Development of a morphological accurate simulation model to evaluate cardiogenic pulmonary edema monitoring

Heart failure is a large and growing problem, accompanied by a dramatic increase in the total number of hospitalizations for the treatment of acute decompensation. Ambulatory detection of pulmonary edema in its early stages of development, before the clinically obvious stage of alveolar flooding, has been a long sought-after but elusive goal in a sustained effort to improve the living quality of patients suffering chronic heart failure (CHF). Unfortunately this has not been possible up to now because no suitable methods have been available. The inadequacies of physical and radiologic examination as a means of monitoring the gradual development of pulmonary edema in an ambulatory setting have been well documented. Recent advances in the development of multi-electrode transthoracic impedance tomography may well change this situation, and become the driving force behind future approaches to ambulatory monitoring and therapeutic remediation of gradually developing cardiogenic edema. Based on the phenomenon that air content influences the bioelectrical properties of pulmonary tissue, multi-electrode transthoracic electrical impedance tomography already today shows its potential in guiding ventilation therapy. The technology is completely non-invasive and non-hazardous, and connects to the patient via an array of tiny surface electrodes mounted around the thorax. Transthoracic electrical impedance tomography makes it possible to literally look into the lungs during prolonged monitoring periods. In this way the technology provides a continuous view of the regional distribution and retention of fluids throughout the pulmonary volume. This opens completely new ways for clinicians to accurately follow up gradually developing heart failure decompensation. In earlier publications, general concerns regarding the limited clinical value of transthoracic impedance measurements have been linked to the variation in electrode placement, the high skin-electrode contact impedance, and the wide variability of normal values. Despite these studies, no systematic attempts have been made to quantize these effects in the context of multi-electrode transthoracic impedance tomography. In this paper we report on the development of a realistic morphological simulation model capable of replicating to high accuracy the bioelectrical response of the human thorax to external electrical measurement stimuli. Derived from high-resolution CT scans, such multi-physics model provides an accurate finite element discretization of the thorax volume, while at the same time accounting for the intricate dispersive electrical properties of living tissue. Some first tomographic representations obtained with a proprietary image reconstruction algorithm are summarized.

Jaar van publicatie:2013

Trefwoorden:heart failure, pulmonary edema, ambulatory detection, transthoracic impedance tomography