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

Abstract

Objective: The objective of this study was to assess the association between increased central venous-to-arterial carbon dioxide difference (ΔPCO₂) 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 ΔPCO₂ ≥ 6 mmHg was considered to be abnormal. Data were first analyzed globally, and then according to 4 subgroups based on time course of ΔPCO₂ during the study period: [(1) persistently normal ΔPCO₂; (2) increasing ΔPCO₂; (3) decreasing ΔPCO₂; and (4) persistently high ΔPCO₂].

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). ΔPCO₂ was correlated weakly with perfusion parameters.

Conclusions: These results suggested that ΔPCO₂ is not predictive of postoperative complications or mortality.

Keywords: cardiac surgery; cardiopulmonary bypass; central venous oxygen saturation; central venous-to-arterial carbon dioxide difference; postoperative complications.