Chen C H, Nevo E, Fetics B, Pak P H, Yin F C, Maughan W L, Kass D A
Department of Internal Medicine, Johns Hopkins University Medical Institutions, Baltimore, Md, USA.
Circulation. 1997 Apr 1;95(7):1827-36. doi: 10.1161/01.cir.95.7.1827.
Central aortic pressures and waveform convey important information about cardiovascular status, but direct measurements are invasive. Peripheral pressures can be measured noninvasively, and although they often differ substantially from central pressures, they may be mathematically transformed to approximate the latter. We tested this approach, examining intersubject and intrasubject variability and the validity of using a single averaged transformation, which would enhance its applicability.
Invasive central aortic pressure by micromanometer and radial pressure by automated tonometry were measured in 20 patients at steady state and during hemodynamic transients (Valsalva maneuver, abdominal compression, nitroglycerin, or vena caval obstruction). For each patient, transfer functions (TFs) between aortic and radial pressures were calculated by parametric model and results averaged to yield individual TFs. A generalized TF was the average of individual functions. TFs varied among patients, with coefficients of variation for peak amplitude and frequency at peak amplitude of 24.9% and 16.9%, respectively. Intrapatient TF variance with altered loading (> 20% variation in peak amplitude) was observed in 28.5% of patients. Despite this, the generalized TF estimated central arterial pressures to < or = 0.2 +/- 3.8 mm Hg error, arterial compliance to 6 +/- 7% accuracy, and augmentation index to within -7% points (30 +/- 45% accuracy). Individual TFs were only marginally superior to the generalized TF for reconstructing central pressures.
Central aortic pressures can be accurately estimated from radial tonometry with the use of a generalized TF. The reconstructed waveform can provide arterial compliance estimates but may underestimate the augmentation index because the latter requires greater fidelity reproduction of the wave contour.
中心主动脉压及其波形传递有关心血管状态的重要信息，但直接测量具有侵入性。外周血压可通过非侵入性方法测量，尽管外周血压通常与中心血压有很大差异，但可通过数学变换来近似中心血压。我们测试了这种方法，研究了个体间和个体内的变异性以及使用单一平均变换的有效性，这将增强其适用性。
在20例患者处于稳态以及血流动力学瞬变（瓦尔萨尔瓦动作、腹部加压、硝酸甘油或腔静脉阻塞）期间，通过微测压法测量有创中心主动脉压，通过自动眼压计测量桡动脉压。对于每位患者，通过参数模型计算主动脉压与桡动脉压之间的传递函数（TFs），并将结果平均以得出个体TFs。广义TFs是个体函数的平均值。TFs在患者之间存在差异，峰值幅度和峰值幅度频率的变异系数分别为24.9%和16.9%。在28.5%的患者中观察到患者内TFs随负荷改变（峰值幅度变化>20%）。尽管如此，广义TFs估计中心动脉压的误差≤0.2±3.8 mmHg，动脉顺应性的准确率为6±7%，增强指数在-7个百分点以内（准确率为30±45%）。在重建中心压力方面，个体TFs仅略优于广义TFs。
使用广义TFs可通过桡动脉眼压计准确估计中心主动脉压。重建的波形可提供动脉顺应性估计值，但可能低估增强指数，因为后者需要更高保真度地再现波形轮廓。
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