Process and apparatus for measuring blood pressure
First Claim
1. A process for measuring a person'"'"'s blood pressure, comprising the steps of:
- (a) temporarily blocking the flow of blood on an extremity of such person'"'"'s body by the application of astringent pressure;
(b) applying a photosensitive element to an illuminated skin area of said extremity, downstream of the flow-blocking location, with a contact pressure ranging between substantially 50 and 150 g/cm2 ;
(c) continuously measuring an output signal of said photosensitive element, representative of the instantaneous transparency of said skin area, during a period of progressive relaxation of said astringent pressure;
(d) averaging said output signal to obtain a mean-transparency curve plotted against time;
(e) measuring several values of said astringent pressure at instants corresponding to respective points of said mean-transparency curve; and
(f) calculating a predetermined fraction of the sum of said several values as an indication of systolic blood pressure.
1 Assignment
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Accused Products
Abstract
A photoelectric transparency detector juxtaposed under a certain contact pressure with the tip of a finger works into a computer also receiving the values of an astringent pressure simultaneously applied to another part of the finger by an inflatable air cushion of a flow-blocking cuff. The computer calculates a predetermined fraction, specifically one-half, of the sum of several air-pressure values measured during a period of progressive relaxation of the astringent pressure, taken at instants coinciding with certain points of a continuous curve representing changes in the mean transparency of a skin area contacted by the detector, which constitutes a close approximation of systolic blood pressure. Diastolic blood pressure may be measured during a heartbeat immediately following a low point of the mean-transparency curve.
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Citations
10 Claims
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1. A process for measuring a person'"'"'s blood pressure, comprising the steps of:
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(a) temporarily blocking the flow of blood on an extremity of such person'"'"'s body by the application of astringent pressure; (b) applying a photosensitive element to an illuminated skin area of said extremity, downstream of the flow-blocking location, with a contact pressure ranging between substantially 50 and 150 g/cm2 ; (c) continuously measuring an output signal of said photosensitive element, representative of the instantaneous transparency of said skin area, during a period of progressive relaxation of said astringent pressure; (d) averaging said output signal to obtain a mean-transparency curve plotted against time; (e) measuring several values of said astringent pressure at instants corresponding to respective points of said mean-transparency curve; and (f) calculating a predetermined fraction of the sum of said several values as an indication of systolic blood pressure. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for measuring a person'"'"'s blood pressure, comprising:
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a cuff provided with an air-inflatable cushion applicable to an extremity of a person'"'"'s body for exerting an astringent pressure temporarily cutting off the blood flow; a detector including a light source and a photosensor positionable, with a contact pressure ranging between substantially 50 and 150 g/cm2, on a skin area of said extremity downstream of said cuff; operating means connected with said cushion for inflating and controlledly deflating same; transducer means coupled with said operating means for converting measured values of said astringent pressure into first electrical signals representative of blood pressure; circuit means connected to said detector for continuously converting output signals of said photosensor into second electrical signals representative of the mean transparency of said skin area; and computer means connected to said circuit means and to said transducer means for calculating a predetermined fraction of the sum of several values of said first electrical signals, coinciding with predetermined points of a mean-transparency curve derived from said second electrical signals, as an indication of systolic blood pressure. - View Dependent Claims (7, 8, 9, 10)
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Specification