Methods for inducing temporary changes in ventilation for estimation of hemodynamic performance

• US 20030225339A1
• Filed: 04/28/2003
• Published: 12/04/2003
• Est. Priority Date: 05/06/2002
• Status: Abandoned Application

• Current Assignee: RIC INVESTMENTS LLC (Respironics Incorporated)
• Original Assignee: Respironics Novametrix
• Inventors: Orr, Joseph A., Jaffe, Michael B., Brewer, Lara, Kuck, Kai
• Application Number:
  US10/424,656
• Publication Number:
  US 20030225339A1
• Time in Patent Office: Days
• US Class Current: 600/532
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production

Abstract

Methods for inducing changes in the effective ventilation of an individual by varying one or more respiratory parameters to derive measurements which may be utilized to calculate measures of hemodynamic performance, e.g., pulmonary capillary blood flow and cardiac output, are provided. The methods of the present invention are used to attain measurements under the wide array of ventilatory modes available with modem ventilation machines to calculate indicators of hemodynamic performance using a differential form of the carbon dioxide Fick equation.

Claims

1. A method of estimating hemodynamic performance of an individual, comprising:

causing an individual to effect a first breath at a first set of ventilatory conditions including a ventilation parameter, wherein the ventilation parameter comprises inspiratory pressure, flow rate, tidal volume, inspiratory duration, expiratory duration, or a combination thereof;

altering the ventilation parameter to define a second set of ventilatory conditions; and

causing such an individual to effect a second breath at the second set of ventilatory conditions.

2. The method of claim 1, wherein the altering is manually performed.

3. The method of claim 1, further comprising:

obtaining first measurements of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of carbon dioxide content or oxygen content in blood of the individual at the first set of ventilatory conditions;

obtaining second measurements of (a) the carbon dioxide elimination or oxygen consumption and (b) the indicator of carbon dioxide content or oxygen content of blood of such an individual at the second set of ventilatory conditions; and

applying the first and the second measurements to a differential Fick equation.

4. The method of claim 3, wherein obtaining the first and the second measurements of the indicator of carbon dioxide content comprises obtaining a first measurement and a second measurement of partial pressure of end-tidal carbon dioxide.

5. The method of claim 3, further comprising inputting the first set of ventilatory conditions into a mechanical ventilation machine.

6. The method of claim 5, wherein the altering is performed automatically by the mechanical ventilation machine.

7. The method of claim 1, further comprising:

obtaining first measurements of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of carbon dioxide content or oxygen content in blood of the individual at the first set of ventilatory conditions or at the second set of ventilatory conditions;

obtaining second measurements of (a) the carbon dioxide elimination or oxygen consumption and (b) the indicator of carbon dioxide content or oxygen content of blood of such an individual at a transition between the first set of ventilatory conditions and the second set of ventilatory conditions; and

applying the first and the second measurements to a differential Fick equation.

8. A method for estimating hemodynamic performance of an individual using a differential Fick technique, comprising:

determining a first value indicative of carbon dioxide content in the blood of a individual at a first ventilatory state, the first ventilatory state including a ventilation parameter, wherein the ventilation parameter comprises inspiratory pressure, flow rate, tidal volume, inspiratory duration, expiratory duration, or a combination thereof;

altering the ventilation parameter to define a second ventilatory state;

determining a second value indicative of carbon dioxide content in the blood of such an individual at the second ventilatory state; and

estimating hemodynamic performance by applying the first value and the second value to a differential Fick equation.

9. The method of claim 8, wherein determining the first and the second values indicative of carbon dioxide content include obtaining a first measurement and a second measurement of a partial pressure of end-tidal carbon dioxide.

10. The method of claim 8, wherein the altering is manually performed.

11. The method of claim 8, wherein the first ventilatory state is input into a mechanical ventilation machine.

12. The method of claim 11, wherein the altering is performed automatically by the mechanical ventilation machine.

13. A method for determining at least one of cardiac output and pulmonary capillary blood flow of an individual, comprising:

(1) defining a baseline ventilatory state including a baseline value of at least one of (a) a limit variable other than time, (b) a cycle variable other than time, and (c) a triggering variable for triggering an inspiratory phase of a breathing cycle;

(2) obtaining a first measurement of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of carbon dioxide content or oxygen content of blood of an individual at the baseline ventilatory state;

(3) defining an altered ventilatory state including an altered value of the at least one of the limit variable, the cycle variable, and the triggering variable;

(4) obtaining a second measurement of (a) the carbon dioxide elimination or oxygen consumption and (b) the indicator of carbon dioxide content or oxygen content of blood of such an individual at the altered ventilatory state; and

(5) applying the first measurement and the second measurement to a differential Fick equation.

14. The method of claim 13, further comprising:

effecting an inspiratory period at the baseline ventilatory state prior to obtaining the first measurements; and

effecting an inspiratory period at the altered ventilatory state prior to obtaining the second measurements.

15. The method of claim 13, wherein the obtaining the first measurement and the second measurement of the indicator of the carbon dioxide content comprises obtaining a first measurement and a second measurement of partial pressure of end-tidal carbon dioxide.

16. The method of claim 13, further comprising inputting the baseline ventilatory state and the altered ventilatory state into a mechanical ventilation machine.

17. The method of claim 16, wherein defining the altered ventilatory state is performed automatically by the mechanical ventilation machine.

18. The method of claim 13, wherein defining an altered ventilatory state is manually performed.

19. A method for estimating at least one of cardiac output and pulmonary capillary blood flow of an individual utilizing a mechanical ventilation machine, comprising:

obtaining a baseline value of at least one of (a) a limit variable other than time, (b) a cycle variable other than time, and (c) a triggering variable for triggering an inspiratory phase of a breathing cycle;

storing the baseline value in the mechanical ventilation machine;

obtaining an altered value of the at least one of the limit variable, the cycle variable, and the triggering variable; and

storing the altered value in the mechanical ventilation machine.

20. The method of claim 19, further comprising:

determining a first measurement of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of carbon dioxide content or oxygen content of blood of such an individual at the baseline value;

determining a second measurement of (a) the carbon dioxide elimination or oxygen consumption and (b) the indicator of carbon dioxide content or oxygen content of blood of such an individual at the altered value; and

applying the first measurement and the second measurement to a differential Fick equation.

21. The method of claim 19, further comprising:

determining a first measurement of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of carbon dioxide content or oxygen content of blood of such an individual at the baseline value or at the altered value;

determining a second measurement of (a) the carbon dioxide elimination or oxygen consumption and (b) the indicator of carbon dioxide content or oxygen content of blood of such an individual at a transition between the baseline value and the altered value; and

applying the first measurement and the second measurement to a differential Fick equation.

22. The method of claim 19, wherein determining the first measurement and the second measurement of the indicator of the carbon dioxide content comprises obtaining a first measurement and a second measurement of a partial pressure of end-tidal carbon dioxide.

23. The method of claim 19, further comprising causing the individual to effect an inspiratory period and an expiratory period at the baseline value and at the altered value of the limit variable.

24. A method for inducing a measurable change in ventilation of an individual utilizing a ventilation machine, comprising:

defining a first ventilatory state including a ventilation parameter, the ventilation parameter comprising an inspiratory pressure, flow rate, tidal volume, inspiratory duration, expiratory duration, or combination thereof;

altering the at least one ventilation parameter to define a second ventilatory state; and

effecting an inspiratory period and an expiratory period at the first and the second ventilatory states.

25. The method of claim 24, wherein the altering is manually performed.

26. The method of claim 24, further comprising:

obtaining a first measurement of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of at least one of carbon dioxide content or oxygen content of blood of such an individual at the first ventilatory state;

obtaining a second measurement of (a) the carbon dioxide elimination or oxygen consumption and (b) the indicator of carbon dioxide content or oxygen content of blood of such an individual at the second ventilatory state; and

applying the first measurement and the second measurement to a differential Fick equation.

27. The method of claim 26, wherein the obtaining the first and the second measurement of the indicator of the carbon dioxide content comprises obtaining a first measurement and a second measurement of a partial pressure of end-tidal carbon dioxide.

28. The method of claim 24, further comprising:

obtaining a first measurement of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of at least one of carbon dioxide content or oxygen content of blood of such an individual at the first ventilatory state or at the second ventilatory state;

obtaining a second measurement of (a) the carbon dioxide elimination or oxygen consumption and (b) the indicator of carbon dioxide content or oxygen content of blood of such an individual at a transition between the first ventilatory state and the second ventilatory state; and

applying the first measurement and the second measurement to a differential Fick equation.

29. The method of claim 24, further comprising inputting the first ventilatory state into the ventilation machine.

30. The method of claim 29, wherein the altering is performed automatically by the ventilation machine.

31. A method of estimating hemodynamic performance of an individual, comprising:

determining a first value indicative of carbon dioxide content of blood of the individual at a first ventilatory state;

determining a second value indicative of carbon dioxide content of blood of the individual at a second ventilatory state, wherein the second ventilatory state comprises a series of at least three sigh breaths; and

applying the first value and the second value to a differential Fick equation.

32. The method of claim 31, wherein the determining the first and second values indicative of carbon dioxide content comprise obtaining first and second values of a partial pressure of end-tidal carbon dioxide.

33. A method of estimating hemodynamic performance of an individual utilizing differential Fick techniques, comprising:

obtaining a plurality of measurements of (a) carbon dioxide elimination or oxygen consumption and (b) an indicator of carbon dioxide content or oxygen content of blood of such an individual at a plurality of ventilatory states; and

applying the plurality of measurements to a probabilistic distribution.

34. A method for estimating hemodynamic performance of an individual using a differential Fick technique, comprising:

providing a first ventilatory state for an individual, wherein the first ventilatory state includes a ventilation parameter, wherein the ventilation parameter comprises inspiratory pressure, flow rate, tidal volume, inspiratory duration, expiratory duration, or a combination thereof;

altering the ventilation parameter to define a second ventilatory state;

determining a first value indicative of carbon dioxide content in the blood of a individual at the first ventilatory state or at the second ventilatory state;

determining a second value indicative of carbon dioxide content in the blood of such an individual at a transition between the first ventilatory state and the second ventilatory state; and

estimating hemodynamic performance by applying the first value and the second value to a differential Fick equation.

35. The method of claim 34, wherein determining the first and the second values indicative of carbon dioxide content include obtaining a first measurement and a second measurement of a partial pressure of end-tidal carbon dioxide.

36. The method of claim 34, wherein the altering is manually performed by the individual.