THOMAS BEPNER

The session “Strategies to Deliver Optimal Dose of Dialysis” was opened with a lecture by Professor Bernard Charra, MD, who argued that “length of time on dialysis is more important than Kt/V.” He began with a review of his experience in Tassin, France, with slow prolonged hemodialysis using conventional membranes and acetate dialysate. He showed that the mix of patients has changed in recent years to include a higher percentage of older patients and patients with diabetes (20%) and other comorbid diseases. As a consequence, the prolonged average survival rate reported from his clinic has fallen dramatically, as shown by Kaplan–Meier analysis, but he has continued to maintain some of his patients for many years using slow prolonged dialysis three times weekly.

More recently, he compared 8-hour with 5-hour dialyses and found that mean arterial pressures were more easily maintained in the normal range, and that the incidence of hypotension during dialysis was much less frequent, with 8-hour treatments. In all patients, better survival was observed in those whose mean arterial pressures were better controlled. Dr. Charra proposed that the vicious cycle of short dialysis was the explanation for the benefit of prolonged dialysis. As dialysis time is shortened, fluid removal rates must be increased, leading to more frequent hypotension and cramps during the treatment. The physician responds by shortening the dialysis even further, by increasing the dialysate sodium concentration, and by treating cramps with hypertonic saline. The physician may also increase the target weight. This leads to increased thirst and hypertension between dialyses, essentially negating the efforts of the physician and, in many cases, promoting further fluid gain. The patient experiences an increased incidence of cramps and hypotension (observed more in his 5-hour-dialysis patients), and worsening control of blood pressure. Dr. Charra acknowledged that increasing Kt/V is beneficial but he feels, based on these experiences, that increasing time on dialysis is preferable to increasing the clearance rate.

Another proponent of prolonged dialysis, but on a daily basis, Andreas Pierratos, MD, Humber River Regional Hospital, Toronto, Ontario, reviewed the latest experience with prolonged nighttime dialysis in Toronto. He echoed the improved hemodynamic stability voiced by Dr. Charra in comparisons of standard with nocturnal hemodialysis, and noted that neither remote monitoring nor a partner were required for his patients dialyzed at home. Most patients were maintained with central lines because they were dialyzed at home, but increasingly more are managing with peripheral arteriovenous fistulas, using cannulas properly secured to prevent accidental dislodgment. Catheter infections were not increased and he continued to note the near complete absence of exit-site infections, an observation that is unexplained. He warned about the loss of calcium and phosphate in the dialysate due to prolonged daily treatments, and advised increasing calcium concentrations and adding phosphate to the dialysate. In general, his patients do not require phosphate binders. Other benefits of prolonged nighttime dialysis include the use of marginal fistulas (since high blood flow rates are not required), decreased erythropoietin requirements resulting in a considerable cost savings, improved cognitive functions documented by objective testing, improved quality of life, and improvement in sleep apnea.

Taking a somewhat opposite point of view, Robert Lindsay, MD, from London Health Sciences Centre, London, Ontario, explained that his dialysis center has embarked upon a study (funded by the Canadian government) of short versus prolonged daily hemodialysis. This study has just begun so he is not in a position to recommend either therapy, but is attempting to remain objective and to select a mix of patients with preferences for one or the other treatment. He will compare outcomes and other measures in these two groups and examine similar parameters in a cohort of patients currently dialyzed on the standard three-per-week schedule. Dr. Lindsay noted that the first few patients treated with prolonged daily dialysis developed increases in serum bicarbonate concentration, requiring adjustment of bicarbonate in the dialysate. He also noted that serum phosphorus concentration remained unchanged until after the first month of dialysis, when it began to fall. He plans to monitor access blood flow and access survival as part of this study.