Mathematical formulas for oscillometric blood pressure estimation revealed that the maximum amplitude algorithm yields a weighted average of systolic and diastolic BP rather than mean BP.
Mathematical formulas were established to explain and evaluate three popular oscillometric blood pressure estimation algorithms, revealing specific sources of inaccuracy.
Oscillometry is the blood pressure (BP) measurement principle of most automatic cuff devices. The oscillogram (which is approximately the blood volume oscillation amplitude-external pressure function) is measured, and BP is then estimated via an empirical algorithm. The objective was to establish formulas to explain three popular empirical algorithms in the literature-the maximum amplitude, derivative, and fixed ratio algorithms. A mathematical model of the oscillogram was developed and analyzed to derive parametric formulas for explaining each algorithm. Exemplary parameter values were obtained by fitting the model to measured oscillograms. The model and formulas were validated by showing that their predictions correspond to measurements. The formula for the maximum amplitude algorithm indicates that it yields a weighted average of systolic and diastolic BP (0.45 and 0.55 weighting) instead of commonly assumed mean BP. The formulas for the derivative algorithm indicate that it can accurately estimate systolic and diastolic BP (40). The established formulas allow for easy and complete interpretation of perhaps the three most popular oscillometric BP estimation algorithms in the literature while providing new insights. The model and formulas may also be of some value toward improving the accuracy of automatic cuff BP measurement devices.
Chandrasekhar et al. (Thu,) conducted a other in Blood pressure measurement (n=21). Mathematical formulas for oscillometric BP estimation vs. Invasive intra-arterial blood pressure was evaluated on Normalized-root-mean-squared-error (NRMSE) of model-predicted vs. measured oscillograms. Mathematical formulas for oscillometric blood pressure estimation revealed that the maximum amplitude algorithm yields a weighted average of systolic and diastolic BP rather than mean BP.