A recent Core Curriculum published in AJKD from Bieber and Young focused on home hemodialysis. In this interview, Timothy Yau @Maximal_Change (AJKD) interviews Osama El Shamy @osamaelshamy88 (OES). Dr. El Shamy is a nephrologist and faculty member at Vanderbilt University Medical Center with a special interest in home dialysis modalities.
AJKD: The article starts by including a well-known, yet harrowing statistic about home hemodialysis (HHD) – in 2016, only 1.8% of prevalent patients were treated with home dialysis. What are some of the major reasons for this small number?
OES: When assessing the dialysis landscape, it is important to note that approximately 23%-38% of patients “crash” into dialysis. This leaves little room for patient education and understanding of modality options. Dialysis initiation is a daunting task that patients with end stage kidney disease deal with. Imagine crashing into dialysis, being started on in-center dialysis, slowly becoming familiar with the logistics and idea of being on dialysis, then being asked if you would like to switch modalities. It is a difficult decision because at that point, you are introducing a new foreign concept to an already overwhelmed patient population.
For those patients undergoing modality education, I believe the first hurdle they face when choosing between home and in-center dialysis is that many are accustomed to the idea that medical centers and institutions are clean, but that the home is dirty and not fit to host such a complex medical procedure. Depending on the patient’s residence, physical space may also be an issue. HHD requires room for medical supplies and the dialysis machine.
If a patient feels comfortable doing their dialysis at home, the next and most important step is HHD training. Medicare covers up to 25 training sessions. While that sounds comforting, it is a big time and monetary investment for patients to come back and forth to the dialysis unit up to 25 times. In a way, it is counterintuitive for the patient that they are going on a home modality but need to come to the dialysis unit so often. During their training, many patients report fear of performing self-cannulations. A line I often hear from patients is “I can’t imagine putting a needle in my arm.”
One aspect that needs to be addressed is that a large proportion of nephrologists do not feel comfortable managing HHD. An internet-based survey of ASN members who completed training between 2004 and 2008 found that only 15.8% of nephrologists reported being well-trained and competent in HHD. And although there has been a growth in the number of dialysis-providing facilities that offer HHD, in some parts of the country patients do not have access to or knowledge of these centers.
AJKD: What are ways to overcome these barriers and increase home dialysis uptake?
OES: Patients cannot be on home dialysis unless they are offered it. This is where the barriers start; educating nephrologists about home dialysis options and formulating education materials that can then be used to teach eligible patients about their dialysis options. Educating providers will help both debunk some of the myths and misconceptions that some may have about home dialysis, as well as increasing the number of nephrologists who are comfortable providing home dialysis – expanding the home dialysis network. Furthermore, many existing fellowship programs have turned their attention to improving their fellows’ home dialysis education during their years of fellowship. Some even opted to offer their fellows an additional year of dialysis education; similar to what happens with kidney transplant, interventional nephrology, critical care nephrology and onconephrology.
Building on the concept of dialysis education, nephrologists should be discussing dialysis options before they are in a situation where dialysis initiation is imminent. As a simple rule of thumb, I discuss dialysis options with my patients when they have an eGFR of less than or equal to 30 mL/min/1.72m2. This will lower the number of patients who require crash initiation of in-center dialysis with hopes of potentially changing modalities to home dialysis.
Overcoming the barrier of patients’ anxiety about doing their dialysis at home starts with informing them that there will be a home visit conducted by a member of the dialysis team to assess whether their home is fit for home dialysis. Inquiring about patients’ support system and living conditions and bringing in a family member or caregiver to dialysis discussions is also key. For patients with limited space in their homes, there are options available that can help. One such example is having supplies delivered every 2 weeks rather than once a month – this will reduce the amount of space needed to store items at any one time. There also social services available that can establish self-care programs for patients.
Patients who are anxious about self-cannulation can have customized training sessions to focus more on technique and desensitization. Bringing in caregivers to be co-trained can alleviate anxiety as well. I find that on average patients on HHD spend more time learning self-cannulation than they do other aspects of their training and that helps them familiarize themselves with their dialysis access.
While patients invest a lot of time and energy traveling to and from the unit during their training period, the use of telemedicine for their monthly visits once they have completed their training can help make up for some of this burden. After completing their first 3 monthly visits, CMS allows for 2 telehealth visits per quarter. Moreover, it is important to underscore to patients that this is an early investment that they will reap the dividends of in the future when they only need to come to the unit 1-3 times every 3 months rather than 3x/week on in-center hemodialysis.
AJKD: Are there any exciting new technological developments in the world of home dialysis? I am thinking specifically about not only the machine itself but water treatment and ways to increase ease of use and access to home modalities.
OES: There are currently three FDA-approved HHD systems: Fresenius 2008K, NxStage System One and the Tablo HD machine. The Fresenius 2008K machine is essentially identical to the dialysis machines used for in-center HD.
The NxStage machine is more user friendly, has an analog patient display and focuses on dialysis efficiency maximization the utilization of dialysate. Dialysate bags are stored in patients’ homes. This is different from the conventional HD machines used in-center, where large volumes of dialysate are used. Moreover, there is the NxStage PureFlow system which generates its own dialysate using its water purification system. This system is comprised of a sediment filter, carbon media filter, dual deionization resins, ultrafilters and ultraviolet light to produce product water that is then mixed with concentrate to form the final dialysate. One thing to note, however, is that producing a full batch of dialysate require about 8 hours. This can be utilized for patients with space issues who are unable to store large bags of preformed dialysate.
Finally, the Tablo HD machine is the most recent addition to this lineup. It has a reverse-osmosis system and a disinfection system which provides daily disinfection. The Tablo also has its own miniature water system that is similar to the conventional water treatment system. Given its relatively small size compared to conventional HD machines, water production is not as quick – therefore limiting dialysate flow rates. Another consideration when sending patients home with Tablo is that it requires a chemical cleaning once a week.
An advantage of using low dialysate flow rates, while maximizing the efficiency of the dialysis prescription is avoiding our patients incurring significantly increased utility bills. This is especially relevant for systems that utilize patients’ home water supply; NxStage PureFlow and Tablo.
AJKD: One of the fundamental differences in home vs in-center hemodialysis is the slower dialysate flow (Qd). At its most basic, there is a good reason for this, which is that in-center hemodialysis is extremely water voracious and consuming that much dialysate at home is not feasible. But this also leads to new terminology (eg, flow fraction) and new calculations for clearance (standard Kt/V vs single pool Kt/V). Can you explain these concepts to our readers, and ways in which you use these calculations to adjust home dialysis prescriptions?
OES: Current KDOQI clinical practice guidelines recommend a target standardized Kt/V (std Kt/V) of 2.3, and a minimal std Kt/V of 2.1. As we know std Kt/V is a weekly measurement based on thrice weekly dialysis, however HHD patients are often on dialysis 4 days per week or more. In those cases, we use the single pool Kt/V (sp Kt/V). The relationship between sp Kt/V and std Kt/V is not linear due to post-dialysis urea rebound.
Knowing what sp Kt/V to target in order to achieve a std Kt/V of >2 depends on the number of days per week that patients will be doing their HHD: 4 days/week – sp Kt/V 0.8, 5 days/week – sp Kt/V 0.6 and 6 days/week – sp Kt/V 0.5. Of course, bear in mind that the greater the number of days on HHD, the shorter the individual treatments.
So, let’s say that we have a 100kg woman starting on HHD. Assuming that her total body water is 50% of her weight, that means that her V in the Kt/V equation will be 50. Now, let’s assume that she prefers to be on HHD 5 days a week, that means that we need to target a sp Kt/V of 0.6 as outlined above. I use this in order to calculate the minimum amount of dialysate (Kt) I would need. In this case Kt = 0.6 x 50 = 30L. So I now know that in order to achieve a sp Kt/V of 0.6 – assuming 100% dialysate efficiency – I would need a minimum of 30L of dialysate per treatment session.
We know that reaching 100% efficiency in terms of dialysate saturation is very difficult. So, we use higher volume of dialysate. In the case of the NxStage One for example, dialysate bags are 5L. In that particular case, I would then use 35L (7 bags).
This is where the concept of flow fraction becomes relevant. Flow Fraction (FF) = dialysate flow rate/blood flow rate (Qd/Qb). As a result, the lower the Qd is, the lower the FF and the more saturated the dialysate will be. FF prescribed tend to range from 0.2 to 0.5. At a FF of 0.2 for example, dialysate saturations of urea and creatinine are approximately 95% and 90%, respectively.
For simplicity’s sake, let’s assume that we want to target a FF of 0.5. If we are using a Qb of 400mL/min, we can determine the Qd; 0.5 x 400 = 200mL/min.
We can now determine how long a dialysis session is going to be: 35,000/200 = 175 minutes (2 hrs 55 mins).
This is assuming no ultrafiltration is prescribed. If we wish to prescribe an ultrafiltration (UF) of 2L per treatment, that would add 10 minutes to the patient’s treatment time. This is because UF is removed at the same rate as the Qd (2,000/200 = 10).
AJKD: Final thoughts? What are the most important concepts about home dialysis that you think every nephrology trainee should know about home hemodialysis?
OES: As disappointing at it sounds, there have not been truly meaningful advancements in the management of our dialysis patients. There is a lot of room for improvement and innovation, and this is an opportunity for our young nephrology trainees to help revolutionize the field. Home dialysis focuses on providing patients with an alternative treatment to in-center HD that considers patients’ social support system, living conditions, and working hours while minimizing space requirements for supplies and in the case of HHD maximizing the efficiency and utilization of dialysate.
At the end of the day, we are here to help our patients navigate their way through their care. This starts with making sure that we are as informed as we can be about their different treatment options so that we can provide them with as much information and insight as we can. Home dialysis may not be suitable for all patients but given our current incident and prevalent home dialysis rates in the United States, there is definitely potential for growth. Home dialysis can provide our patients with a great deal of autonomy while making them an active part of their medical care team.
To view this Core Curriculum (FREE), please visit AJKD.org.
Articles in the Core Curriculum aim to give trainees in nephrology a strong knowledge base in core topics in the specialty by providing an overview of the topic and citing key references, including the foundational literature that led to current clinical approaches.