Method for noninvasive continuous determination of physiologic characteristics

• US 6,819,950 B2
• Filed: 11/07/2001
• Issued: 11/16/2004
• Est. Priority Date: 10/06/2000
• Status: Expired due to Fees

• Current Assignee: Woolsthorpe Technologies Corporation
• Original Assignee: Woolsthorpe Technologies Corporation
• Inventors: Mills, Alexander K.
• Primary Examiner(s): Jones, Mary Beth
• Assistant Examiner(s): KREMER, MATTHEW J
• Application Number:
  US10/008,245
• Publication Number:
  US 20030109772A1
• Time in Patent Office: 1,105 Days
• Field of Search: 600/309-310, 600/322-326, 600/316, 600/334, 600/335
• US Class Current: 600/322
• 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 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• 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 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• 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 methods for noninvasively monitoring physiological characteristics of a patient'"'"'s blood. Determinations of blood constituent concentrations may be made by comparing absorbance of radiation at varying parameters, such as path length and blood pressure. Preferably, changes in pressure are effected by changing the height of the probes relative to the patient'"'"'s heart. Determinations of blood pH may be made by comparing absorbance of the blood at different wavelengths. The temperature of the blood, and thus of the patient'"'"'s core, may also be accurately determined. Further, cardiac output characteristics and blood pressures may be noninvasively determined using the methods of the invention.

Claims

1. A method for noninvasively determining the concentration of a blood constituent comprising the steps of:

providing a tissue probe, said tissue probe including a first radiation emitter adapted to emit radiation having a first wavelength and a first radiation detector adapted to receive said radiation after absorbance through a radiation path length of a patient'"'"'s blood;

measuring absorbance of said patient'"'"'s blood by transmitting said radiation at said first wavelength through said patient'"'"'s blood and detecting said radiation after passage through said patient'"'"'s blood;

varying the volume of said patient'"'"'s blood through gravitational force to change said path length of said tissue probe to provide multiples of said path length;

measuring absorbance of said patient'"'"'s blood at each multiple of said path length; and

determining the concentration of the blood constituent based on said measured absorbance.

2. The method of claim 1, wherein said blood constituent comprises hemoglobin.

3. The method of claim 1, wherein said blood comprises venous blood.

4. The method of claim 1, wherein said blood comprises arterial blood.

5. The method of claim 1, further comprising the step of:

verifying said determination of concentration by comparing said radiation path length multiplied by said determined concentration to said measured absorbance.

6. The method of claim 1, wherein said step of providing tissue probe comprises providing a tissue probe having a first and second radiation emitters, said first radiation emitter being adapted to emit first radiation having a first wavelength, said second radiation emitter being adapted to emit second radiation having a second wavelength, and first and second radiation detectors adapted to receive said first and second radiations, respectively, after absorbance through a radiation path length of said patient'"'"'s blood and wherein said step of measuring said absorbance comprises measuring said absorbance at said first and second wavelengths.

7. A method for noninvasively determining the concentration of a blood constituent comprising the steps of:

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

measuring absorbance of said patient'"'"'s blood by transmitting said radiation at said first wavelength through said patient'"'"'s blood and detecting said radiation after passage through said patient'"'"'s blood;

determining absorbance values of said patient'"'"'s blood at multiples of said path length; and

determining the concentration of the blood constituent based on said absorbance values.

8. The method of claim 7, wherein said blood constituent comprises hemoglobin.

9. The method of claim 7, wherein said blood comprises venous blood.

10. The method of claim 7, wherein said blood comprises arterial blood.