Hemodialysis vascular access: the Achilles' heel remains.

Maintaining vascular access for hemodialysis remains a leading cause of patient morbidity. Surveillance and other technologies continue to improve, but the goal of dramatically improved AV access patency remains elusive.

Comparison of transposed brachiobasilic fistulas to upper arm grafts and brachiocephalic fistulas.

BACKGROUND: Renewed interest in transposed brachiobasilic fistulas has occurred since the release of the National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) guidelines because it is an alternative method to achieve an upper arm fistula in patients who cannot achieve a functional brachiocephalic fistula. The objective of this study was to compare outcomes among transposed brachiobasilic fistulas, upper arm grafts, and brachiocephalic fistulas. METHODS: A cohort of patients with upper arm accesses was retrospectively identified. Access outcomes were determined from medical records and contact with physicians, dialysis providers, and patients. Primary outcome was thrombosis-free survival. Secondary outcomes were primary failure, time to use, risk of catheter-related bacteremia, need for intervention, incidence of access-related complications, cumulative, and functional patency. Group differences in age, sex, race, diabetes, peripheral vascular disease, and number of previous accesses were adjusted for in the analysis where appropriate. RESULTS: Transposed brachiobasilic fistulas, upper arm grafts, and brachiocephalic fistulas were compared in 59, 82, and 56 patients, respectively. Compared with transposed brachiobasilic fistulas, upper arm grafts were more likely to thrombose with an adjusted relative risk (RR) of 2.6 (95% CI, 1.3 to 5.3) excluding primary failures and 1.6 (95% CI, 1.0 to 2.7) when accounting for the lower risk of primary failure for grafts. Transposed brachiobasilic fistulas also required less intervention (0.7 vs. 2.4 per access-year, P < 0.01) and were less likely to become infected (0 vs. 13%, P < 0.05) than grafts. Mature brachiocephalic fistulas were less likely to fail (RR 0.3, 95% CI, 0.1 to 1.0) and showed a trend for less thrombosis (RR 0.3, 0.1 to 1.1) than mature brachiobasilic fistulas. There was no significant difference in cumulative patency (failure-free survival) among the three types of access if primary failure was included at the median follow-up of 594 days. Transposed brachiobasilic fistulas provided catheter-free access one month sooner than brachiocephalic fistulas and one month later than upper arm grafts. CONCLUSIONS: Transposed brachiobasilic fistulas provide cumulative patency equivalent to upper arm grafts and brachiocephalic fistulas. They are less likely to thrombose and become infected than upper arm grafts. Compared with brachiocephalic fistula, they are more likely to mature but are at increased risk of thrombosis after maturation. Transposed brachiobasilic fistulas should be considered before placing an upper arm graft for patients that cannot achieve a functional brachiocephalic fistula.

Hemodialysis arteriovenous access: detection of stenosis and response to treatment by vascular access blood flow.

BACKGROUND: Hemodialysis access to the circulation is best provided by native and synthetic arteriovenous fistulae (AVF and AVG). Thromboses caused by venous outflow stenoses prevent the long-term use of AV access. This pilot study was performed to evaluate the ability of ultrasound dilution-derived access blood flows to detect AV access stenosis and to evaluate the response to treatment. METHODS: This pilot study was a single-center, prospective observational intervention trial. The monitoring technique used was ultrasound dilution access blood flow measurements performed monthly and after any intervention. Screening criteria for interventions were decrements in access flow of 20% when the flow value fell under 1000 mL/min or absolute flow of <600 mL/min. The primary intervention when flow criteria were met was biplanar venography of the access with percutaneous transluminal angioplasty (PTA) of detected stenoses. Stenoses unresponsive to PTA were sent for surgical revision. Access thrombosis was considered a study ending event. RESULTS: Baseline access flow at study entry for AVF was 919 and 1237 mL/min for AVG. Sequential measurement of AV access flow detected AV access stenosis. PTA and surgical revision significantly restored AV access flow back toward the baseline flow measurement. Failure to restore access flow by at least 20% following intervention occurred in 14% of AVF and 21% of AVG PTA attempts. Transluminal angioplasty, once successfully performed, was required at a mean of 5.8-month intervals in order to maintain AVG flow. In contrast, AVF flow was restored for a much longer period of time following angioplasty (11.4 month follow-up at the time of study end). Compared with historic controls, which used venous dialysis pressure as the primary monitoring technique, the overall (AVF-AVG) thrombosis rates improved from 25 to 16% per patient year, and AVF thrombosis rates improved from 16 to 7% per patient year. When flow was not successfully restored, thrombosis ensued. Eight of 10 thrombosis episodes were predicted based on inability to improve access flow either as a result of stenosis treatment failure or unsuccessful referral for treatment. CONCLUSION: Sequential measurement of AV access flow is an acceptable means of both monitoring for the development of access stenoses and assessing response to therapy. PTAs of AVF are more durable than PTAs of AV grafts.

Catheter access for hemodialysis: an overview.

The provision of hemodialysis requires repeated, reliable access to the central circulatory system. Long-term hemodialysis has best been provided by arteriovenous fistulae and arteriovenous grafts. In recent years, more and more patients have been chronically dialyzed with tunneled dialysis catheters. These catheters, which were originally developed as a short-term bridge to permanent vascular access, have made up an increasing percentage of maintenance vascular access. While these catheters have the advantage of ease of placement and are immediately ready for use, they substantially increase the risk of bacteremia, stenosis of central veins, and even mortality.

Dialysis access infections.

Infections and specifically infectious complications of vascular access remain a major cause of morbidity and mortality in the hemodialysis population. Primary arteriovenous fistulas have the lowest rates of infections and are the access of choice whenever vascular anatomy allows. The dialysis outcomes quality initiative (DOQI) guidelines have thus stressed the need for increasing the utilization of arteriovenous fistulas. Unfortunately, comorbid disease processes and late referrals for vascular access have maintained our dependence on synthetic grafts and indwelling catheters. Indwelling catheters, in particular, have the highest rate of infection and are often associated with more serious metastatic complications. Appropriate antibiotics along with aggressive surgical debridement remain crucial in bacteremia occurring in arteriovenous fistulas or synthetic grafts (polytetrafluoroethylene). Catheter related bacteremia necessitates catheter removal with either guidewire exchange or replacement after a period of antibiotic therapy. Measures to increase our utilization of primary fistulas whenever possible will lower the risk of these complications in our patients.

Risk of bacteremia from temporary hemodialysis catheters by site of insertion and duration of use: a prospective study.

BACKGROUND: Uncuffed, nontunneled hemodialysis catheters remain the preferred means to gain immediate access to the circulation for hemodialysis. Bacteremia is the primary complication that limits their use. The risk of bacteremia by site of insertion and duration of use has not been well studied. METHODS: Two hundred eighteen consecutive patients who required a temporary hemodialysis catheter were prospectively followed. RESULTS: Catheters were placed at 318 new insertion sites and remained in use for a total of 6235 days. The incidence of bacteremia was 5.4% after three weeks of placement in internal jugular vein and 10.7% after one week in femoral vein [relative risk for bacteremia 3.1 (95% CI, 1.8 to 5.2)]. The incidence of bacteremia was 1.9% one day after the onset of an exit site infection but increased to 13.4% by the second day if the catheter was not removed. Guidewire exchange for malfunction and patient factors did not significantly affect the risk of bacteremia. CONCLUSIONS: Internal jugular catheters may be left in place for up to three weeks without a high risk of bacteremia, but femoral catheters in bed-bound patients should be removed after one week. Catheter exchanges over a guidewire for catheter malfunction do not increase bacteremia rates. Temporary catheters should be removed immediately if an exit site infection occurs.

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.

Normalization of hematocrit in hemodialysis patients with cardiac disease does not increase blood pressure.

UNLABELLED: Since the earliest reports of the use of Epoetin alfa in hemodialysis patients, it has been described that Epoetin alfa may exacerbate preexisting hypertension or induce hypertension in End Stage Renal Disease (ESRD) patients not previously hypertensive. We undertook this study to determine if the correction of anemia in ESRD patients with cardiac disease from a hematocrit of 30+/-3% to 42+/-3% with the use of Epoetin alfa would result in increased blood pressure. This study was a substudy of the "Normal hematocrit Study". METHODS: Thirty-one patients were randomized into one of two arms. Patients in Group A had their hematocrit increased with the use of slowly escalating doses of Epoetin alfa to 42+/-3% and patients in Group B were maintained with a hematocrit of 30+/-3% throughout the course of the study. All patients had their blood pressure recorded with a 24 hour ambulatory BP device at study entry and at 28 weeks following randomization when they had achieved their target hematocrit. Pre-dialysis systolic and diastolic BP was also recorded. RESULTS: The mean hematocrit increased in Group A from 29.1+/-2.4% to 40.8+/-5.2% after 30 weeks. The hematocrit in Group B remained stable at 30+/-3% throughout the course of the study. There was no difference in mean daytime, mean nighttime or 24 hour systolic or diastolic blood pressure between Groups A and B at either baseline or follow-up. Neither was there a difference in mean pre-dialysis systolic or diastolic BP between Groups A or B at baseline or Follow-up. Four patients in Group A and 4 patients in Group B required an increase in their antihypertensive medication during the course of the study. CONCLUSION: It is possible to increase hematocrit to normal levels in hemodialysis with the administration of Epoetin alfa. The increase in hematocrit from 30+/-3% to 42+/-3% is not associated with increased blood pressure.

Normalization of hematocrit in hemodialysis patients does not affect silent ischemia.

UNLABELLED: Transient ST-segment depression measured on ambulatory ECG monitors has been described as representing silent ischemia. Patients who demonstrate silent ischemia have been reported to show increased mortality compared to patients without silent ischemia. We undertook this study to determine if the correction of anemia in End Stage Renal Disease (ESRD) patients from (+/- = standard deviation) 30 +/- 3 to 42 +/- 3 with the use of Epoietin alfa would result in decreased silent ischemia in patients with clinically evident ischemic heart disease or congestive heart failure. METHODS: Thirty one ESRD patients with congestive heart failure or patients with clinically-evident ischemic heart disease were randomized into one of two arms. Patients in Group A had their hematocrit increased with the use of slowly escalating doses of Epoietin alfa to 42 +/- 3% and patients in Group B were maintained with a hematocrit of 30 +/- 3% throughout the course of the study. All patients had a 24 hour Holter monitor recording at baseline and at 28 weeks after randomization (when they had reached their target hematocrit). Significant silent ischemia was considered to be present if patients demonstrated at least 60 seconds of > or = 1 mm ST segment depression. RESULTS: Fifteen patients were randomized to Group A and 16 patients were randomized to Group B. The mean hematocrit increased in group A from 29.1 +/- 2.4% to 40.8 +/- 5.2% after 30 weeks. The mean hematocrit in Group B remained stable at 30 +/- 3% throughout the course of the study. Ten patients demonstrated silent ischemia at baseline. At follow up patients in group A demonstrated a mean of 1.7 +/- 4.9 minutes of ischemia compared to 1.1 +/- 3.4 minutes in group B. These were not significantly different. A similar number of patients in group A and Group B required adjustments in their anti-anginal medication during the course of the study. CONCLUSION: It is possible to increase hematocrit to near normal levels in hemodialysis with the administration of exogenous Epoietin alfa. The increase in hematocrit form 30 +/- 3% to 42 +/- 3% is not associated with a change in the level of silent ischemia these patients demonstrate.

Exacerbation of radiocontrast nephrotoxicity by endothelin receptor antagonism.

BACKGROUND: Endothelin is a potent vasoconstrictor that has been implicated in the pathogenesis of radiocontrast nephrotoxicity. Endothelin antagonists may reduce the renal hemodynamic abnormalities following radiocontrast administration. METHODS: One hundred fifty-eight patients with chronic renal insufficiency [mean serum creatinine +/- SD = 2.7 +/- 1.0 mg/dL (242. 3 to +/- 92.8 micromol/L)] and undergoing cardiac angiography were randomized to receive either a mixed endothelin A and B receptor antagonist, SB 290670, or placebo. All patients received intravenous hydration with 0.45% saline before and after radiocontrast administration. Serum creatinine concentrations were measured at baseline, 24 hours, 48 hours, and 3 to 5 days after radiocontrast administration. The primary end point was the mean change in serum creatinine concentration from baseline at 48 hours; the secondary end point was the incidence of radiocontrast nephrotoxicity, defined as an increase in serum creatinine of > or =0.5 mg/dL (44 micromol/L) or > or = 25% from baseline within 48 hours of radiocontrast administration. RESULTS: The mean increase in serum creatinine 48 hours after angiography was higher in the SB 209670 group [0.7 +/- 0. 7 mg/dL (63.5 +/- 58.6 micromol/L)] than in the placebo group [0.4 +/- 0.6 mg/dL (33.6 +/- 55.1 micromol/L), P = 0.002]. The incidence of radiocontrast nephrotoxicity was also higher in the SB 209670 group (56%) compared with placebo (29%, P = 0.002). This negative effect of SB 209670 was apparent in both diabetic and nondiabetic patients. Adverse effects, especially hypotension or decreased blood pressure, were more common in the SB 209670 group. CONCLUSIONS: In patients with chronic renal insufficiency who were undergoing cardiac angiography, endothelin receptor antagonism with SB 209670 and intravenous hydration exacerbate radiocontrast nephrotoxicity compared with hydration alone.

The hemodialysis catheter conundrum: hate living with them, but can't live without them.

BACKGROUND: Hemodialysis requires reliable recurrent access to the circulation. On a chronic basis, this has been best provided by the use of arteriovenous fistulae and arteriovenous grafts. In recent years, hemodialysis catheters have come to play an increasingly important role in the delivery of hemodialysis. The use of both temporary as well as cuffed hemodialysis catheters has emerged as a significant boon for both patients and practicing nephrologists. The complications, however, associated with each of these hemodialysis catheters, both in terms of anatomic, thrombotic, and infectious issues, have emerged as a major problem with their continued use. This significant morbidity and complication rate has forced many nephrologists to face a basic conundrum: they have come to hate having to deal with the problems inherent in catheter usage, but the enormous utility of these devices have forced physicians to accept the fact they cannot live without them in their current practice. METHODS: We used a comprehensive literature review to describe the types, use and dilemmas of hemodialysis catheters. RESULTS: This article provides a comprehensive review of both the benefits inherent with the use of these hemodialysis catheters while cataloging their complications and offering some possible solutions. CONCLUSION: Hemodialysis vascular access catheters are essential in the maintenance of hemodialysis vascular access. However, they have a significant infectious, thrombotic, anatomic complication rate that are detailed with proposed problem-solving guidelines.

Implementation of the Dialysis Outcomes Quality Initiative Vascular Access Guidelines.

To better care for patients with chronic renal failure and end-stage renal disease, the National Kidney Foundation has published a set of Clinical Guidelines, the Dialysis Outcomes Quality Initiative, based on current available evidence and, where such evidence is lacking, the expert opinions of current leaders in vascular access research. These Guidelines were developed to standardize the care of chronic renal failure and end-stage renal disease patients. This report describes some of the more important aspects of these recommendations and the authors' implementation strategies.

Progression of renal artery stenosis in patients undergoing cardiac catheterization.

BACKGROUND: Renal artery stenosis is potentially correctable by either revascularization surgery or percutaneous methods. However, appropriate use of these techniques has been hampered by a lack of data on the natural history of this disease. This study assesses the prevalence, risk factors for progression, and effect on renal function of angiographically demonstrated renal artery disease in patients undergoing cardiac catheterization. METHODS: The severity of renal artery stenosis was quantified in all patients who underwent abdominal aortography as part of a diagnostic cardiac catheterization study at Duke University Medical Center between January 1989 and February 1996. RESULTS: There were 14,152 patients in the study (mean age 61+/-12 years, 62% male). Normal renal arteries were identified in 12,543 (88.7%) patients, insignificant disease (<50% stenosis) in 1 or more vessels in 726 patients (5.1 %), and significant stenosis in 883 patients (6.3%). Significant bilateral renal artery stenosis was present in 178 patients (1.3%). By multivariate logistic regression, elevated serum creatinine level, coronary artery disease, peripheral vascular disease, hypertension, cerebrovascular disease, older age, female sex, and family history of coronary artery disease were identified as independent predictors of significant renal arterial disease. Disease progression was assessed in 1189 patients. Mean time between cardiac catheterizations was 2.6+/-1.6 years. Significant disease progression occurred in 133 patients (11.1 %). Independent predictors of disease progression were female sex, age, coronary artery disease at baseline, and time between baseline and follow-up. At follow-up, serum creatinine level was significantly higher in patients who demonstrated > or =75% stenosis in 1 or more vessels (mean creatinine level 141+114 micromol/L compared with those with insignificant disease (mean creatinine level 97+/-44 micromol/L (P= .01). CONCLUSIONS: Renal artery disease is frequently progressive in patients who undergo cardiac catheterization for investigation of coronary artery disease. Significant stenotic disease may develop over a short period despite evidence of normal renal arteries at prior catheterization.