[Respiratory response and acid-base equilibrium in acetate dialysis and bicarbonate dialysis]

In order to elucidate the mechanisms responsible for the hypoxemia observed during acetate dialysis, but not found during bicarbonate dialysis, the authors studied ventilation, blood gases and their exchanges in the lungs and across the dialyzer on 9 patients. Oxygen consumption was similar both in acetate and bicarbonate dialysis. At the beginning of acetate dialysis, hypocapnia, due to CO2 losses through the dialyzer, causes hypoventilation and hypoxemia; afterwards, the worsening of acidosis (due to bicarbonate losses) stimulates ventilation, thus correcting the initial imbalance. Authors also hypothesize a pulmonary mechanism for CO2 "sparing" contributing to compensate CO2 losses through the dialyzer. The absence of hypoxemia during bicarbonate dialysis would be due to the absence of CO2 losses through the dialyzer.