Discrepancy between superior vena cava oxygen saturation and mixed venous oxygen saturation can predict postoperative complications in cardiac surgery patients.

OBJECTIVE: To determine if increases in discrepancy between ScvO2 and SvO2 (ScvO2 - SvO2 = ΔSO2) during surgery in cardiac surgery patients can predict postoperative complications.

DESIGN: Prospective, observational study.

SETTING: University hospital.

PARTICIPANTS: One hundred two patients undergoing cardiac surgery were enrolled.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Central venous oxygen saturation (ScvO2) and mixed venous oxygen saturation (SvO2) values during surgery automatically were collected. The average value of ΔSO2 for every minute was calculated. The area under the receiver operating characteristic curve for prolonged postoperative ICU stay (≥3 days) was 0.745 for ΔSO2, which was significantly different from those of ScvO2 and SvO2 (p<0.05) (ScvO2; 0.584, SvO2; 0.598). The optimal threshold value of ΔSO2 to predict prolonged ICU stay (≥3 days) was 12% (sensitivity: 72.0%, specificity: 76.9%). Postoperative ICU duration, ventilation time, and hospital stay were significantly longer in Group D patients (intraoperative maximum ΔSO2 ≥12%) than those in Group N patients (intraoperative maximum ΔSO2<12%). As for postoperative complications, the number of patients with postoperative use of intra-aortic balloon pumping, delirium, respiratory failure requiring tracheotomy, and severe complications was significantly higher in Group D patients. Multivariate logistic regression models were used to evaluate the independent effects of perioperative variables on the risk of developing prolonged ventilation (>24 hours) and prolonged ICU stay (≥3 days). A discrepancy in intraoperative ΔSO2 was an independent risk factor for prolonged postoperative ventilation and ICU stay.

CONCLUSION: The discrepancy between ScvO2 and SvO2 during cardiac surgery is an independent risk factor of postoperative complications such as prolonged ICU stay and ventilation time.