Red Blood Cell Transfusions and the Risk of ARDS Among Critically Ill: A Cohort Study

Introduction: Recent data indicate that transfusion of packed red cells (pRBCs) may increase the risk for the development of Acute Respiratory Distress Syndrome (ARDS) in critically ill patients. Uncertainty remains regarding the strength of this relationship.

Methods: In order to quantify the association between transfusions and ICU-onset ARDS, we performed a cohort study within CRIT, a multicenter, prospective, observational study of transfusion practice in the ICU that enrolled 4,892 critically ill patients in 284 US ICUs. Diagnostic criteria for ARDS were prospectively defined, and we focused on subjects without ARDS on admission. The development of ARDS in the ICU served as the primary endpoint.

Results: Among the 4,730 patients without ARDS at admission, 246 (5.2%) developed ARDS in the ICU. At baseline, ARDS cases were younger, more likely to be in a surgical ICU, and were more likely to be admitted with pneumonia or sepsis than controls without ARDS. Cases also were more likely to have serum creatinine > 2.0 mg/dL (23% versus 18%), serum albumin [less than or equal to]2.3 g/dL (54% versus 30%) and were more severely ill upon ICU admission as measured by either the APACHE II or SOFA score (p<0.05 for all). Sixty-seven percent and 42% of cases and controls, respectively, had exposure to pRBC transfusions (p<0.05), and the unadjusted odds ratio of developing ARDS in transfused patients was 2.74 (95% CI: 2.09-3.59, p<.0001) compared to those never transfused. After adjusting for age, baseline severity of illness, admitting diagnosis, and process of care factors, the independent relationship between pRBC transfusions and ICU-onset ARDS remained significant (adjusted odds ratio 2.80, 95% CI: 1.90-4.12, p<.0001).

Conclusion: Development of ARDS after ICU admission is common, occurring in approximately 5% of critically ill patients. Transfusion of pRBCs is independently associated with the development of ARDS in the ICU.