[Pulmonary complications of sickle cell disease in children]

Acute and chronic pulmonary complications are frequent in sickle cell disease (SCD), with different spectrum and characteristics in children and adults. Chronic hypoxia is frequent and plays a role in several respiratory complications in SCD. Furthermore, hypoxia has been associated with a higher risk of cerebral ischemia. Despite differing oxygen affinity between hemoglobin A and S, standard pulse oximetry was shown to be accurate in diagnosing hypoxia in SCD patients. Whereas acute hypoxia management is similar to non-SCD patients, chronic hypoxia treatment is mainly based on a transfusion program rather than long-term oxygen therapy. Acute chest syndrome (ACS) is the foremost reason for admission to the intensive care unit and the leading cause of premature death. Guidelines on its management have recently been published. Asthma appears to be a different comorbidity and may increase the risk of vaso-occlusive crisis, ACS, and early death. Its management is not specific in SCD, but systemic steroids must be used carefully. Pulmonary hypertension (PH) is a major risk factor of death in adult patients. In children, no association between PH and death has been shown. Elevated tricuspid regurgitant velocity was associated with lower performance on the 6-min walk test (6MWT) but its long-term consequences are still unknown. These differences could be due to different pathophysiology mechanisms. Systematic screening is recommended in children. Regarding lung functions, although obstructive syndrome appears to be rare, restrictive pattern prevalence increases with age in SCD patients. Adaptation to physical exercise is altered in SCD children: they have a lower walking distance at the 6MWT than controls and can experience desaturation during effort, but muscular blood flow regulation maintains normal muscular strength. Sleeping disorders are frequent in SCD children, notably Obstructive sleep apnea syndrome (OSAS). Because of the neurological burden of nocturnal hypoxia, OSAS care is primordial and mainly based on adenotonsillectomy, which has been shown to reduce ischemic events. The high morbidity and mortality related to pulmonary impairments in SCD require a careful pulmonary assessment and follow-up. Mainly based on clinical examination, follow-up aims to the diagnosis of SCD-related respiratory complications early in these children.