Acid-base changes in acute exacerbation of chronic hypercapnia in man

Acid-base parameters were studied in 10 adult patients with chronic respiratory failure during spontaneous acute exacerbations of chronic hypercapnia and after return and stabilization of PaCO2 values at previous levels with improvement of clinical conditions. All factors interfering with acid-base equilibrium were carefully avoided. The results of this investigation confirm qualitatively those obtained by GOLDSTEIN et al. [7] in dog studies and those of INGRAM et al. [9]in human studies: increasing degrees of chronic hypercapnia tend to minimize the pH reduction induced by acute PACO2 changes. From a quantitative standpoint INGRAM's data in humans are considerably different from GOLDSTEIN's data obtained in dogs. Our data, although numerically limited, confirm the acute deltaH+/deltaPaCO2 slope obtained from dogs by GOLDSTEIN et al. As data are not yet sufficient, definitive conclusions cannot be drawn. However the pattern of acid-base equilibrium changes in man in this situation seems to be similar to that observed by GOLDSTEIN et al. in the dog and could be described with reasonable accuracy by the theoretical model of LEUENBERGER et al.[13].