Method and apparatus for continuously monitoring systolic blood pressure
First Claim
1. A method for continuously monitoring systolic pressure in a human or animal subject by means of a calibrated instrument including light transducer means for converting variations in light intensity to variations in amplitude of an electrical quantity comprising:
- detecting, with said transducer means, variations in light intensity corresponding to variations in blood volume of the tissue of said subject under said transducer means;
whereby the output of said tranducer means comprises variations in amplitude of said electrical quantity corresponding to said variations in blood volume;
differentiating said variations in amplitude of said electrical quantity with respect to time to provide a differentiated amplitude representative of the rate of said variations in blood volume;
periodically selecting a sample of said differentiated amplitude; and
adding to said sample an amplitude of a like electrical quantity representative of a reference pressure;
to thereby produce an electrical signal whose amplitude is proportional to systolic pressure of said subject; and
providing said electrical signal to a display means to drive said display means whereby the magnitude of said systolic pressure is displayed on said display means.
0 Assignments
0 Petitions
Accused Products
Abstract
The invention relates to a method and apparatus for continuously monitoring systolic blood pressure of a subject. The instrument includes a light transducer for detecting variations in light intensity corresponding to variations in blood volume of tissue of the subject under the transducer and for converting the changes in light intensity to changes in voltage. In one embodiment, a heater is provided to dilate the tissue under the transducer. The voltage signals are differentiated with respect to time, and the differentiated signal is sampled once every heart beat of the subject at the beginning of diastole, or at the maximum value of the differentiated signal sampled during diastole, to produce a sampled voltage signal. To this sampled voltage signal is added a voltage representative of a steady pressure, and the sum is a voltage representative of systolic pressure. The amplitude of the steady pressure is a function of blood pressure in the aorta and large arteries of the subject, stiffness of the aorta and large arteries, and the total peripheral resistance of the subject.
-
Citations
18 Claims
-
1. A method for continuously monitoring systolic pressure in a human or animal subject by means of a calibrated instrument including light transducer means for converting variations in light intensity to variations in amplitude of an electrical quantity comprising:
-
detecting, with said transducer means, variations in light intensity corresponding to variations in blood volume of the tissue of said subject under said transducer means; whereby the output of said tranducer means comprises variations in amplitude of said electrical quantity corresponding to said variations in blood volume; differentiating said variations in amplitude of said electrical quantity with respect to time to provide a differentiated amplitude representative of the rate of said variations in blood volume; periodically selecting a sample of said differentiated amplitude; and adding to said sample an amplitude of a like electrical quantity representative of a reference pressure; to thereby produce an electrical signal whose amplitude is proportional to systolic pressure of said subject; and providing said electrical signal to a display means to drive said display means whereby the magnitude of said systolic pressure is displayed on said display means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A calibrated instrument for continuously monitoring the systolic pressure of a human or animal subject comprising;
-
transducer means for detecting variations in light intensity corresponding to variations in blood volume of the tissue of said subject under said transducer means; means for converting said variations in light intensity to variations in amplitude of an electrical quantity; differentiating means for differentiating said variations in amplitude of said electrical quantity with respect to time to provide a differentiated amplitude representative of the rate of said variations in blood volume; sampling means for periodically selecting a sample of said differentiated amplitude; means for providing an amplitude of a like electrical quantity representative of a reference pressure; adding means to add said sample and said amplitude representative of reference pressure; whereby to produce an electrical signal whose amplitude is proportional to the systolic pressure of said subject; display means for receiving said electrical signal and displaying the magnitude of the systolic pressure. - View Dependent Claims (16, 17, 18)
-
Specification