Assessment of concentration of inhalational compounds in the brain

• US 7,001,340 B2
• Filed: 07/27/2004
• Issued: 02/21/2006
• Est. Priority Date: 03/16/2001
• Status: Expired due to Fees

• Current Assignee: Chung-Yuan Lin
• Original Assignee: Chung-Yuan Lin
• Inventors: Lin, Chung-Yuan
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US10/900,158
• Publication Number:
  US 20050010126A1
• Time in Patent Office: 574 Days
• Field of Search: 600529-544, 600/309, 424/9.1
• US Class Current: 600/532
• CPC Class Codes: A61K 49/00 Preparations for testing in vivo

Abstract

This invention directs to a method of assessing the concentration of an inhalational compound in the brain of a subject. The method includes administering a gas containing the compound into a subject to fill the pulmonary functional residual capacity, which is defined as the remaining lung volume at the end of an unforced respiration. The method also includes measuring an inspired compound concentration (C_i′) and an expired compound concentration (C_e′) after having filled the functional residual capacity with the gas. Therefore, a mixed venous compound concentration (C_b′) can be assessed based on the formula C_b′=[C_i′(M−1)+C_e′]/M, in which M is an alveolar membrane factor for the compound; and a brain compound concentration (C_b) can be assessed based on the formula C_b=(C_e′+2C_b′)/3 or C_b=(C_e′+3C_b′)/4.

Claims

1. A method of assessing the concentration of a compound in the brain of a subject, the method comprising:

administering a gas containing the compound into a subject to fill the pulmonary functional residual capacity;

after having filled the functional residual capacity with the gas, measuring an inspired compound concentration (C_i′

) and an expired compound concentration (C_e′

);

assessing a mixed venous compound concentration (C_b′

) based on Formula I;

C_b′

=[C_i′

(M−

1)+C_e′

]/M, in which M is an alveolar membrane factor for the compound; and

assessing a compound concentration in the brain (C_b′

) based on Formula II;

C_b=(C_e′

+2C_b′

)/3 or C_b=(C_e′

+3C_b′

)/4.

2. The method of claim 1, wherein M is assessed based on Formula III:

M=1−

(C_e/C_i), in which C_i and C_e are an inspired compound concentration and an expired compound concentration, respectively, measured at the time when about 90% of the functional residual capacity is filled with the gas.

3. The method of claim 1, wherein the compound is an anesthetic.

4. The method of claim 2, wherein the compound is an anesthetic.

5. The method of claim 3, wherein the anesthetic is isoflurane, haloflurane, desflurane, sevoflurane, or enflurane.

6. The method of claim 4, wherein the anesthetic is isoflurane, haloflurane, desflurane, sevoflurane, or enflurane.

7. The method of claim 6, wherein the anesthetic is sevoflurane and the compound concentration in the brain (C_b) is assessed based on C_b=(C_e′

+2C_b′

)/3.

8. The method of claim 6, wherein the anesthetic is desflurane and the compound concentration in the brain (C_b) is assessed based on C_b=(C_e′

+3C_b′

)/4.

9. An article comprising a machine-readable medium that stores machine-executable instructions, the instructions causing a machine to:

receive values representing the concentration of a compound administered in a gas into a subject to fill the pulmonary functional residual capacity, the values including an inspired compound concentration (C_i′

) and an expired compound concentration (C_e′

), wherein the inspired compound concentration (C_i′

) and the expired compound concentration (C_e′

) are obtained after having filled the functional residual capacity with the gas; and

output a representation of a compound concentration in the brain (C_b), in which the representation of the compound concentration in the brain (C_b) is assessed by the formula C_b=(C_e′

+2C_b′

)/3 or C_b=(C_e′

+3C_b′

)/4, wherein C_b′

=[C_i′

(M−

1)+C_e′

]/M, M being an alveolar membrane factor for the compound.

10. The article of claim 9, wherein the values further include a second inspired compound concentration (C_i) and a second expired compound concentration (C_e), in which C_i and C_e are measured at the time when about 90% of the functional residual capacity is filled with the gas, and M is assessed based by the formula M=1−

(C_e/C_i).

11. The article of claim 10, wherein the instructions further cause the machine to:

trigger a detector to sample the compound from an inspiration and an expiration measured at the time when about 90% of the functional residual capacity is filled with the gas;

monitor a time interval; and

trigger the detection to sample the compound from an inspiration and an expiration after filling the functional residual capacity with the gas.

12. An apparatus comprising:

a display; and

a processor, the processor configured to;

receive values representing the concentration of a compound administered in a gas into a subject to fill the pulmonary functional residual capacity, the values including an inspired compound concentration (C_i′

) and an expired compound concentration (C_e′

), wherein the inspired compound concentration (C_i′

) and the expired compound concentration (C_e′

) are obtained after having filled the functional residual capacity with the gas; and

control the display to depict a representation of a compound concentration in the brain (C_b), in which the representation of the compound concentration in the brain (C_b) is assessed by the formula C_b=(C_e+2C_b′

)/3 or C_b=(C_e′

+3C_b′

)/4, wherein C_b′

=[C_i′

(M−

1)+C_e′

]/M, M being an alveolar membrane factor for the compound.

13. The apparatus of claim 12, wherein the values include a second inspired compound concentration (C_i) and a second expired compound concentration (C_e), in which C_i and C_e are measured at the time when about 90% of the functional residual capacity is filled with the gas, and M is assessed based by the formula M=1−

(C_e/C_i).

14. The apparatus of claim 13 further comprising a detector.

15. The apparatus of claim 14, wherein the instructions further cause the machine to:

trigger the detector to sample the compound from an inspiration and an expiration measured at the time when about 90% of the functional residual capacity is filled with the gas;

monitor a time interval; and

trigger the detector to sample the inhalation compound from an inspiration and an expiration after filling the functional residual capacity with the gas.