Division of Gerontology, Beth Israel Deaconess Medical Center, 110 Francis Street, Boston, MA 02215, USA.
Stroke. 2010 Jan;41(1):61-6. doi: 10.1161/STROKEAHA.109.565556. Epub 2009 Dec 3.
Target blood pressure (BP) values for optimal cerebral perfusion after an ischemic stroke are still debated. We sought to examine the relationship between BP and cerebral blood flow velocities (BFVs) during daily activities.
We studied 43 patients with chronic large vessel ischemic infarctions in the middle cerebral artery territory (aged 64.2+/-8.94 years; at 6.1+/-4.9 years after stroke) and 67 age-matched control subjects. BFVs in middle cerebral arteries were measured during supine baseline, sitting, standing, and tilt. A regression analysis and a dynamic phase analysis were used to quantify the BP-BFV relationship.
The mean arterial pressure was similar between the groups (89+/-15 mm Hg). Baseline BFVs were lower by approximately 30% in the patients with stroke compared with the control subjects (P=0.0001). BFV declined further with postural changes and remained lower in the stroke group during sitting (P=0.003), standing (P=0.003), and tilt (P=0.002) as compared with the control group. Average BFVs on the stroke side were positively correlated with BP during baseline (R=0.54, P=0.0022, the slope 0.46 cm/s/mm Hg) and tilt (R=0.52, P=0.0028, the slope 0.40 cm/s/mm Hg). Regression analysis suggested that BFV may increase approximately 30% to 50% at mean BP >100 mm Hg. Orthostatic hypotension during the first minute of tilt or standing was independently associated with lower BFV on the stroke side (P=0.0008). Baseline BP-BFV phase shift derived from the phase analysis was smaller on the stroke side (P=0.0006).
We found that BFVs are lower in patients with stroke and daily activities such as standing could induce hypoperfusion. BFVs increase with mean arterial pressure >100 mm Hg. Dependency of BFV on arterial pressure may have implications for BP management after stroke. Further prospective investigations are needed to determine the impact of these findings on functional recovery and strategies to improve perfusion pressure during daily activities after ischemic stroke.
缺血性脑卒中后最佳脑灌注的目标血压值仍存在争议。我们旨在研究日常活动中血压（BP）与脑血流速度（BFV）之间的关系。
我们研究了 43 例大脑中动脉区域慢性大血管缺血性梗死患者（年龄 64.2+/-8.94 岁；卒中后 6.1+/-4.9 年）和 67 名年龄匹配的对照受试者。在仰卧位基础状态、坐位、站立位和倾斜位时测量大脑中动脉的 BFV。采用回归分析和动态相位分析来量化 BP-BFV 关系。
两组平均动脉压相似（89+/-15 mm Hg）。与对照组相比，卒中患者的基础 BFV 低约 30%（P=0.0001）。随着体位变化，BFV 进一步下降，且在坐位（P=0.003）、站立位（P=0.003）和倾斜位（P=0.002）时卒中组的 BFV 仍低于对照组。卒中侧平均 BFV 与基础状态时的血压呈正相关（R=0.54，P=0.0022，斜率 0.46 cm/s/mm Hg）和倾斜状态时的血压呈正相关（R=0.52，P=0.0028，斜率 0.40 cm/s/mm Hg）。回归分析表明，平均血压＞100 mm Hg 时，BFV 可能增加约 30%至 50%。倾斜或站立开始后 1 分钟内的直立性低血压与卒中侧较低的 BFV 独立相关（P=0.0008）。来自相位分析的基础 BP-BFV 相位偏移在卒中侧更小（P=0.0006）。
我们发现，卒中患者的 BFV 较低，日常活动如站立可能会导致灌注不足。BFV 随平均动脉压＞100 mm Hg 而增加。BFV 对动脉压的依赖性可能对卒中后血压管理具有重要意义。需要进一步前瞻性研究来确定这些发现对缺血性脑卒中后功能恢复和改善日常活动中灌注压的策略的影响。
