Key result
Head elevation to 30 degrees increases blood pressure and cerebral blood flow velocity variability after stroke.
Why the study?
Larger blood pressure variability post-stroke onset worsens outcomes, but information regarding the relationship between systemic and cerebral haemodynamic and variability parameters is limited.
Does a gradual change in head position to 30° upright affect cerebral blood flow velocity variability and mean arterial blood pressure variability in acute ischaemic stroke patients?
Does a gradual change in head position to 30° upright affect cerebral blood flow velocity variability and mean arterial blood pressure variability in acute ischaemic stroke patients?
This study challenges the standard upright head positioning post-stroke, suggesting that a supine position may better optimize cerebral haemodynamics by minimizing blood pressure variability.
Supports caution with upright positioning in acute stroke; hypothesis-generating for supine preference and needs prospective confirmation.
(1) Background: Larger blood pressure variability (BPv) in the first 3 h post-stroke onset increases pathophysiological effects such as infarct size, and leads to greater risk of disability, comorbidities and mortality at 90 days. However, there is limited information on the relationship between systemic and cerebral haemodynamic and variability parameters. (2) Objectives: This study determined the effect of a gradual change in head position (GHP) on cerebral blood flow velocity variability (CBFVv) and mean arterial blood pressure variability (MABPv), in healthy controls and acute ischaemic stroke (AIS) patients. Methods: CBFVv and MABPv were expressed as standard deviation (SD) and coefficient of variation. A total of 16 healthy controls (mean age 57 ± 16 years) were assessed over two visits, 12 ± 8 days apart, and 15 AIS patients (mean age 69 ± 8.5 years) were assessed over three visits (V1: 13.3 ± 6.9 h, V2: 4.9 ± 3.2 days and V3: 93.9 ± 11.5 days post-stroke). (3) Results: In response to GHP, MABPv does not initially increase, but over time MABPv showed a significant increase in response to GHP in AIS (visits 2 and 3) and controls (visit 2). Additionally, in response to GHP in AIS, CBFVv increased in the affected hemisphere. Lastly, in AIS, a significant correlation between CBFVv and MABPv, assessed by SD, was seen in the unaffected hemisphere, whereas this relationship was not demonstrated in the affected hemisphere. (4) Conclusions: To our knowledge, this is the first study to analyse the relationship between CBFVv and MABPv. Shedding light on the effect of head position on the relationship between cerebral blood flow and blood pressure is important to improve our understanding of the underlying effects of cerebral autoregulation impairment. This early mechanistic study provides evidence supporting supine head positioning in healthy controls and stroke patients, through demonstration of a reduction of MABPv and increase in CBFVv.
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Sands et al. (2020) studied Acute Ischaemic Stroke (n=31). Gradual change in head position (supine to 30° upright) vs. Supine head position was evaluated on Mean arterial blood pressure variability (MABPv) and cerebral blood flow velocity variability (CBFVv). Gradual change in head position from supine to 30 degrees upright significantly increased mean arterial blood pressure variability and cerebral blood flow velocity variability in stroke patients.
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