Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 640638, 4 pages http://dx.doi.org/10.1155/2013/640638 Clinical Study Cerebral Blood Flow Dynamics and Head-of-Bed Changes in the Setting of Subarachnoid Hemorrhage David K. Kung, 1 Nohra Chalouhi, 2 Pascal M. Jabbour, 2 Robert M. Starke, 3 Aaron S. Dumont, 2 H. Richard Winn, 1 Matthew A. Howard III, 1 and David M. Hasan 1 1 Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, JCP 1616, Iowa City, IA 52242, USA 2 Department of Neurosurgery, omas Jeferson University and Jeferson Hospital for Neuroscience, Philadelphia, PA, USA 3 Department of Neurological Surgery, University of Virginia School of Medicine, Charlottesville, VA, USA Correspondence should be addressed to David M. Hasan; david-hasan@uiowa.edu Received 16 September 2013; Accepted 30 October 2013 Academic Editor: Steven J. Monteith Copyright © 2013 David K. Kung et al. his 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. Head-of-bed (HOB) elevation is usually restricted in patients with aneurysmal subarachnoid hemorrhage (SAH). he goal of this study is to correlate HOB changes (0 ∘ and 90 ∘ ) with cerebral blood low using transcranial Doppler (TCD) and thermal difusion probe in SAH patients. hirteen patients with SAH were prospectively enrolled in the study. Eight patients underwent placement of a thermal difusion probe for regional CBF measurement. CBF values were measured with the patients in lat (0 ∘ ) and upright sitting positions (90 ∘ ) at days 3, 7, and 10. he average increase in blood low velocity when changing HOB from 0 ∘ to 90 ∘ was 7.8% on day 3, 0.1% on day 7, and 13.1% on day 10. he middle cerebral artery had the least changes in velocity. he average regional CBF measurement was 22.7 ± 0.3 mL/100 g/min in the supine position and 23.6 ± 9.1 mg/100 g/min in the sitting position. he changes were not statistically signiicant. None of the patients developed clinical cerebral vasospasm. Changing HOB position in the setting of SAH did not signiicantly afect cerebral or regional blood low. hese data suggest that early mobilization should be considered given the detrimental efects of prolonged bed rest. 1. Introduction Patients who sufer aneurysmal SAH are at risk of secondary injuries including cerebral edema and delayed cerebral vasospasm. Traditionally, as a part of the overall treatment protocol for SAH, patients are kept in prolonged bed rest. he assumption is that bed rest will help maintain adequate blood low to the brain. However, the data supporting this assumption are limited [1]. Blood low to the brain is critical and complex. CBF is inluenced by multiple factors including systemic arterial pressure, distance of the head above the heart, venous and CSF drainage, and vascular tone of cerebral vessels [2]. In a normal individual, as the head is raised, the systemic arterial pressure is maintained by blood pressure relexes. At the same time, the arterial perfusion pressure to the head is reduced by the distance the head is raised above the heart, but the intracranial pressure is also reduced because of the improved venous drainage. Together with an intact autoregulation response of the cerebral vasculature, the net efect is little change in CBF [3–5]. However, in patients with impaired autoregulation or with vasospasm following SAH, a raise in head position may theoretically diminish CBF. Conversely, in the case of signiicant cerebral edema ater SAH, it may be important to raise the head to improve venous drainage and maximize cerebral perfusion pressure. Prolonged bed rest, particularly in the elderly and the critically ill, carries its own morbidity [6]. Extensive research has documented the deleterious efects of prolonged bed rest in multiple organ systems, including cardiovascular, musculoskeletal, cognitive, hematologic, and respiratory [7– 10]. Signiicant physiological deterioration begins on the irst few days of bed rest. hese complications add to the already devastating neurologic injury incurred by SAH. Considering the potential deleterious efects of prolonged bed rest and its dubious beneit in maintaining cerebral blood