Haemodynamic monitoring

• US 7,338,453 B2
• Filed: 11/13/2002
• Issued: 03/04/2008
• Est. Priority Date: 11/13/2001
• Status: Expired due to Fees

• Current Assignee: Medics Limited
• Original Assignee: Medics Limited
• Inventors: Warring-Davies, Kenneth James Patrick Peter
• Primary Examiner(s): Nasser; Robert L.
• Application Number:
  US10/495,411
• Publication Number:
  US 20050049511A1
• Time in Patent Office: 1,938 Days
• Field of Search: None
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02152 specially adapted for venous pressure
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

Mean Pulmonary Arterial Pressure (MPAP), Mean Pulmonary Capillary Wedge Pressure (MPCWP) and Cardiac Index are all determinable (in a method or employing apparatus) from Central Venous Pressure (CVP), Mean Arterial Pressure (MAP), Heart Rate (HR), and Core Body Temperature (T) from the following relationships: MPAP=(a×MAP)+CVP (for MAP<58), or Va; MPAP=(a×MPAP)+CVP−(10×INT[(MAX {MAP−109), (CVP−7),0})/10]) for MAP>58); Vb; MPCWP=(b×MPAP)+CVP−(10×INT [CVP−7/10]; and VI; CI=K (T.CVP)/HR2, VII; where a and b are about 0.15; MAX (x, y, z)=largest of the three terms x, y, and z; INT [x]=integer part of x; MAP and CVP is measured in mmHg; T in Celsius and HR in counts per minute; CI is liters per square meter per minute; and K is a variable constant whose value is between 0 and 1000 depending on the values of CVP and HR.

Claims

1. A method of determining at least one of MPAP, MPCWP and CI, comprising:

obtaining CVP and MAP and/or HR and T from a subject using at least one sensor; and

employing one or more of the relationships;

MPAP=f(MAP,CVP);

 

 

II

MPCWP=f(MPAP, CVP); and

 

 

III

CI=f(CVP,HR²,T),  

 

IV

where MPAP is mean pulmonary artery pressure, MPCWP is mean pulmonary capillary wedge pressure, CI is cardiac index, MAP is mean arterial pressure, CYP is central venous pressure, HR is heart rate, and T is body core temperature.

2. A method as claimed in claim 1, in which said relationships II, III and/or IV respectively comprise:

$\begin{array}{cc}\mathrm{MPAP}=\left(a_1\times <br><br>\mathrm{MAP}\right)+\mathrm{CVP}-k_1& V\\ \mathrm{MPCWP}=\left(a_2\times <br><br>\mathrm{MPAP}\right)+\mathrm{CVP}-k_2& \mathrm{VI}\\ \mathrm{CI}=K<br><br>\frac{T.\mathrm{CVP}}{{\mathrm{HR}}^2}& \mathrm{VII}\end{array}$

where

a₁ and a₂ are constants between about 0.01 and about 1.0;

k₁ and k₂ are variable constants based on the values of CVP and MAP;

MAP and CVP is measured in mmHg;

T in Celsius; and

HR in counts per minute;

CI is liters per square meter per minute; and

K is a variable constant whose value is between about 10 and about 100 depending on the values of CVP and HR.

3. A method as claimed in claim 2, in which, for MAP less than 58 mmHg:

k₁=0;

 

 

Va

and for MAP equal to or greater than 58 mmHg;

k₁=10×

INT[(MAX{(MAP−

109),(CVP−

7),0}) /10])  

 

Yb

where

MAX {x, y, z}=largest of the three terms x, y and z;

INT [x]=integer part of x.

4. A method as claimed in claim 2, in which:

k₂=10×

INT [CVP−

7/10].  

 

VIa

5. A method as claimed in claim 2 in which K is selected from the following table:

TABLE 1 Values of Values of CVP in mmHg HR in counts/min. 0-5 5-7 7-10 10-14 14-15 15-16 16-25 >

25  

0-59 40 40 32 36 40 27.5 19.5 20 60-68 100 90 56 36 40 40 24 20 68-84 100 90 80 40 40 40 24 20 84-88 100 90 80 40 40 60 24 20 88-96 100 90 80 100 100 80 24 20 96-99 100 95 90 100 100 80 24 20 >

=100 100 100 100 100 100 80 60 50.

6. Apparatus for determining at least one of MPAP, MPCWP and CI comprising:

sensor means to obtain CVP and MAP and/or HR and T; and

calculation means to resolve one or more of the relationships;

MPAP=f(MAP, CVP)  

 

II

MPCWP=f(MAP, CVP); and

 

 

III

CI=f(CVP, HR², T),  

 

IV

where MPAP is mean pulmonary artery pressure, MPCWP is mean pulmonary capillary wedge pressure, CI is cardiac index, MAP is mean arterial pressure, CVP is central venous pressure, HR is heart rate, and T is body core temperature.

7. Apparatus as claimed in claim 6, in which said relationships II, III and/or IV respectively comprise:

$\begin{array}{cc}\mathrm{MPAP}=\left(a_1\times <br><br>\mathrm{MAP}\right)+\mathrm{CVP}-k_1& V\\ \mathrm{MPCWP}=\left(a_2\times <br><br>\mathrm{MPAP}\right)+\mathrm{CVP}-k_2& \mathrm{VI}\\ \mathrm{CI}=K<br><br>\frac{T·<br><br>\mathrm{CVP}}{{\mathrm{HR}}^2}& \mathrm{VII}\end{array}$

where

a₁ and a₂ are constants between about 0.05 and about 0.3;

k₁ and k₂ are variable constants, preferably based on the values of CVP and MAP;

MAP and CVP is measured in mmHg;

T in Celsius; and

HR in counts per minute;

CI is liters per square meter per minute; and

K is a variable constant whose value is between about 0 and about 1000 depending on the values of CVP and HR.

8. Apparatus as claimed in claim 7, in which, for MAP less than 58 mmHg;

k₁=0  

 

Va

and for MAP equal to or greater than 58 mmHg;

k₁=10×

INT[(MAX{(MAP−

109), (CVP−

7), 0}) /10])  

 

Vb

where

MAX {x, y, z}=largest of the three terms x, y and z;

TNT [x]=integer part of x.

9. Apparatus as claimed in claim 7, in which:

k₂=10×

INT [CVP−

7/10]

10. Apparatus as claimed in claim 7, in which K is selected from the following table:

TABLE I Values of Values of CV? mmHg HR in counts/mm 0-5 5-7 7-10 10-14 14-15 15-16 16-25 >

25  

0-59 40 40 32 36 40 27.5 19.5 20 60-68 100 90 56 36 40 40 24 20 68-84 100 90 80 40 40 40 24 20 84-88 100 90 80 40 40 60 24 20 88-96 100 90 80 100 100 80 24 20 96-99 100 95 90 100 100 80 24 20 >

=100 100 100 100 100 100 80 60 50.

11. Apparatus as claimed in claim 6, further comprising means to receive measured values of MAP, CVP, T and HR and means to output at least one of the parameters MPAP, MPCWP, and CI based on computations using said formulae.

12. Apparatus as claimed in claim 6, in which said relationship IV is derived from a Map of Empirical Physiological Formulae for Determining Cardiac Index.

13. Apparatus as claimed in claim 6, in which said relationship II and/or III is derived from Physiological Flowcharts for MPAP and MPCWP.

14. Apparatus as claimed claim 6, further comprising a Central Venous Pressure transducer catheter, which is capable of insertion in the body of a patient into a major vein and be directed to monitor CVP in or near a vessel entering the right atrium of the heart.

15. Apparatus as claimed in claim 6, further comprising display means to display values of MPAP, MPCWP and/or CI based on said measurements and formulae.

16. Apparatus as claimed in claim 15, further comprising means to calculate and display other haemodynamic parameters based on MAP, CVP, HR, T, MPAP, MPCWP, and/or CI.