Time-based pulmonary features from electrical impedance tomography demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease
| Autor: | Alexander Slattery, Katrina O. Tonga, Stephen Milne, David G. Chapman, Cindy Thamrin, Joseph M. Duncan, Gregory G. King, Jacqueline Huvanandana, Chinh Nguyen, Sabine C. Zimmermann |
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| Rok vydání: | 2019 |
| Předmět: |
Adult
Male Physiology Pulmonary disease 030204 cardiovascular system & hematology Time based law.invention Pulmonary Disease Chronic Obstructive Young Adult 03 medical and health sciences 0302 clinical medicine Forced Oscillation Technique law Physiology (medical) Electric Impedance medicine Humans Electrical impedance tomography Aged Aged 80 and over COPD business.industry Middle Aged medicine.disease Respiratory Function Tests 030228 respiratory system Spirometry Temporal resolution Ventilation (architecture) Monitoring ventilation Respiratory Mechanics Pulmonary Ventilation business Biomedical engineering |
| Zdroj: | Journal of Applied Physiology. 127:1441-1452 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/japplphysiol.00304.2019 |
| Popis: | Pulmonary electrical impedance tomography (EIT) is a functional imaging technique that allows real-time monitoring of ventilation distribution. Ventilation heterogeneity (VH) is a characteristic feature of chronic obstructive pulmonary disease (COPD) and has previously been quantified using features derived from tidal variations in the amplitude of the EIT signal. However, VH may be better described by time-based metrics, the measurement of which is made possible by the high temporal resolution of EIT. We aimed 1) to quantify VH using novel time-based EIT metrics and 2) to determine the physiological relevance of these metrics by exploring their relationships with complex lung mechanics measured by the forced oscillation technique (FOT). We performed FOT, spirometry, and tidal-breathing EIT measurements in 11 healthy controls and 9 volunteers with COPD. Through offline signal processing, we derived 3 features from the impedance-time ( Z- t) curve for each image pixel: 1) tE, mean expiratory time; 2) PHASE, mean time difference between pixel and global Z- t curves; and 3) AMP, mean amplitude of Z- t curve tidal variation. Distribution was quantified by the coefficient of variation (CV) and the heterogeneity index (HI). Both CV and HI of the tE and PHASE features were significantly increased in COPD compared with controls, and both related to spirometry and FOT resistance and reactance measurements. In contrast, distribution of the AMP feature showed no relationships with lung mechanics. These novel time-based EIT metrics of VH reflect complex lung mechanics in COPD and have the potential to allow real-time visualization of pulmonary physiology in spontaneously breathing subjects. NEW & NOTEWORTHY Pulmonary electrical impedance tomography (EIT) is a real-time imaging technique capable of monitoring ventilation with exquisite temporal resolution. We report novel, time-based EIT measurements that not only demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease (COPD), but also reflect oscillatory lung mechanics. These EIT measurements are noninvasive, radiation-free, easy to obtain, and provide real-time visualization of the complex pathophysiology of COPD. |
| Databáze: | OpenAIRE |
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