Comparison of measurement of stump pressure and transcranial measurement of flow velocity in the middle cerebral artery in carotid surgery.

Transcranial Doppler ultrasound measurement of the velocity of blood flow in the middle cerebral artery (MCA) was performed in 24 consecutive patients undergoing carotid endarterectomy. Measurements were performed preoperatively at rest, following common carotid artery compression, and continuously during surgery. In addition, internal carotid artery stump pressures were measured and a subjective assessment of back flow was made. No relationship between MCA flow velocity and stump pressure following carotid clamping was demonstrated. Peak and mean MCA flow velocity was significantly lower in patients with stump pressures < 30 mm Hg (p < 0.03) and those with poor back flow (p < 0.02).