Cerebral blood flow during cardiac operations

Comparison of Kety-Schmidt and xenon-133 clearance methods

David J. Cook, Robert E. Anderson, John D. Michenfelder, William C. Oliver, Thomas A. Orszulak, Richard C. Daly, Rex D. Bryce

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

This study simultaneously compared the standard Kety-Schmidt and the modified xenon-133 (133Xe) clearance techniques for measuring cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) during cardiac operations. The validity of the CBF method is important because our management of the patient during cardiopulmonary bypass (CPB) is based, in part, on our understanding of the cerebral hemodynamics during CPB. In 20 patients undergoing coronary artery bypass grafting, CBF and CMRO2 were determined by both methods. Measurements were made before onset of CPB and once during CPB. Ten patients underwent CPB with systemic normothermia (37°C) and 10 with systemic hypothermia (27°C). Anesthesia consisted of fentanyl and midazolam. CPB pump flows were kept at 2.2 to 2.4 L · min-1 · m-2 and α-stat pH management was used. Xenon-133 clearance significantly underestimated CBF and CMRO2 relative to the Kety-Schmidt technique before CPB and at both bypass temperatures. Values obtained by 133Xe clearance were approximately 50% of that measured by the Kety-Schmidt method. The modified 133Xe technique as typically used during cardiac operations does not appear to measure CBF accurately; this leads to corresponding errors in CMRO2 calculations. Determination of CMRO2 and cerebral autoregulatory function during cardiac operations appears to be more appropriate if based on the more direct Kety-Schmidt technique. Accordingly, our management of CPB with respect to cerebral perfusion as it has been determined by the modified 133Xe clearance method may require reassessment.

Original languageEnglish (US)
Pages (from-to)614-620
Number of pages7
JournalThe Annals of Thoracic Surgery
Volume59
Issue number3
DOIs
StatePublished - 1995

Fingerprint

Cerebrovascular Circulation
Xenon
Cardiopulmonary Bypass
Midazolam
Fentanyl
Hypothermia
Coronary Artery Bypass
Anesthesia
Perfusion
Hemodynamics
Oxygen

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Pulmonary and Respiratory Medicine
  • Surgery

Cite this

Cook, D. J., Anderson, R. E., Michenfelder, J. D., Oliver, W. C., Orszulak, T. A., Daly, R. C., & Bryce, R. D. (1995). Cerebral blood flow during cardiac operations: Comparison of Kety-Schmidt and xenon-133 clearance methods. The Annals of Thoracic Surgery, 59(3), 614-620. https://doi.org/10.1016/0003-4975(94)00956-2

Cerebral blood flow during cardiac operations : Comparison of Kety-Schmidt and xenon-133 clearance methods. / Cook, David J.; Anderson, Robert E.; Michenfelder, John D.; Oliver, William C.; Orszulak, Thomas A.; Daly, Richard C.; Bryce, Rex D.

In: The Annals of Thoracic Surgery, Vol. 59, No. 3, 1995, p. 614-620.

Research output: Contribution to journalArticle

Cook, DJ, Anderson, RE, Michenfelder, JD, Oliver, WC, Orszulak, TA, Daly, RC & Bryce, RD 1995, 'Cerebral blood flow during cardiac operations: Comparison of Kety-Schmidt and xenon-133 clearance methods', The Annals of Thoracic Surgery, vol. 59, no. 3, pp. 614-620. https://doi.org/10.1016/0003-4975(94)00956-2
Cook, David J. ; Anderson, Robert E. ; Michenfelder, John D. ; Oliver, William C. ; Orszulak, Thomas A. ; Daly, Richard C. ; Bryce, Rex D. / Cerebral blood flow during cardiac operations : Comparison of Kety-Schmidt and xenon-133 clearance methods. In: The Annals of Thoracic Surgery. 1995 ; Vol. 59, No. 3. pp. 614-620.
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