In vivoquantification of accumulating abdominal fluid using an electrical impedance tomography hemiarray

Abstract

A new method to image and quantify intra-abdominal haemorrhage using electrical impedance tomography (EIT) was tested in vivo. Supine peritoneal dialysis patients were monitored using an 8-electrode hemiarray placed on the anterior abdomen. EIT measurements were recorded using the EPack II data acquisition system before, during, and after the administration of dialysate. The amount of dialysate infused was recorded synchronous with EIT measurements and used as a control. Tomographic images of impedance change were reconstructed using a weighted, sensitivity-based method and then post-processed to obtain a quantitative estimate of the total dialysate volume added and the rate of dialysate administration. Our preliminary study included two subjects, one male and one female, each of whom participated for two sessions spaced about 6 months apart. Data collected from these sessions indicated that with an in vivo SNR of about 35 dB the EPack II can detect accumulations larger than about 100 ml, with a quantification uncertainty of about 50 ml. The rate of accumulation was determined in less than 2 min. This method shows promise for automated detection of other pathologies, eg ascites, and is adaptable to detecting conductive accumulations in other anatomy.

In Vivo Imaging of Twist Drill Drainage for Subdural Hematoma: A Clinical Feasibility Study on Electrical Impedance Tomography for Measuring Intracranial Bleeding in Humans

“…We hence made the sensitivity more uniform using the weighted minimum norm method (WMNM) [32]. In WMNM, columns of the matrix are equalized in terms of its power before pseudo-inversion and recovered by rescaling the pixels.…”

Intravenous administration of normal saline may be misinterpreted as a change of end-expiratory lung volume when using electrical impedance tomography

“…The effect of fluid balance on changes in electrical impedance of human body is well known and widely used in bioelectrical impedance analysis for determination of total body water 10,11 . There are studies that described the effect of fluid accumulation in peritoneum 12,13 , diuresis 14 or intravenous fluid administration 15 upon the changes of thoracic impedance as determined by EIT. However, to the best of our knowledge, there is no study dealing with the direct comparison of lung volume related changes in EIT with those caused by fluid administration.…”

A deep neural network for a hemiarray EIT system

“…Due to blood having a much higher conductivity than many abdominal tissues (about six times [6]), another possible clinical application of EIT is the monitoring of acute intra-abdominal hemorrhages (IAH) [33,34]. IAH is a common consequence of blunt trauma caused by automobile accidents, falls, or detonations and may be undetected from normal clinical signs [14].…”

“…This indicates a need for an approach that does not involve lifting the patient to place the electrode array, such as applying fewer electrodes to only the anterior surface of the abdomen. Using such a 'hemiarray' configuration produces severe artifacts in reconstructed EIT images, with the worst characterization of conductivity properties far away from electrodes [31,34]. However, quantities derived from images, such as the sum of pixel values, were well correlated with the amount of conductive dialysis fluid infused, and the lowest detectable bleeding rate was similar for hemiarrays and circumferential arrays [34].…”