Cerebrovascular Reactivity and Cerebral Ischemia During Chronic Hemodialysis

Cerebral hypo-perfusion during hemodialysis (HD) may contribute to cerebral ischemic lesions and atrophy in HD patients. Vascular disease and stiffness can impair cerebrovascular reactivity (CVR) in HD patients, placing them at higher risk for cerebral hypo-perfusion during the hemodynamic stress of HD. We evaluated the relationship between CVR and change in cerebral perfusion during HD.

In a cohort of in-center HD patients, we used hypercapnia to induce a change in cerebral blood flow velocity measured with transcranial Doppler to assess CVR. We used continuous cerebral oximetry during HD to measure a change in cerebral oxygen saturation (ScO₂), calculating overall decline and the largest drop as markers of cerebral perfusion. We used multiple linear regression to assess the relationship between CVR and the ScO₂-associated endpoints.

We measured CVR in 42 HD patients and of those, 41 had the ScO₂ measurements completed. The mean age was 58.5 (11.0) years, and most were male (90.5%, N = 38) with diabetes (59.5%, N = 25) and hypertension (87.5%, N = 36). The average CVR was 2.7 (1.6)%/mmHg. The average overall decline in ScO₂ during HD was 2.2 (2.5)% and the average largest drop in ScO₂ was 5.9 (2.8)%. CVR was negatively associated with both the largest drop in ScO₂ (β = -0.67 95% CI [-1.20, -0.15], p = 0.01) and the overall decline in ScO₂ (β = -0.62 95% CI [-1.09, -0.15], p = 0.01). Vascular disease was a risk factor for lower CVR (β = -1.21, 95% CI [-2.16, -0.26] p = 0.01).

A lower CVR increases the risk for cerebral hypo-perfusion during HD. Impaired CVR may be an important part of the pathophysiology of ischemic brain injury and cognitive impairment in HD patients.