Spirometry is the most commonly used modality for measuring lung function. However, spirometry is a coordination-dependent test and may lead to erroneous results if subjects are unable to fully comply with the instructions. It also lacks the capability for regional assessment of pulmonary functions.

Electrical impedance tomography (EIT) is a potential alternative test to spirometry. EIT has been employed in clinical use to provide qualitative and quantitative measurements of ventilation in patients on mechanical ventilators to prevent lung damage or patient-ventilator desynchronies.

In this study, we aim to utilize EIT lung device to study EIT-derived indicators in pulmonary functional assessment and develop novel biomarkers for detecting and monitoring pulmonary diseases. This is a non-interventional clinical study on patients with chronic lung diseases, to establish the feasibility of using EIT-lung device in detecting lung functional changes. Specifically, we will establish the relationship between EIT-derived functional indicators and spirometry results. Furthermore, we will explore, develop, and establish EIT-derived regional lung functional indicators in healthy and chronic diseased states.

Subjects with underlying lung disease, and age- and gender-matched healthy control subjects will be recruited in this study. They will perform spirometry and EIT examination, as well as an interview with a structured questionnaire.

The results from spirometry and EIT test will be correlated and compared to identify the feasibility and accuracy of EIT lung device. Lung function parameters (e.g. FEV1, FVC, and FEV1/FVC ratio) measured using a spirometer would also be calculated from lung flow-volume curves derived from continuous EIT functional images. Regional lung function assessment will also be explored using EIT, and establish regional EIT features that could assist in screening and evaluating different chronic lung diseases. The EIT-derived indicators will be finally analyzed together with demographics, clinical assessments and patient history to derive fine grained insights and elucidate the effect of demographics and biometrics on EIT lung data. The parameters include, but not limited to, age, chest size, gender, weight, height, BMI, smoking habits and ethnicity. The analysis will improve the stability of the EIT indicators, and ultimately increase their predictive power towards diseased lung regions.

With the availability of the EIT device on lung function assessment, which was validated with spirometry findings, patients who are unable to perform spirometry but need a proper lung function assessment can benefit by having the EIT test. These patients include but not limited to those who need major lung resection and interstitial lung diseases on anti-fibrotic. EIT can also be a more comfortable alternative to spirometry for patients who need lung function assessment.

Inclusion Criteria:

Pulmonary disease subjects Patients of age 18 to 75 suspected or diagnosed with pulmonary diseases scheduled to undergo standard pulmonary function test will be recruited. These patients will undergo an interview (with a structured questionnaire), Pulmonary Functional Test (PFT) and EIT examination.

Healthy control subjects Healthy adults of age 18 to 75 who do not have any known pulmonary diseases will be examined. These healthy individuals will undergo spirometry and EIT examination, as well as an interview with a structured questionnaire to ensure they do not have any clinical features or symptoms.

Exclusion Criteria:

• Subjects with implanted electronic devices, in case EIT might interfere with the devices
• Subjects with spinal diseases
• Subjects with unstable cardiac or respiratory conditions
• Pregnant women
• Patients who are unable to perform spirometry

Pulmonary disease subjects Patients of age 18 to 75 suspected or diagnosed with pulmonary diseases scheduled to undergo standard pulmonary function test will be recruited. These patients will undergo an interview (with a structured questionnaire), Pulmonary Functional Test (PFT) and EIT examination.

Healthy control subjects Healthy adults of age 18 to 75 who do not have any known pulmonary diseases will be examined. These healthy individuals will undergo spirometry and EIT examination, as well as an interview with a structured questionnaire to ensure they do not have any clinical features or symptoms.