Gas exchange abnormalities in Long COVID are driven by the alteration of the vascular component
Keywords:
COVID-19, gas exchange.DLCO, DLNO, capillary volume, alveolar-capillary membraneAbstract
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.
References
Balbi M, Conti C, Imeri G, Caroli A, Surace A, Corsi A, Mercanzin E, Arrigoni A, Villa G, Di Marco F, Bonaffini PA, Sironi S. Post-discharge chest CT findings and pulmonary function tests in severe COVID-19 patients. Eur J Radiol ; 2021; 138: 109676
Huang C, Huang L, Wang Y, Li X, Ren L, Gu X, Kang L, Guo L, Liu M, Zhou X, Luo J, Huang Z, Tu S, Zhao Y, Chen L, Xu D, Li Y, Li C, Peng L, Li Y, Xie W, Cui D, Shang L, Fan G, Xu J, Wang G, Wang Y, Zhong J, Wang C, Wang J, et al. 6-month consequences of COVID-19 in patients discharged from hospital: a cohort study. The Lancet 2021; 397: 220–232
Zavorsky GS, Hsia CCW, Hughes JMB, Borland CDR, Guénard H, Van Der Lee I, Steenbruggen I, Naeije R, Cao J, Dinh-Xuan AT. Standardisation and application of the single-breath determination of nitric oxide uptake in the lung. European Respiratory Journal; 2017; 49.
Barisione G, Brusasco V. Lung diffusing capacity for nitric oxide and carbon monoxide following mild-to-severe COVID-19. Physiol Rep 2021; 9:
Graham BL, Steenbruggen I, Miller MR, Barjaktarevic IZ, Cooper BG, Hall GL, Hallstrand TS, Kaminsky DA, McCarthy K, McCormack MC, Oropez CE, Rosenfeld M, Stanojevic S, Swanney MP, Thompson BR. Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement. Am J Respir Crit Care Med 2019; 200: e70–e88
Zavorsky GS, Cao J. Reference equations for pulmonary diffusing capacity using segmented regression show similar predictive accuracy as GAMLSS models. BMJ Open Respir Res 2022; 9.
Hughes JMB, van der Lee I. The TL,NO/TL,CO ratio in pulmonary function test interpretation European Respiratory Journal; 2013; 41: 453–461
Carsana L, Sonzogni A, Nasr A, Rossi RS, Pellegrinelli A, Zerbi P, Rech R, Colombo R, Antinori S, Corbellino M, Galli M, Catena E, Tosoni A, Gianatti A, Nebuloni M. Pulmonary post-mortem findings in a series of COVID-19 cases from northern Italy: a two-centre descriptive study. Lancet Infect Dis 2020; 20: 1135–1140
Ravaglia C, Doglioni C, Chilosi M, Piciucchi S, Dubini A, Rossi G, Pedica F, Puglisi S, Donati L, Tomassetti S, Poletti V. Clinical, radiological, and pathological findings in patients with persistent lung disease following SARS-CoV-2 infection. European Respiratory Journal; 2022; 60
Núñez-Fernández M, Ramos-Hernández C, García-Río F, Pérez-González A, Tilve-Gómez A, Rodríguez-Fernández P, Nodar-Germiñas A, Fernández-García A, Ruano-Raviña A, Fernández-Villar A. Evolution and long-term respiratory sequelae after severe COVID-19 pneumonia: nitric oxide diffusion measurement value. Respir Res; 2023; 24; 1-10
Dal Negro RW, Turco P, Povero M. Long-lasting dyspnoea in patients otherwise clinically and radiologically recovered from COVID pneumonia: a probe for checking persisting disorders in capillary lung volume as a cause. Multidiscip Respir Med; 2022
Osiaevi I, Schulze A, Evers G, Harmening K, Vink H, Kümpers P, Mohr M, Rovas A. Persistent capillary rarefication in long COVID syndrome. Angiogenesis; 2023; 26: 53–61
Published
Issue
Section
License
Copyright (c) 2024 The Author(s)
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Mattioli 1885 has chosen to apply the Creative Commons Attribution NonCommercial 4.0 International License (CC BY-NC 4.0) to all manuscripts to be published.
How to Cite
