Evaluation of the pulmonary function test (PFT) in patients affected by severe COVID-19 pneumonia; 6 to 12 weeks after discharge

The most lethal adverse effect of COVID-19 is acute respiratory distress syndrome, which can lead to rapid death. This symptom even causes concern for patients who have recovered and have been discharged. Therefore, it is obligatory to test and monitor variations in their lungs’ function after recovery. In this study we evaluated the pulmonary function of 64 patients with severe COVID-19, 6 weeks to 3 months after discharge. Pulmonary function parameters were measured by spirometry and body box according to the criteria of the American Thoracic Society and under the supervision of an adult pulmonologist. According to the forced expiratory volume (FEV1) /forced vital capacity (FVC) ratio and total lung capacity (TLC) values, it was found that 3.1% of people had obstructive pattern, 40.63% of patients had restrictive pattern and 6.25% of improved individuals showed mixed pattern. Furthermore, the study of diffusion capacity of carbon monoxide (DLCO) index revealed that 13.3%, 25% and 53% of cases had mild, moderate and severe disorders of gas exchange, respectively. In addition, determining the maximum amount of inspiratory muscles (PI max) and expiratory muscles (PE max) disclosed that the rate of these two indicators in 62.5% and 71.88% of the subjects were less than 50%, respectively. In general, the results of the present study suggest that pulmonary function test and follow-up of patients' condition are not only recommended but seems to be essential after recovery due to the large percentage of patients with restricted pattern a few weeks after recovery.