Acute exacerbation of systemic autoimmune rheumatic disease-associated interstitial lung disease: integrated pathophysiology and respiratory care

Acute exacerbation of systemic autoimmune rheumatic disease-associated interstitial lung disease (AE-SARD-ILD) is an uncommon but severe cause of acute respiratory failure, frequently requiring intensive care. Although commonly managed according to paradigms derived from acute exacerbation of idiopathic pulmonary fibrosis or acute respiratory distress syndrome, AE-SARD-ILD encompasses heterogeneous pathological processes with distinct respiratory mechanics, pulmonary vascular involvement, reversibility, and treatment response. Management based solely on the underlying rheumatic disease or radiological pattern may therefore be inadequate. This Perspective reviews current evidence on the diagnosis and critical care management of AE-SARD-ILD and proposes an integrated clinical–radiological–mechanical framework for physiology-guided decision-making. Moving beyond conventional disease- and imaging-based fibrotic classifications, the framework identifies four dominant, potentially overlapping physiological phenotypes arising from the interaction between the chronic pulmonary substrate and the superimposed acute insult: fibrotic/UIP-like, inflammatory/ARDS-like, pulmonary hypertension-dominant, and diffuse alveolar haemorrhage-dominant. These phenotypes provide a physiological rationale for selecting, titrating, and escalating non-invasive and invasive respiratory support, controlling excessive respiratory drive, and integrating immunomodulatory, pulmonary vascular, and extracorporeal strategies. Although prospective validation is required, physiological phenotype-based assessment may support individualized respiratory management, dynamic prognostication, and time-limited intensive care trials in AE-SARD-ILD.