Determinants of cerebral perfusion pressure during carotid endarterectomy.

To define cerebral perfusion pressure during carotid clamping, carotid back and jugular venous pressures were measured in 100 consecutive carotid endarterectomies in 92 patients. The mean +/- 1 SD was 40.5 +/- 16.0 mm Hg for carotid back pressure, 11.8 +/- 4.8 mm Hg for jugular venous pressure, and 28.7 15.4 mm Hg for cerebral perfusion pressure. A number of variables affect jugular venous pressure, including jugular vein compression, patient position, and the anesthetic type. The lower the carotid back pressure, the more likely that back pressure alone is poor determinant of cerebral perfusion pressure and, hence, of the adequacy of collateral cerebral blood flow. To accurately use the carotid back or stump pressure method. The jugular venous pressure must also be measured, and the cerebral perfusion pressure must be calculated. Based on established safe levels of cerebral blood flow, it is probable that patients who undergo a carotid endarterectomy with a cerebral perfusion pressure of less than 18 mm Hg have cerebral ischemia and may require a shunt. Selective shunting, based on the cerebral perfusion pressure, gave a 1% mortality and 2% permanent neurologic deficit in this series.