Device and method for noninvasive continuous determination of physiologic characteristics

• US 6,719,705 B2
• Filed: 07/15/2002
• Issued: 04/13/2004
• Est. Priority Date: 10/07/1999
• Status: Expired due to Fees

• Current Assignee: Woolsthorpe Technologies Corporation
• Original Assignee: Woolsthorpe Technologies Corporation
• Inventors: Mills, Alexander K.
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): MALLARI, PATRICIA C
• Application Number:
  US10/196,474
• Publication Number:
  US 20020188205A1
• Time in Patent Office: 638 Days
• Field of Search: 600/323, 600/324, 600/328, 600/322, 600/326, 600/481, 600/485, 600/500-504, 600/507, 600/526
• US Class Current: 600/526
• CPC Class Codes: A61B 2560/0261 using hydrostatic pressure
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

The invention comprises devices for noninvasively monitoring physiological characteristics of a patient'"'"'s blood. Generally, probes having radiation emitters and detectors are used to determine absorbance of blood within the patient'"'"'s tissue to determine various blood parameters. The device also has either a position sensor for determining the position of the probe with respect to the patient'"'"'s heart or a movement generator for altering the position of the probe with respect to the patient'"'"'s heart. The invention also comprises methods for noninvasively monitoring the physiological characteristics. In one embodiemnt, induced positional changes create differential hydrostatic pressures to facilitate measurement of blood parameters by absorbance. In a second embodiment, delays in pulse arrival times in coupled organs or members on opposite sides of the body are measured to determine cardiac output. The two methods are such that they can advantageously be used together.

Claims

1. A method for noninvasively determining a patient'"'"'s cardiac output, comprising the steps of:

providing a first tissue probe having a first radiation emitter and a first radiation detector, said first radiation emitter being adapted to emit first radiation having at least a first wavelength, said first radiation detector being adapted to receive said first radiation after absorbance through the patient'"'"'s blood;

providing a second tissue probe having a second radiation emitter and a second radiation detector, said second radiation emitter being adapted to emit second radiation having at least a second wavelength, said second radiation emitter being adapted to receive said second radiation after absorbance through the patient'"'"'s blood, said first and second tissue probes being further adapted to measure the patient'"'"'s blood pulse;

placing said first tissue probe proximate a first extremity of the patient;

placing said second tissue probe proximate a second, opposing extremity of the patient;

substantially simultaneously and continuously measuring first extremity oxygen saturation at each blood pulse in said first extremity with said first tissue probe and second extremity oxygen saturation at each blood pulse in said second extremity with said second probe, said first extremity oxygen saturation measurement providing a plurality of first oxygen saturation values, said second extremity oxygen saturation measurement providing a plurality of second oxygen saturation values;

measuring the patient'"'"'s pulse rate;

determining matching oxygen saturation using said first and second oxygen saturation values;

determining the patient'"'"'s blood volume;

determining cardiac stroke volume using said blood volume and said pulse rate; and

determining the patient'"'"'s cardiac output using said cardiac stroke volume and said pulse rate.

2. The method of claim 1, including the steps of:

determining pulse delay by comparing said first and second oxygen saturation values;

estimating pulse distance differential;

determining pulse wave velocity using said pulse distance differential and said pulse delay; and

determining flow wave velocity using said pulse wave velocity.

3. The method of claim 2, further including the steps of estimating aortic root size and determining cardiac stroke volume using said flow wave velocity and said aortic root size.

4. The method of claim 3, further including the step of changing the position of said first and second tissue probes relative to a level corresponding to the patient'"'"'s heart during said step of measuring said first extremity oxygen saturation and said second extremity oxygen saturation.

5. A method for noninvasively determining a patient'"'"'s cardiac output, comprising the steps of:

providing a first tissue probe having a first radiation emitter and a first radiation detector, said first radiation emitter being adapted to emit first radiation having at least a first wavelength, said first radiation detector being adapted to receive said first radiation after absorbance through the patient'"'"'s blood;

providing a second tissue probe having a second radiation emitter and a second radiation detector, said second radiation emitter being adapted to emit second radiation having at least a second wavelength, said second radiation emitter being adapted to receive said second radiation after absorbance through the patient'"'"'s blood, said first and second tissue probes being further adapted to measure blood pulse delay;

placing said first tissue probe proximate a first extremity of the patient;

placing said second tissue probe proximate a second, opposing extremity of the patient;

measuring a first time period between a first cardiac characteristic and a first detected pulse in said first extremity with said first tissue probe to determine a first blood pulse delay;

measuring a second time period between a second cardiac characteristic and a second detected pulse in said second extremity with said second tissue probe to determine a second blood pulse delay;

measuring the patient'"'"'s pulse rate;

estimating pulse distance differential;

determining pulse wave velocity using said first and second blood pulse delays and said pulse distance differential;

determining flow wave velocity using said pulse wave velocity;

estimating aortic root size;

determining cardiac stroke volume using said flow wave velocity and said aortic root size; and

determining the patient'"'"'s cardiac output using said cardiac stroke volume and said pulse rate.

6. The method of claim 5, further including the step of changing the position of said first and second tissue probes relative to a level corresponding to the patient'"'"'s heart to effect a change in said pulse wave velocity.

7. The method of claim 5, wherein said first and second cardiac characteristics comprise R-waves of an electrocardiogram.

8. A method for noninvasively determining a patient'"'"'s cardiac output, comprising the steps of:

providing a first tissue probe having a first radiation emitter and a first radiation detector, said first radiation emitter being adapted to emit first radiation having at least a first wavelength, said first radiation detector being adapted to receive said first radiation after absorbance through the patient'"'"'s blood;

providing a second tissue probe having a second radiation emitter and a second radiation detector, said second radiation emitter being adapted to emit second radiation having at least a second wavelength, said second radiation emitter being adapted to receive said second radiation after absorbance through the patient'"'"'s blood, said first and second tissue probes being further adapted to measure blood pulse delay;

placing said first tissue probe proximate a first extremity of the patient;

placing said second tissue probe proximate a second, opposing extremity of the patient;

measuring a first time period between a first cardiac characteristic and a first detected pulse in said first extremity with said first tissue probe to determine a first blood pulse delay;

measuring a second time period between said first cardiac characteristic and said first detected pulse in said second extremity with said second tissue probe to determine a second blood pulse delay;

determining a blood pulse differential using said first and second blood pulse delays;

measuring the patient'"'"'s pulse rate;

estimating pulse distance differential;

determining pulse wave velocity using said blood pulse differential and said pulse distance differential;

determining flow wave velocity using said pulse wave velocity;

estimating aortic root size;

determining cardiac stroke volume using said flow wave velocity and said aortic root size; and

determining the patient'"'"'s cardiac output using said cardiac stroke volume and said pulse rate.

9. The method of claim 8, further including the step of changing the position of said first and second tissue probes relative to a level corresponding to the patient'"'"'s heart to effect a change in said pulse wave velocity.

10. The method of claim 8, wherein said first cardiac characteristic comprises an R-wave of an electrocardiogram.