Association between postoperative arterial blood gas parameters and cognitive dysfunction following coronary artery bypass grafting: a prospective observational study.

backgroundPostoperative cognitive dysfunction (POCD) is a significant complication of coronary artery bypass grafting (CABG), with impaired quality of life and long-term outcomes. The association between postoperative arterial blood gas (ABG) abnormalities and early cognitive outcomes remains unclear.

objectivesTo investigate the association between perioperative ABG parameters and SMMSE-assessed cognitive function in patients undergoing elective CABG.

methodsThis prospective study of 41 CABG patients recorded SMMSE scores and ABG parameters (pH, PO₂, PCO₂, HCO₃⁻, SO₂, base excess) preoperatively and 3-7 days postoperatively; POCD was defined as a ≥ 2-point SMMSE decline. Analyses included correlation, regression with VIF diagnostics, logistic regression, ROC analysis, and FDR correction.

resultsAge was 63.15 ± 7.42 years; 29 of 41 patients (70.7%) met POCD criteria, with SMMSE declining (p < 0.001). Postoperative pH, PO₂, SO₂, HCO₃⁻, and base excess correlated with SMMSE change (ρ = 0.567-0.608, all p < 0.001) and differed between groups (all p ≤ 0.003); PCO₂ showed neither association. In multivariable regression, the model was significant (adjusted R² = 0.332, p = 0.002), but no individual parameter remained significant, reflecting multicollinearity (VIF up to 5.21); these also predicted POCD by logistic regression, and ROC analysis identified HCO₃⁻ as the strongest discriminator (AUC = 0.885), followed by pH (0.866) and base excess (0.851).

conclusionsPostoperative ABG derangements, metabolic acidosis and hypoxemia, are significantly associated with early cognitive decline after CABG. No single parameter was an independent predictor, reflecting interrelation; pH, HCO₃⁻, and base excess showed the strongest discriminative accuracy. These observational associations warrant confirmation in interventional studies.