# Pulmonary Symptoms After Mild COVID-19: A Retrospective Observational Study

## TL;DR

This study examines lung symptoms in people who had mild COVID-19 and found that breathing difficulties were not linked to lung damage but were connected to fatigue.

## Contribution

The study provides new insights into the causes of persistent pulmonary symptoms after mild COVID-19.

## Key findings

- Dyspnea did not correlate with lung function impairment severity or 6-minute walk test distance.
- A strong positive correlation was found between dyspnea and fatigue.
- The data suggest that lung impairments may not be the main cause of breathing difficulties in these patients.

## Abstract

Background

Patients have reported persisting or emerging symptoms weeks or months after the acute phase of a COVID-19 infection, even when the initial infection was mild or asymptomatic. Since data are limited on patients with a history of a mild acute phase, the pulmonary sequelae have been challenging to treat. The purpose of this study was to review diagnostic testing sessions from patients referred to the pulmonary function lab for a diagnosis or symptoms of long COVID following a mild acute phase. The collection and presentation of this data aim to provide insight into the possible cause of persistent pulmonary symptoms in this specific patient population.

Methodology

A retrospective review of patients at a single center who received pulmonary function test (PFT) and 6-minute walk test (6MWT) for long COVID symptoms following a mild acute phase of COVID-19 was conducted. Adult subjects were identified through electronic medical records if they received services between March 1, 2020, and September 2, 2023. The records of 19 patients were included in this review.

Data analysis

A Pearson correlation coefficient was used to analyze the relationship between dyspnea, pulmonary function impairment severity, and fatigue. The relationship between dyspnea and 6-minute walk test distance (6MWTD) was analyzed using the phi correlation coefficient.

Results

Weak correlations were identified between the reported symptoms of dyspnea and the severity of airway impairment, gas exchange, and 6MWTD. There was a strong positive correlation between dyspnea and fatigue. The sample size limits the analysis, but the data substantiate the need for additional research.

Conclusion

The severity of lung function impairments did not appear to correlate with the severity of dyspnea in patients following a mild acute phase of COVID-19. Therefore, pulmonary function impairments did not appear to be the primary cause of dyspnea. However, the symptoms of dyspnea and fatigue may contribute to each other.