Blood Pressure Measurement: Retrospective and Prospective Views

Measurement of the arterial blood pressure (BP) is a time-honored, vital piece of medical information whose accuracy is seldom questioned. This review identifies the unappreciated weakness of the early validation data that compared the cuff to intra-arterial BP's. Unfortunately, the inaccuracy of the auscultatory systolic (SBP) and diastolic (DBP) measurements are necessarily transmitted to the arithmetically calculated mean (MBP) and pulse pressures (PP). The errors in cuff SBP have limited recent efforts to measure central SBP noninvasively because of the need for cuff pressure calibration of the recorded peripheral pulses. Furthermore, cuff DBP's routinely overestimate intra-arterial values adding to the error in the calculation of central PP-a recognized cardiovascular risk predictor.Validation data for the newer automatic oscillometric SBP and DBP measurements are little better. Oscillometric devices, however, offer some improvement in their recognition of the MBP, a measurement made independently of the SBP and DBP. The algorithms used to identify the SBP and DBP by the oscillometric device manufacturers are proprietary and differ from one another. Thus, the accuracy of the commercial devices cannot be compared or standardized. A data base listing those devices that have been "validated" against the inaccurate auscultatory method is available, but many commercial devices are not listed.In addition to the SBP and DBP, there is increasing interest in the information contained within the arterial and aortic pulses. Values such as pulse augmentation and amplification ratios are independent of calibration requirements and add risk assessment information beyond that of the BP itself.