Optimal designs for studying bioimpedance

Abstract

D-optimal designs for nonlinear fixed and mixed effects models are explored, and the theory is applied to the measurement and analysis of bioelectrical impedance. Bioimpedance is known to vary more at extreme frequencies than others. D-optimal designs that account for this variation, and also possible mis-specification of initial parameter estimates, are considered in an attempt to find designs that will provide good parameter estimates in practice.

Bioimpedance modeling to monitor astrocytic response to chronically implanted electrodes

“…The frequency at which the impedance reactance is maximal, f c , has been cited as being more stable than either the complex or real impedance values alone [16][17][18]. Cole parameters have previously been used to characterize ischemia [19].…”

“…The impedance circular arc locus is fully defined by four independent variables: R o : resistance at zero frequency, R ∞ : resistance at infinite frequency, α: the angle of depression ranging between 0 and 1 and f c : the characteristic frequency, which defines the frequency scale. Because of the advantages of bioimpedance modeling over measurement of a single frequency such as 1 kHz, along with the wide use of the Cole model to relate impedance spectroscopy to tissue structure [9,13,[15][16][17][18][19], we chose to study the usefulness of Cole model parameters for estimating the tissue response to chronic microelectrode arrays. An index derived from the Cole model parameters R o and R ∞ , the Py value, was also investigated.…”

Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry

“…The software fitted the recorded resistance and reactance data to a semicircular plot of resistance vs. reactance, after the Cole model of biological impedance (Thomas et al, 1998) that represents the body as a resistor representing the extracellular water (ECW), in parallel with a resistor representing intracellular water and a capacitor representing the cell membranes. According to this circuit model, the resistance measured at infinite frequency, or other high frequency, (Kyle et al, 2004;McGree et al, 2007), is that of the overall conductive volume, i.e. TBW, while the resistance at zero frequency is that of the ECW (Cornish et al, 1993).…”

Methods of Robust Design of Nonlinear Models with an Application to Pharmacokinetics

“…Waterhouse et al (2004) used the product optimal criterion as a compound criterion to find an optimal design that was efficient simultaneously in model discrimination and parameter estimation, for a set of nonlinear mixed-effects models. McGree et al (2007) applied the product optimal design criterion to locate a design that was efficient for parameter estimation in a study of bioimpedance across a wide range of prior parameter values. They combined the 5th and 95th percentiles of all four parameters in their model to form eight different mixedeffects bioimpedance models.…”