Gas exchange abnormalities in Long COVID are driven by the alteration of the vascular component

Gas exchange abnormalities in Long COVID are driven by the alteration of the vascular component

Authors

Keywords:

COVID-19, gas exchange.DLCO, DLNO, capillary volume, alveolar-capillary membrane

Abstract

Background: There are uncertainties whether the impairment of lung diffusing capacity in COVID-19 is due to an alteration in the diffusive conductance of the alveolar membrane (Dm), or an alteration of the alveolar capillary volume (Vc), or a combination of both. The combined measurement DLNO and DLCO diffusion, owing to NO higher affinity and faster reaction rate with haemoglobin compared to CO, enables the simultaneous and rapid determination of both Vc and Dm. The aim of the present study was to better identify the precise cause of post-COVID-19 diffusion impairment.
Methods: Using the combined NO and CO gas transfer techniques (DLNO and DLCO), it is possible to better understand whether gas exchange abnormalities are due to membrane or alveolar capillary volume components. The present study was aimed at evaluating pulmonary gas exchange one year after severe COVID-19. 
Results: The cohort included 33 survivors to severe COVID-19 (median age 67 years, 70% male) with no pre-existing lung disease, who underwent clinical, lung function and imaging assessments at 12 months due to persistence of respiratory symptoms or radiological impairment. The gas exchange abnormalities were mainly determined by the compromise of the vascular component as demonstrated by vascular pattern of gas exchange impairment (i.e., DLNO/DLCO≥110%, 76% of the sample), and by a reduction of the Vc (73%), while the Dm was reduced only in 9% of the entire sample. We did not find a correlation between the gas exchange impairment and the extent of the chest CT alterations (DLCO p = 0.059 and DLNO p = 0.054), which on average were found to be mild (11% of the parenchyma).
Conclusion: In COVID-19 survivors who are still symptomatic or have minimal CT findings at one year, gas exchange abnormalities are determined by impairment of the vascular component, rather than the diffusive component of the alveolar membrane.

Author Biographies

Gianluca Imeri, ASST Papa Giovanni XXIII , Bergamo, BG, Italy

Medical doctor 

Caterina Conti, ASST Papa Giovanni XXIII , Bergamo, BG, Italy

Medical doctor 

Pietro Bonaffini, ASST Papa Giovanni XXIII , Bergamo, BG, Italy ; Post graduate school of Diagnostic Radiology University Milano Bicocca

Medical doctor 

Sandro Sironi, ASST Papa Giovanni XXIII , Bergamo, BG, Italy ; Post graduate school of Diagnostic Radiology University Milano Bicocca

Professor, Department of Radiology

Luca Novelli, ASST Papa Giovanni XXIII , Bergamo, BG, Italy

Medical doctor 

Federico Raimondi, ASST Papa Giovanni XXIII , Bergamo, BG, Italy

medical doctor 

Greta Chiodini, ASST Papa Giovanni XXIII , Bergamo, BG, Italy

Resident 

Simone Vargiu, ASST Papa Giovanni XXIII , Bergamo, BG, Italy

Resident

Fabiano Di Marco , ASST Papa Giovanni XXIII , Bergamo, BG, Italy

Professor 

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Published

06-03-2024

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Original Research Articles

How to Cite

1.
Imeri G, Conti C, Caroli A, Arrigoni A, Bonaffini P, Sironi S, et al. Gas exchange abnormalities in Long COVID are driven by the alteration of the vascular component. Multidiscip Respir Med [Internet]. 2024 Mar. 6 [cited 2024 Oct. 12];19(1). Available from: https://mrmjournal.org/index.php/mrm/article/view/938