Leslie D. Montgomery

A computer-based bioelectrical impedance spectroscopic system for noninvasive assessment of compartmental fluid redistribution

Bioimpedance methods using fixed frequency stimulation to measure volume changes and hemodynamic parameters in body segments of human subjects under various conditions of body position and orthostatic stress are discussed. An electrical impedance spectroscopic (EIS) system has been developed to allow extension of these studies to include examination of the redistribution of fluids between the intracellular and extracellular compartments of the monitored body segments. Evaluated in studies of the human calf and thigh during 90 min of 6 degrees or 10 degrees head-down bed rest, the system promises to enable tracking of segmental and compartmental fluid redistribution in response to various environmental and physiological stresses with both temporal and anatomic resolution greater than that attainable with other methods.<<ETX>>

Rheoencephalographic and electroencephalographic measures of cognitive workload: analytical procedures

This investigation demonstrates the feasibility of mental workload assessment by rheoencephalographic (REG) and multichannel electroencephalographic (EEG) monitoring. During the performance of this research, unique testing, analytical and display procedures were developed for REG and EEG monitoring that extend the current state of the art and provide valuable tools for the study of cerebral circulatory and neural activity during cognition. REG records are analyzed to provide indices of the right and left hemisphere hemodynamic changes that take place during each test sequence. The EEG data are modeled using regression techniques and mathematically transformed to provide energy-density distributions of the scalp electrostatic field. These procedures permit concurrent REG/EEG cognitive testing not possible with current techniques. The introduction of a system for recording and analysis of cognitive REG/EEG test sequences facilitates the study of learning and memory disorders, dementia and other encephalopathies.

Rheoencephalographic and electroencephalographic analysis of cognitive workload

Changes in brain blood flow and neural activity during mental work are investigated. Multichannel rheoencephalography (REG) and topographical electroencephalography (EEG) were used to measure subject responses to three levels of mathematical processing (MP), as administered by a modified version of the WPAFB criterion task set computer program. REG records were analyzed to provide indices of right and left hemisphere hemodynamic changes during MP. The EEG data were mathematically transformed to provide energy density distribution of the scalp electropotential which reflect the metabolic load required to perform each test sequence. The simultaneous use of these REG and EEG procedures may also be used in the study of a variety of disease states, such as brain injury and neurorehabilitation.<<ETX>>

Bioimpedance monitoring of cellular hydration during hemodialysis therapy

Introduction The aim of this paper is to describe and demonstrate how a new bioimpedance analytical procedure can be used to monitor cellular hydration of End Stage Renal Disease (ESRD) patients during hemodialysis (HD).