High Central Venous-to-arterial CO₂ Difference Is Associated With Poor Outcomes In Patients After Cardiac Surgery

Purpose: In contrast to arterial lactate,previous studies have proposed central venousto-arterial CO₂ difference?P?v-a?CO₂?as a more useful guide for categorizing patients at risk of developing septic shock.It is worthwhile studying P?v-a?CO₂ in determining whether it could serve as a useful predictor for poor postoperative outcomes in patients undergoing cardiac surgery.We investigated the ability of P?v-a?CO₂ to predict poor outcomes of patients with postoperative cardiogenic shock.Methods: In total,1,672 patients were enrolled in this study from January 1,2014 to June 1,2017.Of these patients,143 exhibited complicated and poor outcomes.To address any bias,we derived a propensity score predicting the functions of P?v-a?CO₂ on poor outcomes and matched 114 cases to 114 controls with a similar risk profile.In this cohort study,poor outcomes were defined as the occurrence of any adverse complications,including sudden death,cardiac arrest,extracorporeal membrane oxygenation,oliguria,and the administration of a large amount of vasoactive-inotropic drugs.Results: In propensity-matched patients,significant differences in P?v-a?CO₂?6.11±2.94 mm Hg vs.11.21±5.22 mm Hg,P<0.001?were noted between the control group and poor outcome group.The area under the receiver operating characteristic curve of P?v-a?CO₂?AUC: 0.837,95%CI: 0.782–0.892?for the detection of poor outcomes was significantly better compared to that of the central venous oxygen saturation and arterial lactate.Additionally,there was a negative correlation between cardiac index and P?v-a?CO₂?R=-0.68,P<0.001?.Conclusion: We have shown a correlation between P?v-a?CO₂ to cardiac output which may be used as an alternative metric to predict the poor outcomes of patients with postoperative cardiogenic shock.