A multidisciplinary approach to hemodialysis access: prospective evaluation

Frequency of critical stenosis in primary arteriovenous fistulae before hemodialysis access: Should duplex ultrasound surveillance be the standard of care?

OBJECTIVE

Increasing use of primary arteriovenous fistulae (pAVFs) is a desired goal in hemodialysis patients (National Kidney Foundation /Dialysis Outcome Quality Initiative guidelines). However, in many instances, pAVFs fail to adequately mature due to ill-defined mechanisms. We therefore investigated pAVFs with color duplex ultrasound (CDU) surveillance 4 to 12 weeks postoperatively to identify hemodynamically significant abnormalities that may contribute to pAVF failure.

METHODS

From March 2001 to October 2003, 54 upper extremity pAVFs were subjected to CDU assessment before access. A peak systolic velocity ratio (SVR) of >/=2:1 was used to detect >/=50% stenosis involving arterial inflow and venous outflow, whereas an SVR of >/=3:1 was used to detect >/=50% anastomotic stenosis. CDU findings were compared with preoperative vein mapping and postoperative fistulography when available.

RESULTS

Of 54 pAVFs, there were 23 brachiocephalic, 14 radiocephalic, and 17 basilic vein transpositions. By CDU surveillance, 11 (20%) were occluded and 14 (26%) were negative. Twenty-nine (54%) pAVFs had 38 hemodynamically significant CDU abnormalities. These included 16 (42%) venous outflow, 13 (34%) anastomotic, and 2 (5%) inflow stenoses. In seven (18%), branch steal with reduced flow was found. In 35 of 54 (65%) pAVFs, preoperative vein mapping was available and demonstrated adequate vein size (>/=3 mm) and outflow in 86% of cases. Twenty-one fistulograms (38%) were available for verifying the CDU abnormalities. In each fistulogram, the arterial inflow, anastomosis, and venous outflow were compared with the CDU findings (63 segments). The sensitivity, specificity, and accuracy of CDU in detecting pAVF stenoses >/=50% were 93%, 94%, was 97%, respectively.

CONCLUSIONS

Before initiation of hemodialysis, an unexpectedly high prevalence of critical stenoses was found in patent pAVFs using CDU surveillance. These de novo stenoses appear to develop rapidly after arterialization of the upper extremity superficial veins and can be reliably detected by CDU surveillance. Turbulent flow conditions in pAVFs may play a role in inducing progressive vein wall and valve leaflet intimal thickening, although stenoses may be due to venous abnormalities that predate AVF placement. Routine CDU surveillance of pAVFs should be considered to identify and correct flow-limiting stenoses that may compromise pAVF long-term patency and use.

Association of pelvic arterial calcification with arteriovenous thigh graft failure in haemodialysis patients

BACKGROUND

Arterial calcification is a common problem in patients with chronic kidney disease, and has been associated with adverse clinical outcomes. The goal of the present study was to evaluate whether pelvic artery calcifications are associated with technical failure of arteriovenous thigh grafts in haemodialysis patients.

METHODS

From 1 January 1999 to 30 June 2002, thigh grafts were placed in 54 haemodialysis patients who had exhausted all options for permanent vascular access in the upper extremities. Perioperative computed tomography (CT) of the abdomen and pelvis was obtained in 32 of the patients for diagnostic purposes unrelated to vascular access planning. Two radiologists, who were blinded to the graft outcomes, scored the vascular calcifications on CT of the distal aorta, common iliac, external iliac and common femoral arteries on a semi-quantitative 5-point scale. The association between technical graft failure (inability to complete the anastomosis) and the vascular calcification score was analysed.

RESULTS

There was a high inter-observer agreement in scoring vascular calcification (kappa = 0.801). Among 26 patients with absent or mild pelvic arterial calcifications (grade 1-2) on CT, none (0%) experienced technical graft failure. In contrast, three of six patients (50%) with moderate to severe calcification (grade 3-5) had technical graft failures (P = 0.004 by Fisher's exact test). The cumulative 1 year graft patency was lower in the group with grade 3-5 calcification (33 vs 81%, P = 0.09). The two groups were similar in age, gender, race, diabetes, duration of dialysis, serum calcium, serum phosphorus and serum parathyroid hormone.

CONCLUSION

There is a strong association between pelvic artery calcifications and technical failure of thigh grafts. The presence of moderate to severe vascular calcification is predictive of poor cumulative 1 year graft patency.

Associations with predialysis vascular access management

BACKGROUND

The Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines encourage increasing the proportion of arteriovenous fistulae among incident hemodialysis patients. Achieving optimal outcomes requires predialysis out-patient follow-up by a nephrologist, predialysis placement of a vascular access, and adequate maturation of the vascular access.

METHODS

We assessed the effect of clinical factors on predialysis vascular access management in all incident hemodialysis patients at a single institution during a 2-year period.

RESULTS

Of 157 patients initiating dialysis therapy from January 1, 2001, to December 31, 2002, a total of 73.2% had predialysis follow-up by a nephrologist, 46.5% had predialysis vascular access surgery, and 35.0% initiated their first dialysis session with a permanent access. Among patients using a permanent access on their first dialysis session, 67.3% used a fistula. Patients with diabetes were more likely than those without diabetes to have predialysis nephrology follow-up (81.5% versus 61.5%; P = 0.005), undergo predialysis vascular access surgery (56.5% versus 32.3%; P = 0.003), and initiate their first dialysis session with a fistula or graft (43.5% versus 23.1%; P = 0.008). Duration of predialysis nephrology follow-up was similar between patients with and without diabetes (median, 412 versus 300 days; P = 0.27). Patient age, sex, and race were not predictive of predialysis access management.

CONCLUSION

Despite attempts to follow the K/DOQI guidelines, 65% of incident hemodialysis patients initiated their first dialysis treatment with a catheter. Patients with diabetes were significantly more likely to have predialysis follow-up by a nephrologist and thus more likely to initiate their first dialysis session with a permanent access. Emphasis on early referral of patients with chronic kidney disease without diabetes to nephrologists may increase fistula use among incident hemodialysis patients.

Treatment of catheter-related bacteraemia with an antibiotic lock protocol: effect of bacterial pathogen

BACKGROUND

The standard therapy of dialysis catheter-related bacteraemia involves both systemic antibiotics and catheter replacement. We reported recently that instillation of an antibiotic lock (highly concentrated antibiotic solution) into the catheter lumen after dialysis sessions, in conjunction with systemic antibiotics, can successfully treat many episodes of catheter-related bacteraemia without requiring catheter removal. The present study evaluated whether the likelihood of achieving a cure with this protocol depends on the type of pathogen.

METHODS

This was a historically controlled interventional study of an antibiotic lock protocol for the treatment of catheter-related bacteraemia. We analysed prospectively the likelihood of clinical cure (fever resolution and negative surveillance cultures) with an antibiotic lock protocol among patients with dialysis catheter-related bacteraemia. In addition, infection-free catheter survival was evaluated for up to 150 days, and compared with that observed among patients managed with routine catheter replacement.

RESULTS

Overall, the antibiotic lock protocol was successful in 33 of 47 infected patients (70%) with catheter-related bacteraemia. The likelihood of a clinical cure was 87% for Gram-negative infections, 75% for Staphylococcus epidermidis infections, and only 40% for Staphylococcus aureus infections (P = 0.04). The median infection-free catheter survival with the antibiotic lock protocol was longer than that observed among patients with routine catheter replacement (154 vs 71 days, P = 0.02).

CONCLUSIONS

The clinical success of an antibiotic lock protocol in eradicating catheter-related bacteraemia while salvaging the catheter is highly dependent on the bacterial pathogen. Thus, the overall success rate in an individual dialysis programme will depend on the relative frequencies of different bacterial pathogens.

Comparison of Arteriovenous Grafts in the Thigh and Upper Extremities in Hemodialysis Patients

ABSTRACT. Placement of a thigh graft is an option in hemodialysis patients who have exhausted all upper extremity sites for permanent vascular access. The outcome of thigh grafts has been reported only in retrospective studies. The outcomes of 409 grafts placed at a single institution during a 3.5-yr period were evaluated prospectively, including 63 thigh grafts (15% of the total). Information was recorded on surgical complications, dates of radiologic and surgical interventions, and date of graft failure. The technical failure rate was approximately twice as high for thigh grafts, as compared with upper extremity grafts (12.7versus5.8%;P= 0.046). Intervention-free survival was similar for thigh and upper extremity grafts (median, 3.9versus3.5 mo;P= 0.55). Thrombosis-free survival was also comparable for thigh and upper extremity grafts (median, 5.7versus5.5 mo;P= 0.94). Cumulative survival (time to permanent failure) was similar for thigh and upper extremity grafts (median, 14.8versus20.8 mo;P= 0.62). When technical failures were excluded, the median cumulative survival was 27.6 mo for thigh grafts and 22.5 mo for upper extremity grafts (P= 0.72). The frequency of angioplasty (0.28versus0.57 per year), thrombectomy (1.58versus0.94 per year), surgical revision (0.28versus0.18 per year), and total intervention rate (2.15versus1.70 per year) was similar between thigh and upper extremity grafts. Access loss as a result of infection tended to be higher for thigh grafts than for upper extremity grafts (11.1versus5.2%;P= 0.07). In conclusion, placement of thigh grafts should be considered a viable option among hemodialysis patients who have exhausted all options for a permanent vascular access in both upper extremities. E-mail mdallon@uab.edu

Prophylaxis against dialysis catheter-related bacteremia with a novel antimicrobial lock solution

Catheter-related bacteremia, a frequent complication in patients who are undergoing hemodialysis, may be prevented by eradication of the catheter biofilm. Catheter lock solution (CLS) is an investigational preparation containing taurolidine, a biocompatible antimicrobial agent, and citrate, an anticoagulant agent. CLS was instilled into the catheter lumens after each dialysis session for 20 catheter-dependent hemodialysis patients. Catheter outcomes were compared with those observed in 30 concurrent control patients whose catheters were instilled with heparin. Bacteremia-free survival at 90 days was higher among patients who received CLS than among control patients who received heparin (94% vs. 47%; P<.001). Unassisted catheter patency (without tissue plasminogen activator instillation) was lower among patients who received CLS than among control patients (32% vs. 76%; P<.001). CLS dramatically reduces the frequency of catheter-related bacteremia among patients undergoing hemodialysis, although there is an increased requirement for thrombolytic interventions to maintain catheter patency.

Acesso vascular para hemodiálise: avaliação do tipo e local anatômico em 23 unidades de diálise distribuídas em sete estados brasileiros

OBJETIVO: Demonstrar os acessos vasculares para hemodiálise mais utilizados em 23 unidades de hemodiálise, distribuídas em sete estados brasileiros. MÉTODO: Entre outubro de 1999 a agosto de 2000, foram avaliados 2559 pacientes em 23 unidades de hemodiálise distribuídas em 23 estados brasileiros onde foi observado: A - A freqüência da utilização do acesso vascular, se externo através de cateteres ou se interno através de fístula arteriovenosa (FAV). B - Os tipos de cateteres, se de curta permanência ou de longa permanência, assim como os locais anatômicos utilizados para sua inserção. C - Os tipos de FAV, se direta ou com interposição de algum tipo de prótese e os locais anatômicos onde foram construídas, se distais ou proximais. D - O custo financeiro com os acessos vasculares. RESULTADOS: Constatou-se que 93,4% dos pacientes tinham um acesso vascular através de FAV e 6,6% através de cateter. As FAV diretas distais foram as mais utilizadas em 74,8% dos pacientes; as FAV diretas proximais foram construídas em 21,7% das vezes; as FAV com politetrafluoretileno expandido (PTFE) 3,2% da totalidade; a veia safena foi utilizada em 0,1% e as FAV consideradas como outras em 0,2%. Os cateteres de longa permanência foram utilizados em 8,7% da totalidade dos cateteres e os de curta permanência em 91,3%. Como via de acesso a veia jugular foi utilizada em 42,4%, a veia subclávia em 42,4% e a veia femoral em 6,5%. O custo financeiro com acesso para hemodiálise foi de 1% do custo total das unidades. CONCLUSÕES: O acesso vascular no Brasil tem características próprias. O acesso mais utilizado é a FAV distal e o uso do PTFE é baixo.

Renal and cardiovascular effects of renal denervation in conscious rats after adenosine administration and nitric oxide synthase inhibition

The role of renal nerves on renal and cardiovascular responses to adenosine administration and/or acute NO synthase inhibition was investigated. Conscious male Wistar rats with implanted catheters in femoral artery for blood pressure registration, femoral vein for drug infusion and bladder for urine collection were used. Adenosine was applied i.v. (1.0 mg/kg BW bolus) followed by infusion of 0.1 mg/kg.min, and/or nitric oxide synthase inhibition (NOSI) was performed by i.v. administration of 10 mg/kg BW N-Omega-nitro-L-arginine methyl ester (L-NAME) before and 1 week after bilateral renal denervation (BRD). NOSI decreased HR and increased SAP, MAP and DAP both in intact and BRD rats. Baroreflex sensitivity increased in intact and BRD rats. Adenosine did not change HR, blood pressure or baroreflex sensitivity in intact as well as BRD rats. NOSI increased V, VU(Na) and VU(CI) in intact rats but decreased V and did not alter VU(Na) and VU(CI) in BRD rats. Adenosine increased V, VU(CI) and C(cr) in intact rats but did not change renal excretory function in BRD rats. Combined application of adenosine and L-NAME led to a dramatic increase of V, VU(Na), VU(Cl) and C(cr) in intact rats. However, VU(Na) and VU(CI) in BRD rats were lower as compared to intact rats. Therefore, changes in renal excretory function seen after NOSI are not exclusively the result of pressure diuresis and natriuresis but in some way are dependent on renal nerves. Renal denervation attenuates the renal excretory response to adenosine. Sympathetic nervous system is important in mediating the effects of adenosine and/or NO on renal excretory function. Renal denervation did not change the pattern of baroreflex sensitivity after adenosine and/or L-NAME administration.

Overcoming barriers to arteriovenous fistula creation and use

National guidelines advocate the placement of arteriovenous fistulas (AVFs) as the preferred vascular access for hemodialysis (HD) patients because of their low complication rate, lower costs, and prolonged patency, once matured. The current Dialysis Outcomes Quality Initiative (DOQI) guidelines aim for an AVF incidence of 50% and a 40% prevalence in the United States. Although patients currently starting dialysis do so at an increasingly older age and with more comorbidity, they should be given every opportunity to receive an AVF. Meeting this challenge is facilitated by a multidisciplinary approach with early referral to the nephrologist in the predialysis period for access planning. Key components of a vascular access program may include the coordination by a dedicated access coordinator and outcome tracking via a prospective database. Preoperative vessel evaluation and careful selection of an appropriate surgical site, along with an experienced surgeon, improve surgical outcomes. Transposed brachiobasilic or other tertiary fistulas should be offered to patients who cannot receive a native radiocephalic or brachiocephalic fistula. The ability to routinely monitor and salvage failing AVFs is important to achieving successful AVF outcomes. Standardized definitions of AVF outcomes are important to allow individual centers and continuous quality assurance (CQA) programs to track and benchmark their outcomes against local and national standards to help them meet recommended targets.

Determinants of successful synthetic hemodialysis vascular access graft placement

OBJECTIVE

Synthetic vascular grafts, the most common type of permanent dialysis graft used in the United States, are associated with great morbidity and expense. In this cohort study of patients undergoing hemodialysis and receiving a new synthetic vascular graft, detailed intraoperative procedural data were examined as predictors of graft dysfunction and failure.

METHODS

A prospective cohort study of patients receiving hemodialysis who had undergone synthetic (polytetrafluoroethylene) graft placement over 4(1/2) years were followed up until either the graft was no longer usable, kidney transplantation was performed, the patient died, or the study ended. The principal methods of analysis used were the Kaplan-Meier method, to compute survival function for primary and secondary graft patency, and Cox proportional hazards regression, to model associations between predictor variables and graft failure.

RESULTS

Of 284 patients enrolled in the study, 172 patients (61%) had at least one graft-related event, ie, temporary graft dysfunction or graft failure, during follow-up. Three-year cumulative graft survival was 54% (95% confidence interval, 45%-62%). Using proportional hazards analysis, history of claudication (rate ratio [RR], 2.14 [range, 0.97-4.73]; P =.06), number of previous permanent grafts (1 graft: RR, 1.49 [range, 0.88-2.51]; 2 or more grafts: RR, 2.85 [range, 1.43-5.69]; P =.01), dialysis dependency at surgery (RR, 2.96 [range, 1.23-7.12]; P =.02), and use of arterial clamps in construction of the graft (RR, 2.32 [range, 1.14-4.73]; P =.02) were associated with lower survival, even after accounting for medical history. Type of graft material, ie, Gore-Tex versus other material (RR, 0.28 [range, 0.16-0.50]; P <.01) and use of the axillary vein (RR, 0.61 [range, 0.36- 1.02]; P =.06) for the access site were associated with a lower rate of graft failure. Similar results were found with Poisson analysis of all graft-related events. In addition, acute arterial anastomosis, ie, arterial angle less than 90 degrees (RR, 0.63 [range, 0.45-0.91]; P =.01) and use of the brachial artery versus the radial artery (RR, 0.54 [range, 0.33-0.54]; P =.01) were associated with a lower rate of graft-related events.

CONCLUSION

These findings suggest possible areas for intervention to improve synthetic vascular graft outcome.

Preventing vascular access dysfunction: which policy to follow

In the USA, three Clinical Performance Measures are currently in place: increasing the number of autologous arteriovenous fistulas (AVFs) among incident hemodialysis patients to 50% and to 40% in prevalent hemodialysis patients; to foster the surveillance of accesses with preemptive correction of problems before accesses thrombose or fail, and to reduce the use of catheters in prevalent patients to less than 10%. Reduction of catheters will automatically result from initiatives that increase the construction of AVFs and preemptive monitoring and surveillance of accesses for dysfunction. Therefore, policies that promote the latter two vascular access aspects are most important to develop and follow. Of these two, however, the most impact will be made by promoting a policy to increase AVF creation in the timeliest manner possible. Strategies and resources needed to achieve these policies are presented. The need for a team approach is emphasized.

Basic steps for increasing the rate of autogenic vascular accesses for hemodialysis

The number of patients on chronic hemodialysis (HD) is steadily increasing worldwide. The creation of a well-functioning vascular access represents a critical aspect in their management. Autogenous arteriovenous fistulas (AVF) are considered the first choice vascular access in terms of lower morbidity and costs, and higher survival rates when compared with grafts. However, creating AVF at high rates is a complex task that requires a multidisciplinary approach, which includes nephrologists, access surgeons, dialysis nurses and radiologists. In the present work we review concisely the basic steps, for preserving all potential autogenic sites at both upper extremities for future AVF creation and, for prolonging the length of AVF survival. We feel that a more proactive involvement of nephrologists in the basic steps for AVF creation would substantially contribute to increase AVF rates among HD patients.

Improving quality of vascular access care for hemodialysis patients

BACKGROUND

Because quality of care for patients with end-stage renal disease (ESRD) has improved, they require long-term vascular access for hemodialysis. Construction of a native vein arteriovenous fistula (AVF) on the arm is considered best practice; a prosthetic graft (PG) AVF on the arm is a good alternative, although insertion of a central venous catheter (CVC), the third choice, is sometimes necessary. A quality improvement project was initiated at the dialysis unit of Rijnland Hospital (The Netherlands) to improve quality of vascular access care.

METHODS

Seventy-four patients were treated from January 2001 through June 2002. The list of preferred access operations was adapted from evidence-based guidelines. The percentages of CVCs and PGs were chosen as quality indicators.

RESULTS

Twelve of 19 patients (34%) appeared to be using CVCs unnecessarily. Actions were taken, and the CVC indicator decreased by 11%. The PG indicator decreased gradually from 24% to 8%.

DISCUSSION

Reductions in the use of CVCs and PGs suggest that the vascular access improvement project resulted in improvement of long-term vascular access for hemodialysis patients. A considerable decrease in the use of PGs and CVCs was achieved in 2001. However, a decrease of CVCs to < 20% has still not been realized, perhaps because new hemodialysis patients referred to the dialysis unit have already had CVCs inserted.

SUMMARY AND CONCLUSION

Considerable improvement, as reflected in the number of hemodialysis patients with CVCs or PGs, can be achieved with a minimum of costs.

Creation, cannulation and survival of arteriovenous fistulae: data from the Dialysis Outcomes and Practice Patterns Study

BACKGROUND

An arteriovenous (A-V) fistula is the optimal vascular access for hemodialysis. The National Kidney Foundation Dialysis Outcomes Quality Initiative (DOQI) recommends that fistulae should mature for at least one month before cannulation, but this recommendation is not evidence-based. If fistulae are created prior to ESRD and cannulation is possible earlier without compromising fistula survival, the need for temporary catheters would be reduced.

METHODS

Prospective observational data were analyzed for a random sample (N = 3674) of incident patients at the time of initiating hemodialysis, hemofiltration or hemodiafiltration in 309 facilities in France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States, taking part in the Dialysis Outcomes and Practice Patterns Study (DOPPS).

RESULTS

Although the proportion of patients who had pre-dialysis care by a nephrologist differed little between countries, there were large variations in the proportion of patients who commenced hemodialysis via an A-V fistula, A-V graft or central venous catheter. The usual time interval between referral and creation of A-V fistulae also differed greatly between countries. For new hemodialysis (HD) patients initiating HD with an A-V fistula (N = 894) the following results were observed: (1). median time to first cannulation varied greatly between countries: Japan and Italy (25 and 27 days), Germany (42 days), Spain and France (80 and 86 days), UK and US (96 and 98 days). (2). No association was found between cannulation <or=28 days versus>28 days for patient characteristics of age, gender, and fifteen different classes of patient co-morbid factors. (3). Risk of A-V fistula failure was increased for incident patients who had a prior temporary access [relative risk (RR) = 1.81, P = 0.01] or who were female (RR = 1.52, P = 0.02). (4). Cannulation <or=14 days after creation was associated with a 2.1-fold increased risk of subsequent fistula failure (P = 0.006) compared to fistulae cannulated>14 days. (5) No significant difference in A-V fistula failure was seen for fistulae cannulated in 15 to 28 days compared with 43 to 84 days.

CONCLUSION

Significant differences in clinical practice currently exist between countries regarding the creation of A-V fistulae prior to starting hemodialysis and the timing of initial cannulation. Cannulation within 14 days of creation is associated with reduced long-term fistula survival. Fistulae ideally should be left to mature for at least 14 days before first cannulation.

Gender differences in outcomes of arteriovenous fistulas in hemodialysis patients

BACKGROUND

The prevalence of arteriovenous (A-V) fistula use is lower among female than male hemodialysis patients. This difference may be due, in part, to smaller vessel diameter in women. However, even when routine preoperative vascular mapping is used to select vessels with suitable diameters, fistulas are still less likely to mature in women than in men.

METHODS

To explore the reasons for this gender discrepancy, we evaluated the outcomes of 230 A-V fistulas placed at our institution after preoperative mapping. Vessel diameters, radiologic and surgical interventions, and fistula adequacy for dialysis were assessed.

RESULTS

Fistula adequacy for dialysis was lower in women than men (31 vs. 51%, P = 0.001). The inferior outcome of fistulas in women was observed for both forearm fistulas (18 vs. 43%, P = 0.02) and upper arm fistulas (39 vs. 60%, P = 0.04). Differences in vessel diameter did not explain the lower patency rate of fistulas among women. Among fistulas not lost due to technical failure or early thrombosis, 31% underwent one or more interventions (salvage procedures) due to failure to mature. These interventions included angioplasty, ligation of tributaries, superficialization, and surgical revision of the anastomosis. A salvage procedure was more likely in women than in men (42 vs. 23%, P = 0.04). The likelihood of fistula maturation after an intervention was similar among women and men (50 vs. 37%, P = 0.40). Salvage procedures increased the proportion of adequate fistulas to a greater degree in women than in men (relative increases of 68 and 15%, respectively).

CONCLUSIONS

These data suggest that fistulas are less likely to be useable for dialysis in women than in men, despite routine preoperative mapping and frequent interventions undertaken to salvage immature fistulas.

Vascular ultrasonography prior to dialysis access surgery

BACKGROUND

Native arterial venous fistulas (NAVF) are generally considered preferable to synthetic grafts for chronic dialysis access. As increasing numbers of diabetic and elderly patients are treated, adequate NAVFs become more difficult to establish. Vascular ultrasonography (US) prior to NAVF surgery has received little attention.

METHODS

Patients with questionable venous or arterial status underwent 47 US evaluations by the operating surgeon prior to AV fistula surgery. Veins were evaluated for compressibility, size and distensibility. Arterial and venous occlusive lesions were identified.

RESULTS

In all, 74.5% of patients were diabetic. More than half the patients had at least one previous access operation. Ultrasonography examination detected venous occlusions, stenoses, or fibrotic segments in addition to atheromatous disease in the radial artery.

CONCLUSIONS

The use of the origin of the radial artery for anastomotic inflow was frequently helpful. Only once in 47 procedures was placement of a prosthetic graft required. One patient had early thrombosis. There were no infections or ischemic complications. The use of preoperative US by the operating surgeon aids in selection of site and feasibility for NAVFs. Almost all patients can have a NAVF created and avoid the problems associated with synthetic graft material.

Vascular access for dialysis in the elderly

Although not taken in consideration as a special issue in current guidelines, vascular access in the elderly deserve specific recommendations as they are quickly enlarging as a group, with particularly high vascular access morbidity and failure rate. Hemodynamic and endothelial mechanisms of access failure are reviewed and tentative strategies to increase the prevalence of durable native arteriovenous fistulas are analysed.

Increasing arteriovenous fistulas in hemodialysis patients: problems and solutions

National guidelines promote increasing the prevalence of fistula use among hemodialysis patients. The prevalence of fistulas among hemodialysis patients reflects both national, regional, and local practice differences as well as patient-specific demographic and clinical factors. Increasing fistula prevalence requires increasing fistula placement, improving maturation of new fistulas, and enhancing long-term patency of mature fistulas for dialysis. Whether a patient receives a fistula depends on several factors: timing of referral for dialysis and vascular access, type of fistula placed, patient demographics, preference of the nephrologist, surgeon, and dialysis nurses, and vascular anatomy of the patient. Whether the placed fistula is useable for dialysis depends on additional factors, including adequacy of vessels, surgeon's experience, patient demographics, nursing skills, minimal acceptable dialysis blood flow, and attempts to revise immature fistulas. Whether a mature fistula achieves long-term patency depends on the ability to prevent and correct thrombosis. An optimal outcome is likely when there is (1) a multidisciplinary team approach to vascular access; (2) consensus about the goals among all interested parties (nephrologists, surgeons, radiologists, dialysis nurses, and patients); (3) early referral for placement of vascular access; (4) restriction of vascular access procedures to surgeons with demonstrable interest and experience; (5) routine, preoperative mapping of the patient's arteries and veins; (6) close, ongoing communication among the involved parties; and (7) prospective tracking of outcomes with continuous quality assessment. Implementing these measures is likely to increase the prevalence of fistulas in any given dialysis unit. However, differences among dialysis units are likely to persist because of differences in gender, race, and co-morbidity mix of the patient population.

Systemic barriers to improving vascular access outcomes

Vascular access dysfunction is the most frequent cause of hospitalization for end-stage renal disease (ESRD) patients. Our system of vascular access care and industry standards developed for historic reasons have resulted in a haphazard approach to access management. The Dialysis Outcome Quality Initiative has provided a road map for improving vascular access management. However, despite widespread acceptance, these recommendations are not routinely followed. This is largely the result of inertia coupled with systemic barriers to improving access outcomes. These barriers include lack of funded pre-ESRD care and preoperative imaging, lack of reimbursement for access monitoring, unavailable surgical and interventional suites, erosion of the real value of the composite rate, bundling of additional new services without rate adjustment, poor accountability of surgeons and hospitals, and a reimbursement system that rewards procedures and, in particular, graft and catheter placement. Currently, Center for Medicare and Medicaid Services is reevaluating the composite rate and its included bundle of services. To provide the best access care with the fewest complications while insuring multidisciplinary involvement and accountability, a realistic appraisal and realignment of incentives must be developed to insure improvement of access care in the United States.

Management of hemodialysis catheter-related bacteremia with an adjunctive antibiotic lock solution

BACKGROUND

Tunneled dialysis catheters are complicated by frequent systemic infections. Standard therapy of catheter-associated bacteremia involves both systemic antibiotics and catheter replacement. Recent data suggest that biofilms in the catheter lumen are responsible for the bacteremia, and that instillation of an antibiotic lock (highly concentrated antibiotic solution) into the catheter lumen after dialysis sessions can eradicate the biofilm.

METHODS

We analyzed prospectively the efficacy of an antibiotic lock protocol, in conjunction with systemic antibiotics, for treatment of patients with dialysis catheter-associated bacteremia without catheter removal. Protocol success was defined as resolution of fever and negative surveillance cultures one week following completion of the protocol. Protocol failure was defined as persistence of fever or surveillance cultures positive for any pathogen. In addition, infection-free catheter survival was compared to that observed in institutional historical control patients treated with catheter replacement.

RESULTS

Blood cultures were positive in 98 of 129 of episodes (76%) in which patients dialyzing with a catheter had fever or chills. Protocol success occurred in 40 of 79 infected patients (51%) treated with the antibiotic lock. Protocol failure occurred in 39 cases (49%): 7 had persistent fever, 15 had positive surveillance cultures (9 for Candida and 6 for bacteria), and 17 required catheter removal due to malfunction. Each of the pathogens in the surveillance cultures was different from the original pathogen in that patient. Eight of the 9 secondary Candida infections and all 6 secondary bacterial infections resolved after catheter exchange and specific antimicrobial treatment. Overall catheter survival with the antibiotic lock protocol was similar to that observed among patients managed with catheter replacement (median survival, 64 vs. 54 days, P = 0.24).

CONCLUSIONS

Use of an antibiotic lock, in conjunction with systemic antibiotic therapy, can eradicate catheter-associated bacteremia while salvaging the catheter in about one half of cases. Moreover, this management approach offers clinical advantages over routine catheter exchange.

Improving hemodialysis patient outcomes: a step-by-step approach

Hemodialysis patient outcomes are often suboptimal, with one-sixth of patients receiving an inadequate dialysis dose, one-fourth using catheters for vascular access, and more than one-half being malnourished. This review describes a four-step approach for improving dialysis patient outcomes. First, select an outcome to improve. This can be a global outcome such as mortality, morbidity, quality of life, or health care costs or an intermediate outcome (such as dialysis dose) that has a demonstrated link with a global outcome. Second, determine barriers to optimal outcomes. Both patient factors (such as noncompliance) and provider factors (such as the process of care) may act as barriers. Third, intervene on specific barriers. Interventions may involve providing medical or surgical treatment, changing patient or provider behavior, or modifying the system of care. Fourth, disseminate the intervention to other settings. "Early adopters" (those who quickly adopt an innovation) and "opinion leaders" (well-respected local physicians) are especially influential in determining the rate of dissemination. By using this approach, physicians can move from helping an individual patient to improving the outcomes of many patients.

Vascular access use in Europe and the United States: results from the DOPPS

BACKGROUND

A direct broad-based comparison of vascular access use and survival in Europe (EUR) and the United States (US) has not been performed previously. Case series reports suggest that vascular access practices differ substantially in the US and EUR. We report on a representative study (DOPPS) which has used the same data collection protocol for> 6400 hemodialysis (HD) patients to compare vascular access use at 145 US dialysis units and 101 units in five EUR countries (France, Germany, Italy, Spain, and the United Kingdom).

METHODS

Logistic analysis evaluated factors associated with native arteriovenous fistula (AVF) versus graft use or permanent access versus catheter use for prevalent and incident HD patients. Times to failure for AVF and graft were analyzed using Cox proportional hazards regression.

RESULTS

AVF was used by 80% of EUR and 24% of US prevalent patients, and was significantly associated with younger age, male gender, lower body mass index, non-diabetic status, lack of peripheral vascular disease, and no angina. After adjusting for these factors, AVF versus graft use was still much higher in EUR than US (AOR=21, P < 0.0001). AVF use within facilities varied from 0 to 87% (median 21%) in the US, and 39 to 100% (median 83%) in EUR. For patients who were new to HD, access use was: 66% AVF in EUR versus 15% in US (AOR=39, P < 0.0001), 31% catheters in EUR vs. 60% in US, and 2% grafts in EUR vs. 24% in US. In addition, 25% of EUR and 46% of US incident patients did not have a permanent access placed prior to starting HD. In EUR, 84% of new HD patients had seen a nephrologist for> 30 days prior to ESRD compared with 74% in the US (P < 0.0001); pre-ESRD care was associated with increased odds of AVF versus graft use (AOR=1.9, P=0.01). New HD patients had a 1.8-fold greater odds (P=0.002) of starting HD with a permanent access if a facility's typical time from referral to access placement was < or =2 weeks. AVF use when compared to grafts was substantially lower (AOR=0.61, P=0.04) when surgery trainees assisted or performed access placements. When used as a patient's first access, AVF survival was superior to grafts regarding time to first failure (RR=0.53, P=0.0002), and AVF survival was longer in EUR compared with the US (RR=0.49, P=0.0005). AVF and grafts each displayed better survival if used when initiating HD compared with being used after patients began dialysis with a catheter.

CONCLUSION

Large differences in vascular access use exist between EUR and the US, even after adjustment for patient characteristics. The results strongly suggest that a facility's preferences and approaches to vascular access practice are major determinants of vascular access use.

Clinical consequences of infected arteriovenous grafts in hemodialysis patients

Arteriovenous (AV) graft infection is a serious adverse event in hemodialysis patients; however, there is little published literature describing its consequences. We identified prospectively all AV graft infections occurring at our institution during a 4.5-year period. We analyzed immediate complications, as well as long-term consequences, including the need for subsequent vascular-access procedures and duration of catheter-dependent dialysis therapy. Ninety graft infections were identified in 78 patients, yielding a rate of 8.2 infections/100 graft-years. Patients with graft infection were much more likely to have a low serum albumin level (<3.5 g/dL) in the month preceding the infection compared with noninfected controls (73% versus 18%; P < 0.001). Infections occurred within 1 month of graft placement in 15%, at 1 to 12 months in 44%, and longer than 1 year from surgery in 41%. The pathogen was a gram-positive coccus in 97% of cases, particularly Staphylococcus aureus (60%) and Staphylococcus epidermidis (22%). The initial graft infection entailed hospitalization for a mean of 7.5 days. Eleven patients (12%) developed a total of 17 major complications, including death (5 patients), clinical sepsis requiring vasopressors (4 patients), septic arthritis (3 patients), epidural abscess (1 patient), endocarditis (1 patient), osteomyelitis (1 patient), myocardial infarction (1 patient), and cerebrovascular accident (1 patient). After removal of an infected graft, patients were catheter dependent for a median of 3.8 months. The duration of catheter dependence was less than 3 months in 36%, 3 to 6 months in 38%, 6 to 12 months in 14%, and greater than 1 year in 12%. During the period of catheter dependence, patients required a mean of 9.7 access procedures, including graft removal (1.0 procedure), nontunneled dialysis catheters (4.4 procedures), tunneled dialysis catheters (3.0 procedures), and new permanent accesses (1.4 procedures). In addition, patients averaged 0.85 episodes of bacteremia while they were catheter dependent. In conclusion, graft infection results in substantial morbidity, prolonged dependence on dialysis catheters, and multiple vascular-access procedures.

Effect of preoperative sonographic mapping on vascular access outcomes in hemodialysis patients

BACKGROUND

Current DOQI guidelines encourage placing arteriovenous (AV) fistulas in more hemodialysis patients. However, many new fistulas fail to mature sufficiently to be usable for hemodialysis. Preoperative vascular mapping to identify suitable vessels may improve vascular access outcomes. The present study prospectively evaluated the effect of routine preoperative vascular mapping on the type of vascular accesses placed and their outcomes.

METHODS

During a 17-month period, preoperative sonographic evaluation of the upper extremity arteries and veins was obtained routinely. The surgeons used the information obtained to plan the vascular access procedure. The types of access placed, their initial adequacy for dialysis, and their long-term outcomes were compared to institutional historical controls placed on the basis of physical examination alone.

RESULTS

The proportion of fistulas placed increased from 34% during the historical control period to 64% with preoperative vascular mapping (P < 0.001). When all fistulas were assessed, the initial adequacy rate for dialysis increased mildly from 46 to 54% (P = 0.34). For the subset of forearm fistulas, the initial adequacy increased substantially from 34 to 54% (P = 0.06); the greatest improvement occurred among women (from 7 to 36%, P = 0.06) and diabetic patients (from 21 to 50%, P = 0.055). In contrast, the initial adequacy rate of upper arm fistulas was not improved by preoperative vascular mapping (59 vs. 56%, P = 0.75). Primary access failure was higher for fistulas than grafts (46.4 vs. 20.6%, P = 0.001), but the subsequent long-term failure rate was higher for grafts than fistulas (P < 0.05). Moreover, grafts required a threefold higher intervention rate (1.67 vs. 0.57 per year, P < 0.001) to maintain their patency. The overall effect of this strategy was to double the proportion of patients dialyzing with a fistula in our population from 16 to 34% (P < 0.001).

CONCLUSIONS

Routine preoperative vascular mapping results in a marked increase in placement of AV fistulas, as well as an improvement in the adequacy of forearm fistulas for dialysis. This approach resulted in a substantial increase in the proportion of patients dialyzing with a fistula in our patient population. Fistulas have a higher primary failure rate than grafts, but have a lower subsequent failure rate and require fewer procedures to maintain their long-term patency.

Hemodialysis access ultrasound

Maintenance of hemodialysis graft and fistula patency is becoming even more important as the number of patients with end-stage renal disease increases. There are two major categories of dialysis access: native arteriovenous fistula (AVF) and synthetic arteriovenous graft. Arteriovenous fistulas have superior longevity after maturation and are the recommended type of hemodialysis access, if possible. However, AVFs have a higher rate of primary failure as compared with grafts. Close monitoring has been shown to prolong access survival. Ultrasound is a noninvasive means of imaging for access complications. Ultrasound is sensitive in detection of access or draining vein stenosis. Ultrasound is also useful in the evaluation of other graft or fistula abnormalities, such as pseudoaneurysm, steal, or infection. Careful attention to technical detail is required, and avoidance of several diagnostic pitfalls is necessary.

Vascular access problems in dialysis patients: pathogenesis and strategies for management

Repetitive hemodialysis was made possible through the development of a chronic means of accessing the circulation. This was accomplished through the use of arteriovenous fistulae or grafts, using autologous veins or synthetic materials. Although the arteriovenous fistula remains the access of choice, synthetic arteriovenous grafts are used in most patients because of problems with late referral to a nephrologist and poor vasculature. This article describes the means of accessing the circulation for hemodialysis, the pathogenesis of access failure through progressive stenosis followed by thrombosis, methods of detecting access dysfunction before thrombosis, and therapeutic options. Although angiographic or surgical intervention remain the mainstays of management, medical treatments to decrease stenosis and delay thrombosis are currently under investigation.

Predictors of arteriovenous graft patency after radiologic intervention in hemodialysis patients

Arteriovenous grafts in hemodialysis patients are prone to recurrent stenosis and thrombosis, requiring frequent radiologic and surgical interventions to optimize their long-term patency. Little is known about the factors that determine graft outcome after a radiologic intervention. The present study examined the clinical and radiologic predictors of intervention-free graft survival after elective angioplasty or thrombectomy. A prospective computerized database was used to determine the outcomes subsequent to all graft angioplasties (n = 330) and thrombectomies (n = 326) performed at the University of Alabama at Birmingham between April 1, 1996, and June 30, 1999. Primary graft survival rates after angioplasty and thrombectomy were 86% versus 43% at 1 month, 71% versus 30% at 3 months, 51% versus 19% at 6 months, and 28% versus 8% at 12 months, respectively. The median intervention-free graft survival time was substantially longer after angioplasty than thrombectomy (6.7 versus 0.6 months; P < 0.001). The superior outcome of angioplasty over thrombectomy was observed even for the subset of procedures with no residual stenosis (median survival, 6.9 versus 2.5 months; P < 0.001). The median graft survival was inversely related to the magnitude of residual stenosis for both elective angioplasty and thrombectomy. Median intervention-free graft survival after angioplasty was inversely related to the postangioplasty intragraft to systemic systolic pressure ratio (7.6, 6.9, and 5.6 months for ratios <0.4, 0.4 to 0.6, and >0.6, respectively; P < 0.001). Intervention-free graft survival after angioplasty or thrombectomy was not affected by graft location (forearm versus upper arm), number of stenotic sites, or presence of diabetes. In conclusion, graft survival is substantially longer after elective angioplasty than thrombectomy, even when the radiologic appearance after the procedure suggests complete resolution of the stenotic lesion. Moreover, the risk for requiring a subsequent graft intervention can be predicted from two simple radiologic measurements: grade of stenosis and intragraft to systemic systolic blood pressure ratio. These parameters may help determine the frequency of monitoring for recurrent stenosis in a given graft.

Graft surveillance: venous pressure, access flow, or the combination?

BACKGROUND

Increased venous pressure (VP) and decreased access flow (Qa) are predictors of dialysis access graft thrombosis. VP is easily obtainable. Qa assessment requires a special device and takes more time. The aims of our randomized multicenter studies were to compare outcome in patients with grafts monitored by VP or Qa (study A) or monitored by VP or the combination of VP and Qa (study B).

METHODS

We performed VP measurements consisting of weekly VP at a pump flow of 200 mL/min (VP200) and the ratio of VP0/MAP. Qa was measured every eight weeks with the Transonic HD01 hemodialysis monitor. Threshold levels for referral for angiography were VP200> 150 mm Hg or VP0/MAP> 0.5 (both at 3 consecutive dialysis sessions) or Qa <600 mL/min. Subsequent therapy consisted of either percutaneous transluminal angioplasty (PTA) or surgery.

RESULTS

Total follow-up was 80.5 patient-years for 125 grafts. The vast majority of a total of 131 positive tests was followed by angiography and corrective intervention. In study A, the rate of thromboses not preceded by a positive test was 0.19 and 0.24 per patient-year (P = NS), and in study B, it was 0.32 versus 0.28 per patient-year (P = NS). Survival curves were not significantly different between the subgroups.

CONCLUSIONS

These data demonstrate that standardized monitoring of either VP or Qa or the combination of both and subsequent corrective intervention can reduce thrombosis rate in grafts to below the recommended quality of care standard (that is, 0.5 per patient-year, NKF-DOQI). These surveillance strategies are equally effective in reducing thrombosis rates.

Factors associated with the prevalence of arteriovenous fistulas in hemodialysis patients in the HEMO study. Hemodialysis (HEMO) Study Group

BACKGROUND

Arteriovenous (AV) fistulas are the vascular access of choice for hemodialysis patients, but only about 20% of hemodialysis patients in the United States dialyze with fistulas. There is little information known about the factors associated with this low prevalence of fistulas.

METHODS

Multiple logistic regression analysis was used to evaluate the independent contribution of factors associated with AV fistula use among patients enrolled in the HEMO Study. The analysis was conducted in 1824 patients with fistulas or grafts at 45 dialysis units (15 clinical centers).

RESULTS

Thirty-four percent of the patients had fistulas. The prevalence of fistulas varied markedly from 4 to 77% among the individual dialysis units (P < 0.001). Multiple regression analysis revealed five demographic and clinical factors that were each independently associated with a lower likelihood of having a fistula, even after adjustment for dialysis unit. Specifically, the prevalence of fistulas was lower in females than males [adjusted odds ratio (AOR) 0.37, 95% CI, 0.28 to 0.48], lower in patients with peripheral vascular disease than in those without (AOR 0.55, 95% CI, 0.38 to 0.79), lower in blacks than in non-blacks (AOR 0.64, 95% CI, 0.46 to 0.89), lower in obese patients (AOR per 5 kg/m(2) body mass index, 0.76, 95% CI, 0.65 to 0.87), and lower in older patients (AOR per 10 years, 0.85, 95% CI, 0.78 to 0.94). The differences in the prevalence of fistulas among the dialysis units remained statistically significant (P < 0.001) after adjustment for these demographic and clinical factors. Finally, there were substantial variations in the prevalence of fistulas even among dialysis units in a single metropolitan area.

CONCLUSIONS

Future efforts to increase the prevalence of fistulas in hemodialysis patients should be directed at both hemodialysis units and patient subpopulations with a low fistula prevalence.

Increasing AV fistulas: revisiting a time-tested solution

Despite having the lowest complication rate of all hemodialysis accesses, the prevalence of autologous arteriovenous (AV) fistulas has declined to 28% in the United States. The reasons for this decline include high early AV fistula failure rates, long maturation times, the frequent need for emergent dialysis, unavailable or poor pre-ESRD programs and planning, patient resistance to the realities of impending ESRD, and financial disincentives to AV fistula placement. Despite these barriers, programs throughout the country have demonstrated the ability to increase AV fistula prevalence to more than 50%. The strategies employed have included increased reliance on upper arm brachiocephalic and transposed basilic vein fistulas, the use of preoperative imaging to identify the best sites for fistula creation, and aggressive attempts at salvage of nonmaturing fistulas. Other groups have systematically and successfully replaced failed grafts with upper arm brachiocephalic or bracheobasilic fistulas. These experiences clearly show that exceeding the National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) goal of more than 50% fistula placement is achievable in the United States. Declining numbers of AV fistulas are the result of a combination of factors, including changes in our patient population and learned practice patterns coupled with a failure of our delivery system to provide education, timely referral, and incentives for fistula placement. Increasing AV fistula prevalence in the United States is achievable and will improve patient outcomes and decrease the costs of ESRD.

US vascular mapping before hemodialysis access placement

PURPOSE

To prospectively assess the effect of preoperative ultrasonographic (US) mapping on surgical selection, placement of arteriovenous fistulas (AVFs) and grafts, and negative surgical exploration rates.

MATERIALS AND METHODS

US assessment of the upper extremity arterial and venous anatomy was performed in 70 patients with chronic renal failure before surgical evaluation. The surgeon documented the planned access procedure, which was based on physical examination results, and then reviewed the US preoperative mapping report. The surgical procedure and outcome were recorded.

RESULTS

Fifty-two of the 70 patients who underwent mapping had vascular access placement. Preoperative US mapping resulted in a change in the planned surgical procedure in 16 (31%) of the 52 patients. An AVF rather than the planned graft was placed in eight (15%) patients. The AVF placement rate increased from 32% (126 of 395 patients) to 58% (30 of 52 patients). Unsuccessful surgical explorations decreased from 11% (28 of 256) to 0%.

CONCLUSION

Preoperative US mapping before hemodialysis access placement can result in a change in surgical management, with an increased number of AVFs placed and an improved likelihood of selecting the most functional vessels preoperatively. Further study is needed to determine longer term outcomes.

Vascular access for haemodialysis

BACKGROUND

The recent expansion of renal replacement therapy programmes has been associated with an increase in the number and complexity of patients requiring permanent vascular access. The introduction of strategies designed to maximize secondary access patency is, therefore, increasingly important as a means of prolonging patient survival on dialysis, reducing morbidity and reducing the escalating cost of such programmes.

METHODS

A review of the current literature on the planning of vascular access, access surveillance methods and treatment of the most common complications was performed.

RESULTS

Multidisciplinary vascular access planning, increased use of preoperative imaging and the preferential use of autogeneous vein are essential to obtain the best long-term results. While vascular access surveillance, in particular protocols involving direct measurement of access flow, enables the prospective detection and treatment of venous stenosis, the precise indications for treating venous stenosis remain unclear. Surgical revision remains the gold standard for the treatment of failing arteriovenous fistulas, but recent advances in interventional radiological techniques along with the suitability of arteriovenous fistulas for percutaneous intervention may offer an effective alternative. The effect of both these interventions on access patency requires comparison in a randomized trial.

CONCLUSION

The introduction of strategies to improve access patency rates will change vascular access surgical practice away from the construction of new fistulas towards an increase in outpatient percutaneous intervention and surgical revisional procedures. The role of surgical interventions requires clearer definition.

Natural history of arteriovenous grafts in hemodialysis patients

Most hemodialysis patients in the United States have an arteriovenous graft as their vascular access. Grafts have a relatively short life span and are prone to recurrent stenosis and thrombosis, requiring multiple salvage procedures to maintain their patency. There is little information in the literature regarding the clinical factors that determine graft survival and complications. We evaluated prospectively the outcomes of 256 grafts placed at a single institution during a 2-year period. A salvage procedure to maintain graft patency (thrombectomy, angioplasty, or surgical revision) was required in 29% of the grafts at 3 months, 52% at 6 months, 77% at 12 months, and 96% at 24 months. Thus, primary graft survival (time from graft placement to the first intervention) was only 23% at 1 year and 4% at 2 years. Primary graft survival was significantly less among patients with hypoalbuminemia compared with patients with a normal serum albumin level (P = 0.003). Secondary graft survival (time from graft placement to permanent graft failure) was 65% at 1 year and 51% at 2 years. Neither primary nor secondary graft survival was significantly correlated with patient age, sex, diabetic status, body mass index, or graft site. A mean of 1.22 interventions per graft-year were required to maintain access patency, including 0.51 thrombectomies, 0.54 angioplasties, and 0.17 surgical revisions. In conclusion, hypoalbuminemia is a strong predictor of the requirement for an early graft intervention. Patients with hypoalbuminemia may require a heightened index of suspicion in monitoring their grafts for evidence of stenosis.

Bacteremia associated with tunneled dialysis catheters: comparison of two treatment strategies

BACKGROUND

Tunneled dialysis catheters are often used for temporary vascular access in hemodialysis patients, but are complicated by frequent systemic infections. The treatment of bacteremia associated with infected tunneled catheters requires both antibiotic therapy and catheter replacement. We compared the outcomes of two treatment strategies for catheter-associated bacteremia: exchange of the existing catheter with a new one over a guidewire versus catheter removal with delayed replacement.

METHODS

We retrospectively analyzed the outcomes of all cases of tunneled dialysis catheter-associated bacteremia during a two-year period. The infection-free survival time of the subsequent catheter was evaluated in two groups of patients: group A (31 catheters), exchange of the existing infected catheter with a new catheter over a guidewire, and group B (38 catheters), removal of the infected catheter followed by delayed catheter replacement 3 to 10 days later. Patients in both groups received three weeks of systemic antibiotic therapy. Cox proportional hazard models were used to evaluate the factors predictive of infection-free survival time of the replacement catheter.

RESULTS

On univariate proportional hazard regression analysis, the infection-free survival time of the replacement catheter was similar for groups A and B (P = 0.72), whereas the hazard of infection was significantly greater for patients with hypoalbuminemia (serum albumin < 3.5 g/dL), as compared with patients with a normal serum albumin (hazard ratio 2.81, 95% CI, 1. 21, 6.53, P = 0.016). The infection-free survival time was not affected by patient age, sex, diabetic status, or type of organism (gram-positive coccus vs. gram-negative rod).

CONCLUSIONS

The infection-free survival time associated with the subsequent catheter is similar for the two treatment strategies. However, exchanging the catheter for a new one over a guidewire minimizes the number of separate procedures required by the patient. Hypoalbuminemia is the major risk factor for recurrent bacteremia in the replacement catheter.

Haemodialysis access: the case for prospective monitoring

Thrombosis in haemodialysis accesses remains a major problem. It is associated with stenosis that causes haemodynamic and anatomical changes. By prospective monitoring it is possible to identify patients at risk of thrombosis. Those patients should be referred for corrective intervention. This approach can result in a thrombosis rate below the advised quality of care standard of 0.5 thromboses/patient-year.

A practical approach to vascular access for hemodialysis and predictors of success

PURPOSE

The long-term results and predictors of success for vascular access at The Toronto Hospital were studied. This report describes the access program and emphasizes the role of the vascular access coordinator.

METHODS

A total of 384 consecutive patients underwent 466 vascular access procedures. The access program is centered around a dedicated, full-time vascular access coordinator, who is a registered nurse and is responsible for all aspects of access care, including follow-up. Outcome variables were collected prospectively. Primary, primary-assisted, and secondary success was determined by means of Kaplan-Meier analysis, and the stepwise Cox proportional hazards model was used for multivariate analysis of the factors that were independently predictive of primary success.

RESULTS

There were 235 autogenous arteriovenous fistulae (AVFs) and 231 arteriovenous grafts (AVGs). The cumulative primary, assisted-primary, and secondary success (patent and functional for effective dialysis) at 24 months for all 466 cases combined was 36% +/- 3%, 54% +/- 3%, and 66% +/- 3%, respectively. The primary success for AVFs and AVGs at 2 years was 54% +/- 4% and 18% +/- 4%, respectively (P <.001; log-rank test); the primary-assisted success for AVFs and AVGs at 2 years was 62% +/- 4% and 44% +/- 6%, respectively (P <.001; log-rank test); and the secondary success for AVFs and AVGs at 2 years was 70% +/- 4% and 60% +/- 5%, respectively (P =.331; log-rank test). Stratification of variables revealed significant benefit for AVFs (P =.001), the female sex (P =.014), and the absence of diabetes mellitus (P =.001). Multivariate analysis with Cox regression determined that access type (AVF vs AVG; P =.001) and diabetes mellitus (P =.024) were independently predictive of primary success. The improved clinical coordination of access patients with the initiation of the vascular access program resulted in a significant reduction in length of hospital stay before and after the program was organized (2.5 +/- 0.06 vs 1.1 +/- 0.03 days; P =.001).

CONCLUSION

The organization of a vascular access program in a practical and cost-effective way for reduced length of hospital stay is streamlined through a dedicated access coordinator, who ensures an integrated, multidisciplinary approach. The results for the Cox model is useful when discussing the anticipated results of access procedures with individual patients.

Predictors of adequacy of arteriovenous fistulas in hemodialysis patients

BACKGROUND

Dialysis access procedures and complications represent a major cause of morbidity, hospitalization, and cost for chronic dialysis patients. To improve the outcomes of hemodialysis access procedures, recent clinical guidelines have encouraged attempts to place an arteriovenous (A-V) fistula, rather than an A-V graft, whenever possible in hemodialysis patients. There is little information, however, about the success rate of following such an aggressive strategy in the prevalent dialysis population.

METHODS

We evaluated the adequacy of all A-V fistulas placed in University of Alabama at Birmingham dialysis patients during a two-year period. A fistula was considered adequate if it supported a blood flow of >/=350 ml/min on at least six dialysis sessions in one month. Fistula adequacy was correlated with clinical and demographic factors.

RESULTS

The adequacy could be determined for 101 fistulas; only 47 fistulas (46.5%) developed sufficiently to be used for dialysis. The adequacy rate was lower in older (age >/= 65) versus younger (age < 65) patients (30.0 vs. 53.5%, P = 0.03). It was also marginally lower in diabetics versus nondiabetics (35.0 vs. 54.1%, P = 0.061) and in overweight (BMI >/= 27 kg/m2) versus nonoverweight patients (34.5 vs. 55.2%, P = 0.07). The adequacy rate was not affected by patient race, smoking status, surgeon, serum albumin, or serum parathyroid hormone. The adequacy rate was substantially lower for forearm versus upper arm fistulas (34.0 vs. 58.9%, P = 0.012). The adequacy of forearm fistulas was particularly poor in women (7%), patients age 65 or older (12%), and diabetics (21%). In contrast, upper arm fistulas were adequate in 56% of women, 54% of older patients, and 48% of diabetics.

CONCLUSIONS

An aggressive approach to the placement of fistulas in dialysis patients results in a less than 50% early adequacy rate, which is considerably lower than that reported in the past. Moreover, the success rate of fistulas is even lower for certain patient subsets. To achieve an optimal outcome with A-V fistulas, we recommend that they be constructed preferentially in the upper arm in female, diabetic, and older hemodialysis patients.

The cost of implementing the Dialysis Outcomes Quality Initiative Clinical Practice Guidelines

For a clinical practice guideline to be accepted by the end-user, the system of reimbursement for the targeted service must be favorable. The National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) Guideline recommendations were developed without primary concern for the costs of their execution. Arguably, an unfavorable financial environment and excessive mercantile behavior by providers and payers would offer a considerable hindrance to their implementation. Toward addressing these concerns, three leaders in the development of the DOQI Guidelines for the Treatment of Anemia of Chronic Renal Failure, Hemodialysis Adequacy, and Vascular Access, have evaluated the hypothesis that implementing the recommendations of the DOQI Guidelines will increase the treatment costs for dialysis providers but will effect savings in the entire end-stage renal disease (ESRD) program. Their analyses suggest that under the current reimbursement system, this assumption may be true. However, restructured global reimbursement in the ESRD program will permit financial incentives for dialysis providers and the payer to coincide.

Hemodialysis access failure: a call to action

Recent evidence suggests that the cost as well as the morbidity associated with the maintenance of hemodialysis access is increasing rapidly; currently, the cost exceeds 1 billion dollars and access related hospitalization accounts for 25% of all hospital admissions in the U.S.A. This increase in cost and morbidity has been associated with several epidemiological trends that may contribute to access failure. These include late patient referral to nephrologists and surgeons, late planning of vascular access as well as a shift from A-V fistulaes to PTFE grafts and temporary catheters, which have a higher failure rate. The reasons for this shift in the types of access is multifactorial and is not explained by changes in the co-morbidities of patients presenting to dialysis. Surgical preference and training also appear to play an important role in the large regional variation and patency rate of these PTFE grafts. We propose a program for early placement of A-V fistulae, a continuous quality improvement, multidisciplinary program to monitor access outcome, the development of new biomaterials, and a research plan to investigate pharmacological intervention to reduce development of stenosis and clinical interventions to treat those that do develop, prior to thrombosis.