Study objectives: Acute chest syndrome (ACS) is a frequent and potentially severe pulmonary illness in sickle cell disease (SCD). The aim of the study was to report the clinical features and outcome of consecutive ACS episodes in adult patients in a French SCD center. All patients were treated according to an uniform therapeutic protocol applying transfusion only in the more severe clinical form of ACS.
Results: There were 107 consecutive episodes in 77 adult patients (mean age, 29 +/- 7 years; 78% hemoglobin [Hb] SS; 14% Hb SC; and 8% Hb Sbeta + thalassemia) over a 6-year period. Seventy-eight percent of our patients had an associated vaso-occlusive crisis that preceded the chest signs in half of the cases. Comparison between acute and baseline levels showed a statistically significant difference in Hb levels (drop of 1.6 to 2. 25 g/dL depending on Hb genotype), WBC count (increase of 9.2 +/- 8. 3 x 10(9)/L); platelet count (increase of 67 +/- 209 x 10(9)/L); and lactate dehydrogenase values (increase of 358 +/- 775 IU/L) in ACS patients. Hypercapnia was detected in 42% of patients without sign of narcotic abuse. We identified a high percentage of alveolar macrophages containing fat droplets in 31 of 43 (77%) patients who underwent BAL. Bacterial culture findings were almost always negative, but were performed after starting antibiotic therapy that was administered in 96 episodes. Transfusion was required in 50 of 107 ACS events (47%). Five patients died, and all were transfused.
Conclusions: These results confirm that fat embolism is probably a frequent mechanism of ACS in adult patients. However, fat embolism was not associated with a more severe clinical course, suggesting that bronchoscopy and BAL have little impact on the management of these patients. Restricting transfusion to the most severe ACS cases does not seem to increase the mortality rate.