Central Venous-to-Arterial Carbon Dioxide Partial Pressure Difference in Patients Undergoing Cardiac Surgery is Not Related to Postoperative Outcomes

Objective The objective of this study was to assess the association between increased central venous-to-arterial carbon dioxide difference (ΔPCO 2 ) following cardiac surgery with cardiopulmonary bypass and postoperative morbidity and mortality. Design A prospective, observational, non-interventional study. Patients Three hundred ninety-three patients undergoing cardiac surgery with cardiopulmonary bypass. Interventions The primary endpoint was the occurrence of one or more major postoperative complications. A ΔPCO 2 ≥ 6 mmHg was considered to be abnormal. Data were first analyzed globally, and then according to 4 subgroups based on time course of ΔPCO 2 during the study period: [(1) persistently normal ΔPCO 2 ; (2) increasing ΔPCO 2 ; (3) decreasing ΔPCO 2 ; and (4) persistently high ΔPCO 2 ]. Results A total of 238 of the 393 (61%) patients developed complications. The major postoperative complication rate did not differ among the 4 groups: 64% (n = 9) in group 1, 62% (n = 21) in group 2, 53% (n = 32) in group 3, and 62% (n = 176) in group 4 (p = 0.568). Mortality rates did not differ among the 4 groups (p > 0.05). ΔPCO 2 was correlated weakly with perfusion parameters. Conclusions These results suggested that ΔPCO 2 is not predictive of postoperative complications or mortality.