A Novel Instrument for Research and Calibration of Noninvasive Blood Pressure Measurement

Abstract

Hypertension and cardiovascular diseases (CVDs) are the major causes of death, hospital admissions, and disability in the middle-aged, and regular blood pressure (BP) measurement is one of the simplest and most effective public health interventions available. Yet we know that noninvasive BP (NIBP) devices, ostensibly calibrated against auscultatory sphygmomanometry according to the Universal Standard, can underestimate systolic BP (SBP) by up to 30 mmHg. There is an urgent need for research to elucidate the etiology of these errors and ways of remediating them. In this article, we present an integrated, low-cost, battery-powered instrument that records the simultaneous acquisition of intra-arterial BP (IABP), cuff pressure (CP), and other physiological signals, providing a direct reference for evaluating the accuracy of noninvasive techniques. This enables calibration of new instruments in accordance with Universal Standard requirements. Embedded signal processing further estimates systolic and diastolic BPs (DBPs) from Korotkoff sounds (KSs) as well as the oscillometric fixed ratio and gradient method. A preliminary study on 30 lightly sedated patients undergoing catheterization procedures has confirmed recently published data that, in a different cohort of patients, using different equipment, the K1 sound underestimates intra-arterial SBP (IA-SBP) by a mean of 12 mmHg and a maximum of almost 30 mmHg. A novel new method of detecting K4/K5 sounds is also introduced, which provides reliable estimates of IA-DBP. The instrument has demonstrated scalability for large collaborative data collection, promoting resources for the analysis, comparison, and validation of systolic BP estimation methods beyond conventional Korotkoff-based calibration.