Background: Patients with acute ischemic stroke (AIS) have impaired vasomotor reactivity, especially in the affected cerebral hemisphere, such that they may depend directly on systemic blood pressure to maintain perfusion to vulnerable ‘at risk' penumbral tissue. As the sitting up position may affect cerebral perfusion by decreasing cerebral blood flow (CBF) in salvageable tissue, positioning AIS patients with their head in a lying flat position could increase CBF through collateral circulation or gravitational force. We wished to quantify the effect of different head positions on mean flow velocity (MFV) by transcranial Doppler ultrasonography (TCD) in AIS patients to assess the potential for benefit (or harm) of head positioning in a clinical trial. Methods: We performed a systematic review and meta-analysis of observational studies with TCD to evaluate differences in cerebral MFV between the lying flat and sitting up head positions in AIS. For each study and each comparison, we obtained the mean value of changes in MFV and its variance. Results: A total of 303 studies were identified, but 298 were excluded for varying reasons; 4 papers met the inclusion criteria and 57 patients were included in the meta-analysis for calculation of the overall mean difference in MFV. We found a significant increase in MFV from a bed angle of 30 to 15° (4.6 cm/s, 95% confidence interval, CI, 2.9-6.2, p < 0.001) and from 30 to 0° (8.3 cm/s, 95% CI 5.3-11.3, p < 0.001) in the affected hemisphere but not on the normal side in AIS patients. Conclusions: In AIS patients, MFV increased significantly in the side affected by the stroke but not in the unaffected side when they were positioned in a lying flat head position at 0 or 15° compared to an upright head position at 30°. The clinical significance of these findings is now undergoing further randomized evaluation in the international multicenter Head Position in Acute Stroke Trial (HeadPoST).

Keywords:
Stroke, Blood flow velocity, Transcranial Doppler ultrasonography, Head position, Meta-analysis
1.
Markus HS: Cerebral perfusion and stroke. J Neurol Neurosurg Psychiatry 2004;75:353-361.
2.
Reinhard M, Rutsch S, Lambeck J, Wihler C, Czosnyka M, Weiller C, et al: Dynamic cerebral autoregulation associates with infarct size and outcome after ischemic stroke. Acta Neurol Scand 2012;125:156-162.
3.
Žvan B, Zaletel M, Pretnar Oblak J, Pogačnik T, Kiauta T: The middle cerebral artery flow velocities during head-up tilt testing in diabetic patients with autonomic nervous system dysfunction. Cerebrovasc Dis 2003;15:270-275.
4.
National Guideline Clearinghouse: Guide to the Care of the Hospitalized Patient with Ischemic Stroke, ed 2. http://guidelines.gov/content.aspx?f=rss&id=13575.
5.
Shinohara Y, Yanagihara T, Abe K, Yoshimine T, Fujinaka T, Chuma T, et al: I. Stroke in general. J Stroke Cerebrovasc Dis 2011;20(suppl 4):S7-S30.
6.
Toyoda K, Steiner T, Epple C, Kern R, Nagayama M, Shinohara Y, et al: Comparison of the European and Japanese guidelines for the acute management of intracerebral hemorrhage. Cerebrovasc Dis 2013;35:419-429.
7.
Adams HP Jr, del Zoppo G, Alberts MJ, Bhatt DL, Brass L, Furlan A, et al: Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council, and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups: the American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists. Stroke 2007;38:1655-1711.
8.
The European Stroke Organisation (ESO) Executive Committee; ESO Writing Committee: Guidelines for management of ischaemic stroke and transient ischaemic attack 2008. Cerebrovasc Dis 2008;25:457-507.
9.
Hill K: Australian Clinical Guidelines for Acute Stroke Management 2007. Int J Stroke 2008;3:120-129.
10.
Diserens K, Michel P, Bogousslavsky J: Early mobilisation after stroke: review of the literature. Cerebrovasc Dis 2006;22:183-190.
11.
Brethour MK, Nyström KV, Broughton S, Kiernan TE, Perez A, Handler D, et al: Controversies in acute stroke treatment. AACN Adv Crit Care 2012;23:158-172, quiz 173-174.
12.
Sjöholm A, Skarin M, Linden T, Bernhardt J: Does evidence really matter? Professionals' opinions on the practice of early mobilization after stroke. J Multidiscip Healthc 2011;4:367-376.
13.
Sundseth A, Thommessen B, Rønning OM: Outcome after mobilization within 24 hours of acute stroke: a randomized controlled trial. Stroke 2012;43:2389-2394.
14.
Gocze I, Strenge F, Zeman F, Creutzenberg M, Graf BM, Schlitt HJ, et al: The effects of the semirecumbent position on hemodynamic status in patients on invasive mechanical ventilation - prospective randomized multivariable analysis. Crit Care 2013;17:R80.
15.
Nagatani K, Nawashiro H, Takeuchi S, Otani N, Wada K, Shima K: Effects of a head-down tilt on cerebral blood flow in mice during bilateral common carotid artery occlusion. Asian J Neurosurg 2012;7:171-173.
16.
Bhalla A, Tallis RC, Pomeroy VM: The effects of positioning after stroke on physiological homeostasis: a review. Age Ageing 2005;34:401-406.
17.
Hunter AJ, Snodgrass SJ, Quain D, Parsons MW, Levi CR: HOBOE (Head-of-Bed Optimization of Elevation) Study: association of higher angle with reduced cerebral blood flow velocity in acute ischemic stroke. Phys Ther 2011;91:1503-1512.
18.
Wojner-Alexander AW, Garami Z, Chernyshev OY, Alexandrov AV: Heads down: flat positioning improves blood flow velocity in acute ischemic stroke. Neurology 2005;64:1354-1357.
19.
Schwarz S, Georgiadis D, Aschoff A, Schwab S: Effects of body position on intracranial pressure and cerebral perfusion in patients with large hemispheric stroke. Stroke 2002;33:497-501.
20.
Wojner AW, El-Mitwalli A, Alexandrov AV: Effect of head positioning on intracranial blood flow velocities in acute ischemic stroke: a pilot study. Crit Care Nurs Q 2002;24:57-66.
21.
Stroup DF, Berlin JA, Morton SC, Olkin I, Williamson GD, Rennie D, et al: Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis of Observational Studies in Epidemiology (MOOSE) group. JAMA 2000;283:2008-2012.
22.
Shuaib A, Butcher K, Mohammad AA, Saqqur M, Liebeskind DS: Collateral blood vessels in acute ischaemic stroke: a potential therapeutic target. Lancet Neurol 2011;10:909-921.
23.
Menon BK, Smith EE, Modi J, Patel SK, Bhatia R, Watson TW, et al: Regional leptomeningeal score on CT angiography predicts clinical and imaging outcomes in patients with acute anterior circulation occlusions. AJNR Am J Neuroradiol 2011;32:1640-1645.
24.
Miyamoto Y, Tamura T, Hiura T, Nakamura T, Higuchi J, Mikami T: The dynamic response of the cardiopulmonary parameters to passive head-up tilt. Jpn J Physiol 1982;32:245-258.
25.
Butler GC, Xing HC, Hughson RL: Cardiovascular response to 4 hours of 6 degrees head-down tilt or of 30 degrees head-up tilt bed rest. Aviat Space Environ Med 1990;61:240-246.
26.
Aries MJ, Elting JW, Keyser JD, Kremer BPH, Vroomen PC: Cerebral autoregulation in stroke: a review of transcranial Doppler studies. Stroke 2010;41:2697-2704.
27.
Reinhard M, Wihler C, Roth M, Harloff A, Niesen WD, Timmer J, et al: Cerebral autoregulation dynamics in acute ischemic stroke after rtPA thrombolysis. Cerebrovasc Dis 2008;26:147-155.
28.
Grap MJ, Munro CL, Hummel RS 3rd, Elswick RK Jr, McKinney JL, Sessler CN: Effect of backrest elevation on the development of ventilator-associated pneumonia. Am J Crit Care 2005;14:325-332, quiz 333.
29.
Diserens K, Moreira T, Hirt L, Faouzi M, Grujic J, Bieler G, et al: Early mobilization out of bed after ischaemic stroke reduces severe complications but not cerebral blood flow: a randomized controlled pilot trial. Clin Rehabil 2012;26:451-459.
30.
Fan JY: Effect of backrest position on intracranial pressure and cerebral perfusion pressure in individuals with brain injury: a systematic review. J Neurosci Nurs 2004;36:278-288.
31.
Bernhardt J, Dewey H, Thrift A, Collier J, Donnan G: A very early rehabilitation trial for stroke (AVERT). Phase II. Safety and feasibility. Stroke 2008;39:390-396.
32.
Brooks AL, Lyerly MJ, Sands KA, Cronin M, James D, Moore R, Shahripour RB, Alexandrov AV, Alexandrov AW: Risk of pneumonia associated with zero-degree head positioning (heads down) in acute ischemic stroke patients treated with intravenous tPA (abstract). European Stroke Conference. 22nd Conference, London, UK, May 28-31, 2013. Cerebrovasc Dis 2013;35(suppl 3):667.
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2014
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