Abstract
There has been increasing interest in the diagnosis of breathing problems, including chronic obstructive pulmonary disease (COPD), in recent years. In hospitals, the patient's forced expiratory airflow is measured by spirometry to diagnose COPD and to monitor the effectiveness of treatment. However, the commercially available devices used in hospitals are contact-based systems, which may cause the patient to experience discomfort or pain, thus making it difficult to obtain accurate measurements. We have therefore developed a system employing a fiber grating three-dimensional sensor that displays breathing movements as a rough indicator of the patient's physical condition and a respiration monitor to measure body and breathing activity simultaneously. In the present study, we quantitatively analyzed the phase shift between the chest and abdomen seen in the respiratory movement wave patterns using a cross-correlation function. The results showed that patients with COPD exhibited a larger phase shift than healthy people. A significant difference was observed in the phase shift between healthy people and patients with COPD, and patients with more severe COPD showed a larger difference in the forced expiratory volume in one second percent (FEV1%) relative to healthy people. We conclude that this system is able to detect the characteristic changes in breathing pattern observed in patients with COPD and may prove to be useful as a new screening method for COPD.
