A multidisciplinary approach to hemodialysis access: prospective evaluation

Surveillance of hemodialysis vascular access

A mature, functional arteriovenous (AV) access is the lifeline for a hemodialysis (HD) patient as it provides sufficient enough blood flow for adequate dialysis. As the chronic kidney disease (CKD) and end-stage renal disease (ESRD) population is expanding, and because of the well-recognized hazardous complications of dialysis catheters, the projected placement and use of AV accesses for HD is on the rise. Although a superior access than catheters, AV accesses are not without complications. The primary complication that causes AV accesses to fail is stenosis with subsequent thrombosis. Surveying for stenosis can be performed in a variety of ways. Clinical monitoring, measuring flow, determining pressure, and measuring recirculation are all methods that show promise. In addition, stenosis can be directly visualized, through noninvasive techniques such as color duplex imaging, or through minimally invasive venography. Each method of screening has its advantages and disadvantages, and several studies exist which attempt to answer the question of which test is the most useful. Ultimately, to maintain the functionality of the access for the HD patient, a team approach becomes imperative. The collaboration and cooperation of the patient, nephrologist, dialysis nurse and technician, vascular access coordinator, interventionalist, and vascular surgeon is necessary to preserve this lifeline.

The spectrum of infections in catheter-dependent hemodialysis patients

BACKGROUND AND OBJECTIVES

Catheter-dependent hemodialysis patients may develop access-related and nonaccess-related infections that may be managed in the outpatient arena or in the hospital. The goal of this study was to quantify infections in such patients, to characterize their clinical presentations, and to evaluate factors determining need for hospitalization.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We collected prospective data on the clinical management of catheter-dependent hemodialysis patients with suspected infection at a large dialysis center. We documented the presenting symptoms, type of infection, pathogen, and whether hospitalization occurred.

RESULTS

An infection was suspected in 305 separate cases and confirmed in 88%. The 268 diagnosed infections included catheter-related bacteremia (69%), another access-related infection (19%), and nonaccess-related infection (12%). The overall frequency of infection was 4.62 per 1000 catheter-days. Hospitalization occurred in 37% of all infections, but it varied greatly (72% for nonaccess-related infection, 34% for catheter-related bacteremia, and 4% for exit-site infection). Among patients with catheter-related bacteremia, the likelihood of hospitalization varied by pathogen, being 53% for Staphylococcus aureus, 30% for Enterococcus, 23% for Staphylococcus epidermidis, and 17% for gram-negative rods (P < 0.001). The likelihood of hospitalization was not associated with age, gender, or diabetes. Fever was a presenting symptom in only 47% of cases of catheter-related bacteremia.

CONCLUSIONS

Catheter-dependent patients have a high burden of infection. It is important to evaluate patients with suspected infection for various access-related and nonaccess-related infections. A low threshold is indicated for suspecting catheter-related bacteremia because the patients frequently present without fever.

Arteriovenous graft placement in predialysis patients: a potential catheter-sparing strategy

BACKGROUND

When predialysis patients are deemed unsuitable candidates for an arteriovenous fistula, current guidelines recommend waiting until just before or after initiation of dialysis therapy before placing a graft. This strategy may increase catheter use when these patients start dialysis therapy. We compared the outcomes of patients whose grafts were placed before and after dialysis therapy initiation.

STUDY DESIGN

Retrospective analysis of a prospective computerized vascular access database.

SETTING & PARTICIPANTS

Patients with chronic kidney disease receiving their first arteriovenous graft (n = 248) at a large medical center.

PREDICTOR

Timing of graft placement (before or after initiation of dialysis therapy).

OUTCOME & MEASUREMENTS

Primary graft failure, cumulative graft survival, catheter dependence, and catheter-related bacteremia.

RESULTS

The first graft was placed predialysis in 62 patients and postdialysis in 186 patients. Primary graft failure was similar for pre- and postdialysis grafts (20% vs 24%; P = 0.5). Median cumulative graft survival was similar for pre- and postdialysis grafts (365 vs 414 days; HR, 1.22; 95% CI, 0.81-1.98; P = 0.3). Median duration of catheter dependence after graft placement in the postdialysis group was 48 days and was associated with 0.63 (95% CI, 0.48-0.79) episodes of catheter-related bacteremia per patient.

LIMITATIONS

Retrospective analysis, single medical center.

CONCLUSION

Grafts placed predialysis have primary failure rates and cumulative survival similar to those placed after starting dialysis therapy. However, postdialysis graft placement is associated with prolonged catheter dependence and frequent bacteremia. Predialysis graft placement may decrease catheter dependence and bacteremia in selected patients.

Medicare reimbursement policies and hemodialysis vascular access outcomes: a need for change

In March 2010, the Center for Medicare and Medicaid Services (CMS) convened several clinical technical expert panels (C-TEP) to provide recommendations for improving various aspects of hemodialysis management. One of the C-TEPs was tasked with recommending measures to decrease vascular access-related infections. The members of this C-TEP, who are the authors of this manuscript, concluded unanimously that the single most important measure would be to remove financial and regulatory barriers to timely placement and revision of hemodialysis fistulas and the concurrent avoidance of catheter use. The following position paper outlines the financial barriers to improved vascular access outcomes and our proposals for a future CMS demonstration project.

Saving Infected Catheters: Why and How

Conventional management of dialysis catheter-related bacteremia involves administration of systemic antibiotics, as well as removal of the infected catheter. This approach adds burdensome and expensive procedures, and creates short-term problems for dialysis access. Recent research has shown that bacterial biofilms form routinely in the catheter lumen, and act as the nidus for bacteremic episodes. Instillation of a concentrated antibiotic-anticoagulant solution into the catheter lumen ('antibiotic lock') may permit successful treatment of the infection, while salvaging the patient's catheter. A number of recent studies have reported the success of an antibiotic lock protocol in about two thirds of cases of catheter-related bacteremia. Catheter replacement is only performed in those patients with protocol failures (persistent fever or positive surveillance blood cultures). In conclusion, routine application of an antibiotic lock protocol may reduce substantially the need for routine catheter replacement in hemodialysis patients with catheter-related bacteremia.

Comparison of radiocephalic fistulas placed in the proximal forearm and in the wrist

Non-maturation is a common problem in patients receiving an arteriovenous fistula. The first vascular access choice is a distal radiocephalic fistula (dRCF) at the wrist. Patients with a failed dRCF or with vessels unsuitable for dRCF, the recommendation is to place a brachiocephalic fistula in the upper arm. Proximal forearm radiocephalic fistulas (pRCF) are created infrequently, but may permit a second forearm fistula before proceeding to the upper arm. The goal of the present study was to compare the outcomes of them. We retrospectively analyzed a computerized access database to compare the outcomes of 19 RCF and 39 dRCF placed during a 6-month period. The baseline characteristics were similar, except those with a pRCF were more likely to have previous access and be male. Primary failure (non-maturation) was lower for pRCF than dRCF (32 vs. 59%, p = 0.05); and excluding secondary failures, cumulative fistula survival was similar (92 vs. 86% at 1 year and 74 vs. 76% at 2 years, p = 0.56). pRCF may be an attractive alternative to a brachiocephalic fistula in patients who cannot receive a dRCF. pRCF has a lower non-maturation rate than that of a dRCF, and a comparable cumulative survival once it is used successfully for dialysis.

Does the heparin lock concentration affect hemodialysis catheter patency?

BACKGROUND AND OBJECTIVES

Concentrated heparin solutions are instilled into the catheter lumens after each hemodialysis session to prevent catheter thrombosis. The heparin lock concentration at many centers has been decreased recently to reduce the risk of systemic bleeding and contain costs. However, the effect of this change on catheter patency is unknown. We compared catheter patency between two heparin lock solutions: 1000 versus 5000 units/ml.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

With use of a prospective, computerized, vascular access database, 105 patients with newly placed tunneled hemodialysis catheters, including 58 patients receiving a 5000 units/ml heparin lock and 47 patients receiving a 1000 units/ml heparin lock, were retrospectively identified. The primary endpoint was cumulative catheter patency and the secondary endpoint was frequency of thrombolytic instillation.

RESULTS

Cumulative catheter survival was similar in the two groups, being 71% versus 73% at 120 days in the low- and high-concentration heparin lock groups (hazard ratio of catheter failure, 0.97; 95% confidence interval, 0.45 to 2.09; P = 0.95). The frequency of tissue plasminogen activator instillation was significantly greater in the low-concentration heparin group (hazard ratio, 2.18; 95% CI, 1.26 to 3.86; P = 0.005). No major bleeding complications were observed in either treatment group. The overall drug cost for maintaining catheter patency was 23% lower with the low-concentration heparin lock ($1418 versus $1917) to maintain catheter patency for 1000 days.

CONCLUSIONS

Low-concentration heparin lock solutions do not decrease cumulative dialysis catheter patency, but require a twofold increase in thrombolytic instillation to maintain long-term patency.

Does heparin coating improve patency or reduce infection of tunneled dialysis catheters?

BACKGROUND AND OBJECTIVES

Tunneled dialysis catheters are prone to frequent malfunction and infection. Catheter thrombosis occurs despite prophylactic anticoagulant locks. Catheter thrombi may also serve as a nidus for catheter infection, thereby increasing the risk of bacteremia. Thus, heparin coating of catheters may reduce thrombosis and infection. This study evaluated whether heparin-coated hemodialysis catheters have fewer infections or greater cumulative survival than noncoated catheters.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We retrospectively queried a prospective access database to analyze the outcomes of 175 tunneled dialysis catheters placed in the internal jugular vein, including 89 heparin-coated catheters and 86 noncoated catheters. The primary outcome was cumulative catheter survival, and the secondary outcome was infection-free catheter survival.

RESULTS

The two patient groups were similar in demographics and clinical and catheter features. Catheter-related bacteremia occurred less frequently with heparin-coated catheters than with noncoated catheters (34 versus 60%, P < 0.001). Cumulative catheter survival was similar in heparin-coated and noncoated catheters (hazard ratio, 0.87; 95% confidence interval, 0.55 to 1.36; P = 0.53). On multiple variable survival analysis including catheter type, age, sex, diabetes, coronary artery disease, peripheral vascular disease, cerebrovascular disease, catheter location, and previous catheter, only catheter location predicted cumulative catheter survival (hazard ratio, 2.03; 95% CI, 1.27 to 3.25, with the right internal jugular location being the reference group, P = 0.003). The frequency of thrombolytic instillation was 1.8 per 1000 catheter-days in both groups.

CONCLUSIONS

Heparin coating decreases the frequency of catheter-related bacteremia but does not reduce the frequency of catheter malfunction.

Hemodialysis vascular access monitoring: current concepts

Most arteriovenous grafts fail due to irreversible thrombosis, and most clotted grafts have an underlying stenotic lesion. These observations raise the plausible hypothesis that early detection of graft stenosis with preemptive angioplasty will reduce the likelihood of graft thrombosis. A number of noninvasive methods can be used to detect hemodynamically significant graft stenosis with a high positive predictive value. These tests include clinical monitoring, as well as surveillance by static dialysis venous pressures, flow monitoring, or duplex ultrasound. However, these surveillance tests have a much lower positive predictive value for graft thrombosis in the absence of preemptive angioplasty. In other words, none of the currently available surveillance tests can reliably distinguish between stenosed grafts destined to clot, and those that will remain patent without intervention. As a consequence, any program of graft surveillance necessarily results in a substantial proportion of unnecessary angioplasties. Moreover, a substantial proportion of grafts thrombose despite a normal antecedent surveillance test. Numerous observational studies have found an impressive reduction of graft thrombosis after implementation of a stenosis surveillance program. In contrast, 5 of 6 randomized clinical trials failed to show a reduction of graft thrombosis in patients undergoing graft surveillance, as compared with those receiving only clinical monitoring. The lack of benefit of surveillance is largely attributable to the rapid recurrence of stenosis after angioplasty. Thus, routine surveillance for graft stenosis, with preemptive angioplasty, cannot be recommended for reduction of graft thrombosis. Future research should be directed at pharmacologic interventions to prevent graft stenosis.

Clinical outcomes of dialysis catheter-related candidemia in hemodialysis patients

BACKGROUND AND OBJECTIVES

Candidemia is a rare complication in catheter-dependent hemodialysis patients. As a result, there is uncertainty about its optimal medical management. The goal of this retrospective study was to compare the clinical outcomes of catheter-related candidemia managed with two different strategies: Guidewire exchange of the infected catheter versus removal with delayed replacement.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We retrospectively queried a prospective, computerized vascular access database to identify 40 hemodialysis patients with catheter-related candidemia. All patients underwent treatment with antifungal medications for 2 wk, in conjunction with guidewire catheter exchange or catheter removal with delayed replacement. The primary outcomes were major complications, recurrent candidemia, and patient survival.

RESULTS

Candidemia represented approximately 2% of all cases of catheter-related bloodstream infections. Of the 40 patients with candidemia, 27 underwent guidewire catheter exchange and 13 had prompt catheter removal with delayed replacement. The two treatment groups were similar in demographic, clinical, and catheter characteristics. Only 1 (2.5%) patient developed a serious complication (endophthalmitis). Recurrence of candidemia within 3 mo was observed in 15% of each treatment group. Patient survival at 6 mo was similar in both groups.

CONCLUSIONS

Catheter-related candidemia is rare in hemodialysis patients and has a low complication rate. Catheter exchange over a guidewire in conjunction with antifungal therapy is an effective and safe treatment regimen.

Outcomes of brachiocephalic fistulas, transposed brachiobasilic fistulas, and upper arm grafts

BACKGROUND AND OBJECTIVES

An upper arm vascular access is often placed in patients with a failed forearm fistula or with vessels unsuitable for a forearm fistula. The aim of this study was to compare the outcomes of three upper arm access types: brachiocephalic fistulas, transposed brachiobasilic fistulas, and grafts.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A prospective, computerized access database was queried retrospectively to identify the clinical outcomes of upper arm accesses placed in 678 patients at a large dialysis center, including 322 brachiocephalic fistulas, 67 brachiobasilic fistulas, and 289 grafts.

RESULTS

Primary access failures were less common for brachiobasilic fistulas and grafts compared with brachiocephalic fistulas (18%, 15%, and 38%; hazard ratio of brachiocephalic fistulas versus brachiobasilic fistulas 2.76; 95% confidence interval 1.41 to 5.38; P < 0.003). For the subset of patients receiving a brachiocephalic fistula, a multiple variable logistic regression analysis including age, sex, race, diabetes, coronary artery disease, peripheral vascular disease, cerebrovascular disease, prior access, surgeon, arterial diameter, and venous diameter found that only vascular diameters predicted primary failure (P < 0.001). When primary failures were excluded, cumulative access survival was similar for brachiobasilic and brachiocephalic fistulas, but superior to that of grafts. Total access interventions per year were lower for brachiobasilic and brachiocephalic fistulas than for grafts (0.84, 0.82, and 1.87, respectively, P < 0.001).

CONCLUSIONS

Transposed brachiobasilic fistulas may be preferred, due to (1) a lower primary failure rate (similar to grafts), and (2) a lower intervention rate (similar to brachiocephalic fistulas). However, this advantage must be balanced against the more complex surgery.

Treatment of dialysis catheter-related Enterococcus bacteremia with an antibiotic lock: a quality improvement report

BACKGROUND

Catheter-related bacteremia (CRB) is a frequent complication of tunneled dialysis catheters, and Enterococcus is a common infecting organism. CRB may be treated by instilling an antibiotic lock into the catheter lumen in conjunction with systemic antibiotics. The efficacy of this approach in Enterococcus bacteremia is unknown.

DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

64 catheter-dependent hemodialysis outpatients with vancomycin-sensitive Enterococcus bacteremia treated with a uniform antibiotic lock protocol. Clinical outcomes were tracked prospectively. QUALITY IMPROVEMENT PLANS: Patients received intravenous vancomycin for 3 weeks in conjunction with a vancomycin lock instilled into both catheter lumens after each dialysis session.

MEASURES

Treatment failure was defined as persistent fever 48 hours after initiation of antibiotic therapy or recurrent Enterococcus bacteremia within 90 days. A clinical cure was defined as fever resolution without recurrent bacteremia. Major infection-related complications within 6 months were documented.

RESULTS

Treatment failure occurred in 25 patients (39%) because of persistent fever in 10 and recurrent bacteremia in 15. Treatment success occurred in 39 patients (61%). A serious complication of Enterococcus CRB occurred in 4 of 64 patients (6%); endocarditis in 1 and osteomyelitis in 3. The frequency of serious complications was 16% (4 of 25 patients) in those with treatment failure compared with 0% (0 of 39 patients) in those with treatment success (P = 0.01).

LIMITATIONS

This was a single-center study. We did not measure serum vancomycin.

CONCLUSIONS

An antibiotic lock protocol permits catheter salvage in 61% of hemodialysis patients with Enterococcus CRB. Serious complications occur in 6% of patients and are more common in those with treatment failure.

Time to symptomatic vascular stenosis at different locations in patients with arteriovenous grafts

Most arteriovenous grafts fail due to irreversible thrombosis, superimposed on hemodynamically significant vascular stenosis. Previous studies observed the highest frequency of stenosis at the venous anastomosis, without addressing the timing of stenosis. The present study quantified time to symptomatic stenosis at different vascular locations, and related it to permanent graft failure. A prospective computerized vascular access database was queried retrospectively to identify 309 hemodialysis patients receiving new upper extremity grafts during a 4-year period at a large dialysis center. For each vascular site we calculated the time to symptomatic stenosis using survival techniques. The cumulative likelihood of symptomatic stenosis at 2 years was 67% for venous anastomotic stenosis, 19% for intra-graft stenosis, 16% for venous outlet stenosis, 13% for central vein stenosis, and 5% for arterial anastomotic stenosis. The cumulative risk of graft failure at 2 years was 40%. Stenosis at the venous anastomosis was twice as likely as cumulative graft failure (hazard ratio [HR] 1.95; 95% confidence interval [CI], 1.65-2.52, p < 0.001). In contrast, intra-graft stenosis was half as likely as cumulative graft failure (HR 0.45; 95% CI, 0.36-0.61, p < 0.001). Central vein stenosis was more likely in patients with a previous ipsilateral catheter compared with those without one (HR 2.40; 95% CI, 1.39-5.58, p = 0.004). Symptomatic stenosis occurs much earlier at the venous anastomosis compared with other vascular sites. Moreover, preexisting ipsilateral internal jugular dialysis catheters more than double the risk of central vein stenosis.

Autogenous arteriovenous elbow fistula for haemodialysis and upper extremity ischemia

BACKGROUND

The autogenous brachiocephalic or brachiobasilic arteriovenous elbow fistula is not considered to be only the secondary haemodialysis access. In patients with an unsuitable forearm vessel bundle, it is indicated as primary access and it is the method preferred to the fistula creation using a vascular prosthesis. Its rather rare complication is the development of upper extremity ischemia.

AIM

To summarise current knowledge of this fistula type and its associated complications

METHODS

Review of the literature.

RESULTS

The creation and maturation of the fistula and occurrence of the steal syndrome is influenced by a number of factors. The analysis and awareness of such factors will provide for creation of a suitable fistula as well as for timely complication diagnostics and treatment.

CONCLUSIONS

The autogenous elbow fistula utilising the brachial artery and the cephalic or basilic vein in the upper extremity represents a high-quality haemodialysis access. Its potential complication is the occurrence of the steal syndrome. Its occurrence and manifestations do not constitute indications for ligation of the access. The gathered information shows that a suitable surgical procedure can help meet the basic rule for haemodialysis access--resolving the ischemia and maintaining the access.

Ultrasound/fluoroscopy-assisted placement of peritoneal dialysis catheters

Peritoneal dialysis (PD) catheters may be inserted blindly, surgically, and either by laparoscopic, peritoneoscopic, or fluoroscopic approach. A modified fluoroscopic technique by adding ultrasound-assistance was performed in the present study to ensure entry into the abdominal cavity under direct ultrasound visualization. From March 2005 to May 2007, ultrasound-fluoroscopic guided placement of PD catheters was attempted in 32 end-stage renal disease (ESRD) patients. Preoperative evaluation was performed on all patients prior to the procedure. After initial dissection of the subcutaneous tissue anterior to the anterior rectus sheath, the needle was inserted into the abdominal cavity under the guidance of ultrasound. The position of the epigastric artery was also examined using ultrasonography to avoid the risk of arterial injury. PD catheters were successfully placed in 31 of the 32 ESRD patients using this technique. In all of these patients, the needle could be seen entering the abdominal cavity using an ultrasound. In one patient the procedure was abandoned because of bowel puncture by the micro-puncture needle that was inadvertently advanced into a loop of bowel. This patient did not develop acute abdomen nor needed any intervention. One patient died 4 days after placement of the catheter of unrelated causes. One patient was started on acute peritoneal dialysis the same day of catheter placement without any complications. The rest of the patients started peritoneal dialysis within 2-6 weeks of catheter placement. None of the patients had bleeding related to arterial injury as ultrasound was able to visualize the epigastric artery. Our experience shows that ultrasound-fluoroscopic technique is minimally invasive and allows for accurate assessment of the entry into the abdominal cavity. This technique can avoid the risk of vascular injury altogether.

Disparities in fistula maturation persist despite preoperative vascular mapping

BACKGROUND AND OBJECTIVES

Failure to mature (primary failure) of new fistulas remains a major obstacle to increasing the proportion of dialysis patients with fistulas. This failure rate is higher in women than in men, higher in older than in younger patients, and higher in forearm than in upper arm fistulas. These disparities in the frequency of failure to mature may be due in part to marginal vessels in the high-risk groups and should be reduced by routine preoperative vascular mapping.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A prospective, computerized database was queried retrospectively to evaluate the frequency of primary fistula failure in 205 hemodialysis patients for whom preoperative mapping was obtained. The association between clinical characteristics and risk for primary fistula failure was analyzed by univariate and multiple variable regression analysis.

RESULTS

The overall primary fistula failure rate was 40% (82 of 205 patients). On multiple variable logistic regression, three clinical factors were associated with an increased risk for failure to mature among patients who underwent preoperative vascular mapping: Female gender, age > or =65 yr, and forearm location. The primary fistula failure rate varied from 22% in younger men with an upper arm fistula to 78% in older women with a forearm fistula. Dynamic preoperative vascular measurements (change in peak systolic velocity and resistive index after tight fist clenching) did not differ between patients with mature and immature forearm fistulas.

CONCLUSION

Disparities in fistula maturation persist despite the use of routine preoperative vascular mapping.

Is surgical salvage of arteriovenous grafts feasible after unsuccessful percutaneous mechanical thrombectomy?

Treatment of thrombosed dialysis ateriovenous (AV) grafts in the radiology interventional suite requires percutaneous mechanical thrombectomy, along with angioplasty of the underlying stenotic lesion. We analyzed the anatomic reasons for unsuccessful percutaneous thrombectomy of AV grafts, and assessed the feasibility of surgical salvage. The radiologic reports of all thrombosed AV grafts undergoing unsuccessful percutaneous mechanical thrombectomy during a 5-year period were analyzed for the specific problem precluding restoration of graft patency. We also compared the features of patients with unsuccessful graft thrombectomy to those with successful thrombectomy. Of 77 AV grafts undergoing unsuccessful percutaneous thrombectomy, only six (or 8%) could be revised surgically. Inability to salvage the graft surgically was because of: severe draining vein occlusion or stenosis (30 patients); severe central vein lesion (12); multiple intragraft stenoses (11); large pseudo-aneurysms (six); venous anastomotic occlusion (six); and arterial anastomotic occlusion (four). When compared with 211 patients with successful graft thrombectomy, those with unsuccessful thrombectomy were more likely to have a forearm graft (53% vs. 27%, p < 0.001), and more likely to have a lesion in the draining vein (42% vs. 10%, p < 0.001), the central vein (17% vs. 3%, p < 0.001), or within the graft itself (23% vs. 1%, p < 0.001). An unsuccessful percutaneous graft thrombectomy is more likely in forearm than in upper arm grafts, and more likely if there is a lesion in the draining vein, central vein, or within the graft itself. Surgical salvage of a thrombosed AV graft after an unsuccessful percutaneous intervention is rarely feasible. Most patients have a severe anatomic lesion that cannot be repaired, and require creation of a new vascular access.

Clinically immature arteriovenous hemodialysis fistulas: effect of US on salvage

PURPOSE

To retrospectively determine whether postoperative ultrasonography (US) of clinically immature dialysis fistulas can be used to identify potential anatomic origins of immaturity and whether correction of immature fistulas promotes fistula maturation.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective study, with waiver of informed consent. Postoperative US was performed in 95 consecutive subjects (52 men, 43 women; mean age, 58 years) with clinically immature fistulas. Fistulas were deemed sonographically mature if they had a diameter of at least 4 mm, an access flow of at least 500 mL/min, and a depth of no more than 5 mm from the skin surface. Fistulas were deemed clinically mature if they could be used for dialysis for at least 1 month. The proportion of subjects in different US subgroups with fistulas that matured during follow-up was compared with chi2 analysis.

RESULTS

Sixty-seven clinically immature fistulas were deemed sonographically immature. One or more remediable anatomic problems were detected with US in 60 subjects with sonographically immature fistulas; these problems included focal stenosis in 23, accessory veins in 34, and excessively deep veins in 19. Multiple abnormalities were present in 13 subjects. Of 58 subjects with sonographically immature fistulas and known clinical outcomes, 32 underwent an intervention. In those subjects who did not undergo a salvage procedure, only eight fistulas were usable for dialysis. Among those who underwent a salvage procedure, 25 fistulas were subsequently usable for dialysis (P < .001).

CONCLUSION

Clinically immature fistulas frequently have one or more potentially remediable problems seen at postoperative US. Problem-specific salvage procedures increase the proportion of fistulas that are usable for dialysis.

Current techniques for assessment of upper extremity vasculature prior to hemodialysis vascular access creation

Vascular access problems lead to increased patient morbidity and mortality and place a large burden on care facilities, manpower and costs. Autogenous arteriovenous fistulas (AVF) are preferred over arteriovenous grafts (AVG) because of a lower incidence of vascular access related complications. An aggressive increase in the utilization of AVF, however, results in an increased incidence of AVF early failure and non-maturation. Increasing evidence suggests that routine preoperative assessment results in an increased utilization of functioning AVF by better selection of adequate vessels. To date, the reproducibility and standardization of assessment protocols are lacking and assessment of a single morphological parameter has not enabled adequate prediction of postoperative AVF function for individual patients. In this paper, we provide an overview of available diagnostic modalities and parameters that potentially enable better selection of adequate vessels for successful AVF creation.

Noninvasive Methods to Identify Early Vascular Access Dysfunction

A functional vascular access is of critical importance to the hemodialysis patient, the patient's healthcare providers, and the hemodialysis treatment center. A poorly functioning or thrombosed vascular access can lead to increased morbidity, hospitalization, length of stay, and cost. This article reviews the increasing evidence supporting surveillance of arteriovenous (AV) hemodialysis access and the various strategies and techniques available for detection of a failing access.

Treatment of dialysis catheter-related Staphylococcus aureus bacteremia with an antibiotic lock: a quality improvement report

BACKGROUND

Dialysis catheter-related bacteremia is often treated successfully by instilling an antibiotic-heparin solution into the catheter lumen (an antibiotic lock) in conjunction with systemic antibiotic therapy without removal of the catheter. The efficacy of this therapy is uncertain in Staphylococcus aureus bacteremia.

DESIGN

Quality improvement report.

SETTING & PARTICIPANTS

113 catheter-dependent hemodialysis outpatients with S aureus catheter-related bacteremia treated with a standardized antibiotic lock protocol. Data for all patients with catheter-related bacteremia are recorded in a prospective database.

QUALITY IMPROVEMENT PLAN

In conjunction with systemic antibiotic therapy (vancomycin for methicillin-resistant S aureus or cefazolin for methicillin-sensitive S aureus), an antibiotic lock was instilled into each catheter lumen after each dialysis session for 3 weeks.

MEASURES

Treatment failure is defined as persistent fever after 48 hours of antibiotic therapy or recurrent S aureus bacteremia within 90 days. Clinical cure is defined as resolution of fever and no recurrence of bacteremia. Major infection-related complications within 6 months were documented.

RESULTS

The catheter could not be salvaged in 67 patients (59%) because of persistent fever in 40 patients and recurrent bacteremia in 27 patients. A clinical cure was achieved in 46 patients (41%). A serious complication of catheter-related bacteremia occurred in 9.7% of all patients (11 of 113 patients). Serious complications were observed in 25% of patients (10 of 40 patients) with persistent fever, but only 1.4% of all other patients (1 of 73 patients; P < 0.0001).

LIMITATIONS

This was a single-center study. Serum antibiotic levels were not measured.

CONCLUSIONS

Routine antibiotic lock therapy is not appropriate for patients with S aureus catheter-related bacteremia. Serious complications occur primarily in patients with persistent fever.

Current management of vascular access

Optimizing vascular access outcomes remains an ongoing challenge for clinical nephrologists. All other things being equal, fistulas are preferred over grafts, and grafts are preferred over catheters. Mature fistulas have better longevity and require fewer interventions, as compared with mature grafts. The major hurdle to increasing fistula use is the high rate of failure to mature of newly created fistulas. There is a desperate need for enhanced understanding of the mechanisms of failure to mature and the optimal type and timing of interventions to promote maturity. Grafts are prone to frequent stenosis and thrombosis. Surveillance for graft stenosis with preemptive angioplasty may reduce graft thrombosis, but recent randomized clinical trials have questioned the efficacy of this approach. Graft stenosis results from aggressive neointimal hyperplasia, and pharmacologic approaches to slowing this process are being investigated in clinical trials. Catheters are prone to frequent thrombosis and infection. The optimal management of catheter-related bacteremia is a subject of ongoing debate. Prophylaxis of catheter-related bacteremia continues to generate important clinical research. Close collaboration among nephrologists, surgeons, radiologists, and the dialysis staff is required to optimize vascular access outcomes and can be expedited by having a dedicated access coordinator to streamline the process. The goal of this review is to provide an update on the current status of vascular access management.

Comparison of Survival of Upper Arm Arteriovenous Fistulas and Grafts after Failed Forearm Fistula

Although arteriovenous fistulas are considered superior to grafts, it is unknown whether that is true in the subset of patients with a previous failed fistula. For investigation of this question, a prospective vascular access database was queried retrospectively to compare the outcomes of 59 fistulas and 51 grafts that were placed in the upper arm after primary failure of an initial forearm fistula. Primary access failure was higher for subsequent fistulas than for subsequent grafts (44 versus 20%; P = 0.006). Fistulas required more interventions than grafts before their successful use (0.42 versus 0.16 per patient; P = 0.04). The time to catheter-free dialysis was longer for fistulas than for grafts (131 versus 34 d; P < 0.0001) and was associated with more episodes of bacteremia before permanent access use (1.3 versus 0.4 per patient; P = 0.003). Cumulative survival (from placement to permanent failure) was higher for fistulas than for grafts when primary failures were excluded (hazard ratio 0.51; 95% confidence interval 0.27 to 0.94; P = 0.03), but similar when primary failures were included (hazard ratio 0.99; 95% confidence interval 0.61 to 1.62; P = 0.97). Fistulas required fewer interventions to maintain long-term patency for dialysis after maturation (0.73 versus 2.38 per year; P < 0.001). In conclusion, as compared with grafts, subsequent upper arm fistulas are associated with a higher primary failure rate, more interventions to achieve maturation, longer catheter dependence, and more frequent catheter-related bacteremia. However, once the access is usable for dialysis, fistulas have superior cumulative patency than do grafts and require fewer interventions to maintain patency.

Treatment of refractory central vein stenosis in hemodialysis patients with stents

Central venous stenosis is a frequent complication in hemodialysis patients, which can manifest clinically with ipsilateral upper extremity edema. When symptomatic, it is usually treated by percutaneous transluminal angioplasty. When angioplasty is unsuccessful, stent deployment is a therapeutic option. The goal of the present study was to evaluate the primary and secondary patency of refractory central vein stenosis after treatment with a stent. Using a prospective vascular access database we retrospectively identified 23 patients presenting with unilateral upper extremity edema and a significant (> 50%) central vein stenosis, who underwent stent placement due to refractory stenosis following angioplasty. The primary (unassisted) central vein patency was determined from the initial intervention to the next angioplasty for recurrent central vein stenosis, and the secondary (assisted) patency from the initial intervention to permanent central vein occlusion. An immediate technical success was achieved in all patients after the stent deployment. However, the median primary central vein patency was only 138 days, with a 19% patency at 1 year. Recurrence of ipsilateral edema was always due to in-stent restenosis. The median secondary central vein patency was 1036 days, with a 64% patency at 1 year. In patients with symptomatic central vein stenosis that is refractory to percutaneous transluminal angioplasty, stent deployment provides short-term relief of the stenosis and ipsilateral upper extremity edema. However, long-term symptomatic relief can be achieved with multiple subsequent interventions in many patients.

Hemodialysis Access without a Shunt or a Catheter: The Circulating Port

Purpose

To develop a new type of vascular access (VA) avoiding permanent arteriovenous (AV) shunting and intravenous catheter placement using a silicone plug inserted in the vessel wall.

Method

Four different animal studies were conducted to verify the biologic safety of the concept, to check resistance to infection and accessibility and midterm patency.

Results

The circulating ports were found to be very easy to puncture, extremely resistant to infection and their midterm patency rate was acceptable.

Conclusions

The circulating port seems to be a very promising hemodialysis (HD) access method, but it still has to be tested in clinical situations.

Aneurysm Formation in Arteriovenous Grafts: Associations and Clinical Significance

Aneurysms are a common complication of arteriovenous grafts in hemodialysis patients, resulting from repetitive needle sticks in the graft material. Although aneurysms are thought to contribute to graft failure, there are no prospective studies evaluating their risk factors or impact on graft survival. The present study evaluated aneurysms in 117 hemodialysis outpatients with upper extremity grafts at a university-affiliated dialysis center. An arterial aneurysm was defined as a cannulation site defect diameter (difference between arterial cannulation site diameter and normal graft diameter) above the median value for the study population (0.63 cm). Subsequent graft outcomes were determined by retrospective analysis of a prospective vascular access database. Thrombosis-free graft survival was compared among patient subgroups using Cox proportional hazards models. Patients with an arterial aneurysm had significantly longer median graft age, when compared with those not having a aneurysm (888 vs. 588 days, p = 0.01). However, the two groups did not differ in patient age, sex, diabetes, body mass index, or graft location. The hazard ratio for graft thrombosis was 0.45 (95% confidence interval, 0.25-0.82, p = 0.009) for grafts with an arterial aneurysm, when compared with those without a defect (1-year graft survival of 71 vs. 50%). Graft age was not associated with the likelihood of graft thrombosis (p = 0.12). In contrast to the prevailing wisdom, arterial aneurysms are associated with improved graft survival.

Impact of obesity on arteriovenous fistula outcomes in dialysis patients

Fistula use for dialysis is less frequent among obese than non-obese patients. This discrepancy may be due to a lower rate of fistula placement in obese patients, a higher primary failure rate (fistulas that are never usable for dialysis), or a higher secondary failure rate (fistulas that fail after being used successfully for dialysis). Using a prospective, computerized vascular access database, we identified all patients receiving a first fistula or graft at our institution during a 2-year period. The access outcomes were compared between obese (body mass index (BMI) >or=30 kg/m2) and non-obese (BMI<30 kg/m2) patients. Fistula placement was equally likely between obese and non-obese patients (47.4 vs 47.1%). The primary failure rate of fistulas was similar in both groups (46 vs 41%, P=0.45). Among those fistulas that were usable for dialysis, the secondary survival was worse in obese patients (hazard ratio 2.74; 95% confidence interval (CI), 1.48-7.90; P=0.004). Secondary fistula survival in obese vs non-obese patients was 68 vs 92% at 1 year, 59 vs 78% at 2 years, and 47 vs 70% at 3 years. On multiple variable survival analysis with age, sex, race, diabetes, coronary artery disease, peripheral vascular disease, fistula location, surgeon, and obesity in the model, obesity was the only significant factor predicting secondary fistula failure (hazards ratio 2.93; 95% CI, 1.44-5.93; P=0.004). In conclusion, long-term fistula survival is worse in obese than non-obese patients, owing to a higher secondary failure rate.

Vascular access thrombosis prophylaxis

Vascular access thrombosis in the hemodialysis patient leads to significant cost and morbidity. Fistula patency supersedes graft patency, therefore obtaining a mature functioning fistula in patients approaching end-stage renal disease (ESRD) by early patient education and referral needs to be practiced. Current methods to maintain vascular access patency rely on early detection and radiologic or surgical prevention of thrombosis. Study of thrombosis biology has elucidated other potential targets for the prophylaxis of vascular access thrombosis. The goal of this review is to examine the current available methods for vascular access thrombosis prophylaxis.

Routine Surveillance in Vascular Access for Hemodialysis

There is increasing evidence that surveillance of AV access for haemodialysis prevents access thrombosis and improves the quality of care. This article reviews the evidence for surveillance and the various strategies and techniques available for detection of the failing access.

Vascular access for hemodialysis

Establishing and maintaining adequate vascular access is essential to providing an appropriate dialysis dose in patients with end-stage renal disease. Complications related to vascular access have a significant role in dialysis-related morbidity and mortality. The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) clinical practice guideline for dialysis access was last updated in 2000 and provides a framework for the optimal establishment and maintenance of dialysis access, and treatment of complications related to dialysis access. This paper reviews the 2000 K/DOQI dialysis access guideline as well as updated information published subsequently.

Demands for vascular access in a renal dialysis unit: Implications for a regional vascular unit

BACKGROUND

The development of regional dialysis units and the expanding indications for dialysis has led to increased demand for vascular access surgery. Consequently, the provision and maintenance of access, and the management of related complications has created a considerable burden on vascular surgical units in hospitals providing renal replacement therapy (RRT).

AIMS

The objectives of our study were to review our experience with a variety of vascular access modalities for haemodialysis and to quantify the associated surgical workload.

METHODS

We reviewed our experience in a consecutive group of dialysis patients who had access surgery for RRT in a regional hospital setting.

RESULTS

Between January 1995 and January 2000, 69 patients entered the long-term dialysis programme in the Mid-Western region (population = 320,000). Of the 158 procedures performed, 138 (87%) were for access creation, and 20 (13%) related to access revision procedures. Twenty patients (29%) developed a total of 30 access related complications. Vascular access procedures accounted for 10% of the vascular surgical workload (1598 procedures) in the five-year period.

CONCLUSION

Vascular access is an important part of the haemodialysis services and surgical expertise should be available at local level to cope with likely demand.

Outcomes of thrombosed arteriovenous grafts: Comparison of stents vs angioplasty

The usual radiologic approach to thrombosed grafts is a combination of thrombectomy and angioplasty of the underlying lesion. However, the primary (unassisted) graft patency after thrombectomy is quite poor. We evaluated whether graft patency following thrombectomy is improved by placement of a stent in the stenotic lesion. Using a prospective, computerized vascular access database, we identified 14 patients with thrombosed arteriovenous (A-V) grafts treated with a stent at the venous anastomosis (stent group). The outcomes of these grafts was compared to those observed in 34 sex, age-, and date-matched control patients whose thrombosed A-V grafts were angioplastied (control group). Both groups were comparable in age, sex, race, diabetic status, graft age, and number of previous graft interventions. The immediate technical success, as indicated by the post-procedure graft to systemic pressure ratio, was similar in the stent and control groups (0.33+/-0.16 vs 0.41+/-0.17, P=0.14). The primary graft patency (time from thrombectomy to next intervention) was significantly longer for the stent group (median survival, 85 vs 27 days, P=0.02). Assisted or secondary patency (time from thrombectomy to permanent graft failure) was also longer for the stent group (median survival, 1215 vs 46 days, P=0.049). In conclusion, treatment of thrombosed grafts with a stenosis at the venous anastomosis with a stent results in longer primary and secondary graft survival, as compared to treatment with angioplasty. Stent placement may be a useful treatment modality in a subset of patients with thrombosed A-V grafts and stenosis at the venous anastomosis.

Access Monitoring Is Worthwhile and Valuable

During the past several years, a limited number of small clinical trials have questioned the role of surveillance in the management of vascular accesses, since the prolongation of access longevity until replacement was not altered. Although prolongation of access life span is an important endpoint, it is not the only one. Reduction in thrombotic events reduces the risks to the patient resulting from loss of access patency. The body of evidence suggests that the detection of stenosis and prevention of thrombosis are valuable. When a test indicates the likely presence of a stenosis, venography or fistulography should be used to definitely establish the presence and the degree of the stenosis. In most cases, angioplasty should be performed if the stenosis is greater than 50% by diameter. The value of routine use of any surveillance technique for detecting anatomic stenosis alone without concomitant functional assessment by measurement of access flow, venous pressure, recirculation, or other physiologic parameter has not been established. Stenotic lesions should not be repaired merely because they are present. If such correction is performed, then intra-procedural studies of access flow or intra-access pressure prior to and following percutaneous transluminal angioplasty should be conducted to demonstrate a functional improvement with a 'successful' percutaneous transluminal angioplasty.

Outcomes of tunneled femoral hemodialysis catheters: Comparison with internal jugular vein catheters

BACKGROUND

Tunneled femoral vein dialysis catheters are used as a last resort when all other options for a permanent vascular access or thoracic central vein catheter have been exhausted. There is little published literature on the complications or outcomes of tunneled femoral catheters.

METHODS

Using a prospective, computerized vascular access database, we identified all tunneled femoral dialysis catheters placed at the University of Alabama at Birmingham during a five-year period. The clinical features, catheter patency, and complications in these patients were compared to those observed in a group of sex-, age-, and date-matched control patients with tunneled internal jugular vein dialysis catheters.

RESULTS

During the study period, 27 patients received a tunneled femoral dialysis catheter, accounting for 1.9% of all tunneled catheters placed. Only 7 patients (26%) were able to convert to a new permanent dialysis access. The primary catheter patency (time from placement to exchange) was substantially shorter for femoral catheters than for internal jugular dialysis catheters (median survival, 59 vs. >300 days, P < 0.0001). Infection-free survival was similar for both groups (P= 0.66). Seven patients with femoral catheters (or 26%) developed an ipsilateral deep vein thrombosis, but catheter use was possible with anticoagulation.

CONCLUSION

Tunneled femoral dialysis catheters have a substantially shorter primary patency, but a similar risk of catheter-related bacteremia, as compared with internal jugular vein catheters. An ipsilateral lower extremity deep vein thrombosis occurs commonly after placement of a femoral dialysis catheter, but does not preclude continued catheter use.

Tunneled Catheters in Hemodialysis Patients: Reasons and Subsequent Outcomes

BACKGROUND

Reducing the use of tunneled catheters in hemodialysis patients requires concerted efforts to convert them to a usable permanent vascular access. The goal of this study is to evaluate the reasons for tunneled catheter use in our prevalent hemodialysis population and the success in converting them to a permanent vascular access.

METHODS

We identified all catheter-dependent hemodialysis patients at our center on a single date. These patients were followed up prospectively during a 1-year period to evaluate access procedures and conversion to permanent access use.

RESULTS

Of 458 prevalent hemodialysis patients, 108 patients (23.6%) were dialyzing through cuffed tunneled catheters: 18.5% had no further options for creation of a permanent vascular access, 28.7% had an immature access, 43.5% had access placement pending, and 9.2% had repeatedly refused access surgery. For 78 catheter-dependent patients (excluding patients with no access options and those who refused permanent access surgery), the likelihood of using a permanent access was 53% by 6 months and 80% by 1 year. In patients with an immature access, 50% were using a permanent access at 3 months, and 80%, at 6 months. Of patients with access surgery pending, 45% had access surgery performed within 3 months, and 70%, at 6 months. Finally, of all patients, the likelihood of catheter-related bacteremia was 48% at 6 months. On multivariable analysis, only duration of catheter dependence predicted subsequent use of a permanent access (hazard ratio, 3.11; 95% confidence interval, 1.70 to 5.68; P = 0.0002) for catheter dependence less than versus greater than 6 months.

CONCLUSION

Almost one quarter of our hemodialysis population is catheter dependent. Despite concerted efforts, there remain very long delays in achieving a usable permanent access, attributable to delays in both surgical access placement and access maturation. In the interim, this patient population developed a high frequency of catheter-related bacteremia.

Remarks on Surgical Strategy in Creating Vascular Access for Hemodialysis: 18 Years of One Center's Experience

The aim of the study is to evaluate surgical methods for creating vascular access for hemodialysis (HD) in patients with chronic renal failure. Over the last 18 years, 1,827 surgical procedures were performed in 722 patients (399 men and 323 women, mean age 43.7 +/- 17 years) in order to provide and maintain permanent vascular access for HD. Among all the surgical procedures, 992 were based on the construction of arteriovenous fistulas (AVF) and 835 were undertaken as secondary reparative surgical procedures. A total of 992 vascular accesses have been performed, including 904 AVF on upper and 14 on lower extremities as well as insertion of 74 permanent catheters. Radiocephalic AVF (RCAVF) was the principal type of AVF (58.8%). While constructing secondary angio-access after using RCAVF on the other extremity, fistulas with usage of brachial vessels were preferred. A total of 228 AVF of this type were created, including 143 brachiocephalic (BCAVF) and 85 brachiobasilic (BBAVF) AVF. Lately, synthetic grafts (arteriovenous graft, AVG) have been used more frequently, in 90 AVF. A brachial straight graft was the main type procedure performed, with polytetrafluoroethylene (95.6%). The patency of the fistulas has been evaluated. Kaplan-Meier survival curves were calculated to determine primary, primary-assisted, and secondary patency. Log-rank analysis was used to determine differences between curves. Primary, primary-assisted, and secondary patency at 12 months and 24 months were calculated. Comparing AVF patency in two patients' age periods (18-65 years, >65 years), it may be concluded that in the elderly group AVG provides better treatment for AVF. Finally, we conclude that a multidisciplinary approach to vascular access strategy offers the best option to achieve good functional AVF. Autogenous arteriovenous access should be regarded as the most suitable type in creating VA. However, individual conditions should be taken into consideration.