# Lung Diffusion Capacity in Patients With Bilateral COVID-19 Pneumonia: A Three-Month Follow-Up Study

## TL;DR

This study tracks lung function recovery in patients with severe but non-critical COVID-19 pneumonia over three months.

## Contribution

The study provides new insights into the timeline of lung function recovery in non-critical bilateral COVID-19 pneumonia patients.

## Key findings

- Lung function parameters like FEV1 and DLCO improved significantly three months after infection.
- DLCO/SB remained below normal even after three months.
- Patients showed partial recovery one month post-infection but significant improvement by three months.

## Abstract

Objectives: The aim of this study was to determine the short-term consequences of coronavirus disease 2019 (COVID-19) infection on pulmonary diffusion in patients with severe (but not critical) and moderately severe COVID-19 pneumonia during three months after COVID-19 infection.

Methods: A prospective study included 81 patients with an RT-PCR-test confirmed diagnosis of COVID-19 infection treated in the COVID Department of Lung Diseases of University Clinical Hospital Mostar. Inclusion criteria were ≥18-year-old patients, COVID-19 infection confirmed using real-time RT-PCR, radiologically confirmed bilateral COVID-19 pneumonia, and diffusion capacity of the lungs for carbon monoxide (DLCO) one and three months after COVID-19 infection. The pulmonary function was tested using the MasterScreen Body Jaeger (Jaeger Corporation, Omaha, USA) and MasterScreen PFT Jaeger (Jaeger Corporation, Omaha, USA) according to American Thoracic Society guidelines one and three months after COVID-19 infection.

Results: Forced vital capacity significantly increased three months after COVID-19 infection compared to the first-month control (p<0.0005). Also, a statistically significant increase in the FEV1 value (p<0.0005), FEV1%FVC ratio (p<0.005), DLCO/SB (p<0.0005), DLCO/VA value (p<0.0005), and total lung capacity (TLC) (p<0.0005) was observed in all patients.

Conclusion: Our study showed that recovery of DLCO/VA and spirometry parameters was complete after three months, while DLCO/SB was below normal values even after three months. Therefore, one month after the COVID-19 infection patients had partial recovery of lung function, while a significant recovery of lung function was observed three months after the COVID-19 infection.