scholarly journals Regional lung response to bronchodilator reversibility testing determined by electrical impedance tomography in chronic obstructive pulmonary disease

2016 ◽  
Vol 311 (1) ◽  
pp. L8-L19 ◽  
Author(s):  
Barbara Vogt ◽  
Zhanqi Zhao ◽  
Peter Zabel ◽  
Norbert Weiler ◽  
Inéz Frerichs
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Tidal Volume ◽  
Pulmonary Disease ◽  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Chronic Obstructive ◽  
Ventilation Distribution ◽  
Prognostic Information ◽  
Impedance Tomography ◽  
Obstructive Pulmonary Disease

Patients with obstructive lung diseases commonly undergo bronchodilator reversibility testing during examination of their pulmonary function by spirometry. A positive response is defined by an increase in forced expiratory volume in 1 s (FEV1). FEV1 is a rather nonspecific criterion not allowing the regional effects of bronchodilator to be assessed. We employed the imaging technique of electrical impedance tomography (EIT) to visualize the spatial and temporal ventilation distribution in 35 patients with chronic obstructive pulmonary disease at baseline and 5, 10, and 20 min after bronchodilator inhalation. EIT scanning was performed during tidal breathing and forced full expiration maneuver in parallel with spirometry. Ventilation distribution was determined by EIT by calculating the image pixel values of FEV1, forced vital capacity (FVC), tidal volume, peak flow, and mean forced expiratory flow between 25 and 75% of FVC. The global inhomogeneity indexes of each measure and histograms of pixel FEV1/FVC values were then determined to assess the bronchodilator effect on spatial ventilation distribution. Temporal ventilation distribution was analyzed from pixel values of times needed to exhale 75 and 90% of pixel FVC. Based on spirometric FEV1, significant bronchodilator response was found in 17 patients. These patients exhibited higher postbronchodilator values of all regional EIT-derived lung function measures in contrast to nonresponders. Ventilation distribution was inhomogeneous in both groups. Significant improvements were noted for spatial distribution of pixel FEV1 and tidal volume and temporal distribution in responders. By providing regional data, EIT might increase the diagnostic and prognostic information derived from reversibility testing.

scholarly journals Time-based pulmonary features from electrical impedance tomography demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease

2019 ◽  
Vol 127 (5) ◽  
pp. 1441-1452 ◽  
Author(s):  
Stephen Milne ◽  
Jacqueline Huvanandana ◽  
Chinh Nguyen ◽  
Joseph M. Duncan ◽  
David G. Chapman ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Real Time ◽  
Pulmonary Disease ◽  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Lung Mechanics ◽  
Chronic Obstructive ◽  
Impedance Tomography ◽  
Obstructive Pulmonary Disease ◽  
Ventilation Heterogeneity

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.

Macromolecular biomarkers of chronic obstructive pulmonary disease in exhaled breath condensate

2020 ◽  
Vol 14 (11) ◽  
pp. 1047-1063
Author(s):  
Somayeh Kazeminasab ◽  
Babak Emamalizadeh ◽  
Abolghasem Jouyban ◽  
Mohammadali M Shoja ◽  
Maryam Khoubnasabjafari
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Exhaled Breath Condensate ◽  
Clinical Analysis ◽  
Chronic Obstructive ◽  
Biological Macromolecules ◽  
Exhaled Breath ◽  
Prognostic Information ◽  
Obstructive Pulmonary Disease ◽  
Breath Condensate

Biomarkers provide important diagnostic and prognostic information on heterogeneous diseases such as chronic obstructive pulmonary disease (COPD). However, finding a suitable specimen for clinical analysis of biomarkers for COPD is challenging. Exhaled breath condensate (EBC) sampling is noninvasive, rapid, cost-effective and easily repeatable. EBC sampling has also provided recent progress in the identification of biological macromolecules, such as lipids, proteins and DNA in EBC samples, which has increased its utility for clinical scientists. In this article, we review applications involving EBC sampling for the analysis of COPD biomarkers and discuss its future potential.

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