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A doctor's overview of nocturnal dialysis

Conventional hemodialysis shortfalls

It is well known that the mortality rate of patients undergoing maintenance hemodialysis remains unacceptably high. An extremely high morbidity and a relatively low quality of life has also been observed in the chronic hemodialysis patient. The institution of more intensive dialysis regimens appears to improve morbidity and, possibly, mortality among this patient population, although studies are still badly needed for the evaluation of mortality improvement.  Compared to conventional regimens, hemodialysis associated with longer duration and/or higher frequency correlates with enhanced outcomes as defined by improved laboratory and decreased usage of erythropoiten, with improved Kt/V values. With this in mind, nocturnal hemodialysis was introduced as a more desirable alternative to conventional dialysis.  It was thought that nocturnal dialysis could provide superior dialysis based on dose, duration, and frequency. It also takes advantage of the rather unproductive time during the nightly sleep.

About nocturnal hemodialysis treatment

Nocturnal hemodialysis can be either done at home or in center.   Nocturnal hemodialysis at home is generally performed 5-7 nights per week during sleep for a variable amount of time, based upon the length of sleep usually desired. This can be from 6-12 hours. In-center hemodialysis is generally performed 3 nights per week for 8-10 hours depending on the center availability. In either home or in-center nocturnal hemodialysis, the dialysate composition is a sodium bath of 140 mEq/L, a potassium bath  of 2 mEq/L, a bicarbonate bath of 28-35 mEq/L, with a calcium concentration of 2.5-4.0 mEq/L. A higher dialysate calcium is prescribed for patients with high ultrafiltration volumes. The blood flow rate is generally 200300 cc/min, depending on clearances, and the dialysate flow rate is anywhere from 100 cc/min to 800 cc/min.

The in-center nocturnal hemodialysis would tend to favor the higher end of blood and dialysate flows since the actual time per week on dialysis is less than on home nocturnal hemodialysis, i.e. 3 nights versus 5 nights per week. The typical ultrafiltration volume is 1-2 liters, with a range of 1-7 liters per dialysis treatment. Any dialyzer membrane can be used, including smaller surface area dialyzers, but most centers use high-flux dialyzers. In addition, nocturnal hemodialysis can be performed with any hemodialysis machine and existing machines can be modified for the requirements of the longer dialysis treatment. Dialyzer reuse can be used and the usual technique of reuse is applied. Anticoagulation is also used and it accounts for approximately 1,000 U of heparin per hour of dialysis. 

Nocturnal dialysis vascular access

Vascular access for nocturnal dialysis is the same as it is for any hemodialysis. Central venous catheters can be used, although these are considered less popular, especially with the fistula-first initiative.  Preferably, arteriovenous fistulas are used. Arteriovenous grafts have also been successful in nocturnal dialysis.

In-center vs. at-home nocturnal dialysis

As mentioned above, nocturnal hemodialysis can be performed at home or in the dialysis facility. If home hemodialysis is done at night, remote monitoring has been done via regular telephone lines or the Internet.

Live monitoring provides the following benefits: 

1. It helps prevent blood from clotting in an idle extracorporeal system.
2. It ensures compliance.
3. It aids in the collection of data.
4. It aids in the collection of data.

If performed in the dialysis facility, nursing personnel provide the same benefits.

In addition to the monitoring performed above, there are other safety measures that can be employed with in-center or home nocturnal hemodialysis, such as inexpensive moisture sensors that are placed strategically on the floor to detect dialysate and/or blood leaks. Their use should be considered an obligatory safety measure.

Which patients should consider home nocturnal dialysis?

Patient groups that can be preferentially targeted for recruitment for home nocturnal hemodialysis include patients who are followed in a chronic kidney disease clinic prior to development of end stage kidney disease. This prevents the state of dependence frequently encountered in an in-center unit. Training can be instituted very early and patients can recognize the benefits of self-care settings. Another group that can be targeted includes patients who are ineligible for kidney transplantation, in that nocturnal dialysis can be viewed as the modality of independence closest to kidney transplantation. Another group to be considered for home or in-center nocturnal hemodialysis  includes those with significant morbidities such as cardiac disease, diabetes mellitus, severe hypertension, dialysis-related symptoms and/or large interdialytic weight gain.  Patients who fail chronic ambulatory peritoneal dialysis, yet want to maintain some degree of independence, should also be considered for home nocturnal hemodialysis. The final group that is very frequently benefited by nocturnal hemodialysis, whether, in-center or home, include large-sized patients and patients not adequately dialyzed because of poor blood flow in their access.

Quality-of-life improvementsfrom nocturnal hemodialysis

Nocturnal hemodialysis is usually associated with marked benefits including improved solute clearance and quality of life. Patients will declare their improvement of quality of life almost uniformly. There is also noted to be much better blood pressure control and a reduction of medication requirements for control of hypertension. Urea and phosphorus clearances have been increased with nocturnal hemodialysis. Better hemoglobin values with less erythropoiten usage have also been reported. Some have suggested an enhanced survival, however, this requires further analysis. At present, there are no published randomized trials of nocturnal hemodialysis. As a result, some investigators feel that studies comparing nocturnal hemodialysis to conventional hemodialysis should be performed to better understand the benefits of nocturnal hemodialysis.

In summary, nocturnal hemodialysis done at home or in-center offers another modality of care for the patient with end-stage renal disease and should be available to patients. Further studies are required to evaluate the benefits and indications for its usage.

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