Pulmonary Exacerbations and Treatment in PCD: A Narrative Review.

Primary ciliary dyskinesia (PCD) is a rare genetic disorder that causes chronic lung disease. Patients with PCD often experience pulmonary exacerbations with worsening symptoms and lung function decline. This review provides an overview of the existing knowledge regarding the PEx in PCD and reveals understudied topics that should be addressed in the future. We describe the different PCD-specific PEx definitions that exist in the literature, and provide data on the frequency of PEx. Few studies targeted the pathophysiology of PEx, with a focus on the most common microorganisms in the airways and on inflammatory markers that are increased in the sputum (total cells, neutrophils, neutrophil elastase, interleukin-8). Several risk factors for PEx have been identified, among them female sex, age, and airway infection with Pseudomonas aeruginosa. Lung clearance index appears to be a good prognostic factor for future PEx. Current treatment and prevention strategies are described. Further research is needed to enhance our knowledge on PEx mechanisms, on appropriate treatment therapies, and on the long-term consequences of this condition.