Acute renal response to rapid onset respiratory acidosis

Abstract

Renal strong ion compensation to chronic respiratory acidosis has been established, but the nature of the response to acute respiratory acidosis is not well defined. We hypothesized that the response to acute respiratory acidosis in sheep is a rapid increase in the difference in renal fractional excretions of chloride and sodium (FeCl – FeNa). Inspired CO2 concentrations were increased for 1 h to significantly alter PaCO2 and pHa from 32 ± 1 mm Hg and 7.52 ± 0.02 to 74 ± 2 mm Hg and 7.22 ± 0.02, respectively. FeCl – FeNa increased significantly from 0.372 ± 0.206 to 1.240 ± 0.217% and returned to baseline at 2 h when PaCO2 and pHa were 37 ± 0.6 mm Hg and 7.49 ± 0.01, respectively. Arterial pH and FeCl – FeNa were significantly correlated. We conclude that the kidney responds rapidly to acute respiratory acidosis, within 30 min of onset, by differential reabsorption of sodium and chloride.