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.
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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 (psi parameter in accordance with the following expression: psi =Pmi +(1-g0)p pi wherein g0 =constant. 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 pmi in accordance with the following expression: ##EQU31## where PPi =Pulse Pressure=Ps -pd ps =Systolic blood pressure pd =Diastolic blood pressure k=constant K'=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 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 mean pulse pressure in accordance with the following expression: (1) pmi =K1 rica (1) p'mi =Kl ric a where K1 =calibration constant p'mi =(ps +pd)/2-po p'mi =(psi +pdi)/2-po psi =systolic blood pressure, in cycle i pmi =(ps +pd)/2 pmi =(psi +pdi)/2 pdi =diastolic blood pressure, in cycle i a=constant po =constant. 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 arterial pressure pmi in accordance with the following expression: ##EQU23## where K4 =constant determined for each subject b3 =constant pmmi =pseudo mean arterial blood pressure during cycle i ΔVi =maximum volume change during cycle i ΔVimax =maximum time rate of change of ΔVi =Vimax ##EQU24## 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, pmi parameter in accordance with the following expression: ##EQU25## where K4 =constant determined for each subject b3 =constant pmmi =pseudo mean arterial blood pressure during cycle i ΔVi =maximum volume change during cycle i ΔVimax =maximum time rate of change of Vi =Vimax po =constant G(t)=a function of t and t. 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 (psi) parameter in accordance with the following expression: psi =Pmi +(1-gi)p pi wherein: gi =(ΔViAV /ΔVi) ppi =pulse pressure during cycle i ΔVi =represented by said first difference ΔViAV =represented by the difference between said minimum amplitude and an amplitude equal to the average value of a pulse in a cycle i. 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 expression: ##EQU29## where pmo =constant at calibration φ1i +φ2i =PPi =pulse pressure during cycle i k=constant j=constant p2i =Pmo +φ2i +po psi =Pmo +φ2i +po pdi =Pmo -φ1i +po pmi =(p si +pdi)/2 po =constant ri =ratio of exponentials K3 =coefficient (variable or constant). 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 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: ##EQU27## wherein ppi =pulse pressure during cycle i Kpp =constant determined by a first calibration r1 =constant r2 =constant Ri1 =(ΔViVm /Vi) where ΔViVm =volume change at preselected time tiVm during cycle i ΔVi =maximum volume change during cycle i ΔtiVm =time interval from start of cylcle i to predetermined time of tiVm. 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 ppi =pulse pressure during cycle i Kpp =constant determined by a first calibration r1 =constant r2 =constant Ril =(ΔViVm /ΔVi) where ΔViVm =volume change at time tiVm during cycle i corresponding to maximum rate of volume change, Vimax ΔViVm =volume change at time tiVm during cycle i corresponding to maximum rate of volume change, Vimax ΔVi =maximum volume change during cycle i ΔtiVm =time interval from start of cycle i to time of maximum rate of volume change Vimax. 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, amplitude, said maximum rate of change of said signal, said first difference, said second different, 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 systolic pressure (psi) parameter in accordance with the following expression: psi =Pmi +(1-g0)p pi wherein g0 =constant. 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 PPi =Pulse pressure-- ps -pd ps =Systolic blood pressure pd =diastolic blood pressure k=constant K'=constant.
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'mi =K1 rica where K1 =calibration constant p'mi =(ps +pd)/2-po psi =systolic blood pressure, in cycle i pmi =(ps +pd)/2 pdi =diastolic blood pressure, in cycle i a=constant po =constant. 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 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, amplitude, said maximum rate of change of said signal, said first difference, said second different, 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 calculates the magnitude of the mean arterial blood pressure, pmi parameter in accordance with the following expression: ##EQU18## where K4 =constant determined for each subject b3 =constant pmmi =pseudo mean arterial blood pressure during cycle i Δi ΔVi =maximum volume change during cycle i ##EQU19## 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 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, amplitude, said maximum rate of change of said signal, said first difference, said second different, 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 arterial blood pressure, pmi parameter in accordance with the following expression: ##EQU20## where K4 =constant determined for each subject b3 =constant pmmi =pseudo mean arterial blood pressure during cycle i ΔVi =maximum volume change during cycle i ##EQU21## po =constant where G(t)=a function of t. 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, 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 the means for calculating calculates implicitly the magnitude of the mean pulse pressure in accordance with the following expression: ##EQU28## where pmo =constant at calibration φ1i +φ2i =PPi =pulse pressure during cycle i k=constant j=constant psi =Pmo +φ2i +po pdi =Pmo -φ1i +po pmi =(p si +pdi)/2 po =constant ri =ratio of exponentials K3 =coefficient (variable or 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, amplitude, said maximum rate of change of said signal, said first difference, said second different, 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 systolic pressure (psi) parameter in accordance with the following expression: psi =Pmi +(1-gi)p pi wherein: gi =(ΔViAV /ΔVi) ppi =pulse pressure during cycle i ΔVi =represented by said first difference ΔViAV =represented by the difference between said minimum amplitude and an amplitude equal to the average value of a pulse in a cycle i.
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, amplitude, said maximum rate of change of said signal, said first difference, said second different, 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: ##EQU26## wherein ppi =pulse pressure during cycle i Kpp =constant determined by a first calibration r1 =constant r2 =constant Ri1 =ΔViVm /ΔVi where ΔViVm =volume change at preselected time tiVm during cycle i ΔVi =maximum volume change during cycle i ΔtiVm =time interval from start of cycle i to preselected time of tiVm. 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 ppi =pulse pressure during cycle i Kpp =constant determined by a first calibration r1 =constant r2 =constant Ril =(ΔViVm /ΔVi) where ΔViVm =volume change at time tiVm during cycle i corresponding to maximum rate of volume change, Vimax ΔVi =maximum volume change during cycle i ΔtiVm =time interval from start of cycle i to time of maximum rate of volume change Vimax. |
This ((1/Δtc))Y
φi =((1/Δti))Y
Δtc =(Δt'iφc
Δti =Δt'iφ
where
Tc =T at calibration Δtc =Δt at calibration Δt'iφ (see FIG. 4B)
tc =t at calibration Δt'iφc (see FIG. 4B)
φc =(Tc /tc)=(T/t) at calibration φc =(1/Δt)y at calibration
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
Ri =(ΔVit /ΔVi)
where
ΔVit =change in volume at predetermined time ti
ΔVi =total volume change during cycle i
ti =time such that Δti =KT Δt'iφ
KT =constant
Estimation of pulse pressure, PP ##EQU10## where PPi =pulse pressure=ps -Pd
Ps =systolic blood pressure
Pd =diastolic blood pressure
k=constant
K'T =constant ≃ KT
In FIG. 4B
Δ V'i =ΔVi -ΔVit ##EQU11## wherein from the above equation: ##EQU12## multiply numerator and denominator by ekPP i ##EQU13##
Determination of r
From FIG. 4
ri = (Vimax /ΔVi)G(t)
where
Vimax =maximum time rate of volume increase in cycle i
ΔVi =total volume increase during cycle i
From FIG. 4b
ri = (Vit ΔVi)G(t)
ri =(Vit /Vi)G(t)
Vit =time rate of increase of volume Vi(t) at time ti
ΔVi =total volume increase of volume during ΔVi =total increase of volume during time interval Δtiφ
Estimation of Mean Blood Pressure
(1) Pmi '=K1 rica
K1 =calibration constant
Pmi '=(P s +Pd)/2-Po
Psi =systolic blood pressure, in cycle i
Pmi =(P s +Pd)/2
Pdi =diastolic blood pressure, in cycle i
a=constant
Po =constant
(2) ekp mi=K2 Ricb (2) ekp mi=K2 ricb
where
K2 =constant (calibration)
b=constant ##EQU14## where Pmo =constant at calibration
φ1i +φ2i =PPi =pulse pressure during cycle i
k=constant
j=constant
solve equation by making LHS=RHS by varying φ1i and φ2i (φ2i =PPi -φ1i)
then
Psi =Pmo +φ2i +P0
Pdi =Pmo -φ1i +Po
Pmi =(P si +Pdi)/2
P0 =constant
ri =ratio of exponentials
K3 =coefficient (variable or constant)
Correction for ri
ri (corrected)=ric =ri em(φo-φi)
m=constant
φ0 =PPi at calibration
φi =current value of PPi.
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
φ2i +φ1i =PPi =Psi -Pdi
φ2i +φ1i =(P si -Po)-(P di -Po)
Let
P'si =Psi -Po
p'di =Pdi -P0
φ2i +φ1i =P'si -P'di
add and subtract Pmo on RHS above
φ2i +φ1i =P'si -Pmo +Pmo -P'di (A)
φ2i and φ1i can take on any values in satisfying the above equation (A)
Put φ2i =P'si -Pmo
and φ1i =Pmo -P'di in equation (9)
then ##EQU15## simplifying the denominator ##EQU16##
To solve equation 11:
(1) Set P'di =P'si -PPi and solve for P'si
P'mi =(Psi +Pdi)/2-Po
(2) Set P'si =P'di -PPi and solve for P'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.
Pmi =(Psi +Pdi)/2
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