Papaioannou Theodore G, Lekakis John P, Karatzis Emmanouil N, Papamichael Christos M, Stamatelopoulos Kimon S, Protogerou Athanassios D, Mavrikakis Myron, Stefanadis Christodoulos
Unit of Biomedical Engineering, First Department of Cardiology, Hippokration Hospital, and Vascular Laboratory, Department of Clinical Therapeutics, Alexandra Hospital, Medical School, National University of Athens, Greece.
Int J Cardiol. 2006 Jun 7;110(1):46-52. doi: 10.1016/j.ijcard.2005.07.014. Epub 2005 Oct 17.
Aortic pressure waveforms are calculated non-invasively by applying generalized transfer functions (GTF) to tonometric radial pressure waveforms. Input errors mainly during acquisition and calibration of tonometric pressures are "transferred" to aortic pressure calculation. The present study aimed to quantify the proportion of specific input errors which is "transferred" by the GTFs in a wide range of hemodynamic conditions and for different error combinations in brachial systolic (SBP) and diastolic (DBP) blood pressure measurements.
Aortic pulse wave analysis was performed in 103 subjects (52 normotensive and 51 untreated hypertensive) by the SphygmoCor System. Each pressure waveform was initially calibrated by sphygmomanometrical brachial pressures. Isolated, parallel and reverse errors in brachial SBP/DBP from -10 to +10 mmHg were simulated, by recalibration of the recorded radial pressure waveforms, inducing specific "errors" of GTF-input values. For every recalculated aortic SBP and DBP, the difference from the initial estimated value was considered to represent the "transferred error" to the aortic pressure estimation.
Parallel errors by +/-5 mmHg in both SBP and DBP resulted to an identical change in GTF-derived aortic pressures, as expected. When an overestimation in SBP by 5 mmHg and an underestimation in DBP by -5 mmHg occurred (reverse errors), almost 56% of this error (approximately 2.8 mmHg) was transferred. An isolated error in brachial SBP by +/-5 mmHg was transmitted by 76% ( approximately 3.8 mmHg) to GTF-derived aortic SBP. In subjects with mean blood pressure>117 mmHg or with heart rates<74 bpm, a greater percent of the calibration error was transferred to GTF-derived blood pressures.
Input errors in brachial pressure values result in a quantifiable effect on transfer function output (aortic pressures). The percent of the "error transfer" by the GTFs depends on heart rate and BP levels, which should be taken into account when applying GTFs at populations with different hemodynamic conditions.
通过将广义传递函数（GTF）应用于压力传感器测量的桡动脉压力波形，可无创计算主动脉压力波形。主要在压力传感器压力采集和校准过程中出现的输入误差会“传递”到主动脉压力计算中。本研究旨在量化在广泛的血流动力学条件下以及肱动脉收缩压（SBP）和舒张压（DBP）测量中不同误差组合时，由GTF“传递”的特定输入误差的比例。
采用SphygmoCor系统对103名受试者（52名血压正常者和51名未经治疗的高血压患者）进行主动脉脉搏波分析。每个压力波形最初通过血压计测量的肱动脉压力进行校准。通过重新校准记录的桡动脉压力波形，模拟肱动脉SBP/DBP中从 -10至 +10 mmHg的孤立、平行和反向误差，从而产生GTF输入值的特定“误差”。对于每次重新计算的主动脉SBP和DBP，与初始估计值的差值被视为代表向主动脉压力估计“传递的误差”。
正如预期的那样，SBP和DBP中均出现±5 mmHg的平行误差导致GTF得出的主动脉压力发生相同变化。当SBP高估5 mmHg且DBP低估 -5 mmHg（反向误差）时，该误差的近56%（约2.8 mmHg）被传递。肱动脉SBP中±5 mmHg的孤立误差有76%（约3.8 mmHg）传递至GTF得出的主动脉SBP。在平均血压>117 mmHg或心率<74次/分钟的受试者中，更大比例的校准误差被传递至GTF得出的血压值。
肱动脉压力值的输入误差会对传递函数输出（主动脉压力）产生可量化的影响。GTF“误差传递”的比例取决于心率和血压水平，在对不同血流动力学条件的人群应用GTF时应予以考虑。
