A COMPARISON OF VENTILATORY AND CARDIAC-RELATED CHANGES IN EIT IMAGESOF NORMAL HUMAN LUNGS AND OF LUNGS WITH PULMONARY EMBOLI

EIT images have been recorded from the upper thorax of 10 normal subje cts and from two patients with pulmonary emboli. The Sheffield Mk2 sys tem was used to obtain the EIT images during quiet tidal breathing and the images were then analysed to extract the cardiac and respiratory related components. In the 10 normal subjects the mean measured change in resistivity during tidal breathing was 9% (SD 3%) with no signific ant difference in four lung regions. The mean changes during the cardi ac cycle were different in the four regions, ranging from -0.9% to -2. 6%. The two patients showed very different cardiac related changes fro m those found in the normals in the posterior lung regions. The sign o f the changes was positive, whereas it was negative in the normals. Th e changes in the anterior lung regions were within the range found in our normal group.