METHOD AND DISPLAY APPARATUS FOR NON-INVASIVELY DETERMINING PULMONARY CHARACTERISTICS BY MEASURING BREATH GAS AND BLOOD GAS

• US 20100179392A1
• Filed: 03/04/2009
• Published: 07/15/2010
• Est. Priority Date: 03/04/2008
• Status: Abandoned Application

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Bae, Hwang, Chang, Keun-Shik
• Application Number:
  US12/397,425
• Publication Number:
  US 20100179392A1
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• 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 5/0836 Measuring rate of CO2 production
• CPC Class Codes: A61B 5/087 Measuring breath flow

Abstract

A method for non-invasively determining pulmonary characteristics by measuring breath gas and blood gas and a display apparatus for the same, and for estimating major physiological characteristics, such as respiratory characteristics of lungs-pulmonary circulation system, cardiac functional characteristics, structural characteristics of lungs, etc. by applying primary measurement parameters obtained from ventilation gas and blood during breathing; and a display apparatus useful for the same.

Claims

1. A method for determining pulmonary characteristics, the method comprising:

(a) inputting respiratory input parameters, the parameters including additional blood information, gas boundary value, additional gas information, and inhalation flow rate into a computing device;

(b) inputting an initial value of shot concentration of mixed vein V into the computing device;

(c) inputting an initial value of dead space rate X into the computing device;

(d) inputting an initial value of O₂ partial pressure of pulmonary alveolar gas A1 based on the initial value of dead space rate X as respiratory input parameters into the computing device;

(e) applying the respiratory input parameters and the inputted initial values to an operational routine provided in the computing device, so as to obtain a solution from equations for respiratory gas, including mass balance equations for O₂, CO₂, N₂ and Fick'"'"'s equation;

(f) calculating an estimated CO₂ partial pressure of pulmonary alveolar gas A2 as a solution obtained from analytical equations for respiratory gas via the operational routine;

(g) calculating O₂ shunt rate Y1 and CO₂ shunt rate Y2 based on the initial value of O₂ partial pressure and the estimated CO₂ partial pressure of pulmonary alveolar gas A1 and A2;

(h) determining pulmonary characteristics related to shot partial pressure of pulmonary alveolar gas A*, when shunt rate requirements are satisfied;

(i) repeating steps (b) to (h) with multiple shot partial pressures of mixed vein (V*)n at a constant interval as initial values to determine multiple shot partial pressures of pulmonary alveolar gas (A*)n corresponding to the multiple shot partial pressures of mixed vein (V*)n, respectively, as well as pulmonary characteristics related thereto;

(j) when a specific shot pressure of pulmonary alveolar gas A** satisfying requirements for respiratory rate is selected from the multiple shot partial pressures of pulmonary alveolar gas (A*)n, determining a specific pulmonary characteristic corresponding to the specific shot pressure of pulmonary alveolar gas A**; and

(k) calculating a cardiac output.

2. The method according to claim 1, wherein the additional blood information in step (a) is shot partial pressure of arterial blood a* or measured O₂ partial pressure thereof.

3. The method according to claim 1, wherein the gas boundary value in step (a) is shot partial pressure of inhaled gas I* or measured O₂ partial pressure thereof.

4. The method according to claim 1, wherein the additional gas information in step (a) is shot partial pressure of gas at an end of exhalation ET* or measured CO₂ partial pressure thereof.

5. The method according to claim 1, wherein an inhalation flow rate VI in step (a) is total flow rate of external air received by lungs and is setup to be substantially the same level as an exhalation flow rate VE that is a total flow rate of air released from the lungs.

6. The method according to claim 1, wherein the shunt rate requirements in step (h) are to compare and determine if a difference between the O₂ shunt rate Y1 and the CO₂ shunt rate Y2 is within a desired range.

7. The method according to claim 1, wherein the analytic equations for respiratory gas in step (f) include the following equations (1), (2) and (3) as mass balance equations for O₂, CO₂ and/or N₂, respectively:

({dot over (V)}_I/{dot over (Q)})P_IO2−

({dot over (V)}_A/{dot over (Q)})P_ACO2=k×

(C_CO2−

C_VO2) 

 

(1)

({dot over (V)}_A/{dot over (Q)})₂P_ACO2=k (C_VCO2−

C_CCO2) 

 

(2)

({dot over (V)}_I/{dot over (Q)})₃P_IN2−

({dot over (V)}_A/{dot over (Q)})₃P_AN2=λ

(P<sub>C′

N2</sub>−

P_VN2) 

 

(3)

(wherein,

C_CCO2;

CO₂ concentration in capillary [%]

C_CO2;

O₂ concentration in mixed vein [%]

C_VCO2;

CO₂ concentration in mixed vein [%]

C_VO2;

O₂ concentration in mixed vein [%]

P_ACO2;

CO₂ partial pressure in pulmonary alveolus [mmHg]

P_AN2;

N₂ partial pressure in pulmonary alveolus [mmHg]

P_AO2;

O₂ partial pressure in pulmonary alveolus [mmHg]

P_CN2;

N₂ partial pressure of capillary [mmHg]

P_IN2;

N₂ partial pressure of air in atmosphere [mmHg]

P_IO2;

O₂ partial pressure of air in atmosphere [mmHg]

P_VN2;

N₂ partial pressure of mixed vein [mmHg],

{dot over (Q)};

perfusion of capillary [liters/min]

{dot over (V)}_A;

flow rate of air gas-exchanged in pulmonary alveolus [liters/min]

{dot over (V)}_I;

flow rate of inhalation air [liters/min]

k;

respiratory quotient

λ

;

constant for blood and air.

8. The method according to claim 1, wherein the multiple shot partial pressures of mixed vein (V*)n in step (i) correspond to lattice points of a plurality of divided “

mixed vein lattices”

, respectively, each being a blood boundary value and inputted into the computing device.

9. The method according to claim 8, wherein the lattice points of the plurality of divided “

mixed vein lattices”

have irregular spaces between lattices, comprise multi-grids including combined larger and smaller grids and, optionally, a primary larger grid capable of being further re-divided into smaller ones.

10. A method for determining pulmonary characteristics, comprising:

(a) inputting respiratory input parameters, including additional blood information, gas boundary value, additional gas information, and inhalation flow rate, into an computing device;

(b) inputting an initial value of shot concentration of mixed vein V into the computing device;

(c) inputting an initial value of shunt rate Y into the computing device;

(d) inputting an initial value of O₂ partial pressure of pulmonary alveolar gas A1 based on the initial value of shunt Y as respiratory input parameters into the computing device;

(e) applying the respiratory input parameters and the inputted initial values to an operational routine provided in the computing device, to obtain a solution from equations for respiratory gas including mass balance equations for O₂, CO₂, N₂ and Fick'"'"'s equation;

(f) calculating an estimated CO₂ partial pressure of pulmonary alveolar gas A2 as a solution obtained from analytical equations for respiratory gas using the operational routine;

(g) calculating O₂ dead space rate X1 and CO₂ dead space rate X2 based on the initial value of O₂ partial pressure and the estimated CO₂ partial pressure of pulmonary alveolar gas A1 and A2;

(h) determining pulmonary characteristics related to shot partial pressure of pulmonary alveolar gas A*, when dead space rate requirements are satisfied;

(i) repeating steps (b) to (h) with multiple shot partial pressures of mixed vein (V*)n at a constant interval as initial values to determine multiple shot partial pressures of pulmonary alveolar gas (A*)n corresponding to the multiple shot partial pressures of mixed vein (V*)n, respectively, as well as pulmonary characteristics related thereto;

(j) when a specific shot pressure of pulmonary alveolar gas A** satisfying requirements for respiratory rate is selected from the multiple shot partial pressures of pulmonary alveolar gas (A*)n, determining a specific pulmonary characteristic corresponding to the specific shot pressure of pulmonary alveolar gas A**; and

(k) calculating a cardiac output.

11. The method according to claim 10, wherein the dead space rate requirements in step (h) are compared to determine whether a difference between the O₂ dead space rate X1 and the CO₂ dead space rate X2 is within a desired range.

12. A method for determining pulmonary characteristics, comprising:

(a) inputting respiratory input parameters, including additional blood information, gas boundary value, additional gas information, and inhalation flow rate, into a computing device;

(b) inputting an initial value of shot concentration of mixed vein V into the computing device;

(c) inputting an initial value of dead space rate X into the computing device;

(d) inputting an initial value of CO₂ partial pressure of pulmonary alveolar gas A2 based on the initial value of dead space rate X as respiratory input parameters into the computing device;

(e) applying the respiratory input parameters and the inputted initial values to an operational routine provided in the computing device, to obtain a solution from equations for respiratory gas including mass balance equations for O₂, CO₂, N₂ and Fick'"'"'s equation;

(f) calculating an estimated O₂ partial pressure of pulmonary alveolar gas A1 as a solution obtained from analytical equations for respiratory gas via the operational routine;

(g) calculating O₂ shunt rate Y1 and CO₂ shunt rate Y2 based on the initial value of CO₂ partial pressure and the estimated O₂ partial pressure of pulmonary alveolar gas A2 and A1;

(h) determining pulmonary characteristics related to shot partial pressure of pulmonary alveolar gas A*, when shunt rate requirements are satisfied;

(i) repeating steps (b) to (h) with multiple shot partial pressures of mixed vein (V*)n at a constant interval as initial values so as to determine multiple shot partial pressures of pulmonary alveolar gas (A*)n corresponding to the multiple shot partial pressures of mixed vein (V*)n, respectively, as well as pulmonary characteristics related thereto;

(j) when a specific shot pressure of pulmonary alveolar gas A** satisfying requirements for respiratory rate is selected from the multiple shot partial pressures of pulmonary alveolar gas (A*)n, determining a specific pulmonary characteristic corresponding to the specific shot pressure of pulmonary alveolar gas A**; and

(k) calculating a cardiac output.

13. The method according to claim 12, wherein the shunt rate requirements in step (h) are used to compare and determine whether a difference between the O₂ shunt rate Y1 and the CO₂ shunt rate Y2 is within a desired range.

14. A method for determining pulmonary characteristics, comprising:

(a) inputting respiratory input parameters, including additional blood information, gas boundary value, additional gas information, and inhalation flow rate, into an computing device;

(b) inputting an initial value of shot concentration of mixed vein V into the computing device;

(c) inputting an initial value of shunt rate Y into the computing device;

(d) inputting an initial value of CO₂ partial pressure of pulmonary alveolar gas A2 based on the initial value of shunt rate Y as respiratory input parameters into the computing device;

(e) applying the respiratory input parameters and the inputted initial values to an operational routine provided in the computing device, so as to obtain a solution from equations for respiratory gas including mass balance equations for O₂, CO₂, N₂ and Fick'"'"'s equation;

(f) calculating an estimated O₂ partial pressure of pulmonary alveolar gas A1 as a solution obtained from analytical equations for respiratory gas via the operational routine;

(g) calculating O₂ dead space rate X1 and CO₂ dead space rate X2 based on the initial value of CO₂ partial pressure and the estimated O₂ partial pressure of pulmonary alveolar gas A2 and A1;

(h) determining pulmonary characteristics related to shot partial pressure of pulmonary alveolar gas A*, when dead space rate requirements are satisfied;

(i) repeating steps (b) to (h) with multiple shot partial pressures of mixed vein (V*)n at a constant interval as initial values so as to determine multiple shot partial pressures of pulmonary alveolar gas (A*)n corresponding to the multiple shot partial pressures of mixed vein (V*)n, respectively, as well as pulmonary characteristics related thereto;

(j) when a specific shot pressure of pulmonary alveolar gas A** satisfying requirements for respiratory rate is selected from the multiple shot partial pressures of pulmonary alveolar gas (A*)n, determining a specific pulmonary characteristic corresponding to the specific shot pressure of pulmonary alveolar gas A**; and

(k) calculating a cardiac output.

15. The method according to claim 14, wherein the dead space rate requirements in step (h) are used to compare and determine whether a difference between the O₂ dead space rate X1 and the CO₂ dead space rate X2 is within a desired range.

16. The method according to any one of claim 14, wherein the requirements for respiratory rate in step (j) are used to compare and determine whether a difference between a respiratory rate obtained from calculated numerical values and another respiratory rate obtained from the difference between shot partial pressures of inhaled gas and gas at an end of exhalation is within a desired range.

17. The method according to claim 16, wherein the specific pulmonary characteristic determined in step (j) is any one selected from shot partial pressure of pulmonary alveolar gas A**, shot partial pressure of peripheral capillary blood C**, ventilation-perfusion ratio ({dot over (V)}_A/{dot over (Q)})**, shunt rate Y** and physiological dead space rate X.

18. The method according to claim 16, wherein the cardiac output in step (k) is calculated using measured amount of inhaled air V_I or of exhaled air VE and a physiological dead space rate X**.

19. The method according to any one claim 14, wherein the additional blood information in step (a) only includes shot O₂ partial pressure of arterial blood a1*, while shot CO₂ partial pressure of arterial blood a2* is determined by repeating steps (a) to (k).

20. An apparatus for displaying pulmonary characteristics, comprising an information terminal connected to an computing device to visibly display pulmonary characteristics, which are determined by a method for determining the pulmonary characteristics as set forth in any one of claim 1414.

21. The apparatus according to claim 20, wherein the information terminal is wired or wirelessly connected to the computing device and portably carried.

22. The apparatus according to claim 21, wherein the computing device comprises a computer processor or embedded chips.