Effect of acetate upon arterial gases

The effect of dialyzer reuse on peak expiratory flow rate

Peak expiratory flow rates were measured during routine haemodialysis in 18 patients with chronic renal failure who were in receipt of thrice weekly haemodialysis treatment, using both a new cuprophan dialyzer and then the same dialyzer after reprocessing. Acetate buffered dialysate was used on both occasions. The peak expiratory flow rates fell by 10 +/- 0.3%, mean +/- sem, during the first hour of treatment with the new dialyzer, and in seven patients (39%) the fall was greater than 15%. Whereas the reduction in peak expiratory flow rates was significantly less with reuse, 4 +/- 0.1% (P less than 0.5). Similarly, the fall in arterial oxygen tension was also reduced on reuse from 28 +/- 1.2% to 14 +/- 1.3% at 30 min (P less than 0.05) and from 30 +/- 1.4% to 18 +/- 3.1% (P less than 0.05) at 60 min of dialysis. There was also a reduction in the fall in the peripheral platelet count at 30 min of dialysis from 14 +/- 0.8% to 9 +/- 0.4% with reuse (P less than 0.05). However, there was no change in dialysis associated leukopenia with reuse of the dialyzer membrane. These results suggest that reprocessing the dialyzer membrane alters its biocompatibility characteristics resulting in an improvement in biocompatibility and further supports the role of inflammatory cell mediator release in the pathogenesis of dialysis associated hypoxaemia and pulmonary dysfunction during the first hour of dialysis treatment.

Hypoxemia during hemodialysis: a critical review of the facts

The literature describing the fall in PaO2 during dialysis is intensively and critically reviewed. This phenomenon is related to both the type of membrane used (cellulosic v noncellulosic membrane), and to the composition of the dialysate (acetate v bicarbonate). It appears that a ventilation/perfusion mismatch due to pulmonary leukostasis can, in part, explain hypoxemia in patients dialyzed with cellulosic membranes. This phenomenon is especially apparent in patients with preexisting pulmonary abnormalities. However, hypoventilation remains the major cause of hypoxemia. This hypoventilation is mainly due to CO2 consumption during acetate metabolism (acetate dialysis), or alkalinization of the blood (bicarbonate dialysis). The metabolic consequences of acetate metabolism, and of bicarbonate and CO2 losses through the dialyzer are critically analyzed. The cause for the increment in oxygen consumption during acetate dialysis is examined. Finally, the respective role of these combined factors are described and used to explain the changes in VCO2, VO2, respiratory quotient (RQ), and PaO2 reported in the literature during dialysis against acetate and/or bicarbonate.

Pulmonary gas exchange during hemodialysis and peritoneal dialysis: interaction between respiration and metabolism

This review concerns the alterations in pulmonary gas exchange during hemodialysis and peritoneal dialysis. The occurrence of hypoxemia during hemodialysis has led to numerous studies that now provide sufficient data to explain this complex phenomenon. The role of substrate metabolism during hemodialysis and peritoneal dialysis are explored as it relates to alterations in ventilation. Comparison to similar types of ventilatory changes occurring during total parenteral nutrition are discussed. The effect of peritoneal dialysis on pulmonary function is also described.