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

Justine Frija-Masson,Dominique Penaud,Laurent Plantier,Catherine Bancal,Martin Flamant,Marie-Pia D’Ortho,Florence Arnoult,Laurence Mangin,Hélène Benzaquen

doi:10.3389/fphys.2021.624062

Abstract

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 (DLCO) 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 DLCO alteration after SARS-CoV-2 infection and discuss the implication of restrictive disorder in DLCO alteration. Last, we discuss the pathophysiology of DLCO alteration and try to disentangle vascular damage and fibrosis.

Highlights

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has affected more than 100 million of people worldwide and more than 60 million have recovered (Jonhs Hopkins University of Medicine, 2018)
In the data we present here, at 3 months, there was a significant difference in TLC (p < 0.0001) and DLCOGLI (p < 0.0001) but not kCO for patients with residual ground glass opacities compared with normal CT at 3 months
The presence of Neutrophils extracellular traps (NETs) has been confirmed in the lungs of patients with severe COVID-19, infiltrating airways, interstitium, and vascular compartment (Radermecker et al, 2020). This ubiquitous presence could result in vascular damage and fibrosis altogether, but all four patients had been under mechanical ventilation and died of respiratory failure, and these findings might not be generalized to all COVID-19 patients

Summary

INTRODUCTION

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has affected more than 100 million of people worldwide and more than 60 million have recovered (Jonhs Hopkins University of Medicine, 2018). Hu et al (2020) reported that COPD increases all-cause mortality in patients with COVID-19, but no functional data during followup were available These studies highlight the fact that more than half of the patients have altered DLCO after SARS-CoV-2 infection and that lower DLCO is related to older age and severe-to-extremely severe radiological pneumonia. This result suggests that alveolar lesions are a key determinant of reduced lung function. Chest CT results were not reported; the presence of fibrosis was not associated with mechanical ventilation These differences could be explained by different inclusion criteria (deceased patients vs lung sample), number of cases in the series, and difference in time from diagnosis to lung specimen. This ubiquitous presence could result in vascular damage and fibrosis altogether, but all four patients had been under mechanical ventilation and died of respiratory failure, and these findings might not be generalized to all COVID-19 patients. Bendib et al (2019) found NETs in bronchoalveolar lavage and blood of patients with ARDS but no significant relationship between bronchoalveolar lavage neutrophil extracellular trap concentrations and ventilator-free days

CONCLUSION AND PERSPECTIVES

Findings

ETHICS STATEMENT