Apparatus and method for measuring an induced perturbation to determine a physiological parameter

• US 5,810,734 A
• Filed: 11/22/1995
• Issued: 09/22/1998
• Est. Priority Date: 04/15/1994
• Status: Expired due to Term

• Current Assignee: Masimo Corporation
• Original Assignee: Vital Insite, Inc.
• Inventors: Caro, Richard G., Sher, Mark H., Flaherty, Bryan P.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US08/556,547
• Time in Patent Office: 1,035 Days
• Field of Search: 128/632, 128/633, 128/630, 128/664-8, 128/672-696, 128/713, 128/716, 128/719, 128/721, 128/722, 128/736, 128/748
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02133 by using induced vibration of the blood vessel
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers

Abstract

A monitor for determining a patient'"'"'s physiological parameter includes a calibration device configured to provide a calibration signal representative of the patient'"'"'s physiological parameter. An exciter is positioned over a blood vessel of the patient for inducing a transmitted exciter waveform into the patient. A noninvasive sensor is positioned over the blood vessel, where the noninvasive sensor is configured to sense a hemoparameter and to generate a noninvasive sensor signal representative of the hemoparameter containing a component of a physiological parameter waveform and a component of a received exciter waveform. In this context, a hemoparameter is defined as any physiological parameter related to vessel blood such as pressure, flow, volume, velocity, blood vessel wall motion, blood vessel wall position and other related parameters. A processor is configured to determine a relationship between a property of the received exciter waveform and a property of the physiological parameter. The processor is connected to receive the calibration signal and the noninvasive sensor signal, and the processor is configured to process the calibration signal and the noninvasive sensor signal to determine the physiological parameter. In the preferred embodiment, the physiological parameter measured is blood pressure, however, the present invention can also be used to analyze and track other physiological parameters such as vascular wall compliance, strength of ventricular contractions, vascular resistance, fluid volume, cardiac output, myocardial contractility and other related parameters.

Claims

1. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is configured to determine said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a formula Vel(t)=a+bP(t), where a is an offset variable and b is a slope variable; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

2. The monitor of claim 1, further comprising:

a pressure application device positioned on the same limb as said noninvasive sensor and configured to apply a pressure to said blood vessel; and

wherein;

said processor is configured to control said pressure application device to an applied pressure less than a systolic pressure and for less than approximately 1 minute;

said processor is configured to store said applied pressure; and

said processor is configured to determine said offset variable based at least in part on said applied pressure.

7. The monitor of one of claims 1, 3, 4, 5 or 6, further comprising:

a pressure application device positioned on the same limb as said noninvasive sensor and configured to apply a pressure to said blood vessel; and

wherein said processor is configured to control said pressure application device to an applied pressure less than a systolic pressure; and

wherein said processor is configured to determine said slope variable based at least in part on said applied pressure.

3. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is configured to determine said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a formula Φ

(t)=Φ

₀ -2π

df/(a+bP(t)), where a is an offset variable and b is a slope variable; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

4. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is configured to determine said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a piecewise-linear formula Vel1(t)=a1+b1P 1!(t), where a1 is an offset variable and b1 is a slope variable, and according to a second piecewise-linear formula Vel2(t)=a2+b2P 2!(t), where a2 is an offset variable and b2 is a slope variable; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

5. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is configured to determine said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a piecewise-linear formula Φ

1(t)=Φ

₀ -2π

df/(a1+b1P(t)), where a1 is an offset variable and b1 is a slope variable, and according to a second piecewise-linear formula Φ

2(t)=Φ

₀ -2π

df/(a2+b2P(t)), where a2 is an offset variable and b2 is a slope variable; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

6. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is configured to determine said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a non-linear formula relating said transmitted exciter waveform velocity and said blood pressure and having a non-linear slope variable; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

8. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a received exciter waveform component and a physiological waveform component; and

a processor configured to determine a relationship between a property of said received exciter waveform component and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is configured to determine said relationship by comparing a property of said received exciter waveform component to a property of the physiological waveform component; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

9. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship; and

wherein said processor is configured to initiate a calibration to provide said calibration signal when said processor determines that said relationship has changed.

10. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is configured to determine said relationship without occluding an artery of the patient; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

11. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform;

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal; and

a pressure application device positioned on the same limb as said noninvasive sensor and configured to apply a pressure to said blood vessel;

wherein said processor is configured to control said pressure application device to an applied pressure less than a systolic pressure;

wherein said processor is configured to determine said relationship between a property of said exciter waveform and a property of said physiological parameter based at least in part on said applied pressure; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

12. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform;

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal; and

a pressure application device positioned on the same limb as said noninvasive sensor and configured to apply a pressure to said blood vessel;

wherein said processor is configured to control said pressure application device to an applied pressure less than a systolic pressure and for less than approximately 1 minute;

wherein said processor is configured to store said applied pressure;

wherein said processor is configured to determine said relationship based at least in part on said applied pressure; and

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

13. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship;

wherein said exciter is further configured to induce a second transmitted waveform into the patient;

wherein said noninvasive sensor signal further contains a component of a second received exciter waveform; and

wherein said processor is further configured to resolve a cycle-number ambiguity based at least in part on said received exciter waveform and said second received exciter waveform.

14. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship;

wherein said monitor further comprises a second noninvasive sensor positioned over said blood vessel, said noninvasive sensor configured to sense a hemoparameter and to generate a second noninvasive sensor signal containing a component of a second received exciter waveform; and

wherein said processor is further configured to resolve a cycle-number ambiguity based at least in part on said received exciter waveform and said second received exciter waveform.

15. A monitor for determining a physiological parameter of a patient, comprising:

a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform; and

a processor configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said processor is connected to receive said calibration signal and said noninvasive sensor signal and is configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship;

wherein said monitor further comprises a second exciter positioned over said blood vessel, said second exciter configured to induce a second transmitted exciter waveform into the patient;

wherein said noninvasive sensor is configured to generate a noninvasive sensor signal containing a component of a second received exciter waveform; and

wherein said processor is further configured to resolve a cycle-number ambiguity based at least in part on said received exciter waveform and said second received exciter waveform.

16. A processor for determining a physiological parameter of a patient with an apparatus having a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters, an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient, and a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal representative of said hemoparameter, said processor comprising:

a first input configured to receive said calibration signal;

a second input configured to receive said noninvasive sensor signal;

a filter configured to separate from said noninvasive sensor signal a component representing a received exciter waveform;

a relationship routine configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said relationship routine is configured to determine said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device, according to a formula Vel(t)=a+bP(t), where a is an offset variable and b is a slope variable; and

a determination routine configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

17. A processor for determining a physiological parameter of a patient with an apparatus having a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters, an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient, and a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal representative of said hemoparameter, said processor comprising:

a first input configured to receive said calibration signal;

a second input configured to receive said noninvasive sensor signal;

a filter configured to separate from said noninvasive sensor signal a received exciter waveform component and a physiological waveform component;

a relationship routine configured to determine a relationship between a property of said received exciter waveform component and a property of said physiological parameter based at least in part on said calibration signal;

wherein said relationship routine is configured to determine said relationship by comparing a property of said received exciter waveform component to a property of the physiological waveform component; and

a determination routine configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

18. A processor for determining a physiological parameter of a patient with an apparatus having a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters, an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient, and a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal representative of said hemoparameter, said processor comprising:

a first input configured to receive said calibration signal;

a second input configured to receive said noninvasive sensor signal;

a filter configured to separate from said noninvasive sensor signal a component representing a received exciter waveform;

a relationship routine configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal; and

a determination routine configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship; and

wherein said processor is configured to initiate a calibration procedure to provide a calibration signal when said determination routine determines that said relationship has changed.

19. A processor for determining a physiological parameter of a patient with an apparatus having a calibration device configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters, an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient, and a noninvasive sensor adapted to be positioned over said blood vessel and configured to sense a hemoparameter and to generate a noninvasive sensor signal representative of said hemoparameter, and wherein said calibration device includes an inflatable pressure cuff adapted to be positioned on the same limb as said noninvasive sensor, said processor comprising:

a first input configured to receive said calibration signal;

a second input configured to receive said noninvasive sensor signal;

a filter configured to separate from said noninvasive sensor signal a component representing a received exciter waveform;

a relationship routine configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

a control routine configured to control said inflatable cuff to an inflation pressure;

wherein said relationship routine is configured to determine said relationship between a property of said exciter waveform and a property of said physiological parameter based at least in part on said inflation pressure; and

a determination routine configured to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

20. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said determining step is performed by determining said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a formula Vel(t)=a+bP(t), where a is an offset variable and b is a slope variable; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

21. The method of claim 20, wherein a pressure application device is positioned on the same limb as said noninvasive sensor, and wherein said method further comprises the step of:

applying an applied pressure to said blood vessel with said pressure application device, said applied pressure less than a systolic pressure and for less than approximately 1 minute; and

wherein said determining step is performed by determining said offset variable based at least in part on said applied pressure.

26. The method of one of claims 20, 22, 23, 24 or 25, wherein a pressure application device is positioned on the same limb as said noninvasive sensor, and wherein said method further comprises the step of:

applying a pressure to said blood vessel with said pressure application device, said applied pressure less than a systolic pressure; and

wherein said determining step is performed by determining said slope variable based at least in part on said partial inflation pressure.

22. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said determining step is performed by determining said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a formula Φ

(t)=Φ

₀ -2π

df/(a+bP(t)), where a is an offset variable and b is a slope variable; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

23. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said determining step is performed by determining said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a piecewise-linear formula Vel1(t)=a1+b1P 1!(t), where a1 is an offset variable and b1 is a slope variable, and according to a second piecewise-linear formula Vel2(t)=a2+b2P 2!(t), where a2 is an offset variable and b2 is a slope variable; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

24. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said determining step is performed by determining said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a piecewise-linear formula Φ

1(t)=Φ

0-2π

df/(a1+b1P(t)), where a1 is an offset variable and b1 is a slope variable, and according to a second piecewise-linear formula Φ

2(t)=Φ

0-2π

df/(a2+b2P(t)), where a2 is an offset variable and b2 is a slope variable; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

25. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said determining step is performed by determining said relationship by comparing a property of said received exciter waveform to one of the set of diastolic, mean and systolic blood pressure provided by said calibration device as said calibration signal, according to a non-linear formula relating said transmitted exciter waveform velocity and said blood pressure and having a non-linear slope variable; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

27. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a received exciter waveform and a physiological waveform component;

determining a relationship between a property of said received exciter waveform component and a property of said physiological parameter based at least in part on said calibration signal;

wherein said determining step is performed by determining said relationship by comparing a property of said received exciter waveform component to a property of the physiological waveform component; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

28. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship; and

initiating said step of providing a calibration signal when said determining step determines that said relationship has changed.

29. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

wherein said determining step is performed without occluding an artery of the patient; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

30. A method of determining a physiological parameter of a patient using an apparatus for calibration that includes a pressure application device adapted to be positioned on a limb of the patient on which a noninvasive sensor is also positioned, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship;

applying an applied pressure to said blood vessel with said pressure application device; and

wherein said determining step is performed by determining said relationship between a property of said exciter waveform and a property of said physiological parameter based at least in part on said applied pressure.

31. A method of determining a physiological parameter of a patient using an apparatus for calibration that includes a pressure application device adapted to be positioned on a limb of the patient on which a noninvasive sensor is also positioned, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship;

applying an applied pressure to said blood vessel with said pressure application device, said applied pressure less than a systolic pressure and for less than approximately 1 minute; and

wherein said determining step is performed by determining said relationship between a property of said exciter waveform and a property of said physiological parameter based at least in part on said applied pressure.

32. A method of determining a physiological parameter of a patient, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter

wherein said method further comprises the step of resolving a cycle-number ambiguity based at least in part on said received exciter waveform and said second received exciter waveform.

33. A method of determining a physiological parameter, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

noninvasively sensing a second hemoparameter, and generating a second noninvasive sensor signal representative of said second hemoparameter and containing a component of a second received exciter waveform;

resolving a cycle-number ambiguity based at least in part on said received exciter waveform and said second received exciter waveform; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

34. A method of determining a physiological parameter, comprising the steps of:

providing a calibration signal representative of one of the patient'"'"'s physiological parameters and storing the calibration signal;

inducing a transmitted exciter waveform into the patient;

noninvasively sensing a hemoparameter and generating a noninvasive sensor signal representative of said hemoparameter and containing a component of a received exciter waveform;

determining a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal;

inducing a second transmitted exciter waveform into the patient;

wherein said noninvasive sensor signal contains a component of a second received exciter waveform;

resolving a cycle-number ambiguity based at least in part on said received exciter waveform and said second received exciter waveform; and

processing said calibration signal and said noninvasive sensor signal to determine said physiological parameter based at least in part on said noninvasive sensor signal and said relationship.

35. A monitor for determining a patient'"'"'s blood pressure, comprising:

an inflatable cuff positioned on an extremity of the patient and configured to provide a calibration signal representative of one of the patient'"'"'s physiological parameters;

an exciter adapted to be positioned over a blood vessel of the patient and configured to induce a transmitted exciter waveform into the patient;

a noninvasive sensor adapted to be positioned over said blood vessel and at a distance from said exciter and configured to sense a hemoparameter and to generate a noninvasive sensor signal containing a component of a received exciter waveform;

a processor connected to receive said calibration signal and said noninvasive sensor signal including a filter configured to separate from said noninvasive sensor signal a component that varies with blood pressure and a component that does not so vary and configured to determine a relationship between a property of said received exciter waveform and a property of said physiological parameter based at least in part on said calibration signal; and

wherein said processor is configured to determine said blood pressure based at least in part on said component that varies with blood pressure and said relationship.

36. The monitor of claim 35, further comprising:

an exciter sensor adapted to be positioned near said exciter and configured to sense said transmitted exciter waveform and to generate an exciter sensor signal representative of said transmitted exciter waveform; and

wherein said processor is further configured to compare the phase relationship of said transmitted exciter sensor signal and said received exciter waveform to determine said blood pressure.