Red blood cell transfusion practices in acute lung injury: what do patient factors contribute?

OBJECTIVE

To describe red blood cell (RBC) transfusion practices and evaluate the association between patient-related factors and pretransfusion hemoglobin concentration in acute lung injury (ALI).

DESIGN

Secondary analysis of prospectively collected data.

SETTING

Nine intensive care units (ICUs) in three teaching hospitals in Baltimore, MD.

PATIENTS

Two hundred forty-nine consecutive patients with ALI requiring mechanical ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Simple and multiple linear regression analyses were used to evaluate the association between the nadir hemoglobin concentration on the day of initial RBC transfusion and 20 patient-level demographic, clinical and ICU treatment factors as well as ICU type. Of 249 patients with ALI, 47% received an RBC transfusion in the ICU without evidence of active hemorrhage or acute cardiac ischemia. The mean (sd) nadir hemoglobin on the day of first transfusion was 7.7 (1.1) g/dL with 67%, 36%, 15%, and 5% of patients transfused at >7, >8, >9, and >10 g/dL, respectively. Transfused patients received a mean (sd) of 5 (6) RBC units from ALI diagnosis to ICU discharge. Prehospital use of iron or erythropoietin and platelet transfusion in the ICU were independently associated with lower pretransfusion hemoglobin concentrations. No patient factors were associated with higher hemoglobin concentrations. Admission to a surgical (vs. medical) ICU was independently associated with a 0.6 g/dL (95% confidence interval 0.1-1.1 g/dL) higher pretransfusion hemoglobin.

CONCLUSIONS

Patients with ALI commonly receive RBC transfusions in the ICU. The pretransfusion hemoglobin observed in our study was lower than earlier studies, but a restrictive strategy was not universally adopted. Patient factors do not explain the gap between clinical trial evidence and routine transfusion practices. Future studies should further explore ICU- and physician-related factors as a source of variability in transfusion practice.