Cerebral blood flow dynamics and head-of-bed changes in the setting of subarachnoid hemorrhage

David K Kung, Nohra Chalouhi, Pascal M Jabbour, Robert M Starke, Aaron S Dumont, H Richard Winn, Matthew A Howard 3rd, David M Hasan, David K Kung, Nohra Chalouhi, Pascal M Jabbour, Robert M Starke, Aaron S Dumont, H Richard Winn, Matthew A Howard 3rd, David M Hasan

Abstract

Head-of-bed (HOB) elevation is usually restricted in patients with aneurysmal subarachnoid hemorrhage (SAH). The goal of this study is to correlate HOB changes (0° and 90°) with cerebral blood flow using transcranial Doppler (TCD) and thermal diffusion probe in SAH patients. Thirteen patients with SAH were prospectively enrolled in the study. Eight patients underwent placement of a thermal diffusion probe for regional CBF measurement. CBF values were measured with the patients in flat (0°) and upright sitting positions (90°) at days 3, 7, and 10. The average increase in blood flow 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. The middle cerebral artery had the least changes in velocity. The 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. The changes were not statistically significant. None of the patients developed clinical cerebral vasospasm. Changing HOB position in the setting of SAH did not significantly affect cerebral or regional blood flow. These data suggest that early mobilization should be considered given the detrimental effects of prolonged bed rest.

Figures

Figure 1
Figure 1
Postoperative head CT scan demonstrating the position of the thermal diffusion blood flow probe.
Figure 2
Figure 2
A typical tracing of thermal diffusion CBF measurement in response to change in end-tidal CO2.

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