Vol. 275, Issue 1, R339-R342, July 1998
SPECIAL COMMUNICATION
Single-breath CO diffusing capacity influenced by initial alveolar
partial pressure of CO
Hartmut
Heller and
Klaus-Dieter
Schuster
Department of Physiology, University of Bonn, 53115 Bonn,
Germany
The purpose
of this study was to assess the influence of incorrect determinations
of the initial alveolar partial pressure of carbon monoxide (CO) at the
beginning of breath holding
(PIACO) on the pulmonary CO diffusing capacity of the lung
(DLCO).
Single-breath maneuvers were performed on 14 anesthetized and
artificially ventilated rabbits, using 0.2% CO in nitrogen as the
indicator gas mixture. Inflation and deflation procedures were carried
out in an identical manner on each animal, with inflation always
starting from residual volume. End-tidal partial pressure of CO was
determined by respiratory mass spectrometry and was used to calculate
DLCO values
with the application of the three-equation
(method
1), as well as the conventional (method
2), solution. In each rabbit,
method
2 caused
DLCO values to be overestimated when compared with
method
1, and this overestimation decreased
with increasing time intervals of CO uptake. Because we were able to
recalculate this deviation using
PIACO
values that were obtained by taking the diffusive removal of CO during inflation into account, we concluded that errors in estimating PIACO by
applying method
2 significantly contribute to the
discrepancy between both methods.
conventional solution of breath holding equation; rabbit; three-equation methodology; breath holding; pulmonary CO diffusing
capacity of the lung
