Intradialytic changes of the oxyhaemoglobin dissociation curve during acetate and bicarbonate haemodialysis. Possible interactions with haemodialysis-associated hypoxaemia.

ABSTRACT

In nine chronic haemodialysis patients, treated alternately with acetate and bicarbonate, the main critical factors in oxygen supply to the tissues were evaluated Hb values, blood gas parameters, red cell 2-3 diphosphoglycerate (2-3 DPG), phosphataemia and P50 in vivo. Predialytic P50 was higher than in normal controls. During dialysis, arterial pO2 and pCO2 significantly decreased in acetate dialysis, whereas they were stable in bicarbonate dialysis. Rising alkalinisation was accompanied, both in acetate dialysis and in bicarbonate dialysis, by reduction of P50, while 2-3 DPG did not change. The acute increase in Hb-O2 affinity adversely affected peripheral oxygen release. In acetate dialysis this mechanism might magnify the effects of dialysis-induced hypoxaemia, affecting the clinical tolerance.