Changes of Arterio-venous Differences in pH and pCO 2 by Hemodialysis

Abstract

Normally the differences in arterial-venous pH (A-VpH) and veno-arterial pCO₂ (V-ApCO₂) are small and constant. This study deals with A-VpH and V-ApCO₂ and their effect on arterial-venous saturation hemoglobin percentage (A-VSHb%) in uremic patients under hemodialysis (HD). In 17 uremic patients under HD with acetate, blood samples were collected anaerobically in heparinized syringes from artery (fistula) and vein (forearm without fistula) pre- and post-HD. In these samples pH, pCO₂ and SHb% were determined and A-VpH, V-ApCO₂ and A-VSHb% were estimated. Comparison between the values pre- and post-HD of A-VpH, V-ApCO₂ and A-VSHb% shows that these three values were decreased significantly post-HD (p<0.001). The correlation of all values (pre- and post-HD) of A-VpH and V-ApCO₂ with that of A-VSHb% was significant and positive (r=0.514 p<0.01, r=0.505 p<0.01, respectively).