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

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


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.

MeSH terms

  • Adult
  • Aged
  • COVID-19
  • Chi-Square Distribution
  • China / epidemiology
  • Cohort Studies
  • Convalescence
  • Coronavirus Infections / diagnosis*
  • Coronavirus Infections / epidemiology*
  • Exercise Test
  • Female
  • Follow-Up Studies
  • Forced Expiratory Volume
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Muscle Strength
  • Pandemics
  • Patient Discharge
  • Pneumonia, Viral / diagnosis*
  • Pneumonia, Viral / epidemiology*
  • Radiography, Thoracic / methods
  • Respiratory Function Tests
  • Respiratory Muscles / physiopathology*
  • Retrospective Studies
  • Risk Assessment
  • Severe Acute Respiratory Syndrome / diagnosis*
  • Severe Acute Respiratory Syndrome / epidemiology
  • Spirometry / methods
  • Tertiary Care Centers
  • Tomography, X-Ray Computed / methods
  • Vital Capacity / physiology