Monitoring of lung volume in dogs with electrical impedance tomography

Ventilated patients suffering from high pulmonary airway resistance may become dynamically hyperventilated if there is insufficient time to expire before the onset of the next inspiration. Electrical impedance tomography (EIT) is potentially a useful technique to evaluate these changes in lung volume due to changes in the ventilatory regime of patients. Experiments on dogs were conducted to verify the ability of EIT to measure the lung volume increase due to application of positive end expiratory pressure. Estimates by EIT were compared to those calculated from the airway pressure. The difference in volume estimates was approximately proportional to the hyperinflation volume. The rms difference was 143 ml for an average volume increase of 482 ml