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

Vascular access in the hemodialysis patient--personal experience and review of the literature

There is consensus that arteriovenous (AV) fistulae represent the best choice for initial vascular access in patients suffering from chronic renal insufficiency (CRI) or end-stage renal disease (ESRD) approaching the need of initiating hemodialysis therapy. However, this is a challenging task in the rapidly growing population of diabetic, aged, and hypertensive patients. The preexisting damage of the vascular anatomy and the high cardiovascular comorbidity hinder construction of a well functioning arteriovenous fistula. Late referrals to the nephrologist delay access surgery and increase the use of temporary and cuffed tunneled catheters with all their potential risks. Nevertheless, various strategies and tools exist to overcome these problems. Early referral results in venous preservation and early selection of side, site, and type of initial vascular access. Ultrasound findings are essential components of preoperative investigations. Special attention should be paid to the quality of the arteries at each section along the forearm, the elbow region, and the upper arm. Dedicated, meticulous surgery is mandatory. Fistula monitoring and elective revision of the failing AV fistula will result in increasing longevity of the blood access, and will reduce morbidity and costs.

Outcome of surgery for vascular access in patients commencing haemodialysis

OBJECTIVE

assessment of surgical vascular access procedures for haemodialysis.

DESIGN

retrospective cohort audit.

MATERIALS AND METHODS

secondary patency was calculated from surgery until access failure, death, transplant, conversion to peritoneal dialysis, or loss to follow-up. All surgical procedures including immediate failures and failures to mature fistulae were included but not radiological interventions.

RESULTS

four hundred and forty-five operations were undertaken in 197 patients over 87 months comprising 273 access creations and 172 revisions. Median follow-up was 26 months with a mortality of 9.4 deaths per 100 patient-years including eight perioperative deaths. Autogenous access was created in 147 (75%) patients with 142 based on the radial artery whilst 50 prosthetic grafts including 46 PTFE grafts and 40 forearm loops were placed. Patients receiving grafts were more likely to be older, female and die in follow-up. Grafts had higher patencies of 89, 75 and 68% at 1, 2 and 4 years, respectively compared to 69, 63 and 55% for autogenous access. This difference was significant (p=0.049) when the effects of the presence of diabetes and peripheral arterial disease were accounted for but more frequent revisions were required. The final access placed was autogenous in 110 (56%) and prosthetic in 87 (44%) patients.

CONCLUSIONS

in our surgical unit, there was high secondary patency including for prosthetic grafts, high autogenous utilisation and relatively infrequent reintervention.

Tumor necrosis factor-alpha -308 gene polymorphism is associated with synthetic hemodialysis graft failure

BACKGROUND

Progressive venous stenosis mediated, in part, by inflammatory cytokines is a major cause of synthetic hemodialysis graft failure. A tumor necrosis factor-alpha (TNF-alpha) gene polymorphism (G to A, position -308) has been shown to increase plasma cytokine levels and severity of diseases with an underlying inflammatory component.

METHODS

We genotyped 67 patients with synthetic polytetrafluoroethylene (PTFE) grafts and examined the association of the high-(AA or GA) and low- (GG) production TNF-alpha-08 genotypes with the rate of graft failures/thrombosis and graft survival.

RESULTS

Hemodialysis patients with the high-production TNF-alpha genotypes had a significantly increased rate of PTFE graft failure at 90 days (37.2% versus 14%) and 1 year (62.8% versus 34.4%) after graft placement compared with patients with the low-production genotype (respectively). Hemodialysis patients with the high-production TNF-alpha genotypes had significantly lower cumulative PTFE graft survival at 1 year (29.4% +/- 11.1% versus 71.2 +/- 6.8%) and 2 years (22.1% +/- 10.5% versus 48.2 +/- 8.1%) compared with patients with the low-production genotype (respectively). Patients with the A allele had approximately twice the mean thrombosis rate compared with those who had the low-production TNF-alpha genotype (3.3 +/- 0.8 versus 1.7 +/- 0.4 thromboses/patient/year, respectively; mean +/- SEM, p < .05).

CONCLUSIONS

These data suggest that the TNF-alpha -308 A allele is associated with increased PTFE graft thrombosis and failure in hemodialysis patients.

Approach to patients with "complex" hemodialysis access problems

The approach to patients with "complex" permanent hemodialysis (HD) access problems remains poorly defined. The purpose of this review is to outline our current algorithm for patients presenting for dialysis access and to address the management of specific problems that complicate this objective of establishing permanent access. The key components of the algorithm include noninvasive imaging in the diagnostic vascular laboratory to determine all the possible access configurations and invasive imaging with both venography and arteriography to confirm the optimal choice. The specific access-related problems addressed include inadequate ipsilateral vein, inadequate arterial inflow, central vein stenosis/occlusion, multiple previous access failures, and obesity. Despite the label of "complex" access problems, it is possible to construct native arteriovenous fistulas (AVFs) in almost all patients presenting for access using the standard principles of vascular surgery that are based on establishing adequate arterial inflow, adequate venous outflow, and selecting an appropriate conduit.

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 access surgery managed by renal physicians: the choice of native arteriovenous fistulas for hemodialysis

BACKGROUND

After decades of success in dialysis research and treatment, prompt availability of a well-functioning vascular access for dialysis remains a disturbing problem. On the basis of a single-center experience in which nephrologists are responsible for access surgery, we sought to identify predictors of catheter use at the start of hemodialysis (HD) therapy and risk factors affecting first permanent access survival.

METHODS

Demographics, comorbid conditions, predialysis follow-up, and access-related procedures of the 197 consecutive patients beginning extracorporeal treatment between 1995 and 2001 were prospectively entered into our database.

RESULTS

Despite the high prevalence of comorbidities (diabetes, 22%; cardiovascular disease, 50%; neoplasm, 15%), all subjects received a native fistula as a first permanent access, but almost 60% initiated HD therapy using a catheter. The latter showed more comorbidities and were referred later. According to the Kaplan-Meier method, median primary and secondary survivals of the first fistula were 38.1 months and more than 70 months, respectively. The Cox model indicated that diabetes and previous catheter use were independently associated with 85% and 63% greater relative risks for first failure, but only diabetes led to a greater risk for final failure (relative risk, 2.38; P = 0.05).

CONCLUSION

Both the absence of predialysis care and presence of comorbidity influence access type at HD therapy initiation and fistula survival. Earlier intervention strategies can increase the use and durability of a native fistula for HD. Direct involvement of nephrologists in the management of access surgery can be helpful in this respect.

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.

Hemodialysis arteriovenous fistula maturity: US evaluation

PURPOSE

To compare various objective ultrasonographic (US) criteria for native arteriovenous fistula (AVF) maturation with subsequent fistula outcomes and clinical evaluation by experienced dialysis nurses.

MATERIALS AND METHODS

US fistula evaluation results were analyzed retrospectively in 69 patients within 4 months after AVF placement; adequacy for dialysis was known in 54. Measurements included minimum venous diameter and blood flow rate. Experienced dialysis nurses examined 30 fistulas clinically. Predictors of fistula adequacy were analyzed with univariate and multivariate logistic regression. Mean fistula diameters and blood flow rates were compared by using analysis of variance or unpaired Student t tests.

RESULTS

Fistula adequacy for dialysis doubled if the minimum venous diameter was 0.4 cm or greater (89% [24 of 27]) versus less than 0.4 cm (44% [12 of 27]; P <.001). Fistula adequacy for dialysis was nearly doubled if flow volume was 500 mL/min or greater (84% [26 of 31]) versus less than 500 mL/min (43% [nine of 21]; P =.002). Combining venous diameter and flow volume increased fistula adequacy predictive value: minimum venous diameter of 0.4 cm or greater and flow volume of 500 mL/min or greater (95% [19 of 20]) versus neither criterion met (33% [five of 15]; P =.002). Women were less likely to have an adequate fistula diameter of 0.4 cm or greater: 40% (12 of 30) of women versus 69% (27 of 39; P =.015) of men. No significant differences in blood flow or minimum venous diameter were found during 2-4 postoperative months. Experienced dialysis nurses' accuracy in predicting eventual fistula maturity was 80% (24 of 30).

CONCLUSION

US measurements of AVF at 2-4 months in patients undergoing hemodialysis are highly predictive of fistula maturation and adequacy for dialysis.

Pitfalls in achieving the Dialysis Outcome Quality Initiative (DOQI) guidelines for hemodialysis access?

The Dialysis Outcome Quality Initiative (DOQI) mandates that 50% of permanent hemodialysis (HD) access be native arteriovenous fistulae (AVFs). Recent reports have shown that when these guidelines are followed, the percentage of new AVFs can exceed DOQI guidelines. From July 1998 to July 2001, 330 HD access procedures were performed in an academic tertiary care center. Patients were categorized into two groups. Group I followed DOQI guidelines and underwent history and physical examination; duplex vein mapping; use of basilic vein transposition; and a postoperative protocol to determine maturation and start needle access in a stepwise progression. Group II had history and physical examination and basilic vein transposition was not used. Patient data were retrospectively reviewed. Overall, 100 (31%) HD shunts were AVFs. Group I (42/183, 23%) had significantly less AVFs (p = 0.005) than group II (58/147, 39%). For first-time placement of HD access, there was no significant difference (p = 0.95) in the percentage of AVFs in group I (26/62, 42%) and group II (29/68, 43%). For patients with prior history of HD access, significantly less AVFs (p <0.001) were placed in group I (16/121, 13%) than in group II (29/79, 37%). Group I had significantly less first-time HDS (P = 0.03) than group II, 34% VS. 46%, respectively. AVF maturation for hemodialysis occurred in 79% of group I and 71% of group II (P = 0.52). There were no significant differences (P > 0.05) when comparing age, gender, and incidence of diabetes between the two groups. AVF formation based largely on duplex vein mapping in group I and lack of basilic vein transposition in group II contributed to the inability to achieve DOQI guidelines. Integration of knowledge and practice among vascular surgeons may help to avoid these pitfalls.

Vascular access: anatomy, examination, management

A systematic approach to managing vascular access problems is the key to reducing current high rates of access thrombosis and failure. This approach begins with a thorough knowledge of vascular access anatomy that, when combined with the physical examination, can help optimize access planning and maintenance. Because of the high complication rate of synthetic grafts, there has been increased emphasis on creating autogenous arteriovenous (AV) fistulae, which, once established, are more trouble-free. The benefit of increased fistula creation will not be realized, however, until the high rate of early fistula failure is reduced. It is widely recommended that graft surveillance programs be implemented and that stenosis be corrected when accompanied by graft dysfunction. Graft blood flow (Q(a)) is the preferred surveillance method, but has a poor accuracy in predicting thrombosis. Most studies that have evaluated the benefit of Q(a) surveillance have used historical control groups, or have been retrospective or nonrandomized. Consequently, we believe it is not currently possible to make definitive, evidence-based recommendations concerning Q(a) surveillance. The most important factor in access survival may be a team approach with an organized commitment to access planning followed by recognition and treatment of access problems.