Neurologic injury is a common complication of cardiac surgery and is associated with significant morbidity, mortality, and resource utilization. The incidence varies widely according to the definition used, patient age, and complexity of surgery. The manifestations of neurologic injury are broad, ranging from subtle neurocognitive dysfunction to frank stroke. An increasing amount of evidence points to cerebral embolization during cardiopulmonary bypass (CPB) as the principal etiologic factor of these neurologic complications. Cerebral emboli may be composed of atherosclerotic debris, calcium, air, fat, platelet thrombi, or CPB tubing. Advancements in perfusion technology, CPB techniques and surgical strategies may lead to a reduction in neurologic injury during cardiac surgery. In the current paper, we discuss the pathophysiology of neurologic injury after cardiac surgery and methods of reducing cerebral embolization. Reducing emboli and neurologic injury during CPB requires a multidisciplinary approach that includes several simple diagnostic and therapeutic strategies. Reducing cerebral emboli should be a major goal for future research in the fields of cardiac anesthesia, surgery and perfusion.
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References
1.
Gibbon JH Jr: The development of the heart-lung machine. Am J Surg135:608-619, 1978.
Wolman RL, Nussmeier NA, Aggarwal A, et al: Cerebral injury after cardiac surgery: Identification of a group at extraordinary risk. Multicenter study of Perioperative Ischemia Research group (McSPI) and the Ischemia Research Foundation (IRF) Investigations. Stroke30:514-522, 1999.
4.
Newman MF, Kirchner JL, Phillips-Bute B, et al: Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery. N Engl J Med344:395-402, 2001.
5.
Roach GW, Kanchuger M, Mora-Mangano C, et al: Adverse cerebral outcomes after coronary bypass surgery. N Engl J Med335:1857-1863, 1996.
6.
Salazar JD, Wityk RJ, Grega MA, et al: Stroke after cardiac surgery: Short and Long-term outcomes. Ann Thorac Surg72:1195-1202, 2001.
7.
Puskas JD, Winston AD, Wright CE, et al: Stroke after coronary artery operation: Incidence, correlates, outcome, and cost. Ann Thorac Surg69:1053-1056, 2000.
8.
Stump DA, Brown WR, Moody DM, et al: Microemboli and neurologic dysfunction after cardiovascular surgery. Semin Cardiothorac Vasc Anesth3:47-54, 1999.
9.
Hammon JW, Stump DA, Butterworth JB, et al: Approaches to reduce neurologic complications during cardiac surgery. Semin Thorac and Cardiov Surg13:184-191, 2001.
10.
Pugsley W, Klinger L, Paschalis C, et al: The impact of microemboli during cardiopulmonary bypass on neuropsychological functioning. Stroke25:1393-1399, 1994.
11.
Barbut D, Yao F-SF, Lo Y-W, et al: Determination of size of aortic emboli and embolic load during coronary artery bypass grafting. Ann Thorac Surg63:1262-1267, 1997.
12.
Barbut D, Lo Y-W, Gold JP, et al: Impact of embolization during coronary artery bypass grafting on outcome and length of stay. Ann Thorac Surg63:998-1002, 1997.
13.
Taylor RL, Borger MA, Weisel RD, et al: Cerebral microemboli during cardiopulmonary bypass: Increased emboli during perfusionist interventions. Ann Thorac Surg68:89-93, 1999.
14.
Borger MA, Peniston CM, Weisel RD, et al: Neuropsychologic impairment after coronary bypass surgery: Effect of gaseous microemboli during perfusionist interventions. J Thorac Cardiovasc Surg121:743-749, 2001.
15.
Moody DM, Brown WF, Challa VR, et al: Brain microemboli associated with cardiopulmonary bypass: A histologic and magnetic resonance imaging study. Ann Thorac Surg59:1304-1307, 1995.
16.
Harris DNF, Oatridge A, Dob D, et al: Cerebral swelling after normothermic cardiopulmonary bypass. Anesthesiology88:340-345, 1998.
17.
Tovar EA, Del Campo C, Borsari A, et al: Postoperative management of cerebral air embolism: Gas physiology for surgeons. Ann Thorac Surg60:1138-1142, 1995.
18.
Dexter F, Hindman BJ: Computer simulation of microscopic cerebral air emboli absorption during cardiac surgery. Undersea Hyperb Med25:43-50, 1998.
19.
Muth CM, Shank ES: Gas embolism. N Eng J Med342:476-482, 2000.
20.
Nussemeier N, Arlund C, Slogoff S: Neuropsychiatric complications after cardiopulmonary bypass: Cerebral protection by a barbiturate. Anesthesiology64:165-170, 1986.
21.
Zaidan JR, Klochany A, Martin W, et al: Effect of thiopental on neurologic outcome following coronary artery bypass grafting. Anesthesiology74:406-411, 1991.
22.
Roach GW, Newman MF, Murkin JM, et al: Ineffectiveness of burst suppression therapy in mitigating perioperative cerebrovascular dysfunction. Multicenter Study of Perioperative Ischemia (McSPI) Research Group. Anesthesiology90:1255-1264, 1999.
23.
Forsman M, Tubylewicz OB, Semb G, et al: Effects of nimodipine on cerebral blood flow and neuropsychological outcome after cardiac surgery. Br J Anaesth65:514-520, 1990.
24.
Legault C, Furberg CD, Wagenknecht LE, et al: Nimodipine neuroprotection in cardiac valve replacement: Report of an early terminated trial. Stroke27:593-598, 1996.
25.
del Zoppo GJ, Schmid-Schonbein GW, Mori E, et al: Polymorphonuclear leukocytes occlude capillaries following middle cerebral artery occlusion and reperfusion in baboons. Stroke22:1276-1283, 1991.
26.
Murkin JM, Maurer J, Niemcryk SJ, et al: Full dose aprotinin administration is associated with a significant decrease in perioperative stroke in patients undergoing elective cardiac surgery. A meta-analysis [abstr]. Ann Thorac Surg73:S374-S374, 2002.
27.
Smith PK, Muhlbaier LH: Aprotinin: Safe and effective only with full-dose regimen. Ann Thorac Surg62:1575-1577, 1996.
28.
Murkin JM: Attenuation of neurologic injury during cardiac surgery. Ann Thorac Surg72:S1838-S1844, 2001.
29.
Fazel S, Maganti M, Borger MA, et al: Replacement of a severely atherosclerotic aorta at the time of coronary artery bypass grafting is associated with a prohibitive risk of stroke (in press).
30.
Borger MA, Taylor RL, Weisel RD, et al: Decreased cerebral emboli during distal aortic arch cannulation: A randomized clinical trial. J Thorac Cardiovasc Surg118:740-745, 1999.
31.
Schmitz C, Weinreich S, White J, et al: Can particulate extraction from the ascending aorta reduce neurologic injury in cardiac surgery?J Thorac Cardiavasc Surg126:1829-1838, 2003.
32.
Horvath KA, Berry G for the ICEM Investigators: The incidence of emboli during cardiac surgery: A histopathologic analysis of 2297 patients. Proceedings of the 84th Annual Meeting of the American Association of Thoracic Surgeons; Toronto, Canada.
33.
Pugsley W, Klinger L, Paschalis C, et al: Microemboli and cerebral impairment during cardiac surgery. J Vasc Surg24:34-43, 1990.
34.
Webb WR, Harrison LH, Helmeke FR, et al: Carbon dioxide field flooding minimizes residual intracardiac air after open heart operations. Ann Thorac Surg64:1489-1491, 1997.
35.
Brooker RF, Brown WR, Moody DM, et al: Cardiotomy suction: A major source of brain lipid emboli during cardiopulmonary bypass. Ann Thorac Surg65:1651-1655, 1998.
36.
Kincaid EH, Jones TJ, Stump DA, et al: Processing scavenged blood with a cell saver reduces cerebral lipid microembolization. Ann Thorac Surg70:1296-1300, 2000.
