Issue: March 2022

ByMihran Naljayan, MD

March 16, 2022

6 min read

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Residual renal function, lifestyle play key roles in incremental peritoneal dialysis

Issue: March 2022

ByMihran Naljayan, MD

In the United States, the annual rate of growth in incident patients with end-stage kidney disease has slowed.

However, patients selecting home dialysis for the first time increased 85.6% from 2007 to 2016 and those choosing peritoneal dialysis grew 60.2% in that timeframe, according to recent data from the U.S. Renal Data System.

While the baseline historically has been low for home dialysis compared with in-center hemodialysis (ICHD), the increase in patient count shows dialysis providers are focused on growing the use of home therapies.

PD prescription

Compared with prevalent patients on dialysis who transition to PD from ICHD, many incident patients on PD have significant residual kidney function (RKF).¹ Most patients with ESKD begin on a standard PD prescription measured as 8 to 9 hours of continuous cyclic peritoneal dialysis (CCPD) with a day dwell, or four manual exchanges with continuous ambulatory peritoneal dialysis (CAPD).

The prescription for incremental PD can be defined in different ways, including CCPD overnight with dry days, CCPD fewer than 7 days a week or CAPD with fewer than four exchanges a day, possibly with a dry period as well.²

There are several studies that shed light on the use of incremental dialysis, which has been an acceptable standard of care in PD but used less often in hemodialysis.^3,4 A number of studies from around the globe have shown the benefits of incremental PD.^5-8 Clearly, incremental dialysis is not for every incident patient. It is important to measure residual kidney function and design a prescription that considers patient lifestyle considerations.⁹

Personalized approach

Incremental dialysis requires a more individualized approach coupled to a regular assessment of RKF (at monthly intervals or after hospitalization, angiographic procedures or a prolonged antibiotic course, etc.). By closely monitoring RKF measurements, adjustments in the total delivered dialysis dose can be made to achieve a minimum Kt/V urea of 1.7 per week. Without dialysis clearance, a RKF of 9.8 mg/min/1.73 m² would be required.¹⁰

Several authors¹¹ have suggested quantifying dialysis as a GFR equivalent adjusted to surface area. This approach would provide a guide for adjusting incremental dialysis-delivered dose based on gradual losses of RKF similar to how deteriorating RKF is expressed in chronic kidney disease.

A renal adjustment factor would be required only to convert renal urea clearance to a GFR equivalent dose unless RKF is quantified by measuring mean urea and creatinine clearance.

Advantages

When initiating incremental PD, potential advantages include maintenance of RKF, a decreased number of exchanges, decreased risk of peritonitis with fewer exchanges, decreased dextrose exposure, decreased waste and improved quality of life.

Potential disadvantages include patient refusal to increase prescription as RKF decreases, monthly 24-hour urine collections, electrolyte disturbances, uremia and hypervolemia.

Dialysis adequacy is measured every 3 to 4 months (target Kt/V urea of 1.7). In PD, this adequacy measurement is a combination of both RKF and PD clearances.

However, these two clearances are not equal. Although small solute clearance is measured using urea, there are many non-measured solutes cleared by the kidney such as proteins and hydrophobic toxins.¹²

The CANUSA study demonstrated that clearance by RKF impacts survival, but peritoneal clearance does not.¹³ Renal clearance provides additional clearance that the peritoneal membrane does not; therefore, utilizing that residual clearance and preserving RKF as much as possible could be beneficial to patient survival.

Loss of RKF

Patients on PD experience a lower rate of decline in RKF compared with patients on HD.¹⁴ With incremental PD, most of the clearance provided for the patient is by RKF, with only a smaller fraction of clearance provided by the peritoneal membrane to achieve both adequacy and symptom management of ESKD.

By using incremental PD in patients with incident ESKD, RKF can be maintained, as noted in prior studies, while still providing appropriate clearance to achieve adequacy targets. It is important to adjust prescriptions to avoid excessive total ultrafiltration that results in hypovolemia and or hypotension which may alter renal perfusion and potentially contribute to “renal stunning” as is seen in ICHD.¹⁵

Preserving RKF is a primary goal in designing prescriptions (modality selection, dose and frequency), as patients are transitioned from symptomatic late-stage CKD to a dose of renal replacement that resolves symptoms.

In conjunction, additional medication considerations, including ACE inhibitors and angiotensin II receptor blockers, are critical to preserve kidney function. Critical approaches to prescription design have demonstrated the ability to preserve RKF and yet remain an underutilized approach to initiating renal replacement therapy.¹⁶

Exposure to dextrose

Patients on incremental PD typically have less dextrose exposure compared with patients on full-dose prescriptions as new patients with ESKD.⁵ Dextrose exposure over time in PD is one of the contributing factors for drop-out from PD, particularly due to ultrafiltration failure secondary to fibrosis and neovascularization of the peritoneal membrane.¹⁷

If patients are initiated with an incremental prescription during their first few years as incident patients, they will have less cumulative dextrose exposure. This may lengthen the overall time a patient can remain on the PD therapy. Further studies are needed to evaluate this concept.

Quality of life

One of the other causes of dropout from using PD is psychosocial burnout. Patients and caregivers tend to “burn out” from the extensive 7-day-a-week therapy.¹⁸ Patient-centered care should be a focus when nephrologists discuss modality options with patients and consider prescription management for the patient on PD. Issues such as flexibility with time, ability to travel and effect on family are high priorities.

The actual modality utilized to initiate dialysis with incremental dosing may play a role in the quality of life achieved for the individual patient. A presentation at ASN Kidney Week demonstrated that patients who started on CAPD utilizing a non-full dose exchange schedule achieved a higher quality of life vs. patients started on automated peritoneal dialysis (APD).¹⁹

In patients on incremental CAPD prescriptions, having less than four exchanges a day may decrease the burden of therapy by minimizing the number of exchanges, connections and disconnections.

In patients on incremental CCPD, having shorter time on the cycler or no day exchanges may reduce some of the burden of therapy and PD supplies needed. And, without a last fill, the patient may not feel as “full” during the day with daytime dwells.

Clinical considerations

Incremental PD could possibly be used for patients newly diagnosed with ESKD. Although generally this is defined as patients with eGFR of no more than 15 mL/min, there are many variables used to define ESKD and the need to initiate dialysis.

These include electrolyte abnormalities, uremic symptoms (ie, poor appetite, nausea, weight loss and fatigue), increased sodium retention, and hypertension and volume control. As progressive renal decline occurs, patients may begin to experience those symptoms that lead to a poor quality of life and increased risk for hospitalization. Initiation of dialysis can help with symptom management and electrolyte control.²⁰

Incremental PD can be another tool in a nephrologist’s toolbox to provide a dialysis prescription that revolves around a patient’s lifestyle while ensuring adequate and safe dialysis. Using appropriate clinical judgement as to what is best for the patient should be considered and may have an impact on the success of this type of therapy. Setting expectations with the patient early during the dialysis journey around increasing dialysis prescriptions as the RKF declines is important so that the patient is well-informed regarding care.

This type of communication between the patient, the physician and the nurse assists in creating a cohesive care team that can provide the patient with the best possible experience on PD.

References:

1. United States Renal Data System. 2020 USRDS Annual Data Report: Epidemiology of kidney disease in the United States. NIH, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Md. 2020.
2. Ankawi GA, et al. Can J Kidney Health Dis. 2016;doi:3:2054358116679131.
3. Woodrow G, et al. BMC Nephrol. 2017; doi:10.1186/s12882-017-0687-24.
4. Tattersall J. Clin Kidney J. 2018;doi:10.1093/ckj/sfy082.
5 Yan H, et al. Am J Kidney Dis. 2017;doi:10.1053/j.ajkd.2016.08.019.
6. Sandrini M, et al. J Nephrol. 2016;doi:10.1007/s40620-016-0344-z.
7. Jeloka T. et al. Indian J Nephrol. 2013;doi:10.4103/0971-4065.114496.
8. Yan H. et al. Perit Dial Int. 2021;doi:10.1177/08968608211036796.
9. Tangvoraphonkchai K. et al. Semin Dial. 2017;doi:10.1111/sdi.12589 10.
10. Guest S. et al. Perit Dial Int. 2012; doi:10.3747/pdi.2011.00027.
11. Casino FG. et al. Nephrol Dial Transplant. 2017;doi:10.1093/ndt/gfx343.
12. Auguste BL, et al. Semin Dial. 2018;doi.org/10.1177/2054358119871031.
13. Bargman JM, et al. J Am Soc Nephrol. 2001;doi:10.1681/ASN.V12102158.
14. Lysaght MJ, et al. ASAIO Trans. 1991;PMID:11280496.
15. Marants R, et al. J Am Soc Nephrol. 2019;doi:10.1681/ASN.2018121194.
16. Garofalo C, et al. J Nephrol. 2019; doi:10.1007/s40620-018-00577-9.
17. Zhou Q, et al. Kidney Int.2016;doi.10.1016/j.kint.2016.03.040.
18. Mujais S, et al. Kidney Int Suppl. 2006;(103):S21-6.
19. Naljayan M, et al. Poster 1306. ASN Kidney Week (virtual). October 22-25, 2020.
20. Chen T, et al. J Aust.2018;doi:10.5694/mja18.00297.

For more information:
Mihran Naljayan, MD, MHA, FASN, FNKF, is an associate clinical professor of medicine at LSU School of Medicine in New Orleans and the interim chief of the section of nephrology and hypertension at LSU. He can be reached at mihran.naljayan@davita.com.

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Sources/Disclosures

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Disclosures: Naljayan reports being the chief medical officer of home modalities for DaVita Kidney Care.

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