key: cord-0922394-0o4a9h09
authors: Li, Xianyong; Wang, Changsong; Kou, Shengjie; Luo, Peiyao; Zhao, Mingyan; Yu, Kaijiang
title: Lung ventilation function characteristics of survivors from severe COVID-19: a prospective study
date: 2020-06-06
journal: Crit Care
DOI: 10.1186/s13054-020-02992-6
sha: f5df0369adf1b518c055505f123a679e891d0379
doc_id: 922394
cord_uid: 0o4a9h09

nan

The SAS v9.1.3 software was used for statistical analysis. The normally distributed quantitative data were described by the mean ± standard deviation (x ± s). A paired t test and Wilcoxon rank-sum test were used for comparison of lung function variable values, and the paired chi-square test (McNemar's test) was used for comparison of lung function type.

We studied 18 patients, including three with a history of smoking and one with a history of tuberculosis. The second test was obtained a mean of 12 days after the first one. The first lung ventilation function tests (the tests near discharge) showed that 8 patients were normal including 2 smokers; 4 patients had restriction ventilation dysfunction including the patient with secondary pulmonary tuberculosis; 2 patients had restriction ventilation dysfunction with small airway dysfunction; 1 patient who also had the smoking history had obstructive ventilation dysfunction; 3 patients had small airway dysfunction. There was no statistical difference in lung function type between the first and the second pulmonary function test (P = 0.99) ( Table 1) .

Compared with the first test, VC/predicted value, FVC/predicted value, and FEV1/predicted value in the second test were significantly higher (P < 0.05), while FEV1/FVC was significantly lower; no significant difference was found in MMEF/predicted value (Table 1) .

This report gives a picture of the lung ventilation function of severe COVID-19 patients. The abnormal rate of lung ventilation function was high near discharge, with restriction ventilation dysfunction and small airway dysfunction accounting for 50% of all patients. The result of autopsy obtained from three patients showed interstitial lung inflammation, alveolar inflammatory cell infiltration, mild fibrous hyperplasia, partial alveolar hyaline membrane formation, and alveolar structure destruction [4] ; it is suggested that these pathological changes may result in the decrease in lung compliance, which may exhibit restriction ventilation dysfunction in a lung function test. With virus particles observed in distal airway mucosal epithelial through electron microscopy [4] , bronchiolitis may exist and result in dysfunction of the small airway. The significant differences of all variable values but MMEF/predicted value suggest that the lung ventilation function is improving except for small airway function, which may require longer-term follow-up. 

Clinical characteristics of coronavirus disease 2019 in China

Chest CT manifestations of new coronavirus disease 2019 (COVID-19): a pictorial review

Clinical course and outcome of 107 patients infected with the novel coronavirus, SARS-CoV-2, discharged from two hospitals in Wuhan

A pathological report of three COVID-19 cases by minimally invasive autopsies

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Not applicable.

Xianyong Li, Changsong Wang, Mingyan Zhao, and Kaijiang Yu conceived and designed the study. Xianyong Li, Shengjie Kou, and Peiyao Luo collected and analyzed the data. Xianyong Li and Changsong Wang wrote the manuscript. Xianyong Li, Changsong Wang, Mingyan Zhao, and Kaijiang Yu reviewed and revised the manuscript. All authors read and approved the final manuscript.

SjK, an experienced respiratory physician, was in charge of performing and interpreting the results of the lung function test in this study. She worked in The First Affiliated Hospital of Harbin Medical University for more than 10 years. All footnotes within the text used a superscript number; no footnotes were used for references/citations. 

The datasets used and analyzed during the current study are available from the corresponding authors on reasonable request.

The study was approved by the Ethics Committee of the First Affiliated Hospital of Harbin Medical University, code number kyk2020003.

Not applicable.

The authors declare that they have no competing interests.

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