Olavarría Verónica V, Arima Hisatomi, Anderson Craig S, Brunser Alejandro M, Muñoz-Venturelli Paula, Heritier Stephane, Lavados Pablo M
Vascular Neurology, Neurology Service, Department of Medicine, Clínica Alemana de Santiago, Universidad del Desarrollo, Santiago, Chile.
Cerebrovasc Dis. 2014;37(6):401-8. doi: 10.1159/000362533. Epub 2014 Jun 28.
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.
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.
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.
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).
急性缺血性卒中（AIS）患者存在血管舒缩反应受损，尤其是在受影响的大脑半球，以至于他们可能直接依赖全身血压来维持对易损“有风险”半暗带组织的灌注。由于坐立位可能通过减少可挽救组织中的脑血流量（CBF）来影响脑灌注，将AIS患者头部置于平卧位可通过侧支循环或重力增加CBF。我们希望通过经颅多普勒超声（TCD）量化不同头部位置对AIS患者平均血流速度（MFV）的影响，以评估在临床试验中头部定位的潜在益处（或危害）。
我们对采用TCD的观察性研究进行了系统评价和荟萃分析，以评估AIS患者平卧位和坐立位头部时脑MFV的差异。对于每项研究和每次比较，我们获取了MFV变化的平均值及其方差。
共识别出303项研究，但因各种原因排除了298项；4篇论文符合纳入标准，57例患者纳入荟萃分析以计算MFV的总体平均差异。我们发现，在AIS患者中，患侧半球从床头角度30°变为15°时MFV显著增加（4.6 cm/s，95%置信区间，CI，2.9 - 6.2，p < 0.001），从30°变为0°时也显著增加（8.3 cm/s，95%CI 5.3 - 11.3，p < 0.001），而正常侧无此变化。
在AIS患者中，与30°直立位头部相比，当头部置于0°或15°平卧位时，卒中患侧的MFV显著增加，而未患侧则无变化。这些发现的临床意义目前正在国际多中心急性卒中头部位置试验（HeadPoST）中进行进一步的随机评估。
