Περίληψη:
Aims: The classical equations for measuring the mean and the ideal
alveolar O-2 tension are based on assumptions, which are shown to be
invalid. So we thought to develop a new, non-invasive method for
measuring the mean alveolar P,O-2 within the volume domain
(PA,O-2(Bohr)). This method is based on the oxygen uptake vs. tidal
volume curve (VO2 vs. VT) obtained during tidal breathing of room air
and/or air enriched with oxygen.
Methods: PA,O-2(Bohr) and the ideal alveolar PO2 (PA,O-2(ideal)) were
simultaneously measured in 10 healthy subjects and 34 patients suffering
from chronic obstructive pulmonary disease (COPD) breathing tidally room
air at rest. Additionally, 10 subjects (three healthy subjects and seven
COPD patients) were studied while breathing initially room air and
subsequently air enriched with oxygen.
Results: According to the results, PA,O-2(Bohr) considerably differed
from PA,O-2(ideal) (P = 0.004). The cause of the difference, at the
individual’s R, is: (1) the difference between the arterial and Bohr’s
alveolar CO2 tension, mainly in COPD patients, and (2) the inequality
between Bohr’s alveolar part of the tidal volume for CO2 and O-2.
Furthermore, end-tidal gas tension (PET,CO2 and PET,O-2) differed from
Pa,CO2 and PA,O-2(Bohr) respectively.
Conclusion: The deviation of PA,O-2(Bohr) from PA,O-2(ideal) has a
definite impact on Bohr’s dead space ratio for O-2 and CO2, and on the
alveolar-arterial O-2 difference. The difference (PA,O-2(Bohr) -
PA,O-2(ideal)) is not related to the pathology of the disease. So, gas
exchange within the lungs should be assessed at the subject’s R from
PA,O-2(Bohr) and PA,CO2(Bohr) but not from PA,O-2(ideal) nor Pa,CO2.
Συγγραφείς:
Jordanoglou, J.
Latsi, P.
Chroneou, A.
Koulouris, N. G.
