Oscillometric central blood pressure and central systolic loading in stroke patients: Short-term reproducibility and effects of posture and fasting state

Background
This study examined the short-term reproducibility of non-invasive estimates of central and peripheral blood pressure and markers of central systolic loading (augmentation index [AIx; a measure of central systolic loading] and AIx75 [AIx standardised to 75 b·min-1 heart rate]) and the effect of posture and fasting state on these variables in patients with acute stroke.
Methods
Twenty-two acute stroke patients (72 ± 10y) had blood pressure measured using the SphygmoCor XCEL in supine and seated postures and whilst fasted and non-fasted.
Results
Acceptable short-term reproducibility (ICC >0.75) was reported for all peripheral and central variables in all conditions (ICC = 0.77–0.90) and for AIx and AIx75 in both fasted postures (ICC = 0.78–0.81). Food consumption significantly lowered all blood pressures (p <0.05; η2p = 0.20–0.55). The seated posture resulted in a significantly greater AIx than supine (p <0.05; η2p = 0.22). Fasting state had significant main effects on AIx and AIx75 (p <0.05; η2p = 0.14–0.22).
Conslusions
Oscillometric estimates of central blood pressure have high short-term reproducibility in different postures and fasting states but markers of systolic load should be assessed whilst fasted. Fasting state has a large effect on central and peripheral blood pressures and on measures of systolic loading. It is important for clinicians to be aware of optimal assessment conditions without this impacting on patient wellbeing.
Trial registration
Clinical trial registry name: NCT02537652.

1. 研究背景
本研究探讨了急性脑卒中患者中心与外周血压无创评估值的短期重复性，以及中心收缩负荷标志物（增强指数[augmentation index，AIx；中心收缩负荷的衡量指标]与标准化至75次·分钟⁻¹心率的AIx75），同时分析体位与禁食状态对上述指标的影响。

2. 研究方法
本研究纳入22例急性脑卒中患者（年龄72±10岁），采用SphygmoCor XCEL设备分别在仰卧位、坐位，以及禁食、非禁食状态下测量其血压相关指标。

3. 研究结果
所有条件下的外周与中心血压变量均表现出良好的短期重复性（组内相关系数intraclass correlation coefficient, ICC >0.75），ICC值范围为0.77~0.90；禁食状态下的AIx与AIx75同样具有良好重复性，ICC值范围为0.78~0.81。进食可显著降低所有血压指标（p<0.05；偏η方η2p=0.20~0.55）。坐位状态下的AIx显著高于仰卧位（p<0.05；η2p=0.22）。禁食状态对AIx与AIx75均存在显著主效应（p<0.05；η2p=0.14~0.22）。

4. 研究结论
示波法中心血压评估值在不同体位与禁食状态下均具有较高的短期重复性，但收缩负荷标志物应在禁食状态下进行测量。禁食状态对中心与外周血压及收缩负荷指标均存在较大影响。临床医师需明确最佳的评估条件，同时避免该评估流程对患者健康造成不良影响。

5. 试验注册
临床试验登记号：NCT02537652。