1. What is home hemodialysis (HHD)?
HHD is a kidney replacement modality for patients with end-stage kidney disease (ESKD) that can be performed safely in the patient’s home environment. Assistance of a trained caregiver or qualified hemodialysis nurse is a requirement. The frequency of treatment for HHD can vary per individual patient. HHD can be performed as conventional HHD, with treatments 3 days a week for 3 to 4 hours or longer each time. It can also be performed as short daily HHD, occurring 5 to 7 times a week for shorter duration. Lastly, it can be performed overnight as nocturnal NHHD where treatments normally last 6 to 8 hours.
2. How many people today use HHD?
The 2010 United States Renal Data System (USRDS) report showed that 0.51% of incident dialysis patients were undergoing HHD. Based on the 2015 USRDS report, the use of HHD by incident ESKD patients increased by 222% from 2007 to 2013. Even with the large relative rise in HHD, its overall utilization as a home dialysis modality is significantly lower than that of peritoneal dialysis (PD). Home dialysis, either HHD or PD, was utilized by 9.1% of all patients undergoing dialysis as of 2013.
3. What machines are used for HHD?
In the United States HHD is performed with a “low-flow systems” (L-FS) machine. The most frequently used L-FS machine in the United States is the NxStage System. The NxStage machine is portable; it weighs 32 kg (71 lbs) and is 15 × 15 inches. Dialysate for the machine is provided in two ways. Delivery of 5-L dialysate bags can be made to a patient’s home, with four to six bags needed for short daily dialysis. These bags are convenient when patients are traveling. Alternatively, there is a fluid generator (PureFlow) that can prepare up to 60 L of dialysate (enough for two to three treatments) using a filtering system within the machine and connection to a tap water source.
4. How is HHD technically performed when compared with conventional hemodialysis?
The common conventional in-center dialysis machine is a “single-pass system” (SPS) machine. A SPS machine produces dialysate within the machine by proportionally mixing acid and base concentrates with a purified water source. The dialysate then moves as a single-pass, high-flow fluid to the dialyzer for transmembrane contact with the patient’s blood. A SPS machine typically uses a dialysate flow to blood flow (Qd:Qb) ratio of 2:1. With an L-FS machine (like the NxStage), the flow rates are reversed so that Qd:Qb is between 1:2 and 1:3. This permits a more complete equilibrium between dialysate and patient’s blood, ultimately allowing for the use of less dialysate.
5. What type of access is used for HHD?
Patients are able to use a tunneled central venous catheters (CVCs) or arteriovenous fistulae (AVF) to connect themselves to an HHD machine. As in conventional in-center hemodialysis, an AVF is preferred over a CVC, given the increased risk of blood stream infections associated with CVCs.
6. Describe the “buttonhole” method and why it is used.
The conventional method of repeated cannulation of an AVF involves using sharp-tip needles and rotating needle puncture sites (“rope-ladder technique”) with each successive dialysis treatments. A “buttonhole” is a constant fibrous tract established by repeated puncture followed by small eschar formation of the same site. Recannulation of the same two sites eventually allows access with a blunt-tip needle.
7. What are the advantages and disadvantages of buttonholes?
Some observational studies suggest that the buttonhole method helps minimize patient discomfort and adverse effects of repeated cannulation attempts and provides a predictable location for repeated puncture. Buttonholes can allow for greater ease of cannulation by the patient or caregiver. It has also been reported to reduce the pain associated with sharp-needle puncture, although this claim has been disputed with a more recent randomized controlled trial. The primary limitation of buttonhole use is its increased risk of infections. Studies have shown that buttonhole cannulation results in higher rates of both local and systemic infections. In particular, it increases the risk of Staphylococcus aureus bacteremia. The use of the buttonhole technique thus may be more appropriate in some cases, such as for patients with short AVF segments.
8. What are clinical benefits of HHD?
There are randomized and nonrandomized trials that have shown several benefits to more frequent hemodialysis. Daily hemodialysis has been shown to improve cardiovascular parameters such as a reduction in left ventricular (LV) mass, a decrease in systolic blood pressure, and mean arterial pressure. Other surrogate markers of clinical improvement attributed to daily hemodialysis include a reduction in antihypertensive medication use, improved adequacy of dialysis, improved serum phosphate control, and improved quality of life. Some key limitations to these studies deal with the selection bias of home dialysis patients. Patients performing their own dialysis treatments at home tend to have greater social support, financial resources, greater health literacy, motivation, and might be overall healthier than their in-center dialysis counterparts.
9. Describe the clinical outcomes of HHD versus in-center hemodialysis.
One retrospective cohort study showed that patients receiving “intensive” dialysis (five to seven sessions per week) compared with patients receiving in-center hemodialysis (three treatments per week) showed a strong association with improved survival. During the 4-year follow-up period 13% of the intensive HHD group died, compared with 21% of the conventional in-center dialysis group.
10. What was the frequent hemodialysis network (FHN) trials?
The FHN trials are the largest to-date prospective randomized controlled trials to study the safety, feasibility, and efficacy of frequent in-center (Daily Trial) and frequent home-based nocturnal (Nocturnal Trial) hemodialysis. The first arm (FHN-Daily Trial) randomized 245 patients from 10 regional centers to receive six (frequent) or three (conventional) in-center hemodialysis sessions per week for 12 months. The second arm (FHN-Nocturnal Trial) randomized 87 patients from 9 regional centers to 12 months of 6 times per week (frequent) home nocturnal hemodialysis versus 3 times a week (conventional) HHD. All patients were receiving conventional thrice-weekly in-center dialysis prior to the time of randomization.
11. What did we learn from the FHN trials?
The coprimary composite outcomes examined in both daily and nocturnal trials were (1) death or change in LV mass death or (2) change in physical health composite (PHC) score. Secondary outcomes analyzed were cognitive performance, self-reported depression, laboratory markers of nutrition, mineral metabolism and anemia, blood pressure and rates of hospitalization, and vascular access interventions. The FHN-Daily Trial showed a statistically significant benefit of more frequent hemodialysis (HD) for both coprimary composite outcomes (death/LV mass or death/PHC). The FHN-Nocturnal Trial (HHD patients) did not show a definitive benefit of more frequent nocturnal HD for either co-primary outcome. Both arms showed improvement in phosphorus and systolic blood pressure control. Neither trial showed significant benefit among the other main secondary outcomes. Long-term survival (median 3.6 years follow-up) was significantly better in the group of patients who were initially randomized to the frequent dialysis arm of the FHN-Daily trial. In contrast, long-term survival (median 3.7 years follow-up) was worse for the frequent dialysis HHD patients in the FHN-nocturnal trial.
12. Are there studies that compare overall mortality between HHD to PD?
There are few comparative effectiveness studies to help better answer this question. One of the first studies to examine this was an observational cohort analysis using the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA). The primary outcome of mortality between conventional in-center dialysis, PD, and HHD was examined with all patients starting dialysis over a 1-year period. HHD had a 49% lower mortality rate when compared with patients receiving conventional in-center HD. In contrast, patients receiving PD had similar mortality as the conventional in-center HD cohort. However, patients in the HHD group were younger, with fewer comorbid conditions, and hence “healthier” than their PD and in-center HD counterparts.
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