Basic studies in rheoencephalography

A Comparison between Electrical Impedance and Strain Gauge Plethysmography for the Study of Cerebral Blood Flow in the Newborn

“…(15) found that the height of the pulsatile impedance signal varies linearly with respect to CBF. The method has been used to monitor changes in the CBF of individuals passing between different sleep states (1 3), and during the inhalation of increasing C 0 2 concentrations (15). This communication investigates the applicability and validity of this method in sick newborns by comparing the performance of the impedance and strain gauge methods in following the changes in CBF in individual babies while breathing room air, 2% C02 in air, and 100% oxygen.…”

“…Namon et al. (15) found that the height of the pulsatile impedance signal varies linearly with respect to CBF. The method has been used to monitor changes in the CBF of individuals passing between different sleep states (1 3), and during the inhalation of increasing C 0 2 concentrations (15).…”

Comparison of Electrical Impedance and 133Xenon Clearance for the Assessment of Cerebral Blood Flow in the Newborn Infant

“…As blood volume increases in the head after cardiac systole, impedance falls. The cardiac-synchronous component of cerebral impedance is determined predominantly by the instantaneous intracranial blood volume (1). Attempts to correlate cerebral electrical impedance with cerebral blood flow have been made in dogs (1) and in adults (2, 3) with variable results.…”

“…The cardiac-synchronous component of cerebral impedance is determined predominantly by the instantaneous intracranial blood volume (1). Attempts to correlate cerebral electrical impedance with cerebral blood flow have been made in dogs (1) and in adults (2, 3) with variable results. Modeling the thorax or limb as a cylinder allows reasonably accurate estimates of flow to be made (4)(5)(6), but extrapolation of the cylindrical model to the brain is inappropriate because of the complexity of cerebral blood flow.…”

Quantitative Evaluation of Cerebral Blood Flow by Rheoencephalography

“…Recent studies in man showed that the mean rheoencephalogram changes correlate with the cerebral blood flow changes occurring after inhalation of 5 % carbon dioxide and 95 % oxygen and after hyperventilation. 6 Parallelism was established between the relative part of the anacrotic portion of the rheoencephalogram and the cerebral vascular resistance measured by a radioisotope venous dilution technique. '…”