Paulsen A W
Department of Anesthesiology, Baylor University Medical Center, Dallas, TX 75246.
Biomed Instrum Technol. 1993 May-Jun;27(3):217-34.
There is no consensus regarding the minimum acceptable frequency response for a system intended for routine monitoring of invasive blood pressure in the operating rooms or intensive care units. Part of the problem stems from the diverse criteria used to validate faithful reproduction of the pressure waveform and waveform parameters. Another part of the problem is related to the site of pressure measurement: some anatomic sites have waveforms that are more difficult to reproduce than others. The most often quoted criteria, around which many clinical blood pressure monitoring systems have been constructed, are based on reproduction of all details of the pressure waveform from the most demanding anatomic sites. However, the routine clinical setting is primarily concerned with obtaining accurate values for systolic and diastolic blood pressures as recorded from peripheral arterial sites. This study was designed to obtain worst-case, in the sense of most difficult to measure, blood pressure waveforms from the femoral artery and the left ventricle using a canine model. The purpose of worst-case analysis was to create pressure waveforms that were at both extremes of frequency content, i.e., a rapidly beating heart with extraordinary contractility and a more slowly beating heart with little contractility. The premise of this type of analysis is that all naturally occurring pressure waveforms within a very broad physiologic range would fall within these extremes; therefore, the ability to measure the extreme waveforms would imply the ability to measure all those in between. Worst-case waveforms chosen from among 360 pressure waveforms were analyzed to determine the minimum frequency content of each waveform that would be required for faithful reproduction of systolic and diastolic pressures and the dP/dt. The criterion for faithful reproduction was chosen to be +/- 5% or 1 mmHg, whichever is greater. Data from the worst-case canine study, with supporting data collected intraoperatively from three patients, demonstrate that systolic and diastolic pressures can be obtained from a peripheral measurement site within 5%, requiring only two harmonics in conjunction with an appropriately low-pass-filtered catheter manometer system. Left ventricular pressure waveforms require five harmonics to reproduce the systolic and diastolic pressures within 5% or 1.0 mmHg, whichever is greater. Determination of the maximum dP/dt within +/- 5% from the worst-case peripheral and left ventricular waveforms required 20 and 22 harmonics, respectively.
对于用于手术室或重症监护病房有创血压常规监测的系统，其可接受的最低频率响应尚无共识。部分问题源于用于验证压力波形及波形参数能否如实再现的多样标准。问题的另一部分与压力测量部位有关：一些解剖部位的波形比其他部位更难再现。许多临床血压监测系统所依据的、最常被引用的标准，是基于能否从要求最苛刻的解剖部位再现压力波形的所有细节。然而，常规临床环境主要关注从外周动脉部位记录的收缩压和舒张压的准确值。本研究旨在使用犬模型获取股动脉和左心室最难测量的最坏情况血压波形。最坏情况分析的目的是创建频率成分处于两个极端的压力波形，即具有非凡收缩力的快速跳动心脏和收缩力很小的缓慢跳动心脏。这类分析的前提是，在非常宽泛的生理范围内所有自然出现的压力波形都将落在这些极端情况之内；因此，测量极端波形的能力意味着能够测量其间的所有波形。从360个压力波形中选取的最坏情况波形经过分析，以确定忠实地再现收缩压、舒张压及dP/dt所需的每个波形的最低频率成分。忠实地再现的标准选定为±5%或1 mmHg，取较大值。来自最坏情况犬类研究的数据，以及术中从三名患者收集的支持数据表明，从外周测量部位可在±5%范围内获得收缩压和舒张压，仅需两个谐波，并结合适当的低通滤波导管压力计系统。左心室压力波形需要五个谐波才能在±5%或1.0 mmHg（取较大值）范围内再现收缩压和舒张压。从最坏情况的外周和左心室波形中确定±5%范围内的最大dP/dt分别需要20个和22个谐波。
