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. 2020 Jun 29;21(1):163.
doi: 10.1186/s12931-020-01429-6.

Impact of coronavirus disease 2019 on pulmonary function in early convalescence phase

Yiying Huang  1   2 , Cuiyan Tan  1 , Jian Wu  1 , Meizhu Chen  1 , Zhenguo Wang  1 , Liyun Luo  3 , Xiaorong Zhou  1 , Xinran Liu  1 , Xiaoling Huang  1 , Shican Yuan  1 , Chaolin Chen  1 , Fen Gao  1 , Jin Huang  1 , Hong Shan  2 , Jing Liu  4   5
Affiliations

Impact of coronavirus disease 2019 on pulmonary function in early convalescence phase

Yiying Huang et al. Respir Res. .

Abstract

Objective: This study investigated the influence of Coronavirus Disease 2019 (COVID-19) on lung function in early convalescence phase.

Methods: A retrospective study of COVID-19 patients at the Fifth Affiliated Hospital of Sun Yat-sen University were conducted, with serial assessments including lung volumes (TLC), spirometry (FVC, FEV1), lung diffusing capacity for carbon monoxide (DLCO),respiratory muscle strength, 6-min walking distance (6MWD) and high resolution CT being collected at 30 days after discharged.

Results: Fifty-seven patients completed the serial assessments. There were 40 non-severe cases and 17 severe cases. Thirty-one patients (54.3%) had abnormal CT findings. Abnormalities were detected in the pulmonary function tests in 43 (75.4%) of the patients. Six (10.5%), 5(8.7%), 25(43.8%) 7(12.3%), and 30 (52.6%) patients had FVC, FEV1, FEV1/FVC ratio, TLC, and DLCO values less than 80% of predicted values, respectively. 28 (49.1%) and 13 (22.8%) patients had PImax and PEmax values less than 80% of the corresponding predicted values. Compared with non-severe cases, severe patients showed higher incidence of DLCO impairment (75.6%vs42.5%, p = 0.019), higher lung total severity score (TSS) and R20, and significantly lower percentage of predicted TLC and 6MWD. No significant correlation between TSS and pulmonary function parameters was found during follow-up visit.

Conclusion: Impaired diffusing-capacity, lower respiratory muscle strength, and lung imaging abnormalities were detected in more than half of the COVID-19 patients in early convalescence phase. Compared with non-severe cases, severe patients had a higher incidence of DLCO impairment and encountered more TLC decrease and 6MWD decline.

Keywords: COVID-19; Early convalescence; Lung function; Respiratory muscle strength.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Enrollment of COVID-19 patients in Early Convalescence
Fig. 2
Fig. 2
HRCT scan of a 44-year-old man in acute stage demonstrated bilateral peripheral ground-glass opacities (GGO). Lung total severity score (TSS)was 7. B. Follow-up CT of the same patient at 30 days after discharge from hospital showed that patchy ground glass opacity had obvious absorption.TSS was 3 .C. Worst CT scan of a severe patient during acute stage showed diffuse GGO, consolidation also could be seen in some area. TSS was 13. D: HRCT scan of the same patient obtained 30 days after discharge showed peripheral fibrosis consists of irregular linear opacities. Concomitant presence of GGO was also visible.TSS is 5
Fig. 3
Fig. 3
Correlation of total severity score on worst CT (from a1 to h1) and follow-up CT (from a2 to h2) with pulmonary function parameters.
See this image and copyright information in PMC

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