Shaltis P, Reisner A, Asada H
Dept. of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
Conf Proc IEEE Eng Med Biol Soc. 2005;2005:3970-3. doi: 10.1109/IEMBS.2005.1615331.
It is well known that the photoplethysmogram (PPG) is related to the underlying arterial blood pressure (ABP). However, there is ambiguity regarding the precise relationship of these two circulatory signals: some investigators have described a static relationship, while others have used more complex dynamic characterizations. This paper attempts to reconcile these models, employing results obtained from controlled human subject tests. Our data indicate that there is no simple relationship between the continuous PPG and ABP. However, when several serial beats are aggregated, a static, reproducible relationship is observed. This suggests that, in a stable experimental environment, most of the factors that decouple the ABP and PPG operate over short time scales. When these factors are eliminated through beat averaging, calibrated plethysmography offers a near-continuous estimation of ABP. Our data suggest that this PPG/ABP relationship is not stationary, since it is less consistent over time scales greater than 20 minutes. Variable local ABP was generated by raising and lowering the subjects' hands; this method also offered the means for oscillometric BP measurement without any additional actuator such as a conventional pneumatic cuff.
众所周知，光电容积脉搏波图（PPG）与潜在的动脉血压（ABP）相关。然而，这两种循环信号的确切关系尚不明朗：一些研究者描述了一种静态关系，而另一些研究者则采用了更复杂的动态表征。本文试图通过从人体对照试验中获得的结果来协调这些模型。我们的数据表明，连续的PPG与ABP之间不存在简单关系。然而，当聚合几个连续的搏动时，会观察到一种静态的、可重复的关系。这表明，在稳定的实验环境中，使ABP和PPG解耦的大多数因素在短时间尺度上起作用。当通过搏动平均消除这些因素时，校准体积描记法可提供ABP的近连续估计。我们的数据表明，这种PPG/ABP关系并非固定不变，因为在大于20分钟的时间尺度上它不太一致。通过抬高和降低受试者的手来产生可变的局部ABP；这种方法还提供了示波法测量血压的手段，无需任何额外的驱动装置，如传统的气动袖带。
