfunction at 48 h after CBP due to the pathophysiological process that occurs after CBP.