Method for Using a Pulse Oximetry Signal to Monitor Blood Pressure

• US 20130296671A1
• Filed: 05/04/2012
• Published: 11/07/2013
• Est. Priority Date: 05/04/2012
• Status: Active Grant

• Current Assignee: Guy P. Curtis And Frances L. Curtis Trust
• Original Assignee: Guy P. Curtis And Frances L. Curtis Trust
• Inventors: Curtis, Guy P.
• Granted Patent: US 8,951,204 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters

Abstract

A system for continuously monitoring the blood pressure of a patient over an extended time interval requires using a blood pressure measuring unit (e.g. a sphygmomanometer) to calibrate an oximeter. Specifically, the oximeter is used to continuously detect and measure amplitudes for each blood flow pulse of the patient. Periodically, the sphygmomanometer is used to measure blood pressures (systolic and diastolic) in an artery of the patient. Immediately after the measurement cycle is completed, a computer correlates the measured systolic pressure with the pulse amplitude that is detected by the oximeter. Thereafter, the pulse amplitudes that are detected by the oximeter are used as indications of variations in the systolic pressure during the extended time interval that follows.

Claims

1. A system for continuously monitoring the blood pressure of a patient which comprises:

a unit for measuring blood pressures in an artery of the patient during a measurement cycle, wherein the measurement cycle has a beginning and an end, and wherein a systolic pressure (p_systolic) is measured at the beginning of the measurement cycle and a diastolic pressure (p_diastolic) is measured at the end of the measurement cycle;

a device for detecting blood pressure pulses in the cardio-vasculature of a patient during the measurement cycle, wherein each pulse has a first pulse amplitude value “

V₁”

detected at a determined time within the measurement cycle, and a second pulse amplitude value “

V₂”

detected at the end of the measurement cycle; and

a computer for correlating the systolic pressure (p_systolic) with “

V₂”

, to thereafter identify variations in pulse amplitudes V₂ detected by the detecting device as indications of corresponding variations in systolic pressures (p_systolic) during an extended time interval following the measurement cycle.

2. A system as recited in claim 1 wherein p_systolic is measured by the measuring unit at a time “

t₀”

at the beginning of the measurement cycle, wherein V₁ is detected by the detecting device and a first pressure p₁ is measured by the measuring unit at the determined time (“

t₁”

) in the measurement cycle, and wherein an initial pressure drop Δ

₁ is established at the time t₁, with Δ

₁ equal to the difference between p_systolic and p₁ (Δ

₁=p_systolic−

p₁).

3. A system as recited in claim 2 wherein a pulse differential “

Δ

_v”

(Δ

_v=V₁−

V₂) is compared directly with a pressure differential “

Δ

_p”

(Δ

_p=p₁−

p_diastolic) to correlate the pulse metrics of Δ

_v with the pressure metrics of Δ

_p.

4. A system as recited in claim 3 wherein p_systolic is equated with V₂+Δ

₁ and p_diastolic is equated with V₁.

5. A system as recited in claim 4 further comprising a monitor for presenting the indications of systolic pressure during the extended time interval.

6. A system as recited in claim 4 wherein the detecting device is an oximeter and the measuring unit is a sphygmomanometer.

7. A system as recited in claim 4 wherein the extended time interval is greater than fifteen minutes.

8. A system as recited in claim 4 wherein the pulse amplitude values V₁ and V₂ are detected continuously during the extended time interval.

9. A method for continuously monitoring the blood pressure of a patient which comprises the steps of:

measuring blood pressures in an artery of the patient during a measurement cycle, wherein a systolic pressure (p_systolic) is measured at the beginning of the measurement cycle and a diastolic pressure (p_diastolic) is measured at the end of the measurement cycle;

detecting blood pressure pulses in the cardio-vasculature of a patient, wherein each pulse has a pulse amplitude;

correlating the systolic pressure (p_systolic) measured in the measuring step with a pulse amplitude value detected in the detecting step; and

identifying variations in pulse amplitude values during the detecting step as indications of variations in corresponding systolic pressures during an extended time interval.

10. A method as recited in claim 9 further comprising the steps of:

monitoring blood pressure pulses in the detecting step during the extended time interval; and

presenting a visual display of the indications from the identifying step as the corresponding systolic pressures during the extended time interval.

11. A method as recited in claim 9 wherein the extended time interval immediately follows the measurement cycle.

12. A method as recited in claim 9 wherein the extended time interval is greater than fifteen minutes.

13. A method as recited in claim 9 wherein pulse amplitudes are continuously detected in the detecting step during the extended time interval.

14. A method as recited in claim 9 wherein the detecting step is accomplished using an oximeter, and the measuring step is accomplished using a sphygmomanometer.

15. A method as recited in claim 14 further comprising the step of calibrating the oximeter, wherein the calibrating step further comprises the steps of:

measuring “

p_systolic”

at a time “

t₀”

at the beginning of a measurement cycle;

detecting a pulse amplitude value “

V₁”

at a determined time “

t₁”

during the measurement cycle;

measuring a pressure “

p₁”

at the determined time “

t₁”

;

establishing an initial pressure drop “

Δ

₁”

, from p_systolic to p₁, at the determined time “

t₁”

;

measuring“

p_diastolic”

at a time “

t₂”

at the end of the measurement cycle;

detecting a pulse amplitude value “

V₂”

at the time “

t₂”

;

comparing a pulse differential “

Δ

_v”

(Δ

_v=V₁−

V₂) directly with a pressure differential “

Δ

_p”

(Δ

_p=p₁−

p_diastolic) to correlate the pulse metrics of Δ

_v with pressure the metrics of Δ

_p; and

equating p_systolic with V₂+Δ

₁ and p_diastolic with V₁ during the extended time interval.

16. A computer program product for continuously monitoring the blood pressure of a patient, wherein the computer program product comprises program sections for respectively:

measuring blood pressures in an artery of the patient during a measurement cycle, wherein a systolic pressure is measured at the beginning of the measurement cycle and a diastolic pressure is measured at the end of the measurement cycle;

detecting blood pressure pulses in the cardio-vasculature of a patient, wherein each pulse has a pulse amplitude;

correlating the systolic pressure measured in the measuring program section with a pulse amplitude detected in the detecting program section; and

identifying variations in pulse amplitudes during the detecting step as indications of variations in corresponding systolic pressures during an extended time interval.

17. A computer program product as recited in claim 16 further comprising program sections for respectively:

monitoring blood pressure pulses in the detecting step during the extended time interval; and

presenting the indications from the identifying step as the corresponding systolic pressures during the extended time interval.

18. A computer program product as recited in claim 17 further comprising program sections for respectively:

measuring “

p_systolic”

at a time “

t₀”

at the beginning of a measurement cycle;

detecting a pulse amplitude value “

V₁”

at a determined time “

t₁”

during the measurement cycle;

measuring a pressure “

p₁”

at the determined time “

t₁”

;

establishing an initial pressure drop “

Δ

₁”

, from p_systolic to p₁, at the determined time “

t₁”

;

measuringn “

p_diastolic”

at a time “

t₂”

at the end of the measurement cycle;

detecting a pulse amplitude value “

V₂”

at the time “

t₂”

;

comparing a pulse differential “

Δ

_v”

(Δ

_v=V₁−

V₂) directly with a pressure differential “

Δ

_p”

(Δ

_p=p₁−

p_diastolic) to correlate the pulse metrics of Δ

_v with pressure the metrics of Δ

_p; and

equating p_systolic with V₂+Δ

₁ and p_diastolic with V₁ during the extended time interval.

19. A computer program product as recited in claim 16 wherein the extended time interval immediately follows the measurement cycle, wherein the extended time interval is greater than fifteen minutes, and wherein pulse amplitudes are continuously detected during the predetermined time interval.

20. A computer program product as recited in claim 16 wherein pulse amplitudes are detected using an oximeter, and blood pressures are measured using a sphygmomanometer.