Acute Chest Syndrome, an Acute Pulmonary Complication of Patients with Sickle Cell Anemia

Acute chest syndrome is the second most common reason for hospitalization and the leading cause for mortality in adult patients with sickle cell disease. This complication is not only observed in most severe patients, but can appear in previously non symptomatic patients. Three main mechanisms are involved: infection, vascular obstruction (by fat embolism and/ or pulmonary artery thrombus), and alveolar hypoventilation secondary to surgery or to bone infarcts. The most frequent symptoms are fever, dyspnea, and thoracic pain. In half of patients, vaso-occlusive crisis can precede these symptoms. Basal alveolar consolidation is observed on lung imaging. Hemolysis and systemic inflammation are frequent biological findings. Two prognostic markers have been suggested in the litterature: thrombopenia and right ventricular dysfunction. Supportive treatments (oxygenation, rehydration, and analgesia) are usually prescribed with antibiotics. Transfusion and/ or partial blood exchange depending on the haemoglobin level are used in the severe forms. Preventive transfusion should be discussed in specific conditions such as pregnancy and surgical procedure. Preventive incentive spirometry should also be implemented in hospitalized sickle cell patients, especially during vaso-occlusive crisis.