Alteration of Diffusion Capacity After SARS-CoV-2 Infection: A Pathophysiological Approach

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has affected millions of people worldwide, and pneumonia affects 90% of patients. This raises the possibility of millions of people with altered lung function. Few data exist to date on pulmonary function after SARS-CoV-2 infection, but alteration of diffusion capacity of CO (D(LCO)) is the most frequently described abnormality. First, we present original data on lung function at 3 months after SARS-CoV-2 infection and discuss the effect of using European Coal and Steel Community (ECSC) or Global Lung Function Initiative (GLI) reference equations to diagnose diffusion capacity. Second, we review existing data on D(LCO) alteration after SARS-CoV-2 infection and discuss the implication of restrictive disorder in D(LCO) alteration. Last, we discuss the pathophysiology of D(LCO) alteration and try to disentangle vascular damage and fibrosis.