Changes of arterio-venous differences in pH and pCO2 by hemodialysis

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).