[A virtual respiratory model of the concentration of each gas in the alveoli as a function of time when the inspired and expired volumes are equal].
A specific mathematical ventilation model was assumed to derive a new expression for the concentration of each gas in the alveoli with only the ventilatory parameters or with the functional residual volume, tidal volume, anatomical dead space, and end-tidal gas concentration. The inequality derived from the mean concentration equation showed that, if the I to E ratio was inversed, the end-tidal P(CO2) was higher than the mean alveolar P(CO2), which was almost equal to the sampled arterial P(CO2). In the present model, at the inverse ratio ventilation (IRV), the end-tidal P(CO2) was higher than the arterial P(CO2). The mean equation provided not only the A-a D(O2), but also the a-AD(CO2). The A-aD(O2) was evaluated with respect to cardiac output. In the equation, I is the duration of inspiration; E is the duration of expiration; P(CO2) is the carbon dioxide tension; A-aD(O2) is the mean alveolar/mean arterial P(O2) difference; P(O2) is the oxygen tension; and a-AD(CO2) is the mean arterial/mean alveolar P(CO2) difference.
Department of Anesthesia, Yokosuka-shiritsu-shimin-Hospital, Yokosuka 240-0195.
Hirofumi
H
Nose
Shunji
S
Kitamura
Tatto
T
Nishikawa
D002245:Carbon Dioxide / Q000032:analysis* / Q000097:blood; D008962:Models, Theoretical; D010100:Oxygen / Q000032:analysis* / Q000097:blood; D011650:Pulmonary Alveoli / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D013995:Time
D002245:Carbon Dioxide; D010100:Oxygen