[Changes in intracranial impedance during cerebral dehydration].

The intracranial impedance (34 kHz, AC) decreased by 20--40% during i. v. infusion of hypertonic mannitol and urea solutions (1.5 g/kg) and 1 hr later owing to osmotic dehydration of the brain tissue in cats. The specific resistance of the blood also diminished by 20--30% which contributed significantly to increasing of cerebral impedance oscillations. These findings make impedance methods unreliable for evaluation of cerebral circulation during dehydration therapy.