The choice of a machine is important not only for the patient but also for the home dialysis program. Machines will differ in their cost, maintenance, physical footprint, portability within and outside the home, plumbing and electrical requirements, training time, setup and breakdown time, and water and dialysate preparation. While it is feasible and sometimes helpful to use multiple hemodialysis machines within a home program, this will introduce more required training, knowledge, and experience of the entire staff. Almost any dialysis machine can and has been utilized in the patient’s home.

Several dialysis machines have been studied for safety and efficacy in the home and approved for home use by the US Food and Drug Administration [3, 4]. The NxStage System One utilizes a cartridge-based extracorporeal circuit and dialysate of up to 60 L with lactate as a buffer. Its maximum dialysate flow is 300 ml/min. The Fresenius 2008 K@home is based on a traditional hemodialysis machine requiring water treatment similar to traditional hemodialysis and bicarbonate as a buffer. Four other hemodialysis machines designed specifically for home hemodialysis are under development: the Tablo hemodialysis machine from Outset Medical with an integrated patient interface and production of dialysate from tap water; the PAK hemodialysis system from Fresenius Medical, a sorbent-based hemodialysis system; the Vivia hemodialysis machine from Baxter which reuses the dialysis membrane and bloodlines; and the SC+ hemodialysis machine from Quanta Fluid Solutions which also uses a cartridge-based setup.

Successful dialysis starts with the production of water free from microbiological and chemical contaminants that can harm the patient [5]. The Centers for Medicare and Medicaid Services (CMS) has applied water quality and testing standards developed by the Association for the Advancement of Medical Instrumentation (AAMI) since 1987. These standards are updated approximately every 5 years [6]. While water production in the outpatient unit is similar in each unit, each patient’s home installation will be unique. In the home environment, the water system will be unique in every installation while adhering to the same AAMI standards.

While the cost of providing water and dialysate in the outpatient unit is usually less than 2 % of the overall cost of the treatment, it is a major cost in home hemodialysis and also may entail cost to the patient for additional electricity, water usage, sewer drainage, and plumbing.

Dialysate can be provided in a patient’s home in a number of methods: bagged dialysate delivered to the patient’s home similar to peritoneal dialysis, dialysate prepared in the patient’s home prior to dialysis, or in-line dialysate from an appropriate water source mixed at the machine. Cost, convenience, storage, installation, and maintenance all factor in the type of dialysate to utilize.

Bagged dialysate similar to peritoneal dialysis has the advantage of providing a sterile, ultrapure dialysate to the patient. However, limitations accompany this advantage. Practical considerations of delivery, storage, cost, and logistics generally limit this method to approximately 30 l of dialysate yielding a single-pool urea Kt/V (spKt/V _urea) of approximately 0.7 in the typical 80 kg adult, whereas most current guidelines for thrice weekly hemodialysis recommend a spKt/V _urea of approximately 1.2. Thus, in the absence of significant residual renal function, hemodialysis will need to be performed more than three times per week. Second, lactate is typically the base in bagged dialysate fluid for stability, compatibility with calcium, and microbiological concerns. Lactate showed improvement in tolerability over acetate as a hemodialysis buffer before the widespread introduction of bicarbonate-based buffer [7]. Yet, in hemodialysis with a lactate buffer, serum lactate levels will be increased slightly during the treatment, and patients with significant liver dysfunction, higher volumes of dialysate, and/or poorly controlled diabetes may not tolerate lactate.

Attempting to replicate dialysate production similar to the outpatient unit or the acute care setting in the hospital also has limitations. Typically either a reverse osmosis (RO) machine or a deionized (DI) water system must be installed in the patient’s home. A disadvantage of the RO system is another machine to install, maintain, and monitor. The DI system usually requires an outside vendor to change the tanks and regenerate the beads in addition to plumbing installation delivering the water to the machine in the home.

Several systems that produce water and dialysate in novel methods in the home are being developed. These include the use of sorbent, distillation, and miniaturization of the dialysate production.