System for obtaining hemodynamic information
First Claim
1. A method for determining the cardiac activity of a subject, comprising the steps of:
- (a) sensing a blood-pressure pulse wave produced by the subject, which varies in magnitude with time;
(b) selecting a plurality of characteristic points on said wave;
(c) measuring time intervals from said initial point of said pulse wave to said characteristic points and measuring corresponding ordinates of said pulse wave at said characteristic points;
(d) obtaining a value corresponding to said cardiac activity from a function that relates the cardiac activity to at least one anatomical parameter of said subject, the ordinates of said blood-pressure pulse wave, and the time intervals of said biological object.
1 Assignment
0 Petitions
Accused Products
Abstract
A system (method and apparatus) for hemodynamic measurements of the cardiac activity, including the stroke volume and cardiac output on the basis of a blood pressure pulse wave of a patient. Using a function that relates cardiac activity to an anthropometric parameter of the patient (height or arm span), ordinates of the pulse wave, and time intervals of certain characteristic points of the pulse wave, the stroke volume and/or cardiac output are obtained. The pulse wave can be determined by means of an optical sensor clipped to an ear lobe of the patient. The characteristic points and time intervals from the initial point of the pulse wave to the characteristic points are obtained under computer control. The measured values of the time intervals and ordinates are inputted to the computer which computes cardiac output, stroke volume and other cardiac information related thereto.
-
Citations
20 Claims
-
1. A method for determining the cardiac activity of a subject, comprising the steps of:
-
(a) sensing a blood-pressure pulse wave produced by the subject, which varies in magnitude with time; (b) selecting a plurality of characteristic points on said wave; (c) measuring time intervals from said initial point of said pulse wave to said characteristic points and measuring corresponding ordinates of said pulse wave at said characteristic points; (d) obtaining a value corresponding to said cardiac activity from a function that relates the cardiac activity to at least one anatomical parameter of said subject, the ordinates of said blood-pressure pulse wave, and the time intervals of said biological object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method for determining the stroke volume, cardiac output or both stroke volume and cardiac output of a patient on the basis of a blood-pressure pulse waves of said patient, produced on each heart stroke comprising the steps of:
-
(a) providing a function presenting a mathematical model of the patient'"'"'s cardiovascular system that relates cardiac output and at least one anthropometric parameter of said patient, ordinates of said blood-pressure pulse wave, and time intervals of said blood-pressure pulse wave of said patient at a plurality of characteristic points, said characteristic points being the following;
point A of the beginning of the wave;
point B of the maximum of the first derivative of said pulse wave;
point C which is the point the amplitude of which is the maximum ordinate of said pulse wave;
point D the point where said first derivative is of the minimal value, and point E which is the end of said pulse wave and the beginning of the next pulse wave, said function being represented by the following equation;
space="preserve" listing-type="equation">CO=f.sub.1 (H)·
f.sub.2 (t.sub.E, t.sub.D, R.sub.B, R.sub.C, R.sub.D)-f.sub.3 (t.sub.D, R.sub.B, R.sub.C),where CO is said cardiac output, H is said anthropometric parameter which is the height of said patient, f1 (H) is a function of said height, tE and tD are said time intervals from said point A to said points E &
D, respectively;
RB, RC, RD are values of ordinates of said blood-pressure pulse wave in said points B, C, and D, respectively;
f3 (tD, RB, RC) is a function of tD, RB, RC ;b) measuring the blood-pressure pulse wave of said patient; c) measuring, for said characteristic points, corresponding time intervals from the initial point of said pulse wave and measuring corresponding ordinates of said pulse wave, thus obtaining measured values of said time intervals and measured values of said ordinates; d) entering said measured values of said time intervals and said measured values of said ordinates of said characteristic points into said function; e) calculating the stroke volume and/or cardiac output for said patient with the use of said function; and f) repeating steps (b) to (e) for each said heart stroke. - View Dependent Claims (14, 15, 16)
-
-
17. An apparatus for measuring cardiac activity, stroke volume, or cardiac output of a biological object on the basis of a blood-pressure pulse wave of said biological object, comprising:
-
a pulse wave measuring unit, a data acquisition unit, a computation unit, and an indicator unit, said pulse wave measuring unit, supplying said wave to said data acquisition unit and said data acquisition unit comprising; (a) a pulse-wave minimum/maximum measuring unit; (b) an ordinate measuring unit; (c) a differentiating unit; (d) a controller; (e) a time interval measuring unit; and (f) a pulse-wave derivative minimum/maximum measuring unit, said controller being responsive to units (a) and (f) and controlling when said units (b), (d) and (e) provide inputs to said computation unit. - View Dependent Claims (18, 19, 20)
-
Specification