Increased Cerebral Blood Flow in Anemic Patients on Long-Term Hemodialytic Treatment

Abstract

Summary: CBF was measured in 15 patients on chronic hemodialytic treatment. CBF was measured with xenon-133 inhalation using single photon emission tomography. In addition, computerized tomography (CT) and a neurological examination were done prior to hemodialysis. Mean CBF was 66.2 ± 17.3 (SD) ml 100 g^-1 min^-1, which was significantly higher (t-test, p < 0.05) than for an age-matched control group (54.7 ± 10.2 ml 100 g^-1 min^-1). However, the hematocrit for the patients was considerably lower, 0.30 ± 0.07, as compared to 0.43 ± 0.03 in the controls. A significant negative correlation was observed between CBF and the hematocrit (y = -1.79x + 120.7, r = -0.71, p < 0.01). Calculating CBF from this equation in the dialyzed patients using a hematocrit of 0.43 yielded a mean CBF value of 43.7 ml 100 g^-1 min^-1, i.e., 20% below the expected. Two patients showed a focal CBF decrease. CT showed central or cortical atrophy in five patients, and two had small hypo-dense lesions. The neurological examination revealed slight to moderate dementia in seven cases. Although mean CBF was found to be increased by 21% as compared to the control group, an even higher CBF level would have been expected to outweigh the decreased oxygen carrying capacity of the blood. The findings suggest a lowered metabolic demand of the brain tissue, probably due to subtle brain damage.