Early clinical, quality-of-life, and biochemical changes of "daily hemodialysis" (6 dialyses per week)
Amy W. Williams, MD
Synopsis: Williams AW, Chebrolu SB, Ing TS, Ting G, Blagg, CR, Twardowski ZJ, Woredekal Y, Delano, B, Gandhi VC, Kjellstrand, CM, for the Daily Hemodialysis Study Group. Early clinical, quality-of-life, and biochemical changes of "daily hemodialysis" (6 dialyses per week). American Journal of Kidney Diseases 2004; 43:90-102.
Achieving adequate dialysis with a positive impact on quality of life has been a challenge. Evidence has shown that despite achieving the recommended values for weekly Kt/V in conventional 3 times per week hemodialysis, undesirable intra- and inter-dialytic symptoms continue and patients' morbidity, mortality, and quality of life have not significantly improved. Previous experiences with more frequent nocturnal and daily dialysis have demonstrated hemodynamic and quality of life improvements.
This controlled, prospective study evaluates the early biochemical, clinical and quality of life changes with 6 times a week hemodialysis. Six dialysis centers and 20 adult dialysis patients participated in the study. Patients were sequentially monitored on conventional 3 times per week dialysis for 4 weeks and after immediately switching to 6 times per week dialysis for 4 weeks. The patient's dialysis time for the week was kept constant throughout the two study periods by halving the time per dialysis session used during 3 times a week dialysis, and dialyzing for that new lesser time per session 6 times a week. Dialyzers used, the reuse processes, dialysates, and dialysis machines (whatever machines that the patients happened to be using regularly) were held constant throughout both periods of the study. Ultrafiltration varied, depending on the patients' weight pre-dialysis. All participants had either an arteriovenous fistula or a synthetic arteriovenous graft for access. Hemodynamic parameters including blood pressure and weight were monitored. The number of nursing interventions and the need for changes in blood flow rate, ultrafiltration rate, and the number of times the patient's dialysis needed to be discontinued were recorded. Solute removal was determined using the partial dialysate collection method. Mid-week blood chemistries and hematology parameters were measured the first and last weeks on conventional 3 times per week dialysis and the last week on 6 times per week dialysis. Quality of life and assessment of quality of dialysis were also monitored on both dialysis schedules.
Mean time on dialysis per week was the same for the 3 times per week and 6 times per week dialysis arms of the study (3 times/week mean dialysis time per session, 232 + 32 minutes versus 116 + 17 minutes for the 6 times/week mean dialysis time per session). There was no difference between blood and dialysis flow rates, dialysate composition, or dialysate temperature between the two study periods. There was a significant decrease in pre-dialysis blood urea nitrogen (BUN) during daily dialysis (6 times/week, 55 ± 18 mg/dL versus 3 times/week, 62 ± 20 mg/dL, p=0.0003) as well as an increase in equilibrated BUN (eBUN) (6 times/week, 30 ± 11 mg/dL versus 3 times/week, 21 ± 8 mg/dL, p<0.0001) and single-pool BUN (spBUN) during daily dialysis (6 times/week, 28 ± 11 mg/dL versus 3 times/week, 19 ± 8 mg/dL, p<0.0001). Post-dialysis rebound BUN was 57% greater in the daily dialysis group (p<0.0001), and the mean decrease in BUN per hour as well as mean nitrogen removal per hour was greater with 6 times per week dialysis (p<0.0001). Weekly single-pool urea reduction ratio (spURR) (3 times/week, 210 ± 21% versus 6 times/week, 306 ± 48%, p<0.0001) and weekly equilibrated urea reduction ratio (eURR) (3 times/week, 201 ± 21% versus 6 times/week, 264 ± 42%, p<0.001) were greater during 6 times per week dialysis. Weekly standard Kt/V (stdKt/V) (3 times/week, 2.16 ± 0.67 versus 6 times/week, 2.86 ± 0.39, p<0.0001) was also greater on 6 times per week dialysis.
When dialyzing 6 times a week, urea distribution volume as percent body weight was significantly reduced (3 times/week, 52 ± 12% versus 6 times/week, 49 ± 11%, p=0.007). There was a reduction in pre-dialysis plasma creatinine level (3 times/week, 10.1 ± 2.8 mg/dL versus 6 times/week, 9.1 ± 2.8 mg/dL, p<0.0001) during the 6 times/week period. However, the single-pool, post-dialysis plasma creatinine value (3 times/week, 3.8 ± 1.3 versus 6 times/week, 4.7 ± 1.7, p<0.0001) was lower during the less frequent dialysis period. The weekly amount of creatinine removed, pre-dialysis potassium level, pre-dialysis carbon dioxide value, and pre-dialysis calcium concentration did not change. Weekly phosphorus removal increased by 10% during daily dialysis (3 times a week, 3.3 ± 1.1 g versus 6 times/week, 3.6 ± 1.1 g, p=0.093). Post-dialysis phosphorus rebound was greater during 6 times a week dialysis (p=0.0002). For the daily dialysis group, there was less post-dialysis fall in serum potassium level (p=0.0001) and post-dialysis alkalosis (p=0.002), as well as a decrease in fluctuations in levels of BUN (p<0.0001), serum osmolality (p<0.0001), serum carbon dioxide (p<0.0001), and serum potassium (p<0.0001).
Hemoglobin and hematologic parameters were unchanged and there was no change in the dosing of erythropoietin between the two study periods. Machine alarms due to high venous pressure and high transmembrane pressure were significantly reduced during the 4 weeks in which the patients were dialyzing daily (p=0.0009). There was no difference in arterial or venous pressures, conductivity, or temperature alarm frequencies. While the heparin prime dose was not different in the two arms of the study, heparin boluses and continuous infusion heparin requirements were less on daily dialysis (bolus: 245U versus 362 U, p=0.023; infusion: 259 U versus 830 U, p<0.001).
Hemodynamic parameters improved on daily dialysis with a significant decrease in the quantity of ultrafiltrate obtained per treatment and increase in weight loss per hour with daily treatment (ultrafiltrate/treatment: 3/times/week, 3.2 ± 1.3 kg versus 6 times/week, 1.9 ± 0.9 kg, p<0.0001; weight loss/hour: 3 times/week, 0.81 ± 0.32 kg versus 6 times/week, 0.95 ± 0.49 kg, p<0.0001). Mean pre-dialysis systolic blood pressure was significantly decreased with daily dialysis (132 ± 22 mm Hg versus 140 ± 23 mm Hg, p= 0.0005), and this decrease in blood pressure continued over the 4 weeks of daily dialysis. Weight gain correlated with pre-dialysis systolic blood pressure and diastolic blood pressure (systolic p<0.001, diastolic p<0.0001). During daily dialysis, there was a drop in the number of nursing interventions (p=0.012), the need for the assumption of the Trendelenburg position (p=0.007), and the need to reduce the ultrafiltration rate (p<0.0001) due to hypotension. There was not a significant difference in mean post-dialysis weight or mean number of anti-hypertensive medications required. There was a reduction in reporting of cramps (p<0.0001), chills (p=0.019), or hypertension (p=0.038) in the daily dialysis group. While on daily dialysis, the number of reported episodes of headaches, nausea, vomiting, and other symptoms related to hypotension was also less. There were no significant differences in access complications or problems. Assessment of the quality of dialysis improved (p=0.002) and there was an improvement in intra-dialytic symptoms of shortness of breath (p=0.037) and thirst (p=0.0008) during the 6 times per week dialysis period. There was also improvement in the quality of life between dialysis sessions as well as overall quality of life measurements during the time when the patients were dialyzing 6 times per week (3 times/week, 3.9 ± 0.7 versus 6 times/week, 4.1 ± 0.8, p=0.043).
Along with an improvement in overall quality of life, protein intake also improved on 6 times per week dialysis. This difference was only significant when calculations were based on pre- and post-dialysis BUN levels (p<0.0001). Overall fluid intake measured by daily weight gains, increased during daily dialysis (p=0.0002).
These results confirm that short daily dialysis is safe and well tolerated. There appears to be a rapid improvement in hemodynamic parameters both between dialysis sessions and during dialysis sessions as well as improvement in solute removal with less unphysiologic oscillations of solutes. In addition, patients' assessments of dialysis and of their quality of life are improved on daily dialysis.
Commentary by Andreas Pierratos, MD
This multi-center prospective controlled study by Williams et al. confirms the benefits of short daily hemodialysis over conventional hemodialysis of similar weekly duration in 20 patients. They include improved blood pressure control, decrease in dialysis-related hemodynamic instability and symptoms, and improved quality of life. The study is well-organized and provides accurate information on kinetics of various waste products.
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