Spirometry testing for evaluating respiratory capacity
The Forced expiratory volume in one second (FEV1), Forced vital capacity (FVC), FEV1/FVC ratio, and peripheral oxygen saturation (SPO2) were measured by spirometry to evaluate the pulmonary function and respiratory capacity. Patients were informed to avoid using medications for 24 h and meals for two hours before the test. The participant was seated and in a resting position half an hour before the test. The spirometry test was performed in the evening (between 4 p.m. and 8 p.m.) by the same expert and in the same place. During the test, the subjects were requested to sit on a chair and put a special nose clip on their nose. After taking a deep breath, a full exhalation was directed into the spirometer tube to record the curve. This procedure was repeated thrice, and the highest values were considered [