Authors
   Adler A. Amyot R. Guardo R. Bates JH. Berthiaume Y.
Institution
   Centre de Recherche Hotel-Dieu de Montreal, Universite de Montreal,
   Quebec, Canada.
Title
   Monitoring changes in lung air and liquid volumes with electrical
   impedance tomography.
Source
   Journal of Applied Physiology. 83(5):1762-7, 1997 Nov.
Abstract
   Electrical impedance tomography (EIT) uses electrical measurements at
   electrodes placed around the thorax to image changes in the conductivity
   distribution within the thorax. This technique is well suited to studying
   pulmonary function because the movement of air, blood, and extravascular
   fluid induces significant conductivity changes within the thorax. We
   conducted three experimental protocols in a total of 19 dogs to assess the
   accuracy with which EIT can quantify changes in the volumes of both gas
   and fluid in the lungs. In the first protocol, lung volume increments from
   50 to 1,000 ml were applied with a large syringe. EIT measured these
   volume changes with an average error of 27 +/- 6 ml. In the second
   protocol, EIT measurements were made at end expiration and end inspiration
   during regular ventilation with tidal volume ranging from 100 to 1,000 ml.
   The average error in the EIT estimates of tidal volume was 90 +/- 43 ml.
   In the third protocol, lung liquid volume was measured by instilling 5%
   albumin solution into a lung lobe in increments ranging from 10 to 100 ml.
   EIT measured these volume changes with an average error of 10 +/- 10 ml
   and was also able to detect into which lobe the fluid had been instilled.
   These results indicate that EIT can noninvasively measure changes in the
   volumes of both gas and fluid in the lungs with clinically useful
   accuracy.