Patent ID: 7001340

Claim:
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.