Electrical current can pass through the human body since it consists of conductive biological tissues and fluids. Inhalation increases electrical resistance or impedance of the lung tissue because the increasing air volume further impedes current flow. This increased impedance induces higher voltage inside the body.
When a high-frequency current is injected into the chest through surface electrodes, the induced voltage changes with lung ventilation and cardiac blood flow. Electrical impedance tomography (EIT) utilizes these voltage changes to produce cross-sectional images of lung ventilation and cardiac blood flow.
Unlike the ionizing radiation of X-rays, EIT is safe. The amount of injected currents is below the safety limit specified in the international standard. Whereas other imaging modalities of CT, MRI, and ultrasound produce structural images, EIT produces functional images to monitor lung ventilation and hemodynamics.
BiLab’s EIT platform technology offers