Heart-related parameters monitoring apparatus

• US RE33,834 E
• Filed: 07/20/1990
• Issued: 03/03/1992
• Est. Priority Date: 05/10/1984
• Status: Expired due to Term

• Current Assignee: Priyamvada Sankar, Sylvia Warner
• Original Assignee: Priyamvada Sankar, Sylvia Warner
• Inventors: Warner, Glenfield
• Primary Examiner(s): Pal, Asok
• Application Number:
  US07/556,101
• Time in Patent Office: 592 Days
• Field of Search: 128/666, 128/668, 128/691, 128/694, 128/713
• US Class Current: 600/481
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

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.

Claims

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_pi =pulse pressure during cycle i

K_pp =constant determined by a first calibration

r₁ =constant

r₂ =constant

R_il =(Δ

V_iVm /Δ

V_i)

where Δ

V_iVm =volume change at time t_iVm during cycle i corresponding to maximum rate of volume change, V_imax

Δ

V_i =maximum volume change during cycle i

Δ

t_iVm =time interval from start of cycle i to time of maximum rate of volume change V_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_mi parameter in accordance with the following expression;

##EQU18## where K₄ =constant determined for each subject

b₃ =constant

P_mmi =pseudo mean arterial blood pressure during cycle i

.[.Δ

_i .]. .Iadd.Δ

V_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_si) parameter in accordance with the following expression;

space="preserve" listing-type="equation"> P.sub.si =P.sub.mi +(1-g.sub.0)P.sub. pi

wherein

g₀ =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_si) parameter in accordance with the following expression;

space="preserve" listing-type="equation"> P.sub.si =P.sub.mi +(1-g.sub.i)P.sub. pi

wherein;

g_i =(Δ

V_iAV /Δ

V_i)

P_pi =pulse pressure during cycle i

Δ

V_i =represented by said first difference

Δ

V_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_mi parameter in accordance with the following expression;

##EQU20## where K₄ =constant determined for each subject

b₃ =constant

P_mmi =pseudo mean arterial blood pressure during cycle i

Δ

V_i =maximum volume change during cycle i ##EQU21## P_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_pi =pulse pressure during cycle i

K_pp =constant determined by a first calibration

r₁ =constant

r₂ =constant

R_il =(Δ

V_iVm /Δ

V_i)

where

.[.Δ

V_iVm =volume change at time t_iVm during cycle i corresponding to maximum rate of volume change, V_imax.].

.Iadd.Δ

V_iVm =volume change at time t_iVm during cycle i corresponding to maximum rate of volume change, V_imax .Iaddend.

Δ

V_i =maximum volume change during cycle i

Δ

t_iVm =time interval from start of cycle i to time of maximum rate of volume change V_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_mi in accordance with the following expression;

##EQU23## where K₄ =constant determined for each subject

b₃ =constant

P_mmi =pseudo mean arterial blood pressure during cycle i

Δ

V_i =maximum volume change during cycle i

Δ

V_imax =maximum time rate of change of Δ

V_i =V_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_si parameter in accordance with the following expression;

space="preserve" listing-type="equation"> P.sub.si =P.sub.mi +(1-g.sub.0)P.sub. pi

wherein

g₀ =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_si) parameter in accordance with the following expression;

space="preserve" listing-type="equation"> P.sub.si =P.sub.mi +(1-g.sub.i)P.sub. pi

wherein;

g_i =(Δ

V_iAV /Δ

V_i)

P_pi =pulse pressure during cycle i

Δ

V_i =represented by said first difference

Δ

V_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_mi parameter in accordance with the following expression;

##EQU25## where

K₄ =constant determined for each subject

b₃ =constant

P_mmi =pseudo mean arterial blood pressure during cycle i

Δ

V_i =maximum volume change during cycle i

Δ

V_imax =maximum time rate of change of V_i =V_imax

P_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_pi =pulse pressure during cycle i

K_pp =constant determined by a first calibration

r₁ =constant

r₂ =constant

R_i1 =Δ

V_iVm /Δ

V_i

where

Δ

V_iVm =volume change at preselected time t_iVm during cycle i

Δ

V_i =maximum volume change during cycle i

Δ

t_iVm =time interval from start of cycle i to preselected time of t_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_pi =pulse pressure during cycle i

K_pp =constant determined by a first calibration

r₁ =constant

r₂ =constant

R_i1 =(Δ

V_iVm /V_i)

where

Δ

V_iVm =volume change at preselected time t_iVm during cycle i

Δ

V_i =maximum volume change during cycle i

Δ

t_iVm =time interval from start of cylcle i to predetermined time of t_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'"'"'_mi =K₁ r_ic^a

where

K₁ =calibration constant

.[.P'"'"'_mi =(P_s +P_d)/2-P_o.].

P_si =systolic blood pressure, in cycle i

.[.P_mi =(P_s +P_d)/2.].

P_di =diastolic blood pressure, in cycle i

a=constant

P_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_mi =K₁ r_ic^a.].

.Iadd.(1) P'"'"'_mi =K_l r_ic a .Iaddend.

where

K₁ =calibration constant

.[.P'"'"'_mi =(P_s +P_d)/2-P_o.].

.Iadd.P'"'"'_mi =(P_si +P_di)/2-P_o .Iaddend.

P_si =systolic blood pressure, in cycle i

.[.P_mi =(P_s +P_d)/2.].

.Iadd.P_mi =(P_si +P_di)/2 .Iaddend.

P_di =diastolic blood pressure, in cycle i

a=constant

P_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_mo =constant at calibration

φ

_1i +φ

_2i =PP_i =pulse pressure during cycle i

k=constant

j=constant

P_si =P_mo +φ

_2i +P_o

P_di =P_mo -φ

_1i +P_o

P_mi =(P.sub. si +P_di)/2

P_o =constant

r_i =ratio of exponentials

K₃ =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_mo =constant at calibration

φ

_1i +φ

_2i =PP_i =pulse pressure during cycle i

k=constant

j=constant

.[.P_2i =P_mo +φ

_2i +P_o.].

.Iadd.P_si =P_mo +φ

_2i +P_o .Iaddend.

P_di =P_mo -φ

_1i +P_o

P_mi =(P.sub. si +P_di)/2

P_o =constant

r_i =ratio of exponentials

K₃ =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_i =Pulse Pressure-- P_s -P_d

P_s =Systolic blood pressure

P_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_mi in accordance with the following expression;

##EQU31## where PP_i =Pulse Pressure=P_s -P_d

P_s =Systolic blood pressure

P_d =Diastolic blood pressure

k=constant

K'"'"'=constant.