Quantitative Displacement of Blood Acid-Base Status in Acute Hypocapnia

Abstract

Experiments carried out in anesthetized, ventilated dogs to describe the short-term blood acid-base responses to induction of hypocapnia. In all experiments, a fall in plasma pCO₂ to a level of 10 to 15 mm Hg was associated with a prompt rise in blood base excess (BE), reaching maximum in 10–15 mins followed by a secondary slower fall. These changes in blood base excess were evaluated in terms of the fractional contributions by (a) redistribution of bicarbonate within the body fluids (b) accumulation of lactate; (c) residual (non-renal) contribution. By examining the time course, it was found that the observed δ log pCO₂/δ pH did not reach a steady value within the experimental period, thus explaining the inconsistency of data previously reported in the literature.

Key Words:

• Acid-base equilibrium
• alkalosis
• bicarbonate
• hyperventilation
• in vivo carbon dioxide titration
• lactic acid
• respiratory alkalosis