Monitoring patients with left ventricular failure by electrical impedance tomography

Acute left ventricular failure (LVF) is a common medical emergency but dete ction and monitoring of pulmonary oedema remains problematic. Fluid is an i mportant determinant of tissue impedance. Electrical impedance tomography ( EIT) is a non-invasive technique allowing localisation of impedance changes within tissue. We have investigated the relationship between LVF and the e lectrical impedance of lung tissue. Twenty patients with a clinical diagnos is of acute left ventricular failure were compared with 30 normal subjects. Patients were monitored using serial chest radiographs and electrical impe dance tomography measurements of lung impedance during hospital admission. Radiographs were graded according to the severity of pulmonary oedema by tw o independent radiologists. Lung impedance was significantly (P < 0.0001) l ower than normal in patients with left ventricular failure. Values returned towards the normal range as LVF resolved. There was a similar improvement in the score of the chest radiographs. The electrical impedance of the lung is low in left ventricular failure and increases following treatment. (C) 1999 European Society of Cardiology. All rights reserved.