Method for converting venous blood values to arterial blood values, system for utilising said method and devices for such system

• US 20060105319A1
• Filed: 07/25/2003
• Published: 05/18/2006
• Est. Priority Date: 07/26/2002
• Status: Active Grant

• Current Assignee: OBI APS
• Original Assignee: OBI APS
• Inventors: Rees, Stephen Edward, Andreassen, Steen
• Granted Patent: US 7,395,159 B2
• Time in Patent Office: Days
• US Class Current: 435/4
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: Y10T 436/115831 Condition or time responsive

Abstract

The invention relates to methods of converting venous blood values to arterial blood values. This has the advantage that arterial blood samples need not be taken, and the disadvantages compared to venous blood samples when taking arterial blood samples are eliminated. The method is basically based on three steps, namely the step of measuring arterial oxygenation, the step of measuring and estimating values of venous blood acid/base status and oxygenation status of a venous blood sample, and the step of converting the venous blood values by applying a mathematical model for deriving blood acid/base status and oxygenation status into estimated arterial blood values.

Claims

1. A method of converting venous blood values to arterial blood values, said method comprising the steps of:

a) providing values of arterial oxygenation,

b) measuring and estimating values of acid/base status and oxygenation status in a blood sample, the sample being obtained from venous blood,

c) converting the venous blood values by applying a mathematical model for deriving blood acid/base status and oxygenation status into estimated arterial blood values.

2. A method values according claim 1, said method measuring and analysing comprising the further steps of:

d) providing an anaerobic venous blood sample,

e) analysing said anaerobic venous blood sample for evaluating the acid/base status of the venous blood sample, and

f) analysing said anaerobic venous blood sample for evaluating the oxygenation status of the venous blood sample.

3. A method according to claim 1, said method comprising the further step of:

g) providing the arterial oxygenation such as oxygen saturation, pressure or concentration, said further step being performed at any time in relation to any of the steps a)-c).

4. A method according to claim 3, said method comprising the even further step of:

h) simulating the blood acid/base status and oxygenation status of an arterial blood sample by use of mathematical modelling.

5. A method according to claim 4, said method comprising still even further steps of

i) mathematical modelling comprising simulated addition of oxygen, O₂, to and removal of carbon dioxide, CO₂, from the venous blood sample values in a ratio determined by the respiratory quotient,

j) said mathematical modelling being performed until the simulated oxygen level is equal to the arterial oxygenation level measured or estimated, and

k1) calculating the acid/base status and the oxygenation of the arterial blood by applying the result of said modelling.

6. A method according to claim 5, 4 said method comprising still even further steps of

i) mathematical modelling comprising simulated addition of oxygen, O₂, to and removal of carbon dioxide, CO₂, from the venous blood sample values in a ratio determined by the respiratory quotient,

j) said mathematical modelling being performed until the simulated oxygen level is equal to the arterial oxygenation level measured or estimated, and

k2) estimating the acid/base status and the oxygenation of the arterial blood by applying the result of said modelling.

7. A method according to claim 1, said method comprising a further step of

l) providing the arterial carbon dioxide level such as carbon dioxide pressure, total concentration or bicarbonate concentration), said further step being performed at any time in relation to any of the steps a)-c).

8. A method according to claim 7, said method comprising an even further step of

m) simulating the blood acid/base status and oxygenation status of arterial blood sample by use of modelling.

9. A method according to claim 8, said method comprising the still even further steps of

n) mathematical modelling comprising simulated addition of O₂ to and removing CO₂ from the venous blood sample values in a ratio determined by the respiratory quotient,

o) said modelling being performed until the simulated carbon dioxide level is equal to the arterial carbon dioxide level measured or estimated, and

p1) calculating the acid/base status and the oxygenation of the arterial blood by applying the result of said modelling.

10. A method according to claim 8, said method comprising the still even further steps of

n) mathematical modelling comprising simulated addition of O₂ to and removing CO₂ from the venous blood sample values in a ratio determined by the respiratory quotient,

o) said modelling being performed until the simulated carbon dioxide level is equal to the arterial carbon dioxide level measured or estimated, and

p2) estimating the acid/base status and the oxygenation of the arterial blood by applying the result of said modelling.

11. A method according to claim 10,

where the measuring or estimating of the arterial oxygen saturation is done by pulse oximetry.

12. A system for analysing a venous blood sample, the system comprising:

a blood gas analyzer for

providing values of arterial oxygenation, and

measuring and estimating values of acid/base status and oxygenation status in the venous blood sample, and

means for applying a mathematical model to the values of the arterial oxygenation and the values of acid/base status and oxygenation status in the venous blood sample characterised in that the venous blood acid/base status and oxygenation status are converted into arterial blood values.

13. A system according to claim 12, wherein the arterial blood acid/base status and oxygenation status is calculated or estimated.

14. A system according to claim 12, said system comprising means for measuring arterial oxygenation saturation, where the means preferably is a pulse oximeter.

15. A system according to claim 12, said system comprising a device for anaerobic sampling, preferably by drawing of a venous blood sample.

16. A system according to claim 12 further comprising a computer or a medical device with means for converting the venous blood acid/base status and oxygenation status into arterial blood values.

17. A device for anaerobic drawing of venous blood, said device capable of reducing any residual gases in a blood sample bottle by applying a partial vacuum within the sample bottle.

18. A device for anaerobic drawing of venous blood, said device capable of reducing any residual gases in a blood sample bottle by applying a complete vacuum within the sample bottle.

19. A device for anaerobic drawing of venous blood, said device capable of reducing the effects of any residual gases in a blood sample bottle by using gases with partial O₂ and CO₂ pressures adapted to typical venous values within the sample bottle.

20. A device for anaerobic drawing of venous blood, said device capable of reducing the effects of any residual gases in a blood sample bottle by using one or more inert gases in the sample bottle.

21. A device for anaerobic drawing of blood venous blood, said device capable of reducing any residual gases in a blood sample by dividing the sample bottle into one or more compartments with at least one compartment containing blood only.

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