Time course of changes in cerebral blood flow velocity after tourniquet deflation in patients with diabetes mellitus or previous stroke under sevoflurane anesthesia

We observed an increase in mean middle cerebral artery blood flow velocity (V mca) after tourniquet deflation during orthopedic surgery under sevoflurane anesthesia in patients with diabetes mellitus or previous stroke. Eight controls, seven insulin-treated diabetic patients, and eight previous stroke patients were studied. Arterial blood pressure, heart rate, V mca, arterial blood gases, and plasma lactate levels were measured every minute for 10 min after tourniquet release in all patients. V mca was measured using a transcranial Doppler probe. V mca in all three groups increased after tourniquet deflation, the increase lasting for 4 or 5 min. However, the degree of increase in V mca in the diabetic patients was smaller than that in the other two groups after tourniquet deflation (at 2 min after tourniquet deflation: control 58.5 ± 3.3, previous stroke 58.4 ± 4.6, diabetes 51.7 ± 2.3; P < 0.05 compared with the other two groups). In conclusion, the degree of increase in V mca in diabetic patients is smaller than that in controls and patients with previous stroke.