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Anesthesiology Research and Practice
Volume 2012 (2012), Article ID 647258, 6 pages
http://dx.doi.org/10.1155/2012/647258
Research Article

Effect of Head Rotation on Cerebral Blood Velocity in the Prone Position

1Department of Anaesthesia, Sygehus Nord, 4300 Holbæk, Denmark
2Department of Diagnostic Radiology, Bispebjerg University Hospital, 2400 Copenhagen, Denmark
3Department of Anaesthesia, Bispebjerg Hospital Research Unit for Anaesthesia and Intensive Care (B.R.A.IN), Bispebjerg University Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark
4Department of Clinical Biochemistry, Bispebjerg University Hospital, 2400 Copenhagen, Denmark
5Acute Admissions Unit, Department of Internal Medicine, Laboratory for Clinical Cardiovascular Physiology, AMC Center for Heart Failure, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
6School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2RD, UK

Received 30 April 2012; Revised 3 July 2012; Accepted 25 July 2012

Academic Editor: Peter Andrews

Copyright © 2012 Jakob Højlund et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. The prone position is applied to facilitate surgery of the back and to improve oxygenation in the respirator-treated patient. In particular, with positive pressure ventilation the prone position reduces venous return to the heart and in turn cardiac output (CO) with consequences for cerebral blood flow. We tested in healthy subjects the hypothesis that rotating the head in the prone position reduces cerebral blood flow. Methods. Mean arterial blood pressure (MAP), stroke volume (SV), and CO were determined, together with the middle cerebral artery mean blood velocity (MCA 𝑉 m e a n ) and jugular vein diameters bilaterally in 22 healthy subjects in the prone position with the head centered, respectively, rotated sideways, with and without positive pressure breathing (10 cmH2O). Results. The prone position reduced SV (by 5 . 4 ± 1 . 5 %; 𝑃 < 0 . 0 5 ) and CO (by 2 . 3 ± 1 . 9 %), and slightly increased MAP (from 7 8 ± 3 to 8 0 ± 2  mmHg) as well as bilateral jugular vein diameters, leaving MCA 𝑉 m e a n unchanged. Positive pressure breathing in the prone position increased MAP (by 3 . 6 ± 0 . 8  mmHg) but further reduced SV and CO (by 9 . 3 ± 1 . 3 % and 7 . 2 ± 2 . 4 % below baseline) while MCA 𝑉 m e a n was maintained. The head-rotated prone position with positive pressure breathing augmented MAP further ( 8 7 ± 2  mmHg) but not CO, narrowed both jugular vein diameters, and reduced MCA 𝑉 m e a n (by 8 . 6 ± 3 . 2 %). Conclusion. During positive pressure breathing the prone position with sideways rotated head reduces MCA 𝑉 m e a n ~10% in spite of an elevated MAP. Prone positioning with rotated head affects both CBF and cerebrovenous drainage indicating that optimal brain perfusion requires head centering.