Acid-base changes of arterial plasma during exogenous and endogenous hypercapnia in man

Abstract

Acute hypercapnic conditions have been produced in man by exogenously given and endogenously accumulated CO 2 in order to compare the nature of the CO 2 titration curves of blood in vivo between these conditions. Effects of general anesthesia on these curves have also been investigated. In the anesthetized subjects there was no significant difference between the slopes of the titration curves for these two modes of hypercapnia. Neither were the slopes of the curves for the unanesthetized subjects determined during exogenous hypercapnia greatly different from those of the anesthetized subjects. A clinical implication of these findings is that a CO 2 titration curve of blood defined in any of the above conditions can be applied to other circumstances without serious error. Non-respiratory acidosis did not occur during the hypercapnic period while apparent non-respiratory acidosis developed during the reversal of hypercapnia. Discrepancy in the length of time spent for the establishment and reversal of hypercapnia is thought responsible for the development of this apparent non-respiratory acidosis.