Haemodialysis vascular access and fistula surveillance methods in The Netherlands

Raaja Ezzahiri1, M. Susan Lemson1, Peter J. E. H. M. Kitslaar1, Karel M. L. Leunissen2 and Jan H. M. Tordoir1

1 Department of Surgery and 2 Department of Nephrology, University Hospital Maastricht, Maastricht, The Netherlands

Correspondence and offprint requests to: Dr J. H. M. Tordoir, Department of Surgery, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.

Abstract

Introduction. As the mean age of haemodialysis patients is increasing, fewer patients will have suitable blood vessels for the creation of a Brescia–Cimino fistula and an increased use of graft implants is to be expected.

Methods. To assess the change in vascular access and the use of surveillance techniques, all haemodialysis centres in The Netherlands received a questionnaire regarding the types of vascular accesses and surveillance techniques used in their department on 31 December, 1996. The results were related to a comparable study done in 1987, shown between brackets.

Results. The response of the haemodialysis staff was 96%, of the vascular surgeons this was 91%. Sixty-two per cent (70%) of the patients had Brescia–Cimino fistulas, 21% (13%) Polytetrafluoroethylene (PTFE) graft fistulas, 17% (17%) other vascular accesses. Scheduled surveillance for stenosis detection was done by recirculation measurements in 6%, venous pressure measurements in 31%, Duplex scanning in 11% and angiography in 11% of the centres. When access problems occurred, 79% of the physicians performed recirculation measurements, 38% venous pressure measurements, 79% Duplex scanning and 100% angiography. In 46% of the centres PTA was done occasionally, and in 46% routinely for the treatment of stenotic complications in arteriovenous fistulas.

Conclusions. The use of PTFE grafts and other types of vascular accesses has increased at the expense of BC fistulas. Recirculation and venous pressure measurements are primarily done when problems occur and not according to a standard surveillance schedule. For visualization of failing fistulas, 79% of the centres uses Duplex ultrasound analysis and 100% angiography. The popularity of PTA has increased from 46 to 92% of the centres.

Keywords: arteriovenous fistula; Brescia–Cimino fistula; fistula surveillance; haemodialysis; polytetrafluoroethylene; vascular access

Introduction

Patients with end-stage renal failure require permanent vascular access for haemodialysis treatment. Renal transplantation is the ultimate therapy for patients with renal insufficiency. However the number of patients on the waiting list for kidney transplantation in The Netherlands is still increasing, from 883 in 1992 to 1005 in 1996. Moreover, not all patients are eligible for transplantation. This results in 4128 patients with end-stage renal failure, 2955 of which depend on haemodialysis treatment [1]. Therefore maintenance of a functional vascular access for these patients remains essential [2,3].

Due to the ageing of the Dutch population, more elderly patients with end-stage renal disease are referred to the physician. With the improvements in haemodialysis techniques these older patients can be included in the haemodialysis programme as well. As a result the haemodialysis population will increase both in age and in number. In The Netherlands the number of dialysis patients older than 75 years increased with 9.7% in 1996 compared to an increase of the total haemodialysis population of 3.4% [4]. Older patients have more co-morbidities, like cardiovascular diseases and diabetes mellitus, and consequently an increase of vascular access problems due to poor vessels can be expected.

The Brescia–Cimino (BC) fistula remains the arteriovenous fistula (AVF) of first choice [35]. However, due to the higher age of the haemodialysis patient population an increased need for secondary accesses like graft AVFs can be expected. Graft AVFs are known to have more thrombotic complications compared to BC fistulas [2], and also a higher risk on infection and a lower patency rate. Early detection of failing grafts by means of a programme of surveillance with subsequently elective intervention to prevent thrombotic occlusion, might have a favourable effect on the patency of these secondary access sites [6,7].

In the USA, more PTFE graft AVFs are implanted nowadays than BC fistulas [8]. To assess whether a change in AVF type from native to graft AV fistulas also has occurred in The Netherlands, a questionnaire was distributed to all centres of renal replacement therapy (RRT). The results were compared with a similar survey done in 1987 [9]. Also the number of complications, the types of interventions and methods of AVF surveillance were registered.

Methods

Two different types of questionnaires were mailed to all 52 dialysis centres in The Netherlands (eight academic dialysis centres, 38 dialysis centres in general hospitals and six other centres), one to the staff of the dialysis department and another to the surgeons.

The first questionnaire regarded the number of patients receiving haemodialysis treatment and the different types of vascular accesses used on 31 December, 1996. The number of patients receiving single needle dialysis was recorded. The use of catheters (single lumen, double lumen and insertion location) was assessed along with the types and methods of fistula surveillance (venous and/or arterial pressure measurements, recirculation measurements, Duplex scanning and angiography). The results of this questionnaire were compared to the results of a similar study, done in 1987 (100% response) [9]. The change in use of different accesses over time was analysed with the {chi}2-test. A P-value of <0.05 was considered statistically significant.

A second questionnaire, to the surgeons performing fistula surgery, registered the number and types of new vascular access operations over the year 1996. The number of surgeons performing vascular access operations was noticed. The number of re-interventions performed on the different types of vascular accesses was assessed, as well as the number of Percutaneous Transluminal Angioplasties (PTA). The surgeon's first and second choice treatment of access stenosis was asked. The total number of patients on RRT, their age distribution, the number of patients having diabetes mellitus and the mortality rates were recorded.

Results

Ninety-six per cent of the dialysis department staff and 91% of the surgeons responded to the questionnaires.

Demography
A total of 8283 patients were undergoing RRT in 52 centres. Of these patients, 2864 were on long-term haemodialysis and 1173 were on Continuous Ambulant Peritoneal Haemodialysis (CAPD) or on Continuous Cyclic Peritoneal Haemodialysis (CCPD). Ninety-one patients were receiving HD treatment at home and 4155 patients had a good functioning donor kidney, either from a postmortal donor or a living donor (Table 1Go) [4].


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Table 1. Types of renal replacement therapy (RRT) in 1996 in the Netherlands
 
In the age group of 0–44 years there were 868 patients (21%) receiving dialysis therapy; in the age group of 45–64 years, 1527 patients (37%); and in the age group of 65 years and older there were 1733 patients (42%) receiving dialysis therapy [4]. The total number of patients from all age groups does not correspond with the total number of the dialysis population, because the age of several patients in the Renine statistical report was unknown (Table 2Go). From 1987 to 1996, the number of patients of 65 years and older has increased almost twice as much as the number of patients in the age groups 45–64 years and 0–44 years (respectively 48, 24 and 17% increase of the total number of patients). The outflow of patients on dialysis therapy was due to kidney transplantation or due to death. A total of 508 kidney transplantations were performed in 1996, 76 of living donors and 432 of postmortal donors. The mortality of patients on dialysis therapy has shown an increase from 16% in 1987 to 20% in 1996. The main causes of mortality among the dialysis population were cardiac diseases (34%), social causes (14%), vascular diseases (9%) and sepsis (7%). The social causes meant that patients committed suicide, refused further dialysis treatment, or ended their treatment for other reasons.


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Table 2. Distribution of the dialysis population in different age groups in 1996 and 1987
 
Four hundred and thirty patients receiving dialysis therapy (10%) had diabetes mellitus (DM) as a primary cause of kidney failure, 251 had type I, 179 had type II DM. Other primary causes of kidney failure were renal vascular diseases, pyelonephritis, polycystic kidneys and glomerulonephritis [4].

Haemodialysis treatment and AVF surveillance techniques

The single needle haemodialysis treatment was never used in 79% of the patients, occasionally used in 7% of the patients and frequently used in 14% of the patients. In 1987, these figures were 87, 3 and 10% respectively.

In 75% of the centres, the subclavian vein was the preferred location for temporary catheters, 16% of the centres used the jugular vein and 9% of the centres the femoral vein. Four centres had no preference for any of the different catheter locations. Fifty-four per cent of the centres preferred double lumen catheters and 46% single lumen catheters. Two centres had no preference for single lumen or double lumen catheters. Eighty-nine per cent of the centres used primarily polyurethane catheters and 11% of the centres used primarily silicone catheters.

In most haemodialysis centres no routine vascular access surveillance was performed. When AVF problems occurred, angiography was performed in all centres, 79% of the centres performed additional Duplex scanning or recirculation measurements and 38% performed venous pressure (VP) measurements.

Registration of the venous and/or arterial pressure during haemodialysis treatment at normal dialyser flow was common. However, measurement of a VP curve (using at least three different dialyser flows) was only used in 15% of the centres and the absolute VP (with dialyser flow is 0 ml/min) was measured in 17% of the centres (Figure 1Go).



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Fig. 1. Percentage of dialysis centres using angiography, Duplex scanning, venous pressure (VP) measurements and recirculation measurements as routine surveillance and as diagnostic techniques on indication.

 
New vascular accesses in 1996 and interventions
Of the new vascular accesses created in 1996, 916 (54%) were BC fistulas, 503 (30%) were PTFE grafts, 85 (5%) of which were Diastat® prostheses, 99 (6%) were denaturated homologous vein grafts (DHV), 91 (6%) were elbow fistulas, 56 (3%) were Scribner shunts, 19 (1%) were autologous vein grafts (SVG) and three (0.2%) were other vascular accesses.

A total of 1616 (62%) BC fistulas were indeed used on the haemodialysis unit, compared to 1517 (70%) BC fistulas in 1987 (P<0.001). The number of PTFE graft fistulas increased from 274 (13%) in 1987 to 552 (21%) in 1996 (P<0.001), while elbow fistulas decreased from 139 (6%) in 1987 to 106 (4%) in 1996 (P<0.001). The use of DHV did not change from 1987 (n=124, 6%) to 1996 (n=190, 7%, P=NS). The number of SVG decreased from 63 (3%) to 44 (2%), (P<0.001). Other vascular accesses (including Scribner shunts) decreased from 53 (2%) in 1987 to 7 (0.3%) in 1996 (P<0.001) (Figure 2Go).



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Fig. 2. Percentage of different types of vascular accesses used on 31 December, 1996 and on 31 December, 1987. *Significant change from 1987 to 1996.

 
The vascular access operations were in 30% of the cases performed by one surgeon, in 56% by several surgeons, in 2% by any surgeon available and in 12% of the cases performed by residents.

Eight hundred and fifty six surgical interventions were needed to maintain the vascular access in a total of 472 vascular accesses. Homologous vein grafts had the highest number of interventions per vascular access (1.16 interventions per vascular access). In Diastat® grafts, 76 interventions were carried out (0.89 interventions per vascular access) and in PTFE grafts 302 interventions were performed (0.72 interventions per vascular access). Scribner shunts needed 39 interventions (0.70 interventions per vascular access), while autologous vein grafts (0.47 interventions per vascular access) and elbow fistulas (0.44 interventions per vascular access) underwent less interventions. BC fistulas needed the lowest number of operative interventions (289 interventions=0.32 interventions per vascular access) (Table 3Go). Most physicians preferred PTA as treatment of first choice to maintain the AVF, followed by patch-plasty and a jump-bypass. If PTA had failed, jump-bypasses were performed, followed by patch-plasty and other methods. PTA has been used in 402 instances. PTA was used in 46% of the centres regularly, in 46% occasionally and in 8% of the centres it was never used. This number is significantly higher than in 1987, when only 36% of the centres used PTA regularly and 10% occasionally (Figure 3Go).


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Table 3. Percentage of operative intervention per type of vascular access in 1996
 


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Fig. 3. Percentage of dialysis centres using Percutaneous Transluminal Angioplasty (PTA) for the treatment of AVF stenoses routinely, occasionally and never on 31 December, 1996 and on 31 December, 1987. *=significant change from 1987 to 1996.

 
Discussion

In the past decade the number of older dialysis patients (>65 years), has increased significantly more than that of the younger patients. This can be explained by the fact that the average age of the Dutch population has increased. Also improvement of dialysis treatment has resulted in the inclusion of elderly patients into the dialysis programmes. The percentage of DM as a primary cause of kidney failure among the dialysis population has increased from 7% in 1987 to 10% in 1996. Diabetic patients are a difficult group for maintaining vascular access, because of co-morbidities like cardiovascular and peripheral arterial disease [1012].

The upper extremity vessels of elderly patients are often not suitable for the construction of a primary AVF. Thus, vascular access in this group of patients usually will be achieved with graft implantation, which leads to increased use of PTFE fistulas and a decrease in BC fistulas. This feature is supported by our findings that from 1987 until 1996 the use of PTFE prostheses significantly increased, while the number of BC and elbow fistulas significantly decreased. The use of SVG and other forms of vascular access (including Scribner shunts) decreased significantly as well. Scribner shunts have almost been abandoned because of the numerous complications and the fact that this form of access is unpractical for the patient. Moreover there are better alternatives available nowadays [13].

Regarding vascular access usage, the situation in the USA is different from the situation in Europe. In the USA there are more graft implantations than native AVFs [8]. Recently Sands et al. [14] reported an increase of the number and percentage of AVFs constructed with autologous material in their dialysis population. This increase was achieved through a concerted effort of nephrologists and access surgeons. Further studies are necessary to evaluate whether this increase will prolong access survival and decrease morbidity associated with access maintenance. The percentage of interventions per type of vascular access is higher in grafts compared to AVFs constructed with autologous material. This is due to the high incidence of stenosis, thrombosis, infection and wound complications in PTFE fistulas [2,6,15].

Although routine surveillance and elective intervention can improve graft AVF patency [6,7,16,17], only a few dialysis centres carry out a surveillance programme. Most centres in The Netherlands rely on venous pressure measurements during haemodialysis treatment. If the venous pressure rises or other problems occur, all centres use diagnostic fistulography while 79% of the centres perform Duplex ultrasonography to detect and locate access stenosis. When stenosis occurs, most centres prefer PTA to correct it. The use of PTA as initial treatment of vascular access stenosis increased from 46 to 92% of the centres. If PTA fails or is not possible, a jump-graft or patch-plasty is performed depending on the location and length of the stenosis.

The results of our survey show an increase in single needle haemodialysis from 13% in 1987 to 20% in 1996. With the single needle technique, recirculation may occur leading to less efficient haemodialysis treatment compared to the double needle technique. Single needle technique is mainly used when the double needle method is not possible due to a short vessel traject for puncturing or refusal of the patient. The increased usage of single needle dialysis may indicate more problems with vascular access.

For central vein access more than half of the centres preferred double lumen catheters. Double lumen catheters cause less turbulence than single lumen catheters, resulting in a decreased risk on stenosis. Less recirculation occurs with the double lumen catheter [18]. Results from our survey showed that most centres prefer the subclavian vein over the jugular vein location for catheter insertion. It is well known that subclavian vein catheters may cause subclavian vein stenosis, making the arm less suitable for later creation of AVFs. Venous hypertension, oedema, insufficient flow and thrombosis are important complications of subclavian vein stenosis. Some studies report a 90% stenosis rate due to subclavian vein catheters compared to no stenosis with jugular vein catheters [19,20]. The subclavian vein catheter is still the most frequently used semi-permanent access, because of the long-lasting experience gained with this catheter location. Furthermore, jugular vein catheters are inconvenient to the patient because of the location in the neck. Also the negative cosmetic effect of the jugular vein catheter compared to the subclavian vein catheter may play a role in preferring the subclavian vein location over the jugular vein catheter. Polyurethane and silicone catheters were used in most centres. The literature reports a lower incidence of subclavian vein stenosis with the use of silicone catheters compared to the use of polyurethane catheters (19% vs 68% stenosis) [18]. There are several advantages of silicone catheters over polyurethane catheters. They are more flexible and cause less kinking; also the damage of endothelium of the vessel wall is less severe and the incidence of infection is lower in silicone catheters compared to polyurethane catheters [18]. The main disadvantage of silicone catheters is the fact that they are more expensive than polyurethane catheters and difficult to insert.

Conclusions

The mean age of the dialysis population is increasing. This leads to an increased need for secondary access procedures. However, secondary accesses usually require more interventions to maintain their patency. Therefore BC fistulas should remain the vascular access of first choice.

More attention should be paid to routine surveillance programmes for the detection of stenosis and elective revisions to prevent graft thrombosis. Also the use of jugular vein catheters instead of subclavian vein catheters as an acute vascular access should be promoted.

Acknowledgments

All vascular access surgeons, nephrologists and haemodialysis personnel of the dialysis centres in The Netherlands are gratefully acknowledged for their participation. Furthermore we would like to thank the Renine foundation, which registers the patients on kidney replacement therapy in The Netherlands, for permitting us to use their data.

Notes

Editor's note

Please see also Invited Comment by Konner (pp. 2094–2098) and Dialysis and Transplantation News by Bonucchi et al. (pp. 2116–2118).

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