Abstract
In the course of studying gas exchange during partial liquid ventilation (PLV) in healthy and injured piglets, we noted a reversal in the profile of exhaled CO2 (PECO2) versus time. Rather than a positive slope, the CO2 expirogram often reached a peak early in expiration and fell toward the end of the breath. In addition to a change in sign, the absolute value of the slope was very large. The change in profile led us to question the generally accepted practice of using “end-tidal” PECO2 to represent average alveolar PACO2 during PLV. Given the steep rate of change of PECO2 over a breath, the use of a single point on the CO2 expirogram to represent alveolar gas during PLV seemed in error. We hypothesized that a combination of increased ventilation heterogeneity and diffusion limitation could account for the reversal in sign and exaggeration of the slopes. To further investigate this problem we explicitly measured PECO2 vs. exhaled volume in two additional experiments and compared these findings to 40 previously studied animals.
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© 1996 Plenum Press, New York
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Mates, E.A., Tarczy-Hornoch, P., Hildebrandt, J., Jackson, J.C., Hlastala, M.P. (1996). Negative Slope of Exhaled CO2 Profile. In: Ince, C., Kesecioglu, J., Telci, L., Akpir, K. (eds) Oxygen Transport to Tissue XVII. Advances in Experimental Medicine and Biology, vol 388. Springer, Boston, MA. https://doi.org/10.1007/978-1-4613-0333-6_75
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DOI: https://doi.org/10.1007/978-1-4613-0333-6_75
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