Clinical Bioimpedance

Rapidly assessing intravascular volume

A central thrust of my research has been in developing and validating an impedance plethysmographic technique to assess intravascular volume status (the amount of blood a person has available to work with). To this point, volume status has proven an elusive metric for most currently available techniques, sporting predictive powers between total guessing (AUROC = 0.54) and educated guessing (AUROC = 0.84). The technique I investigated along with researchers from the Department of Emergency Medicine at the University of Michigan proved to correctly assess volume status over 95% of the time over the entire phsyiological range (with many regions of near perfect prediction, AUROC = 1.00).

The technique, referred to internally as dynamic respiratory impedance volume evaluation (DRIVE) used the bioimpedance of the upper limb to predict shifts in blood volume in response to cardiac and respiratory phenomenon. Without going into too much detail (sorry, we are still a little sensitive about IP), we used the respiratory signal to gauge venous return and correlated our results to IVC collapse, a well known predictor of volume status.

Moreover, I have developed (to varying degrees of utility) bioimpedance-based techniques to determine intracranial pressure, mean arterial pressure, stroke volume variation, lung recruitment during mechanical ventilation, vasoconstriction, the extent of edema, and correlating mechanical properties to their passive electrical counterparts.