Abstract
The appropriateness of the ventilatory response to muscular exercise is best considered with respect to the precision of arterial PCO2 (PaCO2) regulation for moderate exercise and by the degree of the compensatory hyperventilation at work rates which engender a metabolic acidemia. But in order to avoid the necessity for intra-arterial sampling, which for sufficient data-density usually requires an indwelling catheter, several investigators have proposed non-invasive techniques for PaCO2 estimation. Techniques which are based upon assumptions of dead space volume (VD) or of a constant relationship between PaCO2 and end-tidal PCO2 (PETCO2) are not useful owing to the large inter-subject variability in the former case1 and the invalidity of the assumption in the latter.2,3 DuBois et al.4 proposed that the mean alveolar PCO2 could be derived from a “reconstruction” of the intra-breath time profile of PACO2 (i.e., time-average: PĀCO T2 ), which in normal subjects would closely approximate PaCO2. Gumming,5 has shown that when the cumulative CO2 output (VCO2) is expressed as a function of the cumulative expired volume (V), the resulting relationship is — to a very close approximation — linear (following a small lag phase) with a slope which represents PĀCO2 (i.e., flow-weighted average: PĀCO F2 ) and an intercept on the volume axis which is a measure of the “series” dead space (VD)). We were interested, therefore, in developing on-line, breath-by-breath techniques for determining these estimators and to define the acccuracy with which they reflect directly-measured PaCO2 during exercise.
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© 1989 Plenum Press, New York
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Whipp, B.J., Lamarra, N., Ward, S.A., Davis, J.A., Wasserman, K. (1989). Estimating Arterial PCO2 from Flow-Weighted and Time-Average Alveolar PCO2 During Exercise. In: Swanson, G.D., Grodins, F.S., Hughson, R.L. (eds) Respiratory Control. Springer, Boston, MA. https://doi.org/10.1007/978-1-4613-0529-3_10
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DOI: https://doi.org/10.1007/978-1-4613-0529-3_10
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