System for measuring blood oxygen levels

• US 5,634,461 A
• Filed: 06/07/1995
• Issued: 06/03/1997
• Est. Priority Date: 06/07/1995
• Status: Expired due to Fees

• Current Assignee: Alliance Pharmaceutical Corporation
• Original Assignee: Alliance Pharmaceutical Corporation
• Inventors: Faithfull, Nicholas S., Rhoades, Glenn
• Primary Examiner(s): Sykes, Angela D.
• Assistant Examiner(s): HUANG, STEPHEN D
• Application Number:
  US08/487,086
• Time in Patent Office: 727 Days
• Field of Search: 128/632, 128/637, 128/668, 128/672, 128/687-689, 128/713
• US Class Current: 600/483
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14551 for measuring blood gases

Abstract

A system and software is described for calculating, in real-time, the mixed venous partial pressure of oxygen in a patient. The system uses a computer, an arterial pressure line and a blood chemistry monitor to assist a physician with an on-line system for accurately determining when to give a patient a blood transfusion or otherwise alter the clinical management of that patient.

Claims

1. A method for determining mixed venous blood oxygen tension (PvO₂) of a patient in real-time, comprising the steps of:

storing constant values corresponding to blood volume, oxygen solubility in plasma and oxygen content of a desired unit of saturated oxyhemoglobin of a patient into a first computer memory;

measuring cardiac output values (CO) of a patient in real-time, wherein said cardiac output values are saved to a second computer memory;

storing a value corresponding to whole body oxygen consumption (VO₂) of said patient into a third computer memory;

determining arterial oxygen content (CaO₂) of said patient using numerical values corresponding to hemoglobin concentration, arterial tension of oxygen (PaO₂), arterial tension of carbon dioxide (CO₂), arterial pH and body temperature wherein said values are obtained contemporaneously with said measurement of cardiac output levels; and

calculating the mixed venous blood oxygen tension (PvO₂) of a patient in real-time.

2. The method of claim 1 further comprising the step of accessing a random access memory for use as said first computer memory.

3. The method of claim 1 further comprising the step of accessing a random access memory for use as said second computer memory.

4. The method of claim 1 further comprising the step of accessing a random access memory for use as said third computer memory.

5. The method of claim 1 further comprising the step of utilizing a blood chemistry monitor to determine one or more numerical values corresponding to hemoglobin concentration, arterial tension of oxygen (PaO₂), arterial tension of carbon dioxide (CO₂), arterial pH and body temperature.

6. The method of claim 1 further comprising the step of employing an equation having the formula

7. An apparatus for determining mixed venous blood oxygen tension (PvO₂) of a patient in real-time, comprising:

a first computer memory for storing constant values corresponding to blood volume, oxygen solubility in plasma and oxygen content of a desired unit of saturated oxyhemoglobin;

an input that measures cardiac output values (CO) of a patient in real-time, wherein said cardiac output values are saved in a second computer memory;

first instructions for storing a value corresponding to whole body oxygen consumption (VO₂) of said patient into a third computer memory;

second instructions for obtaining arterial oxygen content (CaO₂) of said patient using values corresponding to hemoglobin concentration, arterial tension of oxygen (PaO₂), arterial tension of carbon dioxide (CO₂), arterial pH and body temperature wherein said values are obtained contemporaneously with said continuous measurement of the cardiac output levels; and

third instructions in said memory for calculating the mixed venous blood oxygen tension (PvO₂) of a patient in real-time.

8. The apparatus of claim 7 wherein said first computer memory is a random access memory.

9. The apparatus of claim 7 wherein said second computer memory is a random access memory.

10. The apparatus of claim 7 wherein said third computer memory is a random access memory.

11. The apparatus of claim 7 wherein said computer memory is a hard disk.

12. The apparatus of claim 7 wherein said input is an arterial pressure line.

13. The apparatus of claim 7 wherein said second instructions are stored in a blood chemistry monitor.

14. The apparatus of claim 7 wherein said third instructions utilize an equation having the formula

15. The apparatus of claim 7 wherein said second instructions include instructions for obtaining said patient'"'"'s hemoglobin concentration, arterial tension of oxygen (PaO₂), arterial tension of carbon dioxide (CO₂), arterial pH and body temperature from a keyboard input.

16. The apparatus of claim 7 wherein said second instructions include instructions for obtaining said patient'"'"'s hemoglobin concentration, arterial tension of oxygen (PaO₂), arterial tension of carbon dioxide (CO₂), arterial pH and body temperature from a blood chemistry monitor.