CHEST Guidelines-Mixed-Obstructive-and-Restrictive-Ventilatory-Defe

Mixed-Obstructive-and-Restrictive-Ventilatory-Defe

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Sarcoidosis, traditionally seen as a restrictive lung disease, also presents with airway obstruction in about half of patients with lung involvement. This can lead to a mixed obstructive and restrictive ventilatory defect, a potential new phenotype in sarcoidosis. The obstructive component arises from either bronchovascular involvement associated with granuloma formation or from airway distortion due to fibrotic progression, which can result in persistent obstruction.<br /><br />In a study by Kouranos et al., published in CHEST, a subset of sarcoidosis patients was identified with this mixed ventilatory defect. In their cohort, 10% of patients exhibited both obstructive and restrictive patterns, and those with mixed defects had a high prevalence of fibrotic lung disease, the most severe form (Scadding stage 4). These patients often had similar lung diffusing capacities (DLCO) to those with purely restrictive defects, suggesting significant disease burdens.<br /><br />The study elucidated that mixed ventilatory defects might stem from advanced fibrotic sarcoidosis, which often does not respond well to conventional anti-inflammatory treatments. Fibrosis, when it exceeds 20% visible on high-resolution CT scans, is an established independent risk factor for mortality in sarcoidosis patients. This suggests that in some patients, fibrosis could precede and contribute to airway obstruction.<br /><br />Clinicians are advised to avoid prolonged use of high-dose glucocorticoids in patients without symptom improvement, as new antifibrotic treatments could play a critical role in managing these complex cases. Identifying mixed ventilatory defects and better understanding their pathophysiology and progression remain crucial due to their association with increased mortality, mainly due to concomitant pulmonary hypertension and reduced DLCO.

Keywords

sarcoidosis

restrictive lung disease

airway obstruction

mixed ventilatory defect

fibrotic progression

granuloma formation

pulmonary hypertension

high-resolution CT scans

antifibrotic treatments

Kouranos et al. study