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Ann Thorac Surg 1995;59:558-561
© 1995 The Society of Thoracic Surgeons

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Editorials

Cerebral Blood Flow Values During Cardiopulmonary Bypass: Relatively Absolute or Absolutely Relative?

Anesthesiology and Neurological Surgery, College of Physicians and Surgeons of Columbia University, New York, New York, and Department of Anesthesiology, Duke Heart Center, Duke University Medical Center, Durham, North Carolina

The first 300 words of the full text of this article appear below.

Disney, of course, has the best casting. If he doesn't like an actor, he rips him up. Alfred Hitchcock

All of us strive to portray what we believe to be the closest approximation of ``truth'' in our research efforts. The difficulties of reconciling our knowledge of things as something absolute or some distortion of our perceptions are as old as science itself. Elsewhere in this issue Cook and co-workers [1] report findings regarding cerebral blood flow (CBF) during cardiopulmonary bypass (CPB). In their work they raise the methodologic question of how to measure CBF and go a step further by concluding that one method is superior to another. Their conclusions deserve relatively careful scrutiny.

See also 614.

A paramount consideration in comparing the multiple methods for determinations of cerebral perfusion is to understand that no method perfectly describes actual blood flow moving through the capillary bed in precise quantitate terms. All measurements, especially in the cardiac operating room, are relative approximations with inherent errors and limitations. If we are interested in the effects of physiologic and pharmacologic interventions on CBF, we may use any reproducible method that covaries with other similarly reproducible and comparable methods; the choice of method then is dictated by the nature and particular limitations of the experiment. The necessary and sufficient condition for being an acceptable method is that, under the experimental conditions in question, the various CBF estimates covary together. Figure 3 in Cook and co-workers' article makes this point: CBF values for both Kety-Schmidt (KS) and xenon-133 clearance covary together. Because the absolute values in large numbers of studies for both methods are relatively close [2], whether KS overestimates or ¹³³Xe clearance underestimates ``true'' CBF is a secondary issue, especially if the question is how CBF changes under the variable . . . [Full Text of this Article]

Related Article

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, Jr, Thomas A. Orszulak, Richard C. Daly, and Rex D. Bryce
Ann. Thorac. Surg. 1995 59: 614-620. [Abstract] [Full Text]

This article has been cited by other articles:

				K. Bendjelid, B. Poblete, O. Baenziger, and J.-A. Romand The effects of hypothermic cardiopulmonary bypass on Doppler cerebral blood flow during the first 24 postoperative hours Interactive CardioVascular and Thoracic Surgery, March 1, 2003; 2(1): 46 - 52. [Abstract] [Full Text] [PDF]

				R. S. Bonser, C. H. Wong, D. Harrington, D. Pagano, M. Wilkes, T. Clutton-Brock, and M. Faroqui Failure of retrograde cerebral perfusion to attenuate metabolic changes associated with hypothermic circulatory arrest J. Thorac. Cardiovasc. Surg., May 1, 2002; 123(5): 943 - 950. [Abstract] [Full Text] [PDF]

				G. Grubhofer, A. M. Lassnigg, B. Schneider, M. A. Rajek, T. Pernerstorfer, and M. J. Hiesmayr Jugular Venous Bulb Oxygen Saturation Depends on Blood Pressure During Cardiopulmonary Bypass Ann. Thorac. Surg., March 1, 1998; 65(3): 653 - 657. [Abstract] [Full Text] [PDF]

				G. A. Nuttall, D. J. Cook, U. H. Trivedi, R. L. Patel, M. R. J. Turtle, G. E. Venn, and D. J. Chambers Transcranial Doppler Sonography and Cerebral Blood Flow During Cardiopulmonary Bypass Ann. Thorac. Surg., September 1, 1997; 64(3): 891 - 891. [Full Text]

				I. MacVeigh, D. J. Cook, T. A. Orszulak, R. C. Daly, and D. E. Munnikhuysen Nitrous Oxide Method of Measuring Cerebral Blood Flow During Hypothermic Cardiopulmonary Bypass Ann. Thorac. Surg., March 1, 1997; 63(3): 736 - 740. [Abstract] [Full Text]

				U. H. Trivedi, R. L. Patel, M. R. J. Turtle, G. E. Venn, and D. J. Chambers Relative Changes in Cerebral Blood Flow During Cardiac Operations Using Xenon-133 Clearance Versus Transcranial Doppler Sonography Ann. Thorac. Surg., January 1, 1997; 63(1): 167 - 174. [Abstract] [Full Text]

				D. J. Cook, R. E. Anderson, J. D. Michenfelder, W. C. Oliver Jr, T. A. Orszulak, R. C. Daly, and R. D. Bryce Who's Afraid of Kety-Schmidt? Ann. Thorac. Surg., October 1, 1995; 60 (4): 1156 - 1157. [Full Text]