are used for home hemodialysis in the united states. they are made by b. braun melsungen, fresenius and nxstage, a division of fresenius medical care. the systems take different approaches to the process of dialysis. the b braun is a standard hemodialysis machine is used incenter and at home. the fresenius "baby k" home machine is close to a standard hemodialysis machines, but somewhat more user friendly and smaller. both the b braun and the fresenius baby k requires a separate reverse osmosis water treatment system which allow dialysate flow rates generally from 300 to 800 ml/minute. the nxstage system one cycler uses far less dialysate per treatment with a maximum dialysate flow rate of 200 ml/minute but generally runs at rates less than 150 ml/minute. the nxstage system one can be used with bags of ultrapure dialysate – from 15 to 60 liters per treatment (see photo showing treatment in process). this allows the system one to be transportable; as of 2008 the company supports travel within the continental us and will assist travel to alaska and hawaii (travel to ak & hi will result in the patient having additional out of pocket costs). generally, the supplies including the dialysate are delivered as they are scheduled to be used, either bimonthly or monthly but the amount of supplies can become a concern. the system one can also use a separate dialysate production device manufactured by nxstage – the pureflow. the pureflow uses a deionization process to create a 60, 50 or 40 liter batch of dialysate depending on the sak (bag of dialysate concentrate) specified by the md. a batch has a 96-hour shelf life and is usually used for two or three treatments, although some patients are using the entire 60, 50 or 40 liter batch for a single extended treatment. frequency hemodialysis patients on frequent daytime hemodialysis have done well on short sessions (1.5 hours) given 6 times per week, although this would total 9 hours per week, and is fewer hours per week than most patients being dialyzed 3x/week. when changing from a 3x/week to a 6x/week schedule, if total weekly time is left the same (each session length cut in half), patients typically will still remove a little bit more waste products initially than with conventional schedules, since the blood levels of toxins during the initial hour of dialysis are higher than in subsequent hours. most patients treating themselves "daily" (6x/week) with daytime hemodialysis use session lengths of 2–3 hours. longer session lengths give more benefit in terms of fluid and especially, phosphate removal. however, unless sessions are prolonged beyond 3–4 hours, almost all 6x/week patients will still require phosphate binders. fluid and phosphate removal with "daily" dialysis are made more difficult because patients often feel better and increase protein (and thus also, phosphate) as well as fluid intake. when nocturnal dialysis is given 3 or 3.5 times (every other night) per week, the total weekly duration of dialysis is markedly prolonged, since each session typically lasts 6–8 hours, compared to 3–4 hours for conventional dialysis. this gives benefits in terms of fluid removal and phosphate removal, although about 1/2 to 2/3 of patients receiving this kind of treatment will still require phosphate binders. when such long nocturnal sessions are given 6x/week, in almost all patients phosphate binders can be stopped, and in a substantial number, phosphate needs to be added to the dialysate to prevent phosphate depletion. because of the long weekly dialysis time, fluid removal is very well controlled, as the rate of ultrafiltration is quite low. whereas adequacy of conventional dialysis is measured by urea reduction ratio urr or kt/v, the question of adequacy of more frequent dialysis is based on opinion only and not on controlled trials. the kdoqi 2006 adequacy group, in their clinical practice recommendations, suggested using the standardized kt/v as a minimum standard of adequacy for dialysis schedules other than 3x/week. a minimum standardized kt/v value of 2.0 per week was suggested.