controversies in peritoneal dialysis

Peritoneal Dialysis International, Vol. 28, pp. 585–590 Printed in Canada. All rights reserved.

0896-8608/08 $3.00 + .00 Copyright © 2008 International Society for Peritoneal Dialysis

CONTROVERSIES IN PERITONEAL DIALYSIS

VASCULAR ACCESS PLANNING IN PERITONEAL DIALYSIS PATIENTS

Giusy Chiarelli,1,2 Monica Beaulieu,2 Mario Cozzolino,1 Suneet Singh,2 Mercedeh Kiaii,2 Paul Taylor,2 Adeera Levin,2 Diego Brancaccio,1 and Maurizio Gallieni 1

Peritoneal dialysis (PD) is a well-established renal replacement therapy for end-stage renal disease patients. Nonetheless, on an annual basis, at least 10% of patients shift from PD to hemodialysis for a variety of reasons. Thus the issue of vascular access creation needs to be addressed for this small but significant group of patients. Despite the relatively consistent number of dropouts, the creation of an arteriovenous fistula prior to transfer remains suboptimal, and variable from center to center. Literature for this specific area is poor and dated. Guidelines seem to suggest vascular access creation in high-risk failure patients, but they have no detailed criteria to select patients that would likely fail PD and therefore take advantage of a backup access. There is a need to better understand and predict patients that require conversion to hemodialysis to develop a plan that focuses on wellness and maximum quality of life in the lifecycle of PD patients. This review addresses the issue of vascular access planning in adult PD patients, presents the available literature on the topic and the current guidelines and recommendations, and describes a research agenda to guide decision making in clinical practice.

KEY WORDS: Renal replacement therapy; vascular access; dropout; technique failure; arteriovenous fistula.

ease patients. However, many PD patients require conversion to hemodialysis (HD) for a variety of reasons, such as repeated infections, inadequate dialysis due to loss of residual renal function, and deterioration of peritoneal membrane function. There is a need to better understand and predict those patients that require conversion to HD, especially with respect to the creation of vascular access for HD. Given the known benefit of arteriovenous fistulas (AVFs) versus other types of vascular accesses on outcomes in HD, it is important that patients needing to convert from PD to HD have a mature AVF at the time of conversion. Peritoneal dialysis and HD should not be seen as competitive but as complementary methods in an “integrated care concept” of the same renal replacement therapy program (1,2). Thus, a comprehensive and multidisciplinary approach is required to develop a plan that focuses on wellness and maximum quality of life at different stages in the lifecycle of PD patients (3). The focus of this review is to increase awareness of the need for vascular access planning in adult PD patients, describe what is and is not known about this topic, and describe a research agenda that will help guide future decision making to improve the outcomes of patients.

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VASCULAR ACCESS PLANNING IN PD PATIENTS: IS IT WORTH IT?

Correspondence to: G. Chiarelli, Renal Division, San Paolo Hospital, Via Di Rudini 8, 20142 Milan, Italy. [email protected] Received 20 September 2007; accepted 18 April 2008.

Data from the British Columbia Renal Agency database, Canada, highlights the need for vascular access planning in PD patients. In 2006, 853 patients were on

Perit Dial Int 2008; 28:585–590

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eritoneal dialysis (PD) is well established worldwide as a renal replacement therapy in end-stage renal dis-

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Nephrology and Dialysis Unit,1 San Paolo Hospital, University of Milan, Italy; Division of Nephrology,2 University of British Columbia, Vancouver, British Columbia, Canada

CHIARELLI et al.

NOVEMBER 2008 – VOL. 28, NO. 6

40 35 30 25 20 15 10 5 0

≤3

4–24 25–48 Months of PD before HD conversion

>48

Figure 1 — Graphic shows the timing of permanent conversion from peritoneal dialysis (PD) to hemodialysis (HD) by months on PD (data from the British Columbia Renal Agency database).

In the Italian patients, the reason for PD failure and transfer to HD was primarily recurrent peritonitis (37.36%), followed by other reasons related to deterioration of PD technique (loss of ultrafiltration in 15.73%, loss of PD adequacy in 14.33%), catheter-related problems (8.15%), patient’s choice (11.8%), and other unspecified reasons (12.64%). These data from two different countries suggest that, every year, in at least 10% of patients we should be able to foresee the necessity for and plan the creation of a vascular access. Therefore, we need to develop an effective way of identifying those patients that will indeed need a vascular access. Data to guide clinical practice in this specific area are lacking (5). In the absence of data, renal units have established their own policies and procedures: some nephrologists would advocate simultaneous peritoneal catheter insertion and AVF formation, others reserve AVF formation only for those patients that are likely to fail PD in the future; some nephrologists do not think it is useful to prepare a vascular access in PD patients at all and initiate HD through temporary catheters before committing to the conversion. To our knowledge, the outcomes of these different strategies have not been described.

PD Italian Registry data 2004

3174 PD patients

77% of all Italian PD patients

32.4% dropout rate (1032 patients)

13.6% death

37.36% peritonitis

11.2% shift to HD

15.73% loss of UF

14.33% loss of PD adequacy

6.4% transplant

8.15% catheter problems

1.2% other

11.80% patient’s choice

12.64% other

Figure 2 — Diagram shows the entity and the reasons for dropping out of peritoneal dialysis (PD) in a large cohort of Italian patients (data from the Italian Peritoneal Dialysis Registry). Note that, each year, 1 in 10 patients will shift to hemodialysis (HD), requiring a vascular access. UF = ultrafiltration. 586


Percentage (%)

PD; 26% of patients stopped PD in 2006, including the 10.7% (91/853) that switched to HD permanently. Figure 1 illustrates that 53% of patients switched to HD within 24 months of being on PD. Data from the Italian Peritoneal Dialysis Registry (4) indicate the same need. For the year 2004, it reports data from 3174 PD patients, representing 77% of the Italian PD population. During 2004, 1032 of these patients dropped out of PD (a 32% annual rate). Reasons for dropping out were death for 432 patients (13.6%), shift to HD (11.2%), transplantation (6.4%), and other reasons (1.2%) (Figure 2).

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A LANDMARK STUDY SUGGESTS THAT A BACK-UP VASCULAR ACCESS IS NOT NECESSARY IN PD PATIENTS

EVIDENTIARY BASE

The lack of detailed information on how to behave in clinical practice derives from the very few publications on the subject, which are also dated and involve a small number of patients. The first study that can be found in the literature was published in 1986 by a Danish group (7). They divided their 43 PD patients into two groups: 19 patients with an AVF and 24 without a vascular access. As only 4 patients from each group needed HD during the observation period (5.8 years), they concluded that permanent vascular access should be constructed only in PD patients with evident treatment failure. With the exception of a Brazilian study by Divino Filho et al. (8), all the articles available in the literature on the topic, even if different in study design, seem to lead

to the same conclusion as the Danish study. The study by Divino Filho et al. is peculiar because of the influence of economic factors on renal unit clinical policy. Due to the health policies at that time (1991), costs of acute vascular access material were not reimbursed in Brazil by their National Institute for Medical Assistance, while other costs for HD and PD were covered. Their unit had a high rate of peritonitis and therefore a frequent requirement for emergency HD. Given their good AVF survival, and considering their costs and complications, they concluded it was beneficial to establish a primary distal AVF in all nondiabetic PD patients. If the first AVF was unsuccessful, they suggested creating a new AVF or graft only when HD was needed. This study differs from all the other articles in study design as it takes into consideration 35 of 66 PD patients that had some type of vascular access before or during PD. Although interesting for having considered the cost issues, this study lacks details about the dropout rate from PD to HD in Brazil, reasons for dropping out, and the peritonitis rate. In the same year, Farrington et al. (9) compared one group of 56 patients that received a Tenckhoff catheter to another group of 20 patients with a double dialysis access (the AVF was created at the same time as PD catheter implantation). At the end of the observation period, they found that a large proportion of patients in each group were no longer receiving PD, but that only a small percentage had converted to HD; most had died or had been transplanted. They observed that 35% of AVFs failed during the follow-up period and that, in most cases, AVFs were used only for brief periods. Such a high failure rate led the authors to the following hypothesis: The fact that an AVF was considered a reserved access in these patients might have jeopardized optimal observation and care of it. They did not systematically evaluate the complication rates of AVFs, but this issue is stressed in the article as another important factor that may influence the decision of placing a vascular access in PD patients. More recently, Chui et al. (10) carefully considered problems related to AVF complications. That article is a retrospective assessment of the results of AVF procedures, of the risk factors for AVF failure, and of the selection strategy used to choose which end-stage renal disease patients would be given dialysis. They found that the AVF patency rate at approximately 2 years in 136 patients was 75%; the only adverse significant factors linked to fistula failure were smoking and gender (female). Of the 136 patients that underwent creation of an AVF, 33 had PD catheter insertion as a concurrent procedure, and 48.5% of those PD patients did not use their AVF, so they had an unnecessary operation. Moreover, the authors report an AVF complication rate of 22.8%. 587


In 1993, Beckingham et al. (6) published a landmark article. In the United Kingdom, 42% of renal units provided PD patients with an AVF as a “backup”; the aim of the study was to justify this policy. They analyzed 176 patients that started continuous ambulatory peritoneal dialysis (CAPD) from 1986 to 1989 in their unit. Over a median follow-up period of 4 years, 73% of those patients did not require HD. Of the 114 patients with an AVF, only 10 used their fistula; another 23 patients required emergency HD but, when required, their AVF was no longer functioning. Of the 62 patients without an AVF, only 15 required emergency HD via a central venous catheter. As 94% of fistulas were never used for HD, and as 70% of AVFs were not functioning when needed, the authors concluded that creating backup fistulas in CAPD patients to allow emergency access for HD was neither successful nor justifiable. There are limitations to this study however. Patients’ characteristics in 1986 were different than those currently being seen (i.e., more diabetes and cardiovascular disease and advancing age), and the results may not be extendable to the current PD population, who may be more vulnerable to failure than the population studied by Beckingham. Furthermore, the question of simultaneous creations of AVF and PD access may not be entirely relevant to contemporary populations in different countries. The question may not be whether prophylactic AVF is required in all PD patients, but rather when to plan AVF in PD patients. Different types of data are required to answer this question.

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Therefore, they defined as “questionable” the practice of concurrent PD catheter insertion and AVF formation as backup. CURRENT GUIDELINE RECOMMENDATIONS

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also undergo AVF evaluation. Thus, vein protection education and vessel mapping would permit optimal information that could be used to preserve the appropriate veins for possible future AVF use. The second point of the FFBI refers to all PD patients that exhibit treatment failure or recurrent complications: they should have an AVF placed early in order to preserve the vessel, to prevent emergency placement of central vein catheters, and to allow sufficient time for AVF maturation. This group is the only “official body” that has clearly advocated proactive placement of an AVF in PD patients, but they are also careful to outline that this recommendation does not imply preference for or promotion of HD over PD. Of note, neither the European Best Practice Guidelines (16) nor the Canadian Clinical Practice Guidelines for Vascular Access (17) offers suggestions or recommendations on this topic. Thus, current societies and guideline groups have no detailed criteria for defining PD failure or high-risk patients, and no consistent strategies or recommendations regarding access creation and timing. DISCUSSION It is well known that PD is associated with a number of serious complications. Although improvements in CAPD delivery systems and connectors have reduced the peritonitis rate to 1 episode every 2 – 3 years (18), peritonitis remains a principal reason to transfer from PD to HD (18,19). Other recognized causes of PD failure may relate to loss of residual renal function, dialysis adequacy, and patient demands. Furthermore, it is well known that survival of PD patients is significantly improved if they are transferred to HD when PD complications appear (19,20). This observation suggests the importance of shifting patients to HD when needed, rather than continuing a renal replacement therapy that is becoming dangerous to the patient. It would therefore seem more prudent to define the problem more broadly than simply asking, When is an AVF required in a PD patient? In essence, the question is one of facilitating the prediction of PD failure and the timing of PD failure so that appropriate plans, including AVF creation, can be implemented. Thus, the first critical step is recognizing impending PD failure at the appropriate time. Clearly, not all shifts to HD occur with sufficient lead time to plan the transfer with vascular access preparation. As mentioned, recurrent peritonitis, loss of ultrafiltration, loss of PD adequacy, catheter-related problems, and patient’s choice are the leading reasons for shifting to HD. It is


Many guidelines and official groups have addressed the issue of vascular access in PD patients, either directly or indirectly. This section summarizes the positions of the Vascular Access Society, the Australia-based guideline group Caring for Australasians with Renal Impairment (CARI), two USA-based groups K/DOQI and Fistula First Breakthrough Initiative (FFBI), the European Best Practices group, and the Canadian Society of Nephrology Guidelines. On the basis of the single UK study cited above, the Vascular Access Society’s (11) recommendations are clearly stated: Due to low utilization and high probability of occlusion/complications prior to use, there is no indication for preemptive vascular access placement for patients on PD. The NKF-K/DOQI vascular access guidelines (12) state the same concept in a similar manner: While early AVF creation is recommended in those patients that are not transplant candidates, or that lack potential living kidney donors, or seem to be unlikely to perform PD, the guideline describes the need for the nephrologist to estimate probability of success on PD, and to attempt AVF creation at the discretion of the nephrologist. The recent update of the K/DOQI section on PD (13) clearly states that, “patients who choose PD for their modality should not be required to have a HD access placed.” For those patients on PD who may be likely to fail PD in the future, AVF creation is considered reasonable in K/DOQI guidelines. However, there is no guidance as to how to identify those at risk for PD failure. The CARI guidelines (14), aiming to identify patients requiring vascular access, succinctly state that a “back up AVF may not be needed in low risk PD patients, especially if suitable for transplantation.” This recommendation reflects the position of the Vascular Access Society based on the Beckingham study (6), but does not adequately define high- or low-risk PD patients. More-detailed suggestions on the topic can be found in the Position Statement on Kidney Replacement Therapies, by the FFBI (15). The FFBI recognizes that prevention, early diagnosis, and proper evaluation are essential strategies in the management of kidney disease. This group does recognize, but does not quantify, that many patients on PD will convert to permanent HD for any number of reasons. They recommend that, as part of a comprehensive strategy, all patients evaluated for PD should


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a variety of mechanisms, and consequently to cardiac hypertrophy. An unused AVF in a PD patient would expose him to potential cardiovascular risks without the clinical benefits of having a vascular access, which are evident in a HD patient. If one perceives that the causes of PD failure may be linked to intrinsic patient characteristics, then it may be possible to develop a model to predict those at high risk of PD failure. Thus, we would advocate a series of studies that would (1) identify predictors of PD failure in large ethnically diverse populations; (2) describe predictors of AVF outcomes in all patients; (3) explore the impact of an AVF on cardiac function; and (4) determine if proactive placement of an AVF in a well-defined cohort of PD patients at different time points (e.g., at time of PD initiation vs after the first 6 months on PD if specific criteria are met) results in improved outcome. The larger context of course, is the ability to facilitate a timely transfer from PD to HD in patients on PD >6 months, as even this practice is highly variable and is not backed up with any evidence. If transfer to HD is a preterminal event (i.e., the patient dies within 6 months of the conversion), then it is likely that failing PD is simply a surrogate for poor outcome. Alternatively, there are patients that survive for prolonged periods of time on HD after conversion; it is these individuals in whom we are most interested in ensuring an appropriate transition. Resources among units, regions, and countries may vary but it would seem that some organized approach to the establishment of a framework for study and implementation would serve the community well. CONCLUSIONS Several problems remain open and are in need of further investigations: 1. While it is not advisable to provide all PD patients with an AVF, it seems to be good practice in select PD patients, but there are no studies supporting this view. 2. Predictors of PD failure or high-risk PD patients are not well described in the literature and are not consistently implemented in clinical practice. Thus it is not feasible to select PD patients that can take advantage of an AVF. 3. The timing of creation of an AVF in high-risk PD patients (if they can be identified) is not well established. It would appear meritorious to suggest vein protection in all PD patients, given the importance of vein preservation in the success of an AVF. 589


possible to picture three different scenarios: (1) emergency shift to HD (i.e., due to resistant peritonitis, unpredictably nonfunctioning catheter, intercurrent event causing sudden loss of residual renal function or PD adequacy); (2) progressive decline in ultrafiltration and adequacy that leads the patient to HD in a predictable length of time, or patient’s choice to change renal replacement therapy; and (3) shift to HD in patient at risk of failing PD due to a variety of possible factors (i.e., identifiable membrane characteristics, comorbidities, psychosocial situation, inability to cope with PD) that may jeopardize PD technique in the long term. The first scenario obviously cannot lead to planned AVF; however, the remaining two scenarios may be amenable to systematic evaluation and planning. Current research should focus on developing risk models for failure and determining the utility of those models with respect to AVF planning. While current guidelines do address adequacy issues, and provide some guidance regarding transition management, there are no specific and structured criteria that would facilitate decision making. A working AVF in a PD patient can be seen as a beneficial resource for the patient, enabling improved survival with an orderly transfer to HD and avoiding emergency vascular access by central vein catheter. Since it is widely known that AVFs are associated with lower morbidity, hospitalization, and cost compared to central vein access (3), it would seem prudent to articulate this strategy more overtly than is currently being done. Several factors can influence the decision to create an AVF in PD patients: (1) the dropout rate from PD to HD; (2) the expected duration of PD in a specific patient; (3) the AVF failure rate; (4) the AVF complication rate; (5) cost issues; and (6) patient selection for PD and, consequently, the size of the PD center. The AVF failure rate is a crucial point in discussing AVF creation in PD patients. High fistula failure rates and high complication rates are reported in PD patients in the available publications. However, we emphasize that the dialysis population and PD devices as well have been changing over the years. Further, these studies are dated and do not take into consideration all factors affecting the AVF survival rate. Thus, the understanding of specific risk factors affecting fistula survival that exist in the PD population, and whether they affect the ideal timing of vascular access creation, would be very interesting and useful information for the clinical management of PD patients. Another important consideration is the impact of an AVF on cardiac function. It is well known that fistula placement is linked to increased cardiac output through

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4. Are the risk factors for AVF maturation and patency the same in patients on PD compared to an AVF created prior to any dialysis start? Given that, on an annual basis, 10% of PD patients convert to HD, there is a definite need for more rigorous recommendations on how to proceed with the creation of a vascular access in these patients. REFERENCES

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11.

12.

13.

14. 15.

16.

17.

18.

19.

20.

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dialysis catheter insertion and arteriovenous fistula formation in patients needing dialysis. Hong Kong Med J 2000; 6:312–15. Vascular Access Society. Guideline 1. Starting management of vascular access: 4. No vascular access placement in PD and kidney transplanted patients. Available at: http://www.vascularaccesssociety.com/guidelines/ h1.htm#No_vascular_access_placement Clinical practice guidelines and clinical practice recommendations for vascular access, update 2006. Am J Kidney Dis 2006; 48(Suppl 1):S176–276. Clinical practice guidelines and clinical practice recommendations for peritoneal dialysis adequacy, update 2006. Am J Kidney Dis 2006; 48(Suppl 1):S91–175. http://www.cari.org.au/ARCHIVE/DIALYSIS_va_archive/ dialysis_VA_003_pub.php Fistula First Breakthrough Initiative National Coalition. Position statement on kidney replacement therapies. Available at: http://www.fistulafirst.org/pdfs/FFBI_ position_statem_ final.doc The EBPG Expert Group on Peritoneal Dialysis. European best practice guidelines for peritoneal dialysis. 2 The initiation of dialysis. Nephrol Dial Transplant 2005; 20(Suppl 9):ix3–7. Ethier JH, Lindsay RM, Barre PE, Kappel JE, Carlisle EJ, Common A. Clinical practice guidelines for vascular access. Canadian Society of Nephrology. J Am Soc Nephrol 1999; 10(Suppl 13):S297–305. Brunori G, Orazi E, Montanaro D, Ballocchi S, Nicolini M, Quarello F, et al. Peritonitis and drop-out in a multicenter study: 48 months of follow-up [Abstract]. Perit Dial Int 1997; 17(Suppl 1):S28. Panagoutsos S, Kantartzi K, Passadakis P, Yannatos E, Mourvati E, Theodoridis M, et al. Timely transfer of peritoneal dialysis patients to hemodialysis improves survival rates. Clin Nephrol 2006; 65:43–7. Van Biesen W, Dequidt C, Vijt D, Vanholder R, Lameire N. Analysis of the reasons for transfers between hemodialysis and peritoneal dialysis and their effect on survivals. Adv Perit Dial 1998; 14:90–4.


1. Van Biesen W, Vanholder R, Lameire N. The role of peritoneal dialysis as the first-line renal replacement modality [Review]. Perit Dial Int 2000; 20:375–83. 2. Thodis E, Passadakis P, Vargemezis V, Oreopoulos DG. Peritoneal dialysis: better than, equal to, or worse than hemodialysis? Data worth knowing before choosing a dialysis modality. Perit Dial Int 2001; 21:25–35. 3. Davidson I, Gallieni M, Saxena R, Dolmatch B. A patient centered decision making dialysis access algorithm. J Vasc Access 2007; 8:59–68. 4. http://www.dialisiperitoneale.org/files/censimento/ Dati%202004.pps 5. Berardinelli L. The endless history of vascular access: a surgeon’s perspective. J Vasc Access 2006; 7:103–11. 6. Beckingham IJ, O’Rourke JS, Bishop MC, Blamey RW. Are backup arteriovenous fistulae necessary for patients on continuous ambulatory peritoneal dialysis? Lancet 1993; 341(8857):1384–6. 7. Joffe P, Skov R, Olsen F. Do patients on continuous peritoneal dialysis need arterio-venous fistula? Perit Dial Int 1986; 6:193–5. 8. Divino Filho JC, Almeida FP, Lobo E, Boccato N, Moron J, Linardi F, et al. Need for vascular access in CAPD patients in Brazil. Contrib Nephrol 1991; 89:40–2. 9. Farrington K, Brown AL, Mathias MT, Karim MS, Cattell WR, Baker LR. Simultaneous creation of peritoneal and vascular access in patients commencing continuous ambulatory peritoneal dialysis. Nephron 1991; 59:323–5. 10. Chui AK, Chiu EY, White EA, Yumiba T. An investigation into the practice of concurrent chronic ambulatory peritoneal
