[The sickle cell anemia lung from childhood to adulthood]

The pulmonary complications remain the prime cause of morbidity and mortality in sickle cell disease. The pathogenetic mechanisms consists both of an alteration of the rheological properties of the blood, the existence of a hypercoagulability state and above all specific interactions between the abnormal sickle cells and the vascular endothelium and a dysregulation of the vascular reactivity in which nitrous oxide intervenes. The acute chest syndrome (ACS) is characterised by chest pain with dyspnoea and recent radiological abnormalities and it is an acute lung complication whose problem is one of aetiology. The infectious pneumonias are rarely documented. On the other hand, alveolar hypoventilation linked to infarcts of the thoracic ribs, thoracoabdominal trauma, subdiaphragmatic pain, the administration of analgesics causing respiratory depression, obesity or sleep disturbance are frequent causes of ACS. Bronchoalveolar lavage has revealed a frequency of fat emboli following infarcts in the long bones. Pulmonary emboli is rarely a cause. Pulmonary thrombosis is a serious complication, the diagnosis is difficult and is seen in a predisposed clinical setting. The treatment of ACS rests on controlled hydration and antibiotic therapy, oxygen therapy and controlled analgesic therapy. The indications for blood transfusion and for exchange transfusion merits a better evaluation. In the long term patients with sickle cell disease present with a failure of normal thoracopulmonary growth with a restrictive ventilatory defect and progressive diminution in the transfer factor of carbon monoxide with age. A history of ACS favours chronic lung disease. Pulmonary arterial hypertension is less frequent.