Role of Central Venous - Arterial pCO2 Difference in Determining Microcirculatory Hypoperfusion in Off-Pump Coronary Artery Bypass Grafting Surgery

BACKGROUND: Cardiac surgery is frequently associated with macro and microcirculatory hypoperfusion. Patients with normal central venous oxygen saturation (Scvo2) also suffer from hypoperfusion. We hypothesized that monitoring central venous-arterial pco2 difference (dCO(2)) could also serve as additional marker in detecting hypoperfusion in cardiac surgery patient. METHODS: This is a prospective observational study. Patients undergoing off-pump coronary artery bypass grafting included in this study. The dCO2 was measured postoperatively. The patients with a ScvO2 ≥70% were divided in to 2 groups, the high-dCO2 group (≥8 mmHg) and the low-dCO2 group (<8 mmHg). RESULTS: The 65 patient had scvO(2) ≥70%. Out of these, 20 patients were assigned to the high dCO(2) group and 45 patients to the low dCO(2) group. Patients with high dco2 had higher lactate levels after ICU admission. They also had significantly prolonged need for mechanical ventilation (14.90 ± 10.33 vs 10 ± 9.65, P = 0.0402), ICU stay (5.05 ± 2.52 d vs 3.75 ± 2.36 d, P = 0.049) and hospital stay (12.25 ± 5.90 d vs 8.57 ± 5.55 d P = 0.018). The overall rate of post-operative complications was similar in both the group. CONCLUSION: The present study demonstrates dCO(2) as an easy to assess and routinely available tool to detect global and microcirculatory hypoperfusion in off-pump CABG patients, with assumed adequate fluid status and ScvO(2) as a hemodynamic goal. We observed that high dCO(2) (>8 mmHg) was associated with decreased DO(2)I, increased oxygen extraction ratio, the longer need for mechanical ventilation and longer ICU stay.