BackgroundIntraoperative packed red blood cell (PRBC) transfusion during cardiac surgery is associated with increased postoperative morbidity and mortality; however, data on the association between PRBC transfusion and postoperative pulmonary complications (PPCs) are somewhat conflicting. Using The Society of Thoracic Surgeons Adult Cardiac Surgery Database, we sought to determine whether intraoperative PRBC transfusion was associated with PPCs as well as with longer intensive care unit (ICU) stay after isolated coronary artery bypass grafting (CABG) surgery. MethodsA registry-based cohort study was performed on 751,893 patients with isolated CABG between January 1, 2015, to December 31, 2019. Using propensity score–weighted regression analysis, we analyzed the effect of intraoperative PRBC on the incidence of PPCs (hospital-acquired pneumonia [HAP], mechanical ventilation for >24 hours, or reintubation), ICU length of stay, and ICU readmission. ResultsTransfusion of 1, 2, 3, and ≥4 units of PRBCs was associated with increased odds for HAP (odds ratios [ORs], 1.24 [95% CI, 1.21-1.26], 1.28 [95% CI, 1.26-1.32], 1.36 [95% CI, 1.33-1.39], 1.31 [95% CI, 1.28-1.34]), reintubation (ORs, 1.23 [95% CI, 1.21-1.25], 1.38 [95% CI, 1.35-1.40], 1.57 [95% CI, 1.55-1.60], 1.70 [95% CI, 1.67-1.73]), prolonged ventilation (ORs, 1.34 [95% CI, 1.33-1.36], 1.56 [95% CI, 1.53-1.58], 1.97 [95% CI, 1.94-2.00], 2.27 [95% CI, 2.24-2.30]), initial ICU length of stay (mean difference in hours, 6.79 [95% CI, 6.00-7.58], 9.55 [95% CI, 8.71-10.38], 17.26 [95% CI, 16.38-18.15], 22.14 [95% CI, 21.22-23.06]), readmission to ICU (ORs, 1.14 [95% CI, 1.12-1.64], 1.15 [95% CI, 1.12-1.17], 1.15 [95% CI, 1.13-1.18], 1.32 [95% CI, 1.29-1.35]), and additional ICU length of stay (mean difference in hours, 0.55 [95% CI, 0.18-0.92], 0.38 [95% CI, 0.00-0.77], 1.02 [95% CI, 0.61-1.43], 1.83 [95% CI, 1.40-2.26]), respectively. ConclusionsIntraoperative PRBC transfusion was associated with increased incidence of PPCs, prolonged ICU stay, and ICU readmissions after isolated CABG surgery.