Changes in middle cerebral artery blood velocity in uremic patients after hemodialysis

Strokes are a frequent complication in uremic patients on dialysis. We wanted to evaluate the effect of this treatment on cerebral hemodynamic parameters, particularly those of patients with carotid stenosis, who are at higher risk for atherothrombotic ischemic events.

We used transcranial Doppler ultrasonography to evaluate blood velocity of the middle cerebral artery in 18 uremic patients before and after hemodialysis. Carotid stenosis was evaluated by echo-Doppler investigation. Six patients were also studied before and after recombinant human erythropoietin treatment.

Dialysis treatment decreased mean blood velocity in all patients (p less than 0.001). Eight of 18 patients (44%) with mild (16-50%), moderate (51-80%), or severe (greater than 80%) carotid stenosis had lower velocity than patients with normal carotid arteries (p less than 0.01), and they experienced a further decrease to even lower levels after hemodialysis (p less than 0.05). In patients treated with recombinant human erythropoietin, hematocrit increased from 28 +/- 8% to 37 +/- 5% (p less than 0.001), and blood velocity had a further decrease by 11%. All changes were associated with modifications toward normality of pH, PaCO2, and hematocrit.

Transcranial Doppler ultrasonography represents a useful method for monitoring cerebral circulation of uremic patients, especially of those at possible risk for ischemia.