Importance

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Abstract

Intraarterial blood pressure is measured noninvasively by an electromechanical transducer. The correct hold-down force to be applied to the transducer for obtaining accurate blood pressure measurements is determined by obtaining a set of at least one of the diastolic pressure, systolic pressure, and pulse amplitude versus hold-down pressure values over a range of hold-down pressures between which the underlying artery is unflattened and it is occluded. A polynomial is fitted to at least one of the sets of values, from which polynomial the correct hold-down pressure is determined. The hold-down pressure at the point of minimum slope of graphs of the polynominals fitted to the systolic and diastolic versus hold-down pressure values provides an indication of the correct hold-down pressure. An indication of the correct hold-down pressure using the pulse amplitude measurements is provided by locating the midpoint of a pair of hold-down pressures at which the pulse amplitude is substantially sixty percent of the maximum pulse amplitude on the graph of the polynomial fitted to the pulse amplitude versus hold-down pressure values. An alternative method determines the correct hold-down pressure directly from the pulse-amplitude polynomial coefficients. A measure of the compliance of the underlying artery is obtained from the ratio of the minimum slope of the graph of the polynomial fitted to one of the systolic and diastolic versus hold-down pressure values to the slope of a straight line fitted to a subset of one of the systolic and diastolic versus hold-down pressure values over a range of hold-down pressures below which flattening of the underlying artery occurs.

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First Claim