Allogeneic blood transfusion and postoperative duration of mechanical ventilation

BACKGROUND: In patients having open heart surgery, allogeneic blood transfu sion (ABT) may be related to an enhanced inflammatory response and impaired pulmonary function, resulting in the need for prolonged mechanical ventila tion. STUDY DESIGN AND METHODS: The records of 416 consecutive patients undergoin g coronary artery bypass graft surgery at Massachusetts General Hospital we re reviewed. Possible predictors and the number of days of postoperative ve ntilation, as well as the number of RBC units transfused and the length of their storage, were recorded. The association between mechanical ventilatio n after the day of operation and the number of RBC units transfused was cal culated by logistic regression analysis. RESULTS: The number of RBC units transfused, but not the length of their st orage, differed (p <0.0001) among patients ventilated for 0, 1, 2, 3, or 4 or more days after the day of operation. Patients taken off ventilation on the day of operation received (mean +/- SE) 2.01 +/- 0.14 RBC units; patien ts kept on ventilation for 4 or more days received 9.45 +/- 1.83 units. Aft er adjusting for the effects of 18 confounding factors, the number of RBC u nits transfused was not a significant predictor of ventilation past the day of operation. There was, however, a trend suggesting that the likelihood o f such ventilation might increase by 26 percent per RBC unit transfused (p = 0.0628). CONCLUSIONS: Future studies of the outcomes of ABT should examine further t he possibility of a relationship between the number of transfused RBCs and the likelihood of postoperative ventilation after the day of operation.