Spatial Ventilation Inhomogeneity Determined by Electrical Impedance Tomography in Patients With Chronic Obstructive Lung Disease

Abstract

The aim of this study was to examine whether electrical impedance tomography (EIT) could determine the presence of ventilation inhomogeneity in patients with chronic obstructive lung disease (COPD) from measurements carried out not only during conventional forced full expiration maneuvers but also from forced inspiration maneuvers and quiet tidal breathing and whether the inhomogeneity levels were comparable among the phases and higher than in healthy subjects. EIT data were acquired in 52 patients with exacerbated COPD (11 women, 41 men, 68 ± 11 years) and 14 healthy subjects (6 women, 8 men, 38 ± 8 years). Regional lung function parameters of forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), forced inspiratory vital capacity (FIVC), forced inspiratory volume in 1 s (FIV1), and tidal volume (VT) were determined in 912 image pixels. The spatial inhomogeneity of the pixel parameters was characterized by the coefficients of variation (CV) and the global inhomogeneity (GI) index. CV and GI values of pixel FVC, FEV1, FIVC, FIV1, and VT were significantly higher in patients than in healthy subjects (p ≤ 0.0001). The ventilation distribution was affected by the analyzed lung function parameter in patients (CV: p = 0.0024, GI: p = 0.006) but not in healthy subjects. Receiver operating characteristic curves showed that CV and GI discriminated patients from healthy subjects with an area under the curve (AUC) of 0.835 and 0.852 (FVC), 0.845 and 0.867 (FEV1), 0.903 and 0.903 (FIVC), 0.891 and 0.882 (FIV1), and 0.821 and 0.843 (VT), respectively. These findings confirm the ability of EIT to identify increased ventilation inhomogeneity in patients with COPD.

Long-term dyspnea, regional ventilation distribution and peripheral lung function in COVID-19 survivors: a 1 year follow up study

“…The system was composed of a belt, chosen according to the size of the chest-wall and placed around the 4th-5th intercostal space and of a dedicated monitor (PulmoVista ® 500, Dräger Medical, Lübeck, Germany). EIT recording was performed during spirometry, as previously described [19,27].…”

“…The volume expired at FEV1 (∆FEV1 EIT ) was derived by subtracting the FEV1 EIT to FI EIT . For both TV EIT and ∆FEV1 EIT, the coefficient of variation (CV) and the global inhomogeneity index (GI) were calculated as previously described [19,28]. All images were acquired with the patients sitting in a relaxed position (90°).…”

“…In addition, also Electrical impedance tomography (EIT) could be useful in this context. EIT is a non-invasive monitoring technique that can be used to assess the regional inhomogeneity, both during quiet and forced breathing [19]. Static and dynamic volumes may be indeed preserved in PCS patients with dyspnea [20], but their relative distribution may be altered.…”

Pulmonary rehabilitation ameliorates regional lung function in chronic obstructive pulmonary disease: a prospective single-arm clinical trial

“…The full medical assessment of patients with COPD requires the use of medical imaging techniques and a pulmonary function test (PFT). Conventional radiological methods of chest radiography and computed tomography (CT) are preferentially used to visualize the morphological structural changes in the lung tissues, but these examinations are carried out discontinuously and expose patients to radiation (10). Spirometry plays an important role in evaluating the treatment of COPD, but it is derived from the measurement taken at the mouth, so it can only provide the global, average lung function information of patients (11).…”

The evaluation of regional lung function in COPD before and after pulmonary rehabilitation: a prospective clinical study

“…The full medical assessment of patients with COPD requires the use of medical imaging techniques and pulmonary function test. Conventional radiological methods of chest radiography and computed tomography are preferentially used to visualize the morphological structural changes in the lung tissues, but these examinations are carried out discontinuously and exposed to radiation [10]; Spirometry plays an important role in evaluating the treatment of COPD, but it is derived from the measurement carried out at the mouth, so it can only provide the global, average lung function information of patients [11]. Since many lung diseases, including COPD, are characterised by regionally dissimilar evolution of the underlying morphological and pathophysiological lung changes, regional information may be more helpful to accurately describe the characteristics of disease progression, which is not met by conventional detection equipments [12].…”