The effect of acetate on ventilation in haemodialysis patients

This study evaluates the direct effect of acetate upon ventilation during acetate-haemodialysis. Eight patients with end-stage renal failure who were receiving chronic haemodialysis treatment underwent acetate infusion for 1 h on a day outside a haemodialysis session. Ventilation was continuously measured using respiratory inductance plethysmography, starting 20 min before the infusion. Arterial blood samples were drawn and expired gases were analysed at regular intervals. After 1 h of acetate infusion, arterial pH increased rapidly and significantly from 7.38 +/- 0.01 to 7.49 +/- 0.01, the VCO2 and VO2 slightly decreased and increased respectively, resulting in a reduced respiratory exchange ratio from 0.81 +/- 0.04 to 0.69 +/- 0.05. Ventilation slightly decreased only after 60 min, whereas the breathing pattern remained normal; neither apnoea periods nor periodic breathing were observed. We conclude that the hypoventilation and irregular breathing encountered in acetate-cuprophane haemodialysis is related to CO2/HCO3- unloading and the occurrence of complement-activation-induced hypoxaemia rather than to the small changes in VCO2, VO2 during metabolism of acetate.