Can hypocapnia reduce cerebral embolization during cardiopulmonary bypass?

• Published in: The Annals of thoracic surgery Vol. 72; no. 3; pp. 845 - 849
• Main Authors: Plöchl, Walter, Krenn, Claus G, Cook, David J, Gollob, Eva, Pezawas, Thomas, Schima, Heinz, Ipsiroglu, Osman, Wollenek, Gregor, Grubhofer, Georg
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-09-2001
• Subjects: Carbon Dioxide - blood; Cardiopulmonary Bypass - adverse effects; Cerebrovascular Circulation; Echocardiography, Transesophageal; Female; Humans; Hypocapnia; Intracranial Embolism - blood; Intracranial Embolism - diagnostic imaging; Intracranial Embolism - etiology; Intracranial Embolism - prevention & control; Male; Middle Aged; Monitoring, Intraoperative; Ultrasonography, Doppler, Transcranial
• ISSN: 0003-4975; 1552-6259
• DOI: 10.1016/S0003-4975(01)02826-0

Background. Cerebral embolization is a major cause of central nervous dysfunction after cardiopulmonary bypass. Experimental studies demonstrate that reductions in arterial carbon dioxide tension (PaCO
2) can reduce cerebral embolization during cardiopulmonary bypass. This study examined the effects of brief PaCO
2 manipulations on cerebral embolization in patients undergoing cardiac valve procedures.
Methods. Patients were prospectively randomized to either hypocapnia (PaCO
2 = 30 to 32 mm Hg, n = 30) or normocapnia (PaCO
2 = 40 to 42 mm Hg, n = 31) before aortic cross-clamp removal. With removal of the aortic cross-clamp embolic signals were recorded by transcranial Doppler ultrasonography for the next 15 minutes.
Results. Despite significant differences in PaCO
2, groups did not differ statistically in total cerebral emboli counts. The mean number of embolic events was 107 ± 100 (median, 80) in the hypocapnic group and 135 ± 115 (median, 96) in the normocapnic group, respectively (
p = 0.315).
Conclusions. Due to the high between-patient variability in embolization, reductions in PaCO
2 did not result in a statistically significant decrease in cerebral emboli. In contrast to experimental studies, the beneficial effect of hypocapnia on cerebral embolization could not be demonstrated in humans.