699,712,714 716 Pulmonary artery per- foration or rupture is fatal in 50% of patients in whom it occurs. This complication usually can be avoided by 1) withdrawal of the catheter tip into the main pulmonary artery before initiation of CPB; 2) withdrawal of the catheter into the pulmonary artery before balloon inflation, especially if the pressure tracing suggests damping; and 3) avoiding routine measurement of the pulmonary artery wedge pressure, reserving this maneuver as a specific diagnostic event. Perioperative monitoring of cerebral function (primarily with an electroencephalogram) has been used in certain high-risk patients, such as those undergoing neurosurgery or carotid vascular surgery.717 In the setting of cardiac surgery, the potentially deleterious effects of CPB on cerebral hypop- fusion or embolic events (ie, air or aortic calcific debris) have been investigated via transcranial Doppler techniques, with a lesser emphasis on the electroencephalogram (in part because of excessive artifact in this setting).57,718 Although processed electroencephalographic monitors and bifrontal cerebral oxi- metry have been available for more than 2 decades, contro- versy remains about their clinical effectiveness.719,720 Pro- cessed electroencephalographic monitoring is aimed primarily at assessing the risk of conscious recall of intraop- erative events, but it also has been used to gauge the depth of anesthesia, theoretically allowing more precise titration of the anesthetic.721,722 Although a variety of electroencephalo- graphic variables are commonly accepted as markers of cerebral ischemia, the ability of current commercial devices to detect or quantify ischemia is limited.706,707,717,718 Given the intuitive link between reflectance oximetry (ie, for peripheral oxygen or mixed venous oxygen saturation) and clinical interventions (ie, manipulating hemodynamic variables, the fraction of inspired oxygen, etc.)