Techniques for obtaining information associated with an individual's blood pressure including specifically a stat mode technique

• US 4,664,126 A
• Filed: 05/28/1986
• Issued: 05/12/1987
• Est. Priority Date: 12/21/1984
• Status: Expired due to Term

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Baxter Travenol Laboratories Incorporated
• Inventors: Link, Wiliam T.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): Sykes, Angela D.
• Application Number:
  US06/868,313
• Time in Patent Office: 349 Days
• Field of Search: 128/672, 128/677-686
• US Class Current: 600/494
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Techniques for determining different parameters associated with an individual'"'"'s blood pressure in a non-invasive manner are disclosed herein. These techniques include (1) generating a blood pressure waveform corresponding to the individual'"'"'s actual waveform, whereby the means pressure of the individual can be readily calculated, (2) generating a transformation curve unique to the patient from his diastolic and systolic pressures and his cuff pulses, (3) successively monitoring certain parameters of the patients'"'"'s blood pressure including his systolic and diastolic pressures over closely spaced intervals of time without having to subject the patient to cuff pressures much greater than his diastolic pressure, other than initially or not at all utilizing what is referred to as a stat mode, and (4) measuring a patient'"'"'s diastolic and systolic blood pressures at any given instance without ever having to subject the patient to cuff pressures much greater than his diastolic pressure.

Claims

1. A method of monitoring certain blood pressure parameters of a patient including his systolic and diastolic pressures over an extended period of time by taking successive measurements at closely spaced intervals throughout said period, said method comprising the steps of:

(a) Taking an initial measurement at the beginning of said period by

(i) positioning a pressurizable blood pressure cuff or pad at the appropriate location adjacent a suitable artery of the patient,

(ii) maintaining said cuff or pad at different pressure levels including levels at and above the anticipated diastolic and systolic pressures of the patient,

(iii) producing cuff pulses corresponding to said different pressure levels,

(iv) from said cuff pulses, determining the diastolic and systolic pressures of the patient, and

(v) from said cuff pulses and the diastolic and systolic pressures of the patient, generating a transformation curve unique to the patient; and

(b) taking at least one subsequent measurement during said extended period while said cuff or pad is still in position adjacent said artery by

(i) maintaining said cuff or pad at different pressure levels including levels at and above the anticipated diastolic pressure of the patient but below the patient'"'"'s systolic pressure, as determined by said initial measurement,

(ii) producing cuff pulses corresponding to these last mentioned pressure levels,

(iii) from said last mentioned cuff pulses, determining the patient'"'"'s diastolic pressure, and

(iv) from said last mentioned cuff pulses, the patient'"'"'s diastolic pressure and from his transformation curve generated during said initial measurement, determining the patient'"'"'s systolic pressure.

2. A method according to claim 1 wherein said subsequent measurement is successively repeated a plurality of times after said initial measurement is taken at spaced intervals throughout said extended period, whereby the systolic pressure of the patient is monitored throughout said period without having to pressurize the blood pressure cuff or pad to a level at or above the patient'"'"'s systolic pressure except during said initial measurement.

3. A method according to claim 2 wherein, during each of said subsequent measurements, said cuff or pad is maintained at an uppermost level which is only somewhat greater than the patient'"'"'s diastolic level, whereby to minimize the pressure the patient is subjected to.

4. A method according to claim 3 wherein, during each of said initial and subsequent measurements, said cuff or pad is successively maintained at increasing ones of said different pressure levels as the cuff or pad is pressurized from ambient pressure and then depressurized to ambient pressure upon reaching the highest pressure level required by the particular measurement.

5. A method according to claim 4 wherein, during each of said measurement, said cuff or pad is pressurized from ambient pressure to its highest level in a linear manner.

6. A method according to claim 3 wherein, during each of said initial and subsequent measurements, said cuff or pad means is first pressurized to the highest pressure level required by that particular measurement and then depressurized toward ambient pressure during which the cuff or pad is successively maintained at decreasing ones of said different pressure levels.

7. A method according to claim 6 wherein, during each of said measurements, said cuff or pad is depressurizing from said highest level to a level just below the diastolic pressure of the patient in a linear manner.

8. A method according to claim 2 wherein each of said measurements includes generating a blood pressure-like curve corresponding to the patient'"'"'s actual blood pressure versus time curve from the diastolic and systolic pressures of the patient and his initially generated transformation curve and thereafter calculating the patient'"'"'s mean pressure from his blood pressure-like curve during that measurement.

9. A method according to claim 8 including the step of recording, either temporarily or permanently, the diastolic, mean and systolic pressures of the patient during each of said measurements.

10. A method according to claim 1 wherein the patient'"'"'s systolic pressure is determined during said subsequent measurement by (i) selecting at least one cuff pulse produced during said subsequent measurement, (ii) using the diastolic pressure of the patient determined during said subsequent measurement, locating the base and peak of said selected cuff pulse on the vertical axis of the patient'"'"'s transformation curve, and (iii) from the peak point of said selected cuff pulse on the vertical axis of said transformation curve, using the latter curve, locating the systolic pressure of said patient.

11. An apparatus for monitoring certain blood pressure parameters of a patient including his systolic and diastolic pressures over an extended period of time by taking successive measurements at closely spaced intervals throughout said period, said apparatus comprising:

(a) means for taking an initial measurement at the beginning of said period, said initial measurement taking means including

(i) a pressurizable blood pressure cuff or pad positionable at the appropriate location adjacent a suitable artery of the patient,

(ii) means for maintaining said cuff or pad at different pressure levels including levels at and above the anticipated diastolic and systolic pressures of the patient,

(iii) means of producing cuff pulses corresponding to said different pressure levels,

(iv) means for determining the diastolic and systolic pressures of the patient from said cuff pulses, and

(v) means for generating a transformation curve unique to the patient from said cuff pulses and the diastolic and systolic pressures of the patient; and

(b) means for taking at least one subsequent measurement during said extended period while said cuff or pad is still in position adjacent said artery, said subsequent measurement taking means including

(i) means for maintaining said cuff or pad at different pressure levels including levels at and above the anticipated diastolic pressure of the patient but below the patient'"'"'s systolic pressure, as determined by said initial measurement,

(ii) means for producing cuff pulses corresponding to these last mentioned pressure levels,

(iii) means for determining the patient'"'"'s diastolic pressure from said last mentioned cuff pulses, and

(iv) means for determining the patient'"'"'s systolic pressure from said last mentioned cuff pulses, the patient'"'"'s diastolic pressure and from his transformation curve, generated during said initial measurement.

12. An apparatus according to claim 11 wherein said subsequent measurement taking means successively repeats said subsequent measurements a plurality of times after said initial measurement is taken at spaced intervals throughout said extended period, whereby the systolic pressure of the patient is monitored throughout said period without having to pressurize the blood pressure cuff or pad to a level at or above the patient'"'"'s systolic pressure except during said initial measurement.

13. An apparatus according to claim 12 including means for generating a blood pressure-like curve corresponding to the patient'"'"'s actual blood pressure versus time curve from the diastolic and systolic pressures of the patient and his initially generated transformation curve during each of said measurements and thereafter calculating the patient'"'"'s means pressure from his blood pressure-like curve during that measurement.

14. An apparatus according to claim 13 including means for recording, either temporarily or permanently, the diastolic, mean and systolic pressures of the patient during each of said measurements.

15. A method of monitoring certain blood pressure parameters of a patient including his systolic and diastolic pressures over an extended period of time by taking successive measurements at closely spaced intervals throughout said period, said method comprising the steps of:

(a) taking an initial measurement in which cuff pulses of the patient are generated at different pressure levels including levels at and above the anticipated diastolic and systolic levels of the patient and, from these cuff pulses, the patient'"'"'s diastolic and systolic pressures are determined and, from these diastolic and systolic pressures and cuff pulses, a transformation curve unique to the patient is generated; and

(b) taking at least one subsequent measurement during said period in which cuff pulses of the patient are generated at different pressure levels including levels at and above the anticipated diastolic level of the patient but always below the systolic pressure of the patient as determined by the initial measurement and, from these latter cuff pulses, the patient'"'"'s diastolic pressure is determined and, from this latter pressure, these latter cuff pulses and the transformation curve generated by the initial measurement, determining the systolic pressure of the patient.

16. A method according to claim 15 wherein said subsequent measurement is successively repeated a plurality of times after said initial measurement is taken at spaced intervals throughout said extended period, whereby the systolic pressure of the patient is monitored throughout said period without having to generate cuff pulses at levels at or above the patient'"'"'s systolic pressure except during said initial measurement.

17. An apparatus for monitoring certain blood pressure parameters of a patient including his systolic and diastolic pressures over an extended period of time by taking successive measurements at closely spaced intervals throughout said period, said apparatus comprising:

means for taking an initial measurement in which cuff pulses of the patient are generated at different pressure levels including levels at and above the anticipated diastolic and systolic levels of the patient and, from these cuff pulses, the patient'"'"'s diastolic and systolic pressures are determined and, from these diastolic and systolic pressures and cuff pulses, a transformation curve unique to the patient is generated and for taking at least one subsequent measurement during said period in which cuff pulses of the patient are generated at different pressure levels including levels at and above the anticipated diastolic level of the patient but always below the systolic pressure o the patient as determined by the initial measurement and, from these latter cuff pulses, the patient'"'"'s diastolic pressure is determined and, from this latter pressure, these latter cuff pulses and the transformation curve generated by the initial measurement, determining the systolic pressure of the patient.

18. A method of obtaining certain blood pressure parameters of a given patient including his systolic and diastolic pressures, comprising the steps of:

(a) positioning a blood pressure cuff or pad at the appropriate location adjacent a suitable artery of the patient,

(b) selecting first and second points in time t₁ and t₂ on the diastolic decline or systolic rise of the patient'"'"'s actual blood pressure waveform below the patient'"'"'s anticipated systolic pressure;

(c) placing said cuff or pad at different pressure levels including levels above and below the anticipated blood pressures of the patient at the selected points in time t₁ and t₂ on his actual waveform; and

thereby producing cuff pulses at said different pressure levels;

(d) from said cuff pulses, measuring the change in cuff pressure Δ

P at each of said different levels of cuff pressure for relatively narrow first and second intervals of time Δ

t₁ and Δ

t₂ containing times t₁ and t₂, respectively, on the patient'"'"'s actual blood pressure waveform;

(e) generating a transformation curve unique to said patient from at least some of said measurements;

(f) determining the actual blood pressures D₁ and D₂ of the patient at times t₁ and t₂, respectively, on the patient'"'"'s waveform from said measurements;

(g) selecting a cuff pulse at one of said different levels of cuff pressure and, using said transformation curve and said actual blood pressures, D₁ and D₂, establishing the positional relationship between said transformation curve and selected cuff pulse and the correct scaling of the latter relative to said transformation curve; and

(h) from said correctly scaled cuff pulse and from its positional relationship with said transformation curve, determining the systolic pressure of the patient and his diastolic pressure, if the latter is not blood pressure D₁ or D₂.

19. A method according to claim 18 wherein the first point in time t₁ is selected to be in close proximity to the beginning of the systolic rise portion of the patient'"'"'s actual blood pressure waveform, whereby D₁ corresponds nearly to the patient'"'"'s diastolic pressure.

20. A method according to claim 18 wherein said transformation curve is generated by integrating over time the measurements Δ

P at each of said different levels of cuff pressure for only one of said intervals of time Δ

t₁ and Δ

t₂.

21. A method according to claim 18 wherein said transformation curve is generated by integrating over time the measurements Δ

P at each of said different levels of cuff pressure for each of said intervals of time Δ

t₁ and Δ

t₂ and averaging the integrated measurements at each pressure level to produce an averaged transformation curve.

22. A method according to claim 18 including the step of determining the blood pressures of said patient at a sufficient number of points in time other than t₁ and t₂ from said correctly scaled cuff pulse and from its positional relationship with said transformation curve to reproduce the actual blood pressure waveform of said patient.

23. A method according to claim 18 wherein said steps (a)-(h) are repeated at spaced-apart intervals over an extended period of time whereby to monitor the patient'"'"'s diastolic and systolic blood pressures over said period of time.

24. An apparatus for obtaining certain blood pressure parameters of a given patient including his systolic and diastolic pressures, comprising:

(a) a blood pressure cuff or pad positioned at the appropriate location adjacent a suitable artery of the patient,

(b) means for placing said cuff at different pressure levels including levels below the anticipated systolic pressure of the patient but including levels above and below the anticipated blood pressures of the patient at selected first and second points in time t₁ and t₂ on the diastolic decline or systolic rise of his actual blood pressure waveform; and

thereby producing cuff pulses at said different pressure levels;

(c) means responsive to said cuff pulse for measuring the change in cuff pressure Δ

P at each of said different levels of cuff pressure for relatively narrow first and second intervals of time Δ

t₁ and Δ

t₂ containing times t₁ and t₂, respectively, on the diastolic decline of the patient'"'"'s actual blood pressure waveform;

(d) means for generating a transformation curve unique to said patient from at least some of said measurements;

(e) means of determining the actual blood pressures D₁ and D₂ of the patient at times t₁ and t₂, respectively, on the patient'"'"'s waveform from said measurements;

(f) means responsive to a selected one of said cuff pulses, said transformation curve and said actual blood pressures, D₁ and D₂ for establishing the positional relationship between said transformation curve and selected cuff pulse and the correct scaling of the latter relative to said transformation curve; and

(g) means responsive to said correctly scaled cuff pulse and its positional relationship with said transformation curve for determining the systolic pressure of the patient and his diastolic pressure if the latter is not blood pressure D₁ or D₂.

25. An apparatus according to claim 24 wherein the first point in time t₁ is selected to be in close proximity to the beginning of the systolic rise portion of the patient'"'"'s actual blood pressure waveform, whereby D₁ corresponds nearly to the patient'"'"'s diastolic pressure.

26. An apparatus according to claim 24 wherein said transformation curve generating means includes means for integrating over time the measurements Δ

P at each of said different levels of cuff pressure for only one of said intervals of time Δ

t₁ and Δ

t₂.

27. An apparatus according to claim 24 wherein said transformation curve generating means includes means for integrating over time the measurements Δ

P at each of said different levels of cuff pressure for each of said intervals of time Δ

t₁ and Δ

t₂ and means for averaging the integrated measurements at each pressure level to produce an averaged transformation curve.

28. An apparatus according to claim 24 including means for determining the blood pressures of said patient at a sufficient number of points in time other than t₁ and t₂ from said correctly scaled cuff pulse and from its positional relationship with said transformation curve to reproduce the actual blood pressure waveform of said patient.

29. A method of obtaining certain blood pressure parameters of a given patient including his systolic and diastolic pressures, comprising the steps of:

(a) positioning a blood pressure cuff or pad at the appropriate location adjacent a suitable artery of the patient;

(b) selecting first and second points in time t₁ and t₂ on the patient'"'"'s actual blood pressure waveform below the patient'"'"'s anticipated systolic pressure;

(c) placing said cuff or pad at different pressure levels including levels above and below the anticipated blood pressures of the patient at the selected points in time t₁ and t₂ on his actual waveform, and thereby producing cuff pulses at said different pressure levels;

(d) from said cuff pulses, measuring the change in cuff pressure Δ

P at each of said different levels of cuff pressure for relatively narrow first and second intervals of time Δ

t₁ and Δ

t₂ containing times t₁ and t₂, respectively, on the patient'"'"'s actual blood pressure waveform;

(e) generating a transformation curve unique to said patient at least some of said measurements;

(f) determining the actual blood pressures D₁ and D₂ of the patient at times t₁ and t₂, respectively, on the patient'"'"'s waveform from said measurements;

(g) selecting a cuff pulse at one of said different levels of cuff pressure and, using said transformation curve and said actual blood pressures, D₁ and D₂, establishing the positional relationship between said transformation curve and selected cuff pulse and the correct scaling of the latter relative to said transformation curve; and

(h) from said correctly scaled cuff pulse and from its positional relationship with said transformation curve, determining the systolic pressure of the patient and his diastolic pressure, if the latter is not blood pressure D₁ or D₂.

30. A method according to claim 29 wherein said points in time t₁ and t₂ lie on the diastolic decline of said patient'"'"'s blood pressure waveform.

31. A method according to claim 29 wherein said points in time t₁ and t₂ lie on the systolic rise of said patient'"'"'s waveform.

32. An apparatus for obtaining certain blood pressure parameters of a given patient including his systolic and diastolic pressures, comprising:

(a) a blood pressure cuff or pad positioned at the appropriate location adjacent a suitable artery of the patient,

(b) means for placing said cuff at different pressure levels below the anticipated systolic pressure of the patient but including levels above and below the anticipated blood pressures of that patient at selected first and second points in time t₁ and t₂ on his actual blood pressure waveform, and thereby producing cuff pulses at said different pressure levels;

(c) means responsive to said cuff pulses for measuring the change in cuff pressure Δ

P at each of said different levels of cuff pressure for relatively narrow first and second intervals of time Δ

t₁ and Δ

t₂ containing times t₁ and t₂, respectively, on the diastolic decline of the patient'"'"'s actual blood pressure waveform;

(d) means for generating a transformation curve unique to said patient from at least some of said measurements;

(e) means of determining the actual blood pressures D₁ and D₂ of the patient at times from said measurements;

(f) means responsive to a selected one of said cuff pulses, said transformation curve and said actual blood pressures D₁ and D₂ for establishing the positional relationship between said transformation curve and selected cuff pulse and the correct scaling of the latter relative to said transformation curve; and

(g) means responsive to said correctly scaled cuff pulse and its positional relationship with said transformation curve for determining the systolic pressure of the patient and his diastolic pressure if the latter is not blood pressure D₁ or D₂ 1.

33. A method of obtaining certain blood pressure parameters of a given patient including his systolic and diastolic pressures, comprising the steps of:

(a) positioning a blood pressure cuff or pad at the appropriate location adjacent a suitable artery of the patient,

(b) selecting first and second points in time t₁ and t₂ on the patient'"'"'s actual blood pressure waveform below the patient'"'"'s anticipated systolic pressure;

(c) placing said cuff or pad at different pressure levels including levels above and below the anticipated blood pressures of the patient at the selected points in time t₁ and t₂ on his actual waveform, and thereby producing cuff pulses at said different pressure levels,

(d) from said cuff pulses, measuring the change in cuff pressure Δ

P at each of said different levels of cuff pressure for relatively narrow first and second intervals of time Δ

t₁ and Δ

t₂ containing times t₁ and t₂, respectively, on the patient'"'"'s actual blood pressure waveform;

(e) from said cuff pulses and cuff pressures Δ

P, generating information sufficient to provide the patient'"'"'s systolic pressure; and

(f) from said information determining the patient'"'"'s systolic pressure.

34. An apparatus for obtaining certain blood pressure parameters of a given patient including his systolic and diastolic pressures, comprising:

(a) a blood pressure cuff or pad positioned at the appropriate location adjacent a suitable artery of the patient;

(b) means for placing said cuff at different pressure levels below the anticipated systolic pressure of the patient but including levels above and below the anticipated blood pressures of the patient at selected first and second points in time t₁ and t₂ on his actual blood pressure waveform, and thereby producing cuff pulses at said different pressure levels;

(c) means responsive to said cuff pulses for measuring the change in cuff pressure Δ

P at each of said different levels of cuff pressure for relatively narrow first and second intervals of time Δ

t₁ and Δ

t₂ containing times t₁ and t₂, respectively, on the diastolic decline of the patient'"'"'s actual blood pressure waveform;

(d) means responsive to said cuff pulses and said cuff pressures Δ

P for generating information sufficient to provide the patient'"'"'s systolic pressure; and

(e) means responsive to said information to determine the patient'"'"'s systolic pressure.