Hemodialysis Access: General Considerations and Strategies to Optimize Access Placement

As the population ages and the incidence of diabetes rises, chronic kidney disease (CKD) and end-stage renal disease (ESRD) are increasingly common diagnoses in the United States. In 2017, data from the United States Renal Data System (USRDS) showed that 124,500 new patients began therapy for ESRD, whereas the prevalent dialysis population reached 746,557. Of note, after a sharp rise in the incidence of ESRD patients in the 1980s and 1990s, followed by a leveling off in 2000 and a peak in 2006, there has been a slight but steady decline through 2017 ( Fig. 174.1 ). Despite this, the number of ESRD patients continues to rise by about 20,000 patients per year ( Fig. 174.2 ), with a resulting rise in healthcare costs. Medicare fee-for-service spending for ESRD patients increased by 1.3%, from $35.4 billion in 2016 to $35.9 billion in 2017, accounting for 7.2% of overall claims ( Fig. 174.3 ). Not surprisingly, most of these costs occur during the transition from CKD to ESRD and are due to the high use of long-term catheters and frequent hospitalizations for permanent arteriovenous (AV) access failures, requiring thrombectomies, revisions, and repeated access placements.

Initiatives and Guidelines

In 1997, the National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF KDOQI) Clinical Practice Guidelines for Vascular Access were published in an effort to increase the placement of autogenous AV access and prolong the use of created access by detection of dysfunction prior to thrombosis. These original guidelines recommended that autogenous AV accesses should be constructed in at least 50% of all new hemodialysis patients and ultimately 40% of prevalent hemodialysis patients. With subsequent NKF KDOQI guidelines, recommended percentages of placement of new and prevalent autogenous AV access continued. These new NKF KDOQI guidelines, while still recognizing the superiority of autogenous AV access in the long term, emphasize an end-stage kidney disease (ESKD) life-plan which is a patient-centered, individualized and comprehensive map for dialysis modalities and vascular access for the lifetime of the patient. When planning dialysis access, specific considerations are made to the patient’s current medical situation, current and future goals, preferences, social support, functional status, and practical feasibilities – in summary, “the right access for the right patient at the right time”

In 2003, in an effort to reach the goals set forth by the NKF KDOQI guidelines, the Centers for Medicare and Medicaid Services (CMS) established the National Vascular Access Improvement Initiative (NVAII), which included vascular access experts and renal stakeholders who were committed to the development and implementation of sustainable system changes to support autogenous AV access placement. In 2005, the NVAII was expanded to the Fistula First Breakthrough Initiative (FFBI) Coalition ; a toolkit was developed and branded “Fistula First” to support the renal community in improving vascular access for dialysis patients. As a result of their efforts, the national rate of autogenous access reached NKF KDOQI’s original recommendation of 40% prevalence by August 2005, followed by a steady-state incline until 2011, when a plateau of about 60% was reached. The FFBI recognized this plateau was likely due to patient anatomy and that as an unintended consequence of increased attempts at autogenous AV access in small caliber veins was an increased use of central venous catheters (CVC). Therefore, in 2015, FFBI transitioned to the Fistula First Catheter Last (FFCL) Workgroup Coalition whose current goals are to increase the utilization of autogenous AV access in all appropriate hemodialysis patients to 68%, decrease the use of long-term catheters for greater than 90 days to less than 10%, and to engage patients and all providers to work together to achieve these goals. Similar to the new NKF KDOQI, these new goals emphasize decreasing the use of long-term catheters by changing the focus of dialysis access away from autogenous access in all patients to autogenous access in all appropriate patients.

The Society for Vascular Surgery (SVS), recognizing the effect of decision making by the individual access surgeon on the successful construction of AV access, has sponsored two further initiatives. First, in 2002, the Committee on Reporting Standards published the recommended standards for reports dealing with AV hemodialysis access. The purpose of this document was to provide standardized definitions related to AV access procedures and to recommend reporting standards for patency and complications in order to permit meaningful comparisons among AV access procedures. This was followed in 2008 by the clinical practice guidelines for the surgical placement and maintenance of AV hemodialysis access. After a multispecialty panel performed a systematic review of the literature, guideline recommendations were made in seven areas: (1) timing of referral to access surgeons; (2) operative strategies to maximize the placement of autogenous AV accesses; (3) first choice for the autogenous access; (4) choice of AV access when a patient is not a suitable candidate for a forearm autogenous access; (5) the role of monitoring and surveillance in AV access management; (6) conversion of a prosthetic AV access to a secondary autogenous AV access; and (7) management of the nonfunctional or failed AV access. This chapter focuses on strategies to maximize successful long-term access placement, whether autogenous or prosthetic.

Timing of Referral

The NKF KDOQI and the SVS Clinical Practice Guidelines both recommend that patients be referred to a vascular access surgeon for permanent dialysis access when their creatinine clearance is less than 25 mL/min. Once preoperative evaluation is completed, if the patient is felt to be an adequate candidate for autogenous AV access, the access should be constructed as soon as possible to give it adequate time to mature; ideally this should be greater than 6 months before the anticipated need for dialysis. However, since prosthetic access patency is limited by the duration of access placement, not time of access use, if a patient is felt to require a prosthetic access, the access placement should be delayed until 3 to 6 weeks prior to the initiation of dialysis. ^,

Early access placement, greater than 4 months before the initiation of dialysis, has been shown to decrease the risk of sepsis (relative risk [RR] 0.57) and death (RR 0.76) when compared with late access creation (less than 1 month before the initiation of dialysis or after initiation of dialysis), primarily by reducing the use of central venous hemodialysis catheters. Despite this, nationwide data suggest that only 25% of hemodialysis patients initiate dialysis with permanent AV access. Lenz et al. reported that 93% of patients in an academic medical center with a well-established dialysis unit and vascular surgery service initiated hemodialysis with the use of a central venous catheter. In a retrospective review, they identified the reason as inadequate predialysis care in 45% of patients, acute illness with failure to recover from an episode of acute renal failure in 31% of patients, and noncompliance with medical and surgical appointments in 17% of patients. These studies stress the need for early referral and education for predialysis patients to prevent the use of central venous catheters and their subsequent complications. ^,

Preoperative Evaluation

Thorough preoperative evaluation of the arterial and venous system is imperative if long-term, permanent AV access is to be placed successfully.

History and Physical Examination

A thorough history should include the dominant extremity, recent history of peripheral intravenous lines, sites of indwelling or previous central lines including pacemakers and defibrillators, all previous access procedures, any history of trauma or previous nonaccess surgery to the extremity, all comorbid conditions, and current medications. On physical examination, the brachial, radial, and ulnar arteries should be evaluated for compressibility and equality bilaterally. An Allen test should be performed to evaluate palmar arch patency. The superficial venous system should be evaluated with and without a venous pressure tourniquet in place, examining for distensibility and interruptions. The arm should be examined for prominent venous collaterals and edema, which may be signs of central venous stenosis. ^,

Medical Assessment

Multiple patient factors may play a role in AV access patency; these include age, sex, diabetes mellitus (DM), peripheral vascular disease (PVD), smoking, obesity, hyperparathyroidism (hPTH), anemia, and medications. As stated earlier, the new NKF KDOQI place a new emphasis on considering these types of comorbid conditions when planning a patient’s ESKD life-plan. The literature is split on many of these factors; however, best evidence to date suggests that all except sex and obesity have a negative impact on access patency rates ( Table 174.1 ). In the following paragraphs we review further some of the more studied factors that appear to negatively impact patency further.

TABLE 174.1

Medical Factors Affecting Arteriovenous Access Patency

Factor	Level of Best Evidence	Best Evidence Suggests Effect of Patency
Age	Meta-analysis	Yes
Gender	Meta-analysis	No
Diabetes mellitus	Prospective series	Yes
Atherosclerosis	Prospective series	Yes
Smoking	Prospective series	Yes
Obesity	Prospective series	No
Parathyroid hormone	Prospective series	Yes
Anemia	Prospective series	Yes
Medications	Systematic review	Yes

Age

Published reports regarding age and its effect on AV access patency are mostly retrospective observational studies with conflicting results. However, these reports, along with a known shorter life expectancy for patients with ESRD, have raised the following question: Should proximal or prosthetic AV access be the first-line approaches in the elderly? To answer this, Lazarides et al. performed a meta-analysis, 13 studies in all, of dialysis outcomes in elderly patients (age range: 50 to 70 years), including studies that compared subgroups of elderly and nonelderly patients as well as forearm and upper arm accesses. They found a statistically significant higher rate of autogenous radial–cephalic direct AV access primary (OR 1.8), 1-year (OR 1.5), and 2-year (OR 1.4) failure in elderly patients compared with the nonelderly. They also found a statistically significant higher rate of autogenous brachial–cephalic direct upper arm access patency (RR 0.1) compared with autogenous radial–cephalic direct forearm access. They noted no statistical differences with the use of prosthetic access. Based on these data, it is reasonable to recommend autogenous upper arm brachial–cephalic fistula or prosthetic access over distal radial–cephalic fistula in older patients.

Diabetes Mellitus

Published reports are mostly retrospective observational studies with similar results, stating that DM has a negative impact on AV access patency. These reports, along with a known increase in arterial calcification and atherosclerosis, have raised the following question: Should proximal or prosthetic AV access be the first-line approach in diabetics? To further evaluate the impact that DM has on the vasculature, Sedlacek et al. compared preoperative noninvasive vascular mapping between diabetic and nondiabetic patients. They noted an increased number of arterial calcifications in diabetics but no difference in arterial diameter or the ability to place autogenous AV access; they did not evaluate long-term outcomes. Looking at long-term outcomes in diabetic patients, Konner et al. noted an increased risk of thrombosis (0.03/patient year [PY] in nondiabetics vs. 0.07/PY in diabetics) and an increased risk of arterial steal (0.6/PY in nondiabetics vs. 7.0/PY in diabetics). Further studies are needed in this area; however, given the current literature, surgeons should take inflow in diabetics as distal as possible to decrease the risk of arterial steal.

Smoking

Published reports are retrospective observational studies with similar results, stating that cigarette smoking significantly increases early and late failure of AV access. ESRD patients should be referred to a tobacco cessation program before placement of first-time or any new AV access.

Medications

Published reports are mostly observational studies that have yielded conflicting results. One of the largest studies to date, the Dialysis Outcomes and Practice Patterns Study (DOPPS), noted an improvement of autogenous access secondary patency (RR 0.56) with angiotensin-converting enzyme (ACE) inhibitors, an improved prosthetic AV access primary patency (RR 0.86) with calcium channel blockers, an improved prosthetic AV access secondary patency (RR 0.70) with aspirin, and a decreased prosthetic AV access primary patency (RR 1.33) with warfarin. A study sponsored by the USRDS showed a decreased AV access patency with antiplatelet agents including ticlopidine, dipyridamole, and aspirin. Others have shown that angiotensin receptor blockers (ARBs) combined with antiplatelet agents increased autogenous AV access patency by 84%, whereas ARBs alone improved prosthetic AV access patency by 59%. At the present time there is a lack of consensus regarding the role of specific medications in improving AV access patency.

Arterial Assessment

If any abnormality is noted on the clinical arterial examination (absent or reduced peripheral pulses, abnormal Allen test, or asymmetrical arm pressures), the patient should be further evaluated with segmental pressures and duplex ultrasound scanning and/or pulse volume recordings (PVRs). For optimal outcome, no pressure gradient should be noted between the bilateral upper extremities, arterial diameter should be greater than or equal to 2.0 mm throughout the extremity, and a patent palmar arch should be present. Any abnormality noted on noninvasive testing should prompt alternate site selection or be further evaluated with an arteriogram, which gives the surgeon the ability to both identify and possibly treat an arterial inflow stenosis. In patients nearing dialysis, the risk of contrast arteriography should be weighed against the need for access to mature before beginning dialysis. Renal protective measures are commonly used preceding arteriography including intravenous fluids, N -acetylcysteine, and sodium bicarbonate though the data supporting agents other than volume are limited.

Venous Assessment

If superficial veins cannot be visualized with a venous pressure tourniquet in place or any abnormality is noted on the superficial venous examination, the patient should be further evaluated with superficial venous duplex ultrasound vein mapping. Using venous duplex imaging, superficial veins should be examined for diameter, distensibility, and continuity. Minimal diameter for use of the forearm has been reported as low as 2.0 mm by Mendes et al . , who noted a successful early maturation rate of 76%. Using a minimal vein diameter of 2.5 mm, Silva et al. were able to perform 63% autogenous access with a 92% early maturation rate and 83% 1-year patency rate. Using a minimal vein diameter of 3.0 mm, Huber et al. were able to perform 90% autogenous access with an 84% early maturation rate.

Central venous stenosis should be suspected if there are any prominent venous collaterals or edema, a difference in extremity diameter, any history of previous central venous catheter placement, or multiple previous accesses in the planned extremity. If any of these abnormalities are identified, the patient should be examined first with deep venous duplex ultrasound imaging followed by venography if necessary. Passman et al. compared duplex ultrasound and venography in 60 upper extremities of preoperative access patients. Five (8%) ultrasounds were nondiagnostic due to artifact from central venous catheters or incomplete visualization of the central venous system. Of the studies that were diagnostic, they noted 81% sensitivity and 97% specificity of duplex ultrasound imaging with no statistical difference as compared with venography. Venography should be performed for further evaluation and possible treatment in patients with either nondiagnostic or abnormal duplex ultrasound imaging. As with arteriography, in predialysis patients the risk of contrast venography must be weighed against the need for access to mature in time for dialysis. Before venography, patients should be treated with intravenous fluids, N-acetylcysteine, and/or sodium bicarbonate.

Selection of Access Type and Location

As discussed in the introduction to this chapter, with time it has been recognized that permanent autogenous AV access in all patients is not an achievable mission, and instead appropriate dialysis access individualized to the needs of the patients is a far more important goal. This incorporates understanding a patient’s wishes, social support, comorbidities, and anatomy. This has been reflected in the new NKF KDOQI guidelines and summarized as “the right access for the right patient at the right time” as well as the transition from the FFBI to the FFCL workgroups. This has always been recognized by the access surgeon who has been tasked with performing surgery using anesthesia in patients with many medical comorbidities and difficult arterial and venous anatomy. And now has fully been acknowledged as an ESKD life-plan, which is an individualized patient-centered team approach to develop a comprehensive map for dialysis modalities and vascular access for the lifetime of a patient. ^,

The remainder of this chapter focuses on those patients that are felt to be candidates for permanent AV access. The various types of autogenous and prosthetic upper, lower, and body-wall AV access are listed in Box 174.1 ; our focus is on the upper extremity, and further complex access types are discussed in Chapter 175 (Hemodialysis Access: Complex). In planning permanent AV access, a few general principles apply ( Fig. 174.4 ):

1.
Due to easier accessibility and lower infection rates, upper extremity access sites are used first, with the nondominant arm given preference over the dominant arm.
2.
AV accesses are placed as far distally in the extremity as possible to preserve proximal sites for future accesses.
3.
As long as the patient is deemed appropriate, given their superior patency rates and lower complication rates, autogenous AV accesses should always be attempted before a prosthetic AV access.
4.
These autogenous access configurations should include, in order of preference, direct AV anastomosis, venous transpositions, and venous translocations.

BOX 174.1

Configurations of Arteriovenous Access

Adapted from Sidawy AN, Gray R, Besarab A, et al. Recommended standards for reports dealing with arteriovenous hemodialysis accesses. J Vasc Surg . 2002;35:603–610.

Forearm

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