The Application of Electrical Impedance Tomography to Large Animal Internal Medicine

Presentation Description / Summary: Electrical impedance tomography (EIT) is an emerging real-time, radiation-free functional imaging tool. Thoracic EIT involves placement of a belt around the chest of an animal, injection of low amplitude current across the chest, measurement of resulting voltages and thus calculation of impedance in a cross-sectional manner. EIT has been used in human medicine to titrate ventilation settings, particularly in COVID-19 cases. Changes in impedance have been shown to correlate with tidal volume in a range of species and settings. More recently, airflow as calculated by EIT has been shown to be in good agreement with flow calculated by spirometry. EIT has also demonstrated novel physiologic phenomena not previously easily identifiable, such as neck position-dependent ventilation. In internal medicine specifically, there is evidence suggesting EIT can be useful in obstructive airway diseases such as equine asthma, or restrictive lung diseases such as pneumonia. Thoracic EIT can also be used to assess heart rate and cardiac-related changes in ventilation distribution. EIT offers researchers, and in time, internal medicine clinicians, a novel method of assessing lung function in large animals in a non-invasive, repeatable format, with many novel variables. Current limitations of EIT mostly reflect the current need to evaluate many variables offline, and the lack of commercially available systems and belts. However, the flexibility and ability to evaluate a large number of variables, that can be further assessed on a lung-region basis, is a marked advantage over currently available pulmonary function testing technologies.