U.S. patent number RE33,834 [Application Number 07/556,101] was granted by the patent office on 1992-03-03 for heart-related parameters monitoring apparatus.
This patent grant is currently assigned to Priyamvada Sankar, Sylvia Warner. Invention is credited to Glenfield Warner.
United States Patent |
RE33,834 |
Warner |
March 3, 1992 |
Heart-related parameters monitoring apparatus
Abstract
A non-invasive method, and an apparatus, for determining
heart-related parameters in patients. The method and apparatus
determine pulse pressure, time constant of the arterial system,
systolic and diastolic pressure, peripheral resistance, cardiac
output and mean arterial blood pressure.
Inventors: |
Warner; Glenfield (St. Laurent,
CA) |
Assignee: |
Warner; Sylvia (St. Laurent,
CA)
Sankar; Priyamvada (Brossard, CA)
|
Family
ID: |
27490065 |
Appl.
No.: |
07/556,101 |
Filed: |
July 20, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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59520 |
Jun 8, 1987 |
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807693 |
Dec 11, 1985 |
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608955 |
May 10, 1984 |
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Reissue of: |
105803 |
Oct 8, 1987 |
04834107 |
May 30, 1989 |
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Current U.S.
Class: |
600/481; 600/479;
600/504; 600/507; 600/531 |
Current CPC
Class: |
A61B
5/02007 (20130101); A61B 5/029 (20130101); A61B
5/021 (20130101) |
Current International
Class: |
A61B
5/021 (20060101); A61B 5/026 (20060101); A61B
5/029 (20060101); G06F 17/00 (20060101); A61B
005/02 () |
Field of
Search: |
;128/666,668,691,694,713 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Pal; Asok
Attorney, Agent or Firm: Chilton, Alix & Van Kirk
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This .Iadd.application is a reissue of application Ser. No.
105,803, filed Oct. 8, 1987, now U.S. Pat. No. 4,834,107, which
.Iaddend.application is a continuation-in-part application Ser. No.
059,520, filed June 8, .Iadd.now abandoned .Iaddend. which is a
continuation-in-part application Ser. No. 807,693, filed Dec. 11,
1985, now abandoned which is a continuation-in-part of parent
application Ser. No. 608,955, filed May 10, 1984, now all
abandoned.
Claims
I claim:
1. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising;
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude, said minimum aplitude,
said maximum rate of change of said signal, said first difference,
said second different, said first time interval, and said second
time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein means for calculating calculates the magnitude of the pulse
pressure parameter in accordance with the following expression;
##EQU17## wherein P.sub.pi =pulse pressure during cycle i
K.sub.pp =constant determined by a first calibration
r.sub.1 =constant
r.sub.2 =constant
R.sub.il =(.DELTA.V.sub.iVm /.DELTA.V.sub.i)
where .DELTA.V.sub.iVm =volume change at time t.sub.iVm during
cycle i corresponding to maximum rate of volume change,
V.sub.imax
.DELTA.V.sub.i =maximum volume change during cycle i
.DELTA.t.sub.iVm =time interval from start of cycle i to time of
maximum rate of volume change V.sub.imax.
2. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising;
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby .Iadd.detect .Iaddend.said blood volume, and thereby said
blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude, said minimum
.[.aplitude,.]. .Iadd.amplitude, .Iaddend.said maximum rate of
change of said signal, said first difference, said second
.[.different,.]. .Iadd.difference, .Iaddend.said first time
interval, and said second time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein means for calculating .[.calculates.]. .Iadd.calculates
.Iaddend.the magnitude of the mean arterial blood pressure,
P.sub.mi parameter in accordance with the following expression:
##EQU18## where K.sub.4 =constant determined for each subject
b.sub.3 =constant
P.sub.mmi =pseudo mean arterial blood pressure during cycle i
.[..DELTA..sub.i .]. .Iadd..DELTA.V.sub.i .Iaddend.=maximum volume
change during cycle i ##EQU19##
3. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising;
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said volume variation being cyclic in nature whereby said signal
comprises a cyclic curve having, in each cycle of variation, a
variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude, said minimum
.[.aplitude,.]. .Iadd.amplitude, .Iaddend.said maximum rate of
change of said signal, said first difference, said second
.[.different,.]. .Iadd.difference, .Iaddend.said first time
interval, and said second time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein means for calculating calculates the magnitude of the
systolic pressure (P.sub.si) parameter in accordance with the
following expression:
wherein
g.sub.0 =constant.
4. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising:
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude, said minimum
.[.aplitude,.]. .Iadd.amplitude, .Iaddend.said maximum rate of
change of said signal, said first difference, said second
.[.different,.]. .Iadd.difference, .Iaddend.said first time
interval, and said second time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein means for calculating calculates the magnitude of the
systolic pressure (P.sub.si) parameter in accordance with the
following expression:
wherein:
g.sub.i =(.DELTA.V.sub.iAV /.DELTA.V.sub.i)
P.sub.pi =pulse pressure during cycle i
.DELTA.V.sub.i =represented by said first difference
.DELTA.V.sub.iAV =represented by the difference between said
minimum amplitude and an amplitude equal to the average value of a
pulse in a cycle i.
5. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising;
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said blood volume variation being .[.cycle.]. .Iadd.cyclic
.Iaddend.in nature whereby said signal comprises a cyclic curve
having, in each cycle of variation, a variable slope, a maximum
amplitude representative of the maximum amount of blood volume, a
minimum amplitude representative of the minimum amount of blood
volume, a first time interval between said minimum amplitude and
said maximum amplitude, a maximum rate of change of said signal
being representative of the maximum rate of increase of blood
volume, a second time interval between the minimum amplitude and
the time of the maximum rate of change of said signal, a first
difference in amplitude between said maximum amplitude and said
minimum amplitude, a second difference in amplitude between the
maximum amplitude and the amplitude at the time of maximum rate of
change of said signal being representative of the difference in
volume between the maximum amount of blood volume and the volume at
the time of maximum rate of change of said blood volume, and a
pulse repetition period;
means for measuring said maximum amplitude, said minimum
.[.aplitude,.]. .Iadd.amplitude, .Iaddend.said maximum rate of
change of said signal, said first difference, said second
.[.different,.]. .Iadd.difference, .Iaddend.said first time
interval, and said second time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein means for calculating calculates the magnitude of the
arterial blood pressure, P.sub.mi parameter in accordance with the
following expression: ##EQU20## where K.sub.4 =constant determined
for each subject
b.sub.3 =constant
P.sub.mmi =pseudo mean arterial blood pressure during cycle i
.DELTA.V.sub.i =maximum volume change during cycle i ##EQU21##
P.sub.o =constant where
G(t)=a function of t.
6. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representative of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of the pulse pressure parameter in
accordance with the following expression: ##EQU22## wherein
P.sub.pi =pulse pressure during cycle i
K.sub.pp =constant determined by a first calibration
r.sub.1 =constant
r.sub.2 =constant
R.sub.il =(.DELTA.V.sub.iVm /.DELTA.V.sub.i)
where
.[..DELTA.V.sub.iVm =volume change at time t.sub.iVm during cycle i
corresponding to maximum rate of volume change, V.sub.imax.].
.Iadd..DELTA.V.sub.iVm =volume change at time t.sub.iVm during
cycle i corresponding to maximum rate of volume change, V.sub.imax
.Iaddend.
.DELTA.V.sub.i =maximum volume change during cycle i
.DELTA.t.sub.iVm =time interval from start of cycle i to time of
maximum rate of volume change V.sub.imax.
7. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representative of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of the mean .[.artial.]. .Iadd.arterial
.Iaddend.pressure P.sub.mi in accordance with the following
expression: ##EQU23## where K.sub.4 =constant determined for each
subject
b.sub.3 =constant
P.sub.mmi =pseudo mean arterial blood pressure during cycle i
.DELTA.V.sub.i =maximum volume change during cycle i
.DELTA.V.sub.imax =maximum time rate of change of .DELTA.V.sub.i
=V.sub.imax ##EQU24##
8. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representative of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of the systolic pressure (P.sub.si
parameter in accordance with the following expression:
wherein
g.sub.0 =constant.
9. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representive of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of the systolic pressure (P.sub.si)
parameter in accordance with the following expression:
wherein:
g.sub.i =(.DELTA.V.sub.iAV /.DELTA.V.sub.i)
P.sub.pi =pulse pressure during cycle i
.DELTA.V.sub.i =represented by said first difference
.DELTA.V.sub.iAV =represented by the difference between said
minimum amplitude and an amplitude equal to the average value of a
pulse in a cycle i.
10. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representative of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of the arterial blood pressure, P.sub.mi
parameter in accordance with the following expression: ##EQU25##
where
K.sub.4 =constant determined for each subject
b.sub.3 =constant
P.sub.mmi =pseudo mean arterial blood pressure during cycle i
.DELTA.V.sub.i =maximum volume change during cycle i
.DELTA.V.sub.imax =maximum time rate of change of V.sub.i
=V.sub.imax
P.sub.o =constant
G(t)=a function of t and T.
11. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising:
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude, said minimum
.[.aplitude,.]. .Iadd.amplitude, .Iaddend.said maximum rate of
change of said signal, said first difference, said second
.[.different,.]. .Iadd.difference, .Iaddend.said first time
interval, and said second time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein means for calculating calculates the magnitude of the pulse
pressure parameter in accordance with the following expression:
##EQU26## wherein P.sub.pi =pulse pressure during cycle i
K.sub.pp =constant determined by a first calibration
r.sub.1 =constant
r.sub.2 =constant
R.sub.i1 =.DELTA.V.sub.iVm /.DELTA.V.sub.i
where
.DELTA.V.sub.iVm =volume change at preselected time t.sub.iVm
during cycle i
.DELTA.V.sub.i =maximum volume change during cycle i
.DELTA.t.sub.iVm =time interval from start of cycle i to
preselected time of t.sub.iVm.
12. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representative of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
.[.charge.]. .Iadd.change .Iaddend.of blood volume, a second time
interval between the minimum amplitude and the time of the maximum
rate of change of said signal, a first difference in amplitude
between said maximum amplitude and said minimum amplitude, a second
difference in amplitude between the maximum amplitude and the
amplitude at the time of maximum change of rate of said signal
being representative of the difference in volume between the
maximum amount of blood volume and the volume at the time of
maximum rate of change of said blood volume, and a pulse repetition
period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of the pulse pressure parameter in
accordance with the following expression: ##EQU27## wherein
P.sub.pi =pulse pressure during cycle i
K.sub.pp =constant determined by a first calibration
r.sub.1 =constant
r.sub.2 =constant
R.sub.i1 =(.DELTA.V.sub.iVm /V.sub.i)
where
.DELTA.V.sub.iVm =volume change at preselected time t.sub.iVm
during cycle i
.DELTA.V.sub.i =maximum volume change during cycle i
.DELTA.t.sub.iVm =time interval from start of cylcle i to
predetermined time of t.sub.iVm.
13. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising;
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude, said minimum amplitude,
said maximum rate of change of said signal, said first difference,
said second different, said first time interval, and said second
time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein the means for calculating calculates the magnitude of the
mean pressure parameter in accordance with the following
expression:
(1) P'.sub.mi =K.sub.1 r.sub.ic.sup.a
where
K.sub.1 =calibration constant
.[.P'.sub.mi =(P.sub.s +P.sub.d)/2-P.sub.o.].
P.sub.si =systolic blood pressure, in cycle i
.[.P.sub.mi =(P.sub.s +P.sub.d)/2.].
P.sub.di =diastolic blood pressure, in cycle i
a=constant
P.sub.o =constant.
14. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal .[.representation.].
.Iadd.representative .Iaddend.of said blood volume, and thereby
said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of mean pulse pressure in accordance with
the following expression:
.[.(1) P.sub.mi =K.sub.1 r.sub.ic.sup.a.].
.Iadd.(1) P'.sub.mi =K.sub.l r.sub.ic a .Iaddend.
where
K.sub.1 =calibration constant
.[.P'.sub.mi =(P.sub.s +P.sub.d)/2-P.sub.o.].
.Iadd.P'.sub.mi =(P.sub.si +P.sub.di)/2-P.sub.o .Iaddend.
P.sub.si =systolic blood pressure, in cycle i
.[.P.sub.mi =(P.sub.s +P.sub.d)/2.].
.Iadd.P.sub.mi =(P.sub.si +P.sub.di)/2 .Iaddend.
P.sub.di =diastolic blood pressure, in cycle i
a=constant
P.sub.o =constant.
15. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising;
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude, said minimum amplitude,
said maximum rate of change of said signal, said first difference,
said second .[.different,.]. .Iadd.difference, .Iaddend.said first
time interval, and said second time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein the means for calculating calculates implicitly the
magnitude of the mean pulse pressure in accordance with the
following expression: ##EQU28## where P.sub.mo =constant at
calibration
.phi..sub.1i +.phi..sub.2i =PP.sub.i =pulse pressure during cycle
i
k=constant
j=constant
P.sub.si =P.sub.mo +.phi..sub.2i +P.sub.o
P.sub.di =P.sub.mo -.phi..sub.1i +P.sub.o
P.sub.mi =(P.sub. si +P.sub.di)/2
P.sub.o =constant
r.sub.i =ratio of exponentials
K.sub.3 =coefficient (variable or constant).
16. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representative of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and the said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
wherein the means for calculating calculates implicitly the
magnitude of mean pulse pressure in accordance with the following
.[.expressure.]. .Iadd.expression.Iaddend.: ##EQU29## where
P.sub.mo =constant at calibration
.phi..sub.1i +.phi..sub.2i =PP.sub.i =pulse pressure during cycle
i
k=constant
j=constant
.[.P.sub.2i =P.sub.mo +.phi..sub.2i +P.sub.o.].
.Iadd.P.sub.si =P.sub.mo +.phi..sub.2i +P.sub.o .Iaddend.
P.sub.di =P.sub.mo -.phi..sub.1i +P.sub.o
P.sub.mi =(P.sub. si +P.sub.di)/2
P.sub.o =constant
r.sub.i =ratio of exponentials
K.sub.3 =coefficient (variable or constant). .Iadd.
17. Apparatus for determining the magnitude of heart-related
parameters in a patient;
comprising:
means for detecting blood volume, and thereby blood volume
variation, in said patient, and for providing a signal
representative of said blood volume, and thereby said blood volume
variation;
said means for detecting being attachable to said patient to
thereby detect said blood volume, and thereby said blood volume
variation;
said blood variation being cyclic in nature whereby said signal
comprises a cyclic curve having, in each cycle of variation, a
variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
minimum amplitude and said maximum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
increase of blood volume, a second time interval between the
minimum amplitude and the time of the maximum rate of change of
said signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum rate of change of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
means for measuring said maximum amplitude; said minimum amplitude,
said maximum rate of change of said signal, said first difference,
said second difference, said first time interval, and said second
time interval; and
means for calculating the magnitude of selected ones of said
parameters, said means for calculating being connected to both said
means for detecting and means for measuring;
wherein means for calculating calculates the magnitude of the pulse
pressure parameter in accordance with the following expression;
##EQU30## where PP.sub.i =Pulse Pressure-- P.sub.s -P.sub.d
P.sub.s =Systolic blood pressure
P.sub.d =diastolic blood pressure
k=constant
K'=constant..Iaddend. .Iadd.
18. A method for determining the magnitude of heart-related
parameters in a patient;
comprising:
detecting blood volume, and thereby blood volume variation, in said
patient and providing a signal representative of said blood volume,
and thereby said blood volume variation;
said blood volume variation being cyclic in nature whereby said
signal comprises a cyclic curve having, in each cycle of variation,
a variable slope, a maximum amplitude representative of the maximum
amount of blood volume, a minimum amplitude representative of the
minimum amount of blood volume, a first time interval between said
maximum amplitude and said minimum amplitude, a maximum rate of
change of said signal being representative of the maximum rate of
change of blood volume, a second time interval between the minimum
amplitude and the time of the maximum rate of change of said
signal, a first difference in amplitude between said maximum
amplitude and said minimum amplitude, a second difference in
amplitude between the maximum amplitude and the amplitude at the
time of maximum change of rate of said signal being representative
of the difference in volume between the maximum amount of blood
volume and the volume at the time of maximum rate of change of said
blood volume, and a pulse repetition period;
measuring said maximum amplitude, said minimum amplitude, said
maximum rate of change of said signal, said first difference, said
second difference, said first time interval, and said second time
interval; and
calculating the magnitude of the mean arterial pressure P.sub.mi in
accordance with the following expression: ##EQU31## where PP.sub.i
=Pulse Pressure=P.sub.s -P.sub.d
P.sub.s =Systolic blood pressure
P.sub.d =Diastolic blood pressure
k=constant
K'=constant.
Description
BACKGROUND OF INVENTION
1. Field of the Invention
The invention relates to a non-invasive method of measuring
arterial blood pressure and cardiac output. The invention also
relates to an apparatus for carrying out the method.
2. Description of Prior Art
Non-invasive methods and apparatus for measuring arterial blood
pressure and cardiac output are known in the art. Once such method
and apparatus is illustrated in U.S. Pat. No. 4,030,485, Warner,
issued June 21, 1977. A second such method and apparatus is taught
in U.S. Pat. No. 4,418,700, Warner, issued Dec. 6, 1983. The
present invention constitutes an improvement and refinement of the
method and apparatus as taught in the latter patent.
SUMMARY OF INVENTION
The invention relates to a non-invasive method, and an apparatus
for determining heart-related parameters in patients. The method
and apparatus determine pulse pressure, time constant of the
arterial system, systolic and diastolic pressure, peripheral
resistance, and cardiac output and means arterial blood
pressure.
BRIEF DESCRIPTION OF DRAWINGS
The invention will be better understood by an examination of the
following description together with the accompanying drawings in
which:
FIG. 1 is a block diagram of the apparatus for carrying out the
inventive method;
FIG. 2 is a typical sensor output of the system as illustrated in
FIG. 1;
FIG. 3 illustrates arterial blood pressure pulses;
FIGS. 4, 4a and 4b illustrate a blood volume pulse;
FIG. 5 illustrates a blood volume pulse and a blood pressure pulse
to illustrate the ratio g; and
FIG. 6 is a simplified flowchart for a computer program for
performing calculations in accordance with the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
As seen in FIG. 1, an apparatus in accordance with the invention
comprises a volume sensor such as a photo-electric plethysmograph
S, an amplifier A.sub.1, an analog to digital converter A.sub.2, a
microcomputer M and a display device D. The plethysmograph sensor S
is attached to, for example, the earlobe of a subject. The sensor
could also be attached to other suitable parts of the body such as
the forehead, fingertips or toes.
As is known, the plethysmograph, detects changes in blood volume of
the region to which it is attached. A typical sensor output signal
is shown in FIG. 2. As seen in FIG. 2, the output signal has a
pulsating component and a DC component.
The output of the sensor is applied to the plethysmograph amplifier
A.sub.1 where it is amplified and filtered and the DC component is
discarded. The output of A.sub.1 has a DC component, but this is
not directly related to the sensor DC component.
The output of A.sub.1 is fed to the analog to digital (A/D)
converter A.sub.2 which digitizes the signal. In a preferred
embodiment, the sampling rate is 100 per second.
Microcomputer M accepts signals from A.sub.2 and processes them
according to the instructions it contains. These instructions are
schematically represented in the simplified flowchart of FIG.
6.
The computer quantities are then displayed on a CRT monitor D or
other suitable display means.
THEORY
Arterial blood pressure pulses are shown in FIG. 3. The shape of
these curves vary according to the site where they are measured.
The highest pressure reached during a cycle i is called the
arterial systolic blood pressure, P.sub.si. The lowest pressure
reached during the same cycle is called the arterial diastolic
blood pressure, P.sub.di. The pressure rise from P.sub.di to
p.sub.si in the same cycle is the pulse pressure, p.sub.pi.
By definition
To find P.sub.pi
A plethysmographic pulse is shown in FIG. 4. The minimum value at
the beginning of the pulse is V.sub.imin. The maximum value of the
pulse is V.sub.imax. As the pulse volume rises from V.sub.imin to
V.sub.imax, the time rate of volume change reaches a maximum
V.sub.imax at time t.sub.iVm. The pulse volume at time t.sub.iVm is
V.sub.iVm.
let ##EQU1##
In addition to finding the values of V.sub.iVm corresponding to
V.sub.imax, see U.S. Pat. No. 4,418,700, Warner, values of
V.sub.iVm are also found corresponding to V.sub.imax.sup.-1,
V.sub.imax.sup.-2, . . . V.sub.imax.sup.-k, where k is a function
of V.sub.imax.
All of the values of V.sub.iVm corresponding to the time rates of
volume change lying between and including V.sub.imax and
v.sub.imax.sup.-k are averaged and used to compute
.DELTA.V.sub.iVm.
The average value of V.sub.iV m is ##EQU2## where n0=number of
values of V.sub.iV.sbsb.0 m corresponding to V.sub.imax ##EQU3##
nk=number of values of V.sub.iV.sbsb.k m corresponding to
V.sub.imax.sup.-k
k=(V.sub.imax/m) (integral values only)+1
m=constant . . . a preferred value of m=20
l=constant . . . a preferred value of l=1 ##EQU4## K.sub.pp
=constant determined by a first calibration r.sub.1 =constant . . .
preferably equal to 0
r.sub.2 =constant . . . preferably equal to 0
0.ltoreq..alpha..ltoreq.1
R.sub.i1 can now be defined, as per equation (2) above, but using
the average value of V.sub.iVm so that equation (2) can be
rewritten ##EQU5##
From FIG. 4 ##EQU6## wherein
or
No other calibration should be required with different subjects.
However, if desired, K.sub.pp can be determined for each
subject.
To find mean blood pressure
The mean blood pressure P.sub.mi during a cycle i is given by
##EQU7## b.sub.3 =exponent . . . the preferred value of b.sub.3 is
equal to 0.5 K.sub.4 =constant determined at calibration for each
subject. It is only necessary to find this constant once for each
subject. The measurements carried out at different times on the
same subject do not require separate calibration
P.sub.0 =constant . . . preferred 25 mmHg ##EQU8## where g.sub.i
=(.DELTA.V.sub.iAV /.DELTA.V.sub.i)
.DELTA.V.sub.iAV =average value of .DELTA.V.sub.i over the time
interval T.sub.i
The variable g.sub.i can take on a constant value g.sub.0 whose
preferred value is 0.333.
Alternatively, mean blood pressure can be determined using the
following expression: ##EQU9## (for definition of r.sub.i see
Equation 10 below); where
G(t)=a function of t, in a particular case,
G(t)=(.phi..sub.c /.phi..sub.i)
.phi..sub.c =.[.(.].(1/.DELTA.t.sub.c).[.).]..sup.Y
.phi..sub.i =.[.(.].(1/.DELTA.t.sub.i).[.).]..sup.Y
.DELTA.t.sub.c =(.DELTA.t'.sub.i.phi.c
.DELTA.t.sub.i =.DELTA.t'.sub.i.phi.
where
.[.T.sub.c =T at calibration.]. .Iadd..DELTA.t.sub.c =.DELTA.t at
calibration .DELTA.t'.sub.i.phi. (see FIG. 4B) .Iaddend.
.[.t.sub.c =t at calibration .DELTA.t'.sub.i.phi..sbsb.c (see FIG.
4B).].
.[..phi..sub.c =(T.sub.c /t.sub.c)=(T/t) at calibration.].
.Iadd..phi..sub.c =(1/.DELTA.t).sup.y at calibration.Iaddend.
y=constant
The remainder of the terms in equation 5' are the same as similar
terms in equation 5.
Determination of ratio R (FIG. 4b)
From FIG. 4b, the ratio R is
R.sub.i =(.DELTA.V.sub.it /.DELTA.V.sub.i)
where
.DELTA.V.sub.it =change in volume at predetermined time ti
.DELTA.V.sub.i =total volume change during cycle i
t.sub.i =time such that .DELTA.t.sub.i =K.sub.T
.DELTA.t'.sub.i.phi.
K.sub.T =constant
Estimation of pulse pressure, PP ##EQU10## where PP.sub.i =pulse
pressure=p.sub.s -P.sub.d
P.sub.s =systolic blood pressure
P.sub.d =diastolic blood pressure
k=constant
K'.sub.T =constant .perspectiveto. K.sub.T
In FIG. 4B
Determination of r
From FIG. 4
where
V.sub.imax =maximum time rate of volume increase in cycle i
.DELTA.V.sub.i =total volume increase during cycle i
From FIG. 4b
.Iadd.r.sub.i =(V.sub.it /V.sub.i)G(t) .Iaddend.
V.sub.it =time rate of increase of volume V.sub.i(t) at time
t.sub.i
.[..DELTA.V.sub.i =total volume increase of volume during.].
.Iadd..DELTA.V.sub.i =total increase of volume during time interval
.DELTA.t.sub.i.phi..Iaddend.
Estimation of Mean Blood Pressure
(1) P.sub.mi '=K.sub.1 r.sub.ic.sup.a
K.sub.1 =calibration constant
P.sub.mi '=(P.sub. s +P.sub.d)/2-P.sub.o
P.sub.si =systolic blood pressure, in cycle i
P.sub.mi =(P.sub. s +P.sub.d)/2
P.sub.di =diastolic blood pressure, in cycle i
a=constant
P.sub.o =constant
.[.(2) e.sup.kp mi=K.sub.2 R.sub.ic.sup.b.]. (2) .Iadd.e.sup.kp
mi=K.sub.2 r.sub.ic.sup.b .Iaddend.
where
K.sub.2 =constant (calibration)
b=constant ##EQU14## where P.sub.mo =constant at calibration
.phi..sub.1i +.phi..sub.2i =PP.sub.i =pulse pressure during cycle
i
k=constant
j=constant
solve equation by making LHS=RHS by varying .phi..sub.1i and
.phi..sub.2i (.phi..sub.2i =PP.sub.i -.phi..sub.1i)
then
P.sub.si =P.sub.mo +.phi..sub.2i +P.sub.0
P.sub.di =P.sub.mo -.phi..sub.1i +P.sub.o
P.sub.mi =(P.sub. si +P.sub.di)/2
P.sub.0 =constant
r.sub.i =ratio of exponentials
K.sub.3 =coefficient (variable or constant)
Correction for r.sub.i
r.sub.i (corrected)=r.sub.ic =r.sub.i
e.sup.m(.phi..sbsp.o.sup.-.phi..sbsp.i)
m=constant
.phi..sub.0 =PP.sub.i at calibration
.phi..sub.i =current value of PP.sub.i.
Equation (9) above is only one form which this particular equation
can take. By simple mathematical manipulations, the invention may
take two other forms as per (10) and (11) below. What follows is
the manipulations as well as the two other forms of the
equation:
As above noted
Let
P'.sub.si =P.sub.si -P.sub.o
p'.sub.di =P.sub.di -P.sub.0
.phi..sub.2i +.phi..sub.1i =P'.sub.si -P'.sub.di
add and subtract P.sub.mo on RHS above
.phi..sub.2i and .phi..sub.1i can take on any values in satisfying
the above equation (A)
Put .phi..sub.2i =P'.sub.si -P.sub.mo
and .phi..sub.1i =P.sub.mo -P'.sub.di in equation (9)
then ##EQU15## simplifying the denominator ##EQU16##
To solve equation 11:
(1) Set P'.sub.di =P'.sub.si -PP.sub.i and solve for P'.sub.si
.Iadd.P'.sub.mi =(P.sub.si +P.sub.di)/2-P.sub.o .Iaddend.
(2) Set P'.sub.si =P'.sub.di -PP.sub.i and solve for P'.sub.di
Although particular embodiments have been illustrated, this was for
the purpose of describing, but not limiting, the invention. Various
modifications, which will come readily to the mind of one skilled
in the art, are within the scope of the invention as defined in the
appended claims.
.Iadd.P.sub.mi =(P.sub.si +P.sub.di)/2 .Iaddend.
* * * * *