Access Bibliography September 2001

Vascular Access in HD

Overview Native Fistulae, Grafts, Catheters/Ports

AVF GraftCatheter / Port ReferenceWrist Elbow Bovine

XenoSheep Xeno Synthetic

Primary Patency 72-87%9 77.5%16 72-87%20 9Miller PE, et al., Predictors of adequacy of AV fistulas in HD patients. Kidney Int 1999; 56:275-80Secondary Ptncy

1 year 74%22

85%7/8 74.1%17 65%22 71%22 74%23

58%22

7Himmelfarb J et al., Hemodialysis vascular access: emerging concepts. Curr Opin Nephrol Hypertens 1996; 5: 485-91, 8Juan A. et al.,The function of permanent vascular access. Nephrol Dial Transplant 2000; 15:402-8

2 80%7/8 86%15 59%2314Bender MH, et al. The braciocephalic fistula: a useful alternative angioaccess for permanent HD. J. Vasc. Surg. 1994; 20:808-13

3 64%22 24%22 45%22 47%23

40%22

15Winsett OE, et al., Complications of vascular access for HD. South Med J 1985; 513-7

4 61.3%17

80%14

16Revanur VK, et al., Outcome for arterio-venous fistula at the elbow for HD. Clin Transplant 2000; 14:318-22

5 17Elcheroth J, et al., Elbow AVF’s for chronic HD. Br J Surg 1994; 81:982-4

620Hodges TC,et. al., Longitudinal comparison of dialysis access methods : risk factor for failure. J Vasc Surg 1997; 26:1009-19

7 50%7/8 22Enzler MY, et al., Long-term function of vascular access for HD. Clin Transplant 1996; 10:511-5

823Tordoir JH, et al., Long term follow up of the PTFE prosthesis as an arteriovenous fistiula for HD. Eur J Vasc Surg 1988; 2:3-7

91012

0

J Nephrol 2001; 14:146-156

Vascular access for hemodialysis: an indepth reviewNilesh H. Patel et al., Indianapolis, Glasgow, San Diego

ABSTRACT: A multi-disciplinary approach to vascular access planning, early preoperative surgical assessment and increased use of vascular imaging for surveillance, specialist service and pharmacological prevention of intimal hyperplasia will lead to improved patency rates for both autologous AVF and synthetic grafts.

Key Words: Vascular Access, Dialysis, Central Venous

AV-Fistula:Primary patency: 72-87%Secondary patency: 85% after 12 months, 80% after 24 months, 50% at 7 years, 38% at 12 years.

Grafts: Bovine Xenograph: Synthetic Graft:Primary patency: 72-87%Secondary patency 1 year 56% 24%

3 years 58% 40%

1

Nephrol Dial Transplant (2001) 16: Editorial Comments, p1542-1545

Vascular access: care and monitoring of function, R.Vanholder, Gent, Belgium

Key Words: haemodialysis, native Arterio-venous fistula; PTFE graft; thrombosis; vascular access

“Access related problems are responsible for ~50% of the hospitalisation of haemodialysis patients.Unfortunately, ~30% of dialysis patients are refered to the nehrologist in the final months preceeding dialysis treatment (late referral).Infectious endocarditis is a life threatening infectious complication, which is observed particularly in access systems composed of exogenous artificial material, such as PTFE grafts and central vein catheters. The tip of soft indwelling catheters is positioned in the atrium, close to the cardiac valve. Therefore, these access systems carry a special risk of endocarditis. In the future, infectious complications might be prevented by specific treatment of catheters, such as antibiotic bonding or silver impregantation, but unequivocal proof of the usefulness of this approach has, to the best of our knowledge, not yet been provided.”

2

J. Am. Soc.Nephrol. 1995; 6:1613-1618

Parameters of Prognostic Relevance to the Patency of Vascular Access in Hemodialysis Patients1

Friedrich C. Prischl,2 Andreas Kirchgatterer, Eduard Brandstätter, Manfred Wallner, Christian Baldinger, Fran X. Roithinger and Reinhard Kramar. Krankenhaus der barmherzigen Schwestern vom Hl. Kreuz, Wels, AustriaE. Brandstätter, Johannes Kepler University, Linz, Austria.

ABSTRACT: The objectives of this study were to evaluate wheter age, sex, underlying renal disease, or the performing sureon is of prognostic relevance to the patency of the vascular access. In a routine clinical setting, 139 first and 144 further fistula operations were done in 139 patients during 5 yr and were analyzed in retropect. Within a group of 108 patients with first Cimino-Brescia fistulae, Cox multivariate regression analysis revealed the surgeon to be the only determinant with a continuous, significant effect on fistula patency throughout the observation period (Pout < 0.1). The patency rates of the seven surgeons at 1,2, and 3 yr differed from 34 to 69, 13 to 62, and 13 to 62%, respectively. Hazard ratios among the surgeons varied from 0.65 to 2.21.Additionally, age (P < 0.004) and diabetes mellitus (P < 0.02) were disclosed to be significant risk factors for impaired patency, but later in the course of disease (time dependent). Sex had no influence. After the failure of the fistula, revisions of or new Cimino-Brescia fistulae (N = 56 ) were superior to polytetrafluoroethylene grafts ( N= 61). The mean patency of the former amounted to 320 377 versus 156 281 days in polytetrafluoroethylene grafts ( P < 0.005). It was concluded that increasing age and diabetes mellitus are time-dependent risk factors for the shortened patency of arterivenous fistulae. The operating surgeon, however, seems to be the major determinant for the continuous patency of Cimino-Brescia fistulae.

Key Words: Arteriovenous fistula, vascular access surgery, fistula function, risk factor, hemodialysis

3

Eur J Surg 1996; 162: 297-301

Factors Affecting the Lifespan of Autologous and Synthetic Arteriovenous Access Routes for Haemodialysis.Miltos K. Lazarides, 1 Christos E. Iatrou,2 Joannis D. Karanikas,1 Nikos M. Kaperonis,2 Dimitrios I. Petras,2 Panos N. Zirogiannis2 and John N. Dayantas1. From the Departments of 1 Vascular Surgery and 2 Nephrology, Athens General Hospital, Athens, Greece

ABSTRACT: Objective: To try and establish a consensus about the ideal secondary access for haemodialysis by assessing factors that affect the longevity of various access routes.Design: Multicentre survey, by questionnaire.Setting: General hospital, Athens.Subjects: All 1516 patients in the Athens area receiving chronic haemodialysis.Main outcome measures: Longevity of present and any previous access routes (n=2323). Data including type of access, age, sex and the existence of diabetes, hypertension, hyperlipidaemia, or other systematic diseases were recorded.Results: Some 1220 (80%) of the patients were using autologous access. 1049 (69%) arteriovenous (AV) fistulas at wrist and 171 (11%) at elbow. Variables were analysed using Cox’s proportional hazard model. Age and female sex were significantly associated with failure of autogenous access (p<0.001) althoug not affecting synthetic grafts. Autogenous fistula at the elbow was the only secondary access that was less likely to fail than the initial (baseline) fistula at the wrist. Among the various grafts, straight arm grafts had the best prognosis and straight forearm grafts were the most likely to fail (P < 0.001).Conclusion: An AV fistula at the elbow should be considered the second best after the fistula at wrist, but is not always feasible. A sythetic graft is more likely to be needed in elderly patients and women, in whom an autogenous AV fistula is more likely to fail.

4

Clin Transplantation 2000; 14: 318-322

Outcome for arterio-venous fistula at the elbow for haemodialysisVasanth K Revanur, Alan G Jardine, David H Hamilton and Rahul Jindal. Departments of Medicine, Surgery and Renal Unit, University of Glasgow and the Western Infirmary

ABSTRACT:Background: Few studies have examined the outcome of arterio-venous fistulas (AVF) at the elbow for haemodialysis.Methods: All AVF’s at the elbow created between 1994 and 1998 were identified retrospectively from case notes and the comouterised database. Patients were followed until fistula failure, death, or for a minimum of 6 months until June 1999. Life table analysis and Kaplan-Meier actuarial curves with the log rank test were used to assess the influence of age, sex, diabetes, hypertension, heart disease,cerebrovascular disease, use of erythropoietin, aspirin or warfarin, previous insertion of subclavian vein catheter and the levels of haemoglobin and serum albumin on long-term AVF survival.Results: A total of 137 AVF’s (primary procedure in 84 and as secondary procedure in 53 cases) at the elbow were performed in 130 patients; 7 patients had AVF’s attempted at both elbows. The mean age was 56.57 yr with a mean follow-up of 48.54 months. Twenty-two patients died with a functioning AVF, while 7 patients also with a functioning AVF received a renal transplant. Overall 74% ao AVF were patent at the end of 1 yr, while 22,5% failed or did not mature immediately after the procedure. Two patients had their AVF’s tied off due to steal syndrome. Of the various factors known to affect long-term survival of AVF’s in patients receiving haemodialysis, only plasma albumin > 35g/L was associated with poorer long-term patency in our study.Conclusion: Our report supports the view that AVF at the elbow may obviate the disadvantages of AVF at the wrist in elderly patients, females and in diabetics. In this group of patients it may be preferable to create a primary AVF at the elbow rather than the wrist. Patients who have a failed attempt at creating an AVF at the wrist should undergo AVF at the elbow before the placement of a sythetic graft. This strategy will result in saving time and avoid multiple operations. There may also be a reduction in the use of synthetic grafts resulting in cost savings and avoiding the complications associated with synthetic grafts.

Key Words: arterio-venous fistula – elbow – haemodialysis - wrist

5

J of Vascular Surgery; 1994; 20: 896-904

Comparison of basilic vein and polytetrafluoroethylene for brachial arteriomenous fistulaMichael C. coburn, MD, and Wilfred I. Carney, Jr., MD Providence, R.I.

Purpose: The aim of this study was to compare patency and complication rates between basilic vein and polytetrafluoroethylene (PTFE) for brachial arteriovenous fistulas (AVF) for long-term hemodialysis.Methods: All basilic vein and PTFE brachial AVF constructed between March 1988 and April 1993 were retrospectively reviewed. After construction of life-tables, log-rank testing was used to compare the primary patency rate of basilic vein AVF (n=59) with the primary and secondary patency rates of PTFE AVF (n=47). Complication rates were calculated for each type of fistula and compares by use of chi-squared testing.Results: The primary patency rate for basilic vein AVF (90%) was superior to that of PTFE AVF (70%) at 1 year (p < 0.01), and at 2 years (86% vs 49%, p< 0.001). Complications occurred two and a half times more frequently in the PTFE group than in the basilic vein groupe (p < 0.05).Conclusions: Basilic vein AVF provided superior patency rates and lower complication rates compared with PTFE AVF. Prospective randomized trials comparing the two fistula types is required to firmly etablish the basilic vein AVF as the alternative access procedure of choice after a failed or unconstructable radiocephalic fistula.

6

Nephrol Dial Transplant (2000) 15: 1755-1760

Coagulation and haemodialysis access thrombosisJohannes H. M. Smits1, Joke van der Linden2, Peter J. Blankestijn1 and Ton J. Rabelink3

1Department of Nephrology, University Medical Center, Utrecht, 2Department of Internal Medicine, Medisch Centrum Rijnmond-Zuid, location Clara, Rotterdam and 3Department of Internal Medicine, University Medical Center, Utrecht, The Netherlands.

CONCLUSION: Despite the bleeding tendency of of chronic haemodialysis patients, vascular access thrombosis is a frequent complication. Hypercoagulability is one of the causes contributing to the high frequency of access thrombosis, The hypercoagulable state can be explained by platelet and coagulation factor abnormalities. Unfortunately, few randomized placebo-controlled trials have been conducted using antiplatelet or oral anticoagulation therapy. Therefore, no evidence-based consensus has been etablished regarding pharmacological prevention of access thrombosis. It still needs to be determined wheter the potential benefits of anticoagulation and antiplatelet therapy outweigh the risk of adverse events. In the meantime it seems reasonable to give some form of anticoagulant therapy based on pathophysiological considerations and the high incidence of thrombotic complications. Our group recently demonstrated that graft flow measurements could effectively predict thrombotic vascular access events (76). Risk tables that take into account such parameters as well as plasma markers of hypercoagulability may help to develop rationally designed trials and guidelines.

7

JAMA 1983; 249: 219-222

Polytetrafluoroethylene Graft Survival in HemodialysisDepartments of Surgery (Drs Munda, Alexander, Fidler and Kittur) and Medicine (Drs First an Linnemann), University of Cincinnati Medical Center

ABSTRACT: Expanded polytetrafluoroethylene (PTFE) graft fistulas are widely used as secondary vascular access for patients receiving long-term hemodialysis treatment. Sixty-seven grafts were implanted in 48 patients and followed for 12 to 51 months. Cumulative patency for all grafts at 12 months was 67% 6%, at 24 months 50% 7%, and at 48 months 43% 9%. Graft survival rates were different when considering graft configuration and location. Forearm straight graft survival at 12 months was 35% 13%, upper arm curved grafts 60% 19%, and forearm looped grafts 78% 7%. Complications that decreased graft survival were related to thrombosis (21%), infection (25%), and intimal hyperplasia at the venous anastomosis (34%). After reviewing our experience, we believe that the challenge of secondary vascular access has not been solved by PTFE grafts. This should stimulate the search for better grafts and techniques.

8

Surgery, Gynecology & Obstetrics Jan 1988 Volume 166 23-27

EXTENDED PATENCY OF EXPANDED POLYTETRAFLUOROETHYLENE GRAFTS FOR VASCULAR ACCESS USING OPITMAL CONFIGURATION AND REVISIONSRichard P. Rizzuti, M.D., John C. Hale, M.D., F.A.C.S. and Thomas E. Burkart, M.D., Greenville, North Carolina

ABSTRACT: During a seven year period, 189 expanded polytetrafluoroethylene (PTFE) grafts for vascular access were implanted in 131 patients with end stage renal disease requiring long term hemodialysis. Over-all cumulative patency rate for all grafts was 76% at 12 months, 50% at 36 months and 40% at 60 months. Forearm grafts of loop configuration yielded greater over-all patency rates and required fewer revisions than forearm grafts of straight configuration. Graft thrombosis was the universal indicator of graft malfuction. In the isstance of a malfunction, immediate thrombectomy followed by angiography was considered essential to decisions regarding further therapy. Of 95 grafts that malfunctioned, 49 ultimately required revision, extending the survival to a reate equaling that of continously functioning grafts. Extensive venous stenosis limiting outflow and multiple intragraft stenosis were the main causes of graft failure. For patients in whom all vessels of the uüüer extremity had been exhausted, thig grafts of the loop configuration and axilloaxillary grafts proved to be satisfactory alternatives. Although PTFE grafts are not the final solution for vascular access in hemodialysis, in many instances, they will serve well, provided the surgeon gives proper consideration to their most efficacious use.

9

Kidney International, Vol. 57 (2000), pp. 1124-1140

Treatment of failed native arteriovenous fistulae for hemodialysis by interventional radiologyLuc Turmel-Rodrigues, Josette Pengloan, Hervé Rodrique, Georges Brillet, Anne Lataste, Dominique Pierre, Jean-Louis Jourdan and Didier Blanchard; France

Background : We studied the feasibility, technical problems, safety and effectiveneww of percutaneous declotting of thrombosed native arteriovenous fistulae for hemodialysis.Methods: Between 1992 and 1998, 93 declotting procedures were performed in 73 consecutive upper limb native fistulae (forearm 56 and upper arm 17), and 162 procedures were performed in 78 prosthetic grafts using manual catheter-directed thromboaspiration, with or without previous urokinase infusion. Detection of restenosis by clinical surveillance led to redilation or stent placement. Rethromboses in four forearm and six upper arm fistulae were treated by 20 further declottings by aspiration.Results: The initial success was 93% in the forearm and 76% in the upper arm (99% in grafts). The complications included one pulmonary embolisme, one acute pseudoaneurysm, and one blood depletion requiring transfusion. Primary patency rates at one year were 49% in the forearm and 9% in the upper arm (14% in grafts). Secondary patency rates were 81 and 50% at one year, respectively (83% in grafts). Reinterventions were necessary every 19.6 months in the forearm and every 5.7 months in the upper arm ( every 6.4 months in grafts, P < 0.005). Stents were placed in 11% of forearm fistulae and in 41% of upper arm fistulae ( 45% of grafts) for treatment of acute rupture ( 5 out of 19), stenosis recoil ( 6 out of 19), and early (<6 months) recurring stenosis (8 out of 19).Conclusions: The percutaneous declotting of forearm fistulae by manual catheter-directed thromboaspiration was effective in more than 90% of cases an yielded 50% primary and 80% secondary patency rates at one year. The results were poorer in upper arm fistulae. The need for maintenance reinterventions was three times smaller in forearm fistulae than in upper arm fistulae and grafts.

Key Words: fistula, shunts, transluminal angioplasty, thrombectomy, protheses.

10

Current Opinion in Nephrology and Hypertension 1996, 5: 485-491

Hemodialysis vascular access: emerging conceptsJonathan Himmelfarb and Theodore Saad; Portland & Texas

Conclusion: Hemodialysis vascular access remains, in many respects, the Achilles’ heel of chronic hemodialysis therapy. Increasing attention is being paid to the extent and cost of vascular access-related complications. Although the radiocephalic arteriovenous fistula remains the preferred access for hemodialysis, up to 83% of patients in the USA have PTFE grafts. Most dialysis access grafts fail because ot the development of venous stenosis as a result of myointimal hyperplasia. Several approaches have been or are being developed as screening tests for the early detection of venous stenosis before the development of graft thrombosis. Wheter aggressive screening approaches coupled with interventional procedures extend graft function has not yet been demonstrated in a prospective randomized trial. Nevertheless, several studies have suggested that an aggressive screening and intervention program can reduce the incidence of graft thrombosis.Once a graft is thrombosed, mechanical or pharmacomechanical thrombolysis in conjunction with angioplasty is being increasingly being used as an alternative to surgical thrombectomy. No randomized trials have yet compared surgical and percutaneous transcatheter approaches to vascular access thrombosis. Further research into the pathophysiolygy of dialysis graft-associated myointimalhyperplasia, screening tests to detect venous stenosis and alternative approaches to revascularization should help to deduce the morbidity and cost of vascular access complications.

11

AJR 1997; 731-733

A Sonographically Guided Technique for Central Venous AccessUlf K. M. Teichgräber1, Thomas Benter2, Michael Gebel 1, Michael P. Manns1. 1 Div. of Interventional and Diagnostical Ultrasound, Hannover Medical School. 2 Dep. Of Hematology and Oncology, Virchow Klinikum Berlin

Objective: The internal jugular vein (IJV) is an important access to the central venous system. We compared a sonographically guided technique with the traditional anatomic landmark technique for IJV catheterization.Subjects and Methods: In a prospective randomized trial, 100 patients underwent routine cahteterization of the IJV (50 patients in the anatomic landmark group). Access time, failure rates and complication rates were evaluated. In addition, the physician’s number of years of experience with catheter insertion was recorded.Results: Access time was markedly shorter with the sonographically guided technique (mean, 15.2 sec; range, 8-76 sec) than with the anatomic landmark technique (mean 51.4 sec; range, 3-820 sec) (p=.001). The failure rate was significantly lower with the sonographically guided technique (p=.002). Complications were fewer with the sonographically guided technique ( neck hematoma, 2% versus 10%; plexus irritation, 4% versus 6%; carotid artery puncture, 0% versus 12%). We found that the number of years of postgraduate clinical training was greater in the group of physicians using the anatomic landmark technique.Conclusion: The sonographically guided technique is associated with less risk and less inconvenience for patients, especially critically ill patients, for whom the technique provides fast, safe, and easy IJV catheterization.

12

J of Vasc Surg, Dec 1997; 1009-1019

Longitudinal comparison of dialysis access methods: Risk factors for failureTimothy C. Hodges, MD, Mark F. Fillinger, MD, Robert M. Zwolak, MD, PhD, Daniel B. Walsh,MD, Fritz Bech, MD, and Jack L. Cronenwett, MD, Lebanon, N.H.

Purpose: To compare dialysis access patency rates and identify risk factors for failure. Methods: All access procedures at our institution from 1987 to 1996 were reviewed. Primary procedures were surgically implanted dual-lumen central venous hemodialysis catheter’s (SIHC’s), peritoneal dialysis catherers (PDCs), arteriovenous fistulas (AVF’s), and prosthetic shunts (PTFE’s).Results: Five hundred eighty-five primary procedures (236PTFE’s, 87 AVF’s, 112 SIHCs, and 150 PDCs) and 259 secondary procedures ( 215 PTFEs, 14 AVFs, 0 SIHCs, and 30 PDCs) were performed on 350 patients. By life table analysis, SIHCs exhibited the lowest primary patency rate (9% at 1 year; < 0.0001), whereas PDCs had the highest primary patency rate (57% at 1 year; p< 0.02). The primary patency rates of AVFs and PTFEs was similar, with 43% and 41% 1 year patency rates, respectively (p=0.70). Less stringent reporting methods would have increased apparent 1 year patency rates by 9% to 41%. With regard to secondary patency, there was no significant difference between PTFEs and PDCs, with 1 year patency rates of 59% and 70%, respectively (p=0.62), but PTFEs were more frequently revised. In addition, there was no significant difference between AVFs and PTFE secondary patency rates, with 1 year patency rates of 46% and 59%, repectively. Early differences in patency rates for AVFs, PTFEs, and PDCs diminished over time, and at 4 years AVFs had the best secondary patency rate (p=0.6). The most common reasons for access failure were: PTFEs thrombosis; AVFs, thrombosis and failure to mature; SIHCs, inadequate dialysis; PDCs, infections and inadequate exchange. By regression analysis, a history of a previous unsalvageable PTFE was the only significant risk factor for failure of a subsequent PTFE (p < 0.01), and the risk of graft failure increased exponentially with the number of previous PTFE shunts. Diabetes was the only significant risk factor for failure of PDCs ( p< 0.02; odds ratio, 2.0).Conclusion: The patency rate for PTFEs is similar to that for AVFs, but AVFs require fewer revisions. When replacing a failed access graft, the risk of PTFE failure increases with the number of prior unsavageable PTFE shunts. PDCs have exellent patency rates, but failure rates are doubled in patients with diabetes. Because of poor patency rates and inadequate dialysis flow rates, SIHCs should be avoided when possible. Reporting methods damatically affect apparent patency rates, and reporting standards are needed to allow meaningful comparisons in the dialysis access literature

13

Crit Care Med 1991; 19:1516

Anatomical variations of internal jugular vein location: Impact on central venous accessBart G. Denys,MD; Barry F. Uretsky, MD

Objectives: To evaluate whether underlying anatomical variations in the position of the internal jugular vein may account for difficulty in obtaining central venous access in individual patients.Design: Cinsecutive series.Setting: Cardiac catheterization laboratory, coronary care unit, and ICU.Patients: Two hundred patients (52 7 yrs, 147 males) who were undergoing internal jugular vein cannulation for hemodynamic monitoring or endomyocardial biobsy.Intervention: The internal jugular vein and carotid artery were visualized with tow-dimensional ultrasound and their position was compared with their projected location from external landmarks.Results: In 183 (92%) patients, the position of the internal jugular vein was lateral and anterior to the carotid artery and increased in diameter during a Valsalva maneuver. In 5 (2.5%) patients, the internal jugular vein was not visualized and was probably thrombosed, as the internal jugular vein was normal on the other side. In 6 (3%) patients, the internal jugular vein was unusually small and did not increase in diameter during the Valsalva maneuver. In 2 (1%) patients, the internal jugular vein was positioned >1 cm lateral to the carotid artery. 4 (2%) patients had a medially positioned internal jugular vein overlying the carotid artery. In 5.5% of the patients, the position of the internal jugular vein was outside the path that had been predicted by the external landmarks.Conclusions: These findings suggest that anatomical variation may partly account for the inability to cannulate the internal jugular vein in certain patients. In these cases, ultrasound examination quickly establishes the position of the internal jugular vein and may allow for easy and rapid access.

Key words: jugular vein; venous thrombosis; ultrasonography; hemodynamics; catheterization; transducers; carotid artery; biopsy, endomyocardial; critical care medicine.

14

The American Surgeon August 1996 Vol. 62

The Arterivenous Fistula for Hemodialysis Access: Gold Standard or Archaic Relic?Stepen B. Leapman et alDivision fo Organ Transplant Surgery, Dept. of Surgery, Indiana University Medical Center, Indianapolis, Indiana

A five year retrospective review was undertaken to evaluate the patency rates of arterivenous fistulae (AVF) in patients with end stage renal disease. From July 1989 throug June 1994, 150 fistulae were created in the wrist of 144 patients. 34% of the patients had diabetes mellitus. Patient death or irreparable fistulae were considered points in the study. Patency rates were calculated by the Kaplan-Meier Actuarial Analysis. An analysis to assess the impact of the demographic characteristics, underlying renal disease, and effect of revisions on patency rates was calculatec. The results demonstrate a high initial failure rate (less than 1 month) of 13% in the entire cohort undergoing fistulae placement. The 1 and 5-year patency rates were 56% and 30% , respectively. Diabetics had a significantly lower patency rate at 1 and 5 years (42% and 18%) respectively. Others, who had poor patency rates, include patients 70 years old or greater (40% patency at one year). The results suggest that the AVF should not be the first choice of access in elderly diabetics and that these patients would ve better served with other modes of access, such as synthetic condults or permanent indwelling venous catheters.

15

Am J Kidney Dis 1997 Jul; 30(1):50-7

Vascular access survival among incident hemodialysis patients in the United States.Woods JD; Turenne MN; Strawderman RL; Young EW; Hirth RA; Port FK; Held PJSchool of Medicine, University of Michigan, Veterans Administration Medical Center, Ann Arbor 48103

Vascular access failure causes substantial morbidity to hemodialysis patients. We sought to identify factors determining survival of the permanent vascular access in use at the start of end-stage renal disease during 1990 in a national sample of 784 incident hemodialysis patients insured by Medicare. Medicare claims records were used to identify access failures or revisions among patients with an arteriovenous (AV) fistula (n=245) and an AV vascular graft (n=539). A proportional hazards analysis of time to first failure or revision, controlled by stratification for sex, race, and cause of end-stage renal disease, was used to determine the effect of age, accesstype, and peripheral vascular disease on vascular access survival. Patients with a AV fistula and who were older than 65 years had a risk of access failure that was 24% lower than similar patients with an AV graft (p<0.02). The ralative risk of access failure for an AV fistula, but not an AV graft, varied significantly with the age for patients younger than 65 years (P< 0.01). The relative risk of access failure for a patient with an AV fistula, compared with a patient of the same age with an AV graft, was 67% lower at the age of 40 yeats, 54% lower at the age of 50 years, and 24% lower at the age of 65 years. A history of peripheral vascular disease was associated with a 24% higher risk of AV graft or fistula failure (P= 0.05). Measures to decrease vascular access related morbidity among hemodialysis patients should include reversing the current trend toward increasing use of AV grafts, particularly in patients younger than 65 years.

16

Ann Vasc Surg 1999 Mar; 13(2): 191-8

A prospective evaluation of PTFE graft patency and surveillance techniques in hemodialysis access.Cinat ME; Hopkins J; Wilson SEDept. of Surgery, University of California Irvine Medical Center, Orange, CA 92868.

The purpose of this study was to perform a prospective multicenter evaluation of the patency, complications, and predictive factors of patency for 6-mm expanded polytetrafluoroethylene (ePTFE) grafts used in hemodialysis access. 86 patients were evaluated; the mean age was 55.8 years (range 23-90), 46 patients were female. Patency and complications were assessed at the initial dialysis and 1,3,6,9 and 12 months postoperatively. Kaplan-Meier survival curves were calculated to determine primary and secondary patency, and log-rank analysis was used to determine differences between curves. The Student’s t-test was used to compare groups. Primary and secondary patency rates at 1 year were 43% and 64%. Venous line pressures tended to rise over time. Recirculation values and blood flow rates during dialysis showed no correlation to graft patency. The results show that ePTFE provides a suitable secondary choice for vascular access for end-stage renal disease patients in whom an autogenous fistula is not possible. Thrombosis and anastomotic stenosis are common and should be aggressively identified and treated to prolong overall graft survival.

17

Clin Nephrol 2000 May;53 (5):372-7

Survival of vascular access during daily and three times a week hemodialysisQuintaliani G; Buoncristiani U; Fagugli R; Kuluiranu H; Ciao G; Rondini L; Lowenthal DT; Reboldi G;Nephrology and Dialysis Unit, University of Perugia, Italy

AIM: A major cause of morbidity for hemodialysis patients is vascular access failure and/or occlusion. It is commonly believed that an increased frequency of dialysis sessions, among other factors, might lead to a higher rate of fistula complications.Materials and Methods: To evaluate if patients on daily hemodialysis carry a higher risk of vascular access occlusion, we examined the incidence rate of access occlusion and the survival function of native vascular accesses in patients undergoing daily dialysis (DD; n=24) as compared to patients on standard three times a week hemodialysis (TWD; n=124).Results:The mean follow-up time was 3.6 years. In the TWD group 42 patients had a first-access closure, whereas only 2 patients out 24 had a similar event in the DD group. The proportion of first access closure was 33.9% for TWD and 8.3% for DD (p< 0.01). The incidence rate was 9.8 (95% CI: 7.2-13.2) and 2.2 (95% CI: 0.4-7.1) events per 100 patient-years for TWD and DD, respectively.The rate difference was 7.6 (95% CI: 3.4-11.9) events per 100 patient-years, and the unadjusted risk ratio was 4.5 (95% CI: 1.2-16.9; p< 0.01). The mean vascular access survival before closure was 3.3 years in TWD and 3.7 years in DD. Survival curves, obtained considering the first-access closure as the endpoint, showed a significant difference between DD and TWD (log-rank 5.16; p< 0.05). In a Cox-proportional hazard model the relative risk (RR) of vascular-access closure in TWD remained significant (RR =4.3; 95% CI 1.1 – 18.2) after adjustment for age.Conclusion: The results of this observational study, conducted on a limited number of DD patients, suggest that daily dialysis might not have an adverse prognostic significance for access closure.

18

Am J Kidney Dis 1997 Oct; 30(4):525-31

Care pathway reduces hospitalizations and cost for hemodialysis vascular access surgery.Becker BN; Breiterman-White R; Nylander W; Van Buren D; Fotiadis C; Richie RE; Schulman GDept. of Medicine, and Vanderbilt Transplant Center, Vanderbilt University Medical Center, Nashville, TN, USA

Hemodialysis vascular access related hospitalizations account for more than 20% of US end-stage renal disease (ESRD) hospitalizations, with an annual cost approx. $ 675 million. Limiting access related costs while delivering similar degrees of quality care thus would enhance alternative utilization of ESRD funding. We implemented a vascular access care pathway emphasizing coordinated patient evaluation and outpatient surgery to determine whether such an intervention affected outcomes associated with vascular access surgery. Data examining hospitalization and vascular access surgery charges, complications, and patient satisfaction ( determined by questionnaire) were analyzed, comparing patients who underwent vascular access surgery in 1994 and 1995 as inpatient (non-care pathway patients) and patients who underwent vascular access surgery via the care pathway in 1995. Inpatient days declined in 1995 (1994:582 days; 1995: 85 day; P < 0.03) and the average charges per patient for the care pathway cohort were significantly less than charges per patient in 1994 and charges for non-care pathway patients in 1995 ( 1994 patients: $10’524 $ 5’209; 1995 non-care pathway patients: $ 11’196 $ 5’806; 1995 care pathway patients: $ 4’686 2’912/patient; P< 0.02). Incidence rates for major (life-threatening) complications were not significantly different between 1994 patients and care pathway patients in 1995. However, the 1995 non-care pathway patients had a higher incidence of major complications ( 15.4%). 47 repeat access procedures were performed in 29 patients in 1994 versus 35 repeat access procedures in 22 care pathway patients in 1995, and 12 repeat access procedures were performed in 8 non-care pathway patients in 1995. Finally, a majority of the patients entered into the care pathway who responded to a survey stated that they were satisfied with access surgery via the care pathway. These data suggest that a vascular access care pathway can reduce hospital days and costs while achieving acceptable outcomes for access surgery.

19

Kidney International, Vol. 56 (1999), pp. 275-280

Predictors of adequacy of arteriovenous fistulas in hemodialysis patients.Paul E. Miller, Ashita Tolwani, C. Peter Luscy, Mark H. Deierhoi, Robert Bailey, David T. Redden, and Michael AllonDivision of Nephrology, Div. of Transplant Surgery, and Dept. of Biostatistics, University of Alabama at Birmingham, USA

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 AV 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 2 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 determinded 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 ) vs. 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 vs. 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.

20

Nat Foundation f Inf. Diseases Vol. V August 2000

Preventing Antimicrobial-resistant Healthcare Infections: Beyond 2000Alan L. Bisno et al. University of Miami

Conclusion: The advent of multi-drug resistance in a number of pathogens makes prevention of healthcare-associated infections a very difficult challenge. Infections emerge in acute, long-term and outpatient care settings, and move with patients as they are transferred from one point of carre to another. Programs to prevent person-to-person spread and to promote judicious antimicrobial use must involve clinicians at all venues in the delivery system. From this perspective, controlling emerging antimicrobial resistance among healthcare-associated pathogens is a vital link in the prevention and contro of these pathogens in the overall community and will require coordinated efforts by both the health care delivery system and the public health system.

Surgery Sept. 1983

Salvage operations for malfunctioning polytetrafluoroethylene hemodialysis access graftsEdward E. Etheredge,M.D., Ph.D., Stephen D. Haid, B.A., Marge N. Maeser, R.N., Gregorio A. Sicard, M.D., Charles B. Anderson, M.D., Dept. of Surgery, Washington University School of Medicine, St. Louis, Mo.

During the study period a cohort of 170 of patients receiving long-term hemodialysis treatment required placement of 214 PTFE grafts for vascular access; within this period 74 of these patients had significant graft malfunction that required 149 salvage operations. The most common failure/malfunction was thrombosis, and the most commonly appreciated mechanical cause of graft failure was outflow problem. First, second and third revisions were successful in 65%, 53% and 44% of cases, respectively. Multiple revisions, including thrombectomy, were required in some, but the functional life of these salvaged grafts was nearly equal to that of grafts that did not require revision. Abandonment of grafts because of secondary infection exacted a toll in both groups.

21

Southern Medical J May 1985 Vol. 78, No. 5

Complications of Vascular Access for HemodialysisOwen E. Winsett, MD and Fred J. Wolma, MD, Galveston, Tex

This study of 533 vascular access sites for long-term demodialysis in patients with end-stage renal disease, accumulating more than 12’000 patient months, indicated that primary arteriovenous fistula (AVF) is the procedure of choice. The group receiving primary AVF had the greatest duration of patency: 84% at three years compared to 70% for the group receiving PTFE grafts and < 50% for those receiving bovine carotid artery heterografts (BCAH). Furthermore, the primary AVF group had fewer complications (25 complications in 273 fistulas) than either the BCAH group (61 in 58 grafts) or the PTFE group (171 in 202 grafts). No complication resulted in death in the primary AVF group, but 7 death resulted from complications of the access in the graft groups, further solidifying the position of the primary AVF as the procedure of choice for chronic hemodialysis access.

Helv. Chir. Acta 56, 621-627 (1989)

Chirurgische Erfahrungen mit arterio-venösen Hämodialyse-Shunts (1979-1988)H. Wehrli, R. Chenevard, K. Zaruba

Data were collected concerning 307 arteriovenous fistula for hemodialysis created in 186 patients between 1979 and 1988 at the Municipal Hospital Waid of Zurich. The average age of all patients was 52.7 years. The procedure which provides access for 97.2% of all patients is the radiocephalic fistula ( Cimino-Brescia), which became dilated within 4 weeks in 82.9%. There was a primary failure rate of 11.2%. The patency rate was 60.2% after 3 years and 36.6% after 5 years. Early complications, especially thrombosis, occurred in 11.2% and were caused usually by technical faults or hypotonia. Late complications were discovered in 42.8% of the patients (22.5% thrombosis, 7% stenosis, 2,1% aneurysm, 2.6% infection, 2.7% steal syndrom and 5.9% skin alterations). During the average period of dialysis (4.6 years), 38% of the patients needed more than one fistula. In that situation too, the same radiocephalic fistula was performed in the contralaterl forearm (30%) prior to perform advanced procedures like PTFE-grafts (29%), etc. The patency rate after 3 years was 60.4% for radiocephalic fistula and 69.7% for PTFE transplants. The shuntthrombosis was again the main early (9.9%) and late (24%) postoperative complication. With help of a surgical thrombectomy or more conservative procedures like anticoagulation, local thrombectomy and transluminal angioplasty, 81.2%, respectvely 64% of the failed fistulas could be restored. Other complications like bleeding, aneurysms and infections occurred especially in arteriovenous grafts (0.5-5.7%).

22

British J of Surgery 1999, 86. 211-216

Outcome of primary radiocephalic fistula for haemodialysisJ. Golledge, C.J. Smith, J. Emery, K. Farrington, and H.H. ThompsonDept. of Surgery and Renal Medicine, The Lister Hospital, Stevenage, UK

Background: Patient characteristics may help select the most appropriate type of permanent vascular access for haemodialysis. The aim of this study was to assess the influence of patient-related variables on the outcome of radiocephalic fistulas.Methods: Over 3 years 107 consecutive patients underwent formation of a radiocephalic fistula for permanent haemodialysis access. Patients receiving prosthetic, ulnar, brachial or secondary fistulas were excluded. Patients were followed prospectively until access failure, transplantation or death, or for a minimum of 6 months (median follow-up 24 months).Results: Primary patency was 69% at 12 months and 56% at 24 months. Endovascular and surgical intervention led to limited improvement in secondary patency to 63% at 24 months.Regression analysis showed that fistula failure was more common in women (P = 0.02), diabetics (P = 0.03) and young patients (P = 0.02). By life-table analysis, primary and secondary patency were significantly better (P = 0.01) for men and non-diabetics, while the outcome was similar for all age groups.Conclusion: One-third of radiocephalic fistulas fail irreversibly within 2 years. Failure is more likely in women and diabetic patients.

J Nephrol 2001; 14: 146-156

Vascular access for hemodialysis: an indepth reviewNilesh H. Patel et al. USA & UK

Abstract : A multi-disciplinary approach to vascula access planning, early preoperative surgical assessment and increased use of vascula imaging for surveillance, specialist service and pharmacological prevention of intimal hyperplasia will lead to improved patency reates for both autologous AVF and synthetic grafts.

23

Am J of Kidney Diseases, Vol XVI, No 3 (September), 1990: pp 211-215

Use of a Silicone Dual-Lumen Catheter With a Dacron Cuff as a Long-Term Vascular Access for Hemodialysis PatientsAlvin H. Moss, MD, Chris Vasilakis, BS, Jean L. Holley, MD, Charles J. Foulks, MD, Kumar Pillai, MD, and Donald E. McDowell MD

We evaluated our experience over a 4-year period with a silicone dual-lumen catheter with a Dacron cuff (SDLCDC) to determine if the catheter represents an alternative to the PTFE graft for long-term vascular access for hemodialysis patients. Records of 131 patients who used 168 catheters were reviewed for catheter function, duration of use, and occurrence and response to treatment of complications. 85% of catheters functioned adequately until their use was no longer required or the end of the study. 1year catheter survival estimate was 65% and median survival estimate was 18.5 months. Mean blood flow rates achieved was 243 ml/min and recirculation was 7.5%. Exit-site infection occurred in 21% of patients and bacteremia in 12%. There were significantly more exit-site infections in diabetics than nondiabetics (33% v 11%, P < 0.02). Exit-site infections resoved with parenteral antibiotic therapy in 90% and bacteremia in 25% of cases without catheter removal. Unresolved bacteremia was the most common cause of catheter removal and led to the loss of 7% of catheters. Thrombotic complocations occurred in 46% of catheters. Urokinase instillation successfully treated catheter occlusion in 81% of cases. When Urokinase instillation failed, streptokinase infusion restored catheter patency 97% of the time. The literature on the PTFE graft was reviewed, and SDLCDC was found to be similar to the graft in function, duration of use, and frequency of infections and thrombotic complications. We conclude that the catheter represents an alternatice to the graft for long-term vascular access in hemodialysis patients. Because of the frequent complications with both accesses, neither should be considered optimal. Further research is required to improve vascular access for patients in whom placement of an arteriovenous fistula is not possible.

24

Dialysis Times (1998) 5: 5-7

A Reliable Hemodialysis PortAnne Rousssell, Mark Macedo, Frank Prosl

History of Blood Access, Biolink’s Goal, Dialock Description, Anticipated Benefits

Seminars in Dialysis Vol. 12, No 5 (Sept-Oct) 1999 pp. 382-388

Dialock: Pilot Trail of a New Vascular Port Access Device for HemodialysisB. Canaud (1), Nathan Levin (2), Todd Ing (3), Horn My (4), Alan J. Dubrow (2), Hans D. Polaschegg (5), Frank R. Prosl (6)1 Nephrology Div., Lapeyronie University Hosp., Montpellier, France, 2 Beth Israel Hosp., NY, 3 Hines VA Hosp., Chicago, Illinois, 4 Neph. Div., St. Joseph Hosp., Lyon, France, 5 Oberdorf, Austria, 6 Biolink Corp., Massachusetts

Conclusion: The Dialock device catheter offers a new alternative in the armamentarium of vascular access in ESRD patients. This port access device bridges the “gap” existing between permanent catheters and arteriovenous fistulas. This pilot study confirms that such a device specifically designed for high blood flow can satisfy contemporary hemodialysis needs. Dialock offers a new vascular alternative for dialysis that deserves further long-term study do define its role in the vascular access management strategy of ESRD patients.

25

Angioaccess for Hemodialysis 1999 (abs), 167

Dialock, Vascular Port for Hemodialysis . Intermediary Results of an international Pilot TrialCanaud B., Morena M., My H., Levin N., Ing T., Dubrow A., Moragues H., Polaschegg HD., Prosl F.

Permanent catheters now used as an alternative to permanent AV fistula harm the self-body image of patients and are associated with a significant risk of infection. A totally implantable chamer connected to permanent catheter appears highly desirable ot overcome such inconveniences.Dialock, a metallic port-like valve device connected to twin silicone elastomer catheters has been developed (Biolink Corp, Massachusetts, USA). Dialock is implanted subcutaneously and provides a linear flow-passage to two silastic atrial catheters. The valve accessed percutaneously at each dialysis session with needle-cannulal converts the device to conventional twin catheters. Interdialytic patency of catheters is ensured by antithrombotic lock.Dialock was implanted in 23 ESRD patients (59.3 11.4 years) at 4 centers in a pilot prospective study. Treatment schedule consisted of 3 HD sessions per week lasting 3 to 4 hours. 3720 HD sessions were performed. Average duration of use was 11 patient-months ( 22 days-17 months). Patient satisfaction was observed in over 90% of cases. Skin condition at the puncture sites has remained satisfactory in all patients. Nurse training for cannulating was brief (2-3x). Effectiv blood flow was between 300 and 350 ml/min, with a venous pressure ranging 200 and 220 mmHg and a recirculation rate of 6.7 1.3%. Effective Kt/Vdp delivered was 1.48 0.23. Reducing heparin lock volume prevented hematomas and small bleeding of the skin puncture sites observed in the initial period of the study. 25 episodes of infections occurred in 12 patients: 19 episodes were manifested by bacteremias and cured by antibiotics the device being left in place; 3 infections involving skin and device, only 2 cases led to removal of the device. Cumulative infection incidence was 3 episodes per 1000 patient-days. 2 catheter thrombosis was observed: one a partial thrombosis of jugular vein and the other consisting in fibrin sleeve at the distal part of catheter.The Dialock device offers a new alternative to permanent catheter suppressing discomfort and reducing significantly infectious hazard associated with external catheter.

26

ERA/EDTA Congress Abstract 1998: 271

Dialock , a new vascular access divice for extracorporeal renal replacement therapy (RRT).Canaud B 1., Morena M 1., My H. 2, B Lamy-Lacavalerie 2., H Leray 1, JY Bosc 1, PY Chomel 2, Polaschegg HD 3., Prosl F. 3, J Megerman 3.1 Lapeyronie Hosp., Montpellier, 2 St Joseph Hosp, Lyon, 3 Biolink Corp. Massachusetts.

Vascular access (VA) remains the weak component of extracorporeal RRT. VA dysfunction represents the primary cause of morbidity in ESRD patients accounting for a substantial amount of the overall treatment cost. Permanent catheters, proposed as an alternative to arteriovenous fistulae (native or prosthetic), are associated with a significant risk of infection. A totally implantable device that minimizes infection hazards while consistent with the principle of permanent catheters appears highly desirable. In accordance with this concept, a new subcutaneous device (Dialock) has been developed. This access device consists of a metallic port-like valve, implanted subcutaneously below the clavicle, which provides a linear flow passage to two silastic catheters placed in the right atrium via the right internal jugular vein. The valve is accessed percutaneously each dialysis session with needle-cannulas that functionally convert the device to twin catheters for connecting the patient to the HD lines. Interdialytic patency of the catheters is ensured by heparin lock. Dialock was implanted in 8 ESRD patients (58.2 14.7 yr) under general anesthesia, with almost immediata use for HD.RRT consisted of 3 HD sessions per week lasting 4 hours. 300 HD sessions were performed. Cumulative duration of use was 26.6 patient-months. 330 HD sessions were performed. Patient satisfaction was evident in all cases. No infection was detected. Skin condition at the puncture sites has remained satisfactory in all patients. Nurse training for cannulatiion was brief (2-3x). Effective blood flow was 298 10 ml/min, with a venous pressure of 189 18 mmHg and recirculation rate of 6.7 2%. Effective Kt/Vdp delivered was 1.20 0.16 with a nPCR of 1.28 0.19 g/kg/d. Hematomas observed in two patients were effectovely prevented by reducing heparin lock volume. The Dialock device seems to offer a substantial improvement over permanent catheters in suppressing discomfort and infectious hazard associated with eyternal prostheses.

27

Am Soc of Neph 1998; 9: 175A

A NEW SUBCUTANEOUS DEVICE FOR HEMODIALYSIS ACCESSLevin, B Canaud, TS Ing, H My, AJ Dubrow, NS Caraiani, VC Gandhi, H Leray, A Alto, SM Davila, M Morena, J MegermanRenal Research Inst and Beth Israel Med Ctr, NY; Lapeyronie Hosp, Montpellier, France; Hines VA Med Ctr, Hines, IL; St Joseph Hosp, Lyon, France; Biolink Corp. Massachusetts USA.

Vascular access problems continue to adversely affect hemodialysis (HD) treatment, with yearly rates of failure, intervention, and morbidity being essentially unchaged in over 20 years. A new subcutaneous device has been developed that provides adequate blood flow and may reduce the risk of infection. The Dialock is a titanium port that is implanted subcutaneously below the clavicle. It is connected to two tunneled 11F silicone catheters that are inserted into the internal or external jugular vein, whose tips ar staggered within the right atrium. A mechanical valve is opened when special 15-gauge needles are inserted percutaneously, establishing a linear flow passage between the HD tubing and intravenous catheters. There is no degradable septum, chamber or directional change in flow that could promote hemolysis and/or thrombosis. The device has been implanted in 12 patients at 2 centers in the US and in another 10 at 2 centers in France, with a mean implant time of 8.0 3.2 months (mean SD; range 2 to 12.5 months excluding 2 patients who died of unrelated causes at 1 and 4 months and 1 who received a kidney transplant at 8 months). The median time to first use after implantation was 2.5 days, and after just 1-2 sessions of training, nurses have found the device easy to access. Almost 2200 accesses (> 99% success rate) have produced an average flow rate of 330 40 ml/min in the US and slightly lower in France. Delivered Kt/V in all patients was well over 1.2 and average Hct was 34.3 suggesting there is no red cell damage by the device. Skin integrity after a year of repeated puncture remains acceptable. 11 episodes of bacteremia have been managed successfully using standard antibiotic therapy plus interdialytic catheter locks of antibiotic mixed with heparin, with no device being removed due to infection. The cumulative infection rate was 2.3 episodes per 1000 patient-days. One device was removed after 10 months due to the presence of a ball thrombus at the catheter tip. With 2 out of 22 patients having used the device for over 12 months, the cumulative survival rate is 80%. The Dialock may offer a useful alternative where traditional vascular access has yielded unacceptable results.

28

Nephrology Dialysis Transplantation 1999; 14: 692-698

Dialock: a new vascular access device for extracorporeal renal replacement therapy. Preliminary clinical resultsCanaud B 1., Morena M 1., My H. 3, B Lamy-Lacavalerie 3., H Leray 1, JY Bosc 1, J-L. Flavier 2, PY Chomel 3, Polaschegg HD 4., Prosl F. 4, J Megerman 4.1 Nephrology and 2 AIDER, Lapeyronie Hosp., Montpellier, 3 St Joseph Hosp, Lyon, 4 Biolink Corp. Massachusetts.

Background: Vascular access, a vital too for end-stage renal disease patients, remains a weak component of extracorporeal renal replacement therapy (RRT) and the first cause of morbidity. Permanent catheters proposed as an alternative to permanent AV fistulae are associated with a significant risk of infection. A subcutaneously implantable chaber connected to permanent catheter appears highly desirable to reduce such hazards.Methods: Dialock, a metallic port-like valve device connected to permanent silicone twin catheters has been developed (Biolink Corp. Middleboro, MA, USA). After being implanted subcutaneously below the clavicle. Dialock provides a linear flow passage to two Silastic catheters placed in the right atrium via the right internal jugular vein. The valve is accessed percutaneously each dialysis session with needle cannulae that functionally convert the device into twin catheters. Interdialytic patency of the catheters is ensured by antithrombotic lock (heparin or low-molecular-weight heparin).Results:Dialock was implanted in 10 ESRD patients (6412 years) under general anaesthesia, with almost immediate use for HD. RRT consisted of three HD sessions per week lasting 4h; 699 HD sessions were performed. Average duration of use was 5.7 patient-months (1.3-9.6 months). Patient satisfaction was evident in all cases. 3 episodes of bacteraemia occurring in the early phase of the study were cured by appropriate antibiotics. No device was removed because of infection. Skin condition at the puncture sites has remained satisfactory in all patients. Nurse training for cannulating was brief (2-3x). Effective blood flow was 3073.3 ml/min, with a venous pressure of 19539 mmHg and a recirculation rate of 6.70.8%. Effective Kt/V dp delivered was 1.360.03 with a nPCR of 1.200.005 g/kg/day. Haematoma and a small amount of bleeding of the skin puncture sites observed in the initial period of the study were effectively prevented by reducing heparin lock volume.Conclusions: The Dialock device offers a new and interesting vascular access alternative for haemodialysis bridging the “gap” between permanent catheters and arteriovenous fistulae. Dialock’s place in the vascular access strategy for heamodialysis patients deserves further long-term clinical studies.

29

NKF Clinical Nephrology Meetings April 29- May 2, 1999

PATIENT AND NURSE SATISFACTION USING A NEW ACCESS DEVICE FOR HEMODIALYSISDavila SM et al.

Vascular access is a major contributor to high morbidity and costs in the hemodialysis population. A new, totally implantable access device has been developed consisting of a titanium port body attached to twin silicone catheters. During an outpatient procedure, catheters are placed in the right internal or external jugular vein with the tips positioned in the right atrium. Catheter are tunneled to the port pocket, attached to the device and sutured to the fascia. The device is accessed by 15 g special needles which open valves within the device and establishes a straight-line flow path. The device was implanted in 11 patients in 2 clinical sites as part of a pilot trial. Access of the device was done by dialysis unit nurses using sterile technique. Nurses were asked to complete a weekly satisfaction questionnaire (SQ) to reflect ease of device accesses ( 1=very satisfied, 5=very dissatisfied) with the device as a means of access. Nurses were allowed to record other observations, comments or criticsms and to compare experience with the device to other access types. Patients completed a SQ at each dialysis session. Visual analog scales were used to record comfort/pain levels with the device as well as overall device satisfaction (1= very satisfied, 5 = very dissatisfied). Results: 190 nurse and 559 patient SQ’s were collected from May 1997 throug August 1998.

1 2 3 4 5 No response

Ease of access 67% 21% 5.8% 4.7% 1% 1.3%Nurse satisfaction 69% 28% 0.5% 1.6% 0.5% NAPatient satisfaction 67% 31% 0.2% 0 0 1.6%

30

Blood Purif 1998 ; 16 : 242

Hemodialysis (HD) Access with the Dialock DeviceJ. Megerman, N.W. Levin, T.S. Ing, B. Canaud, H. My, Biolink Corp.,MA, USA

The Dialock HD access device was developed to overcome the main problens with current mides of access, I.e., failure due to infection and poor flow. It consists of a titanium port with a mechanical valve attached to 11F twin silicone catheters, contains no degradable septum, and provides a linear flowpath that avoids clotting and damage to red cells. The port is fully implantable below to the clavicle, and the catheters are tunneled to the IJ vein with their tips placed in the rigt atrim. Special neeles are used for percutaneous access, converting the device to a standard catheter system during dialysis. The Dialock was implanted in 21 patients in the US and France for 1-11 months (median 7.5 months). After 2000 accesses, blood flow averaged 330 40 (US) and 315 25 (FR) ml/min and the infection rate was 2.3 per 1000 patient-days. All infections were resolved with local plus systemic antibiotics without removing the device. Fibrin sheath stripping was performed in 2 patients and one device was removed following the visualization of an asymptomatic ball thrombus at the catheter tip. Two patients died from unrelated causes. The Dialock may represent a substantial improvement over conventional devices used to provide hemodialysis access.

31

Artificial Organs (1999) 23 (1): 10-14

Development of a New Approach to Vascular AccessJoseph Megerman (1),Nathan W. Levin (2), Todd S. Ing (3) Alan J. Dubrow (2), and Frank R. Prosl (1)(1) Biolink Corp., Massachusetts; (2) Beth Israel Medical Center and Renal Research Inst., New York; (3) Hines V.A. Medical Center, Illinois

Abstract:: Three modes of access for hemodialysis (HD) have been available for over 20 years, the native arterial to venous (A-V) fistula, the PTFE graft fistula, and the central venous catheter. Overall, vascular access remains the single most costly source of morbidity and hospitalization in HD patients, indicating a severe need for improvement in this area. A significant contributor to access morbidity is the HD catheter, which protrudes through the skin and is subject to frequent infection. Subcutaneous ports have been developed to overcome this problem with catheters, but their application to HD has been exclusive for 2 reasons, the use of a degradable septum that becomes vulnerable to infection with the use of large bore needles and the presence of a nonlinear flow path which produces damage to blood cells and stimulates thrombus formation at the required high flow rates. A new device, the Dialock, overcomes these objections by its use of a mechanical valve that maintains a linear flow path without directly contacting the blood. Results of a pilot study with 23 patients demonstrated a 78% cumulative survival rate after 1 year with a reduced rate of infection compared to catheters and sustained blood flow of 330 ml/min. The device represents a most promising advance in vascular access.

32

ASAIO J 1998; 44:5 M529- M531

New Access Device for HemodialysisN. W. Levin, P. M. Yang, D. A. Hatch, A. J. Dubrow, N. S. Caraiani, T. S. Ing, V. C. Gandhi, A. A. Alto, S. M. Davila, F. R. Prosl, H. D. Polaschegg, J. Megermann

A new subcutaneous device (Dialock; Biolink Corp., Massachusetts) provides vascular access to patients who currently require hemodialysis (HD). The device consists of a port-like valve , implanted subcutaneously below the clavicle, which provides a linear flow passage to two catheters placed in the right atrium via the jugular vein. The valve is accessed percutaneously with needle-cannulas that functionally convert the device to twin catheters for connecting the patient to the HD lines. Interdialytic patency is maintained using a standard heparin lock. The device has been implanted in 10 outpatients under local anesthesia, with almost immediate use for HD (median, 3 days) and has functioned successfully for more than 6 months (mean SD, 4.0 1.7;) > 400 dialysis sessions). Blood flows over 300 ml/min were consistently achieved ( average, 320 50) with venous and arterial pressures of 197 42 mmHg and –241 31 mmHg, respectively. After 40 patient-months, condition of the needle puncture sites remains satisfactory.4 systemic infections have occurred in 3 patients; all have resolved without the need for device removal. There have been no infections at the puncture sites. 1 patient whose heparin lock was not changed for 23 days ( for reasons unrelated to the device) required fibrin sheath stripping of his catheters. Patient and nurse acceptance has been exellent. The device may offer substantial improvement wver conventional devices for HD access.

33

Kidney Int 1998; 54: 1739-1745

Initial results of a new access device for hemodialysis Technical Note

N. W. Levin, P. M. Yang, D. A. Hatch, A. J. Dubrow, N. S. Caraiani, T. S. Ing, V. C. Gandhi, A. A. Alto, S. M. Davila, F. R. Prosl, H. D. Polaschegg, J. Megermann

Background: A new subcutaneous device (Dialock; Biolink Corp., Massachusetts) provides vascular access to patients who currently require hemodialysis (HD). The device consists of a port-like valve , implanted subcutaneously below the clavicle, which provides a linear flow passage to two catheters placed in the right atrium via the jugular vein. The valve is accessed percutaneously with needle-cannulas that functionally convert the device to twin catheters for connecting the patient to the HD lines.Methods: The device was implanted in 10 outpatients under local anesthesia. Patients used the device during dialysis 3 times/week, and date were collected on blood flow, pressures, adverse events and patient and nurse satisfaction.Results: The device was used for HD almost immediately (median 3 days after implantation) and functioned successfully for more than nine months ( mean SD 7.31.5) in all but one patient who died of unrelated causes after one month; there were > 800 dialysis sessions total. Blood flows over 300 ml/min were consistently achieved (average 326 40) with venous and arterial pressures of 20040 and -24629 mm Hg,respectively. After 66 patient-months, condition of the needle puncture sites remained satisfactory. 5 systemic infections occurred in 4 patients, producing 2.3 bacteremic episodes per 1000 patient-days. All resoved without the need for device removal. There were no infections at the puncture sites. 2 patients required fibrin sheath stripping of their catheters, one whose heparin lock was not chaged for 23 days (for reasons unrelated to the device). Patient and nursse acceptande was excellent.Conclusion: The device represents a positive improvement in the area of HD access.

34

J ASN (1996) 7: 1417

A Novel Subcutaneous Blood Access DeviceH.D. Polaschegg et al.

When use of conventional blood access (fistula, graft) is not possible, single or double lumen catheters are used for blood access. These catheters are prone to clotting and infection and are associated with the risk of an air embolism. In long term drug therapy and for parenteral nutrition implantable injection ports have almost completely replaced conventional catheters for long term applications because of their safety, patient preference and longevity. These ports consist of a disk like body covered by a silicone septum implanted under the skin from which a catheter leads to a central vein. Such ports have failed as blood access devices for hemodialysis because of insufficient blood flow and problems with clotting and infection. Clotting is promoted by the dead space of conventional port designs. An increased infection rate may occur due to repeated septum punctures and consequent porousness. Because of the above, a novel dead space free device with excellent flow characteristics has been developed for hemodialysis access. This subcutaneously placed device uses a valve rather than a septum for closure of the flow path when the extracorporeal circuit is not connected. In-vitro test that blood flows of > 500 ml/min. can be achieved at pressure drops of 200 mmHg. For this device, the pressure drop is mostly caused by the turbulent flow in the cannula while for the conventional port, the connection pressure drop is predominant.

35

Nephrology News & Issues 1999; 40

Two New Access Devices Have Potential to Replace the Temporary CatheterMark E. Neumann

Central venous catheters for hemodialysis (HD) access can be a savior for the end-stage renal disease patient. Until a realistic program of pre-ESRD care can be developed by providers and payors, many patients will continue to arrive at the dialysis unit needing dialysis quickly. Temporary catheters can fill that need while arterio venous fistulas or PTFE grafts are placed and allowed time to heal. For patients already on dialysis, patients run our of access sites because or poor vasculature, and permanent catheters can prove the only alternative to establishing access for dialysis. According to 1996-98 data from the DOPP’s study, 38% of patients in the sample (n=9600 patients) had temporary catheters and 27% had permanent catheters.But catheters are prone to thrombosis, infection, dislodging when implanting proves difficult and are no aesthetically comfortable for the patient. In a 1997 study published in the J of Vascular Surgery that reviewed 585 vascular access implants in 350 patients., Hodges et al. reported that central venous catheters exhibited the lowest primary patncy rate at one year (9%9 compared to peritoneal dialysis catheters, arteriovenous fistulas and PTFE grafts.Now, two small companies in the U.S. are pushing new access devices toward FDA approval that would replace the catheter as a bridge device for grafts and fistulas The devices may reduce complications and extend patency rates. Similar to catheters, both devices can be implanted by a nephrologist and used shortly after placement.DIALOCKBiolink Corp., headquartered in Middleboro, Mass., is developing the Dialock access device. Phase III pivotal trials began in April 1998 and are ongoing at 10 major sites in the U.S. and Europe. As of February 1999, 75 patients had been implanted with the device, with 14 patients having usage over one year. The longest implant has been 22 months. The device consists of a port-like titanium valve, implanted subcutaneously below the clavicle, which allows access to two catheters placed in the right atrium via the jugular vein. The valve is accessed percutaneously with needle-cannulas which convert the device to twin catheters which connect to the bloodlines leading to the dialysis machine. In an abstract at the Am soc of Neph Meetin in November 1998, Levin et al. reviewed the results of the Dialock implanted in 12 hemodialysis patients at two centers in the U.S. and two centers in France. The median time to first time use was 2.5 days. Mean implant time ws eight months in the patients, with almost 2200 total accesses. Blood flows averaged 330 ml/min. Delivered Kt/Vs were well over 1.2 and hematocrits averaged 34.3%. 11 episodes of bacteremia occurred in the two patient groups; all were resolved using standard antibiotic therapy without the need for device removal. In a earlier study published in 1998 in the ASAIO Journal, the autors reported that patient and staff acceptance of the device was “excellent”; 6 of 10 patients in that earlier review were placed on the Dialock because there was inadequate vasculature to implant a graft or fistula

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LifeSite A similar access device using a port design is being developed by VascA, based in Topsfield, Mass. Called LifeSite and already being marketed in Europe, the device uses a standard 14 gauge fistula neele for access. The port itself is attached to a 12F silicone catheter placed into a central vein. The main difference between the Dialock an the Lifesite devices is the use of 2 ports on the Lifesite for access.Nephrologist at two study sites, in Ottawa, Canada and Austin, TX, have implanted the device in 22 patients. In an abstract presented at the Am Soc of Neph meeting, Bethard et al. reviewed the results from 10 patients on the LifeSite device after 28 days of use. The catheters were implanted just below the clavicle, with implantation time of 50 to 90 minutes by the nephrologist. After two to six weeks of usage, only one difficulty with cannulation was encountered. Maximum blood flow was measured at 450-480 ml/min cc/min, but was limited by the dialysis machine capabilities, the authors wrote. After the 28-day period, no instance of catheter thrombosis or bacteremia was encountered; Kt/V measurements at the end of the first week of port usage averaged 1.65. “The level of patient acceptance was eycellent”, the authors noted.

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ASAIO Journal 1999; (abs), 180.

ANTIBIOTIC LOCK IN THE TREATMENT OF INFECTIONS ASSOCIATED WITH THE USE OF A SUBCUTANEOUSLY IMPLANTED HEMODIALYSIS ACCESS DEVICER. Boorgu, N.W. Levin, AJ Dubrow, JR Lentino, DW Wenthworth, DA Hatch, TS Ing Loyola/Hines Veterans Affairs Medical Center and Beth Israel Hospital

To improve vascular access for hemodialysis, a new device (Dialock hemodialysis access system) has been developed. The device, implanted subcutaneously, is accessed by percutaneous puncture. Made of titanium, the device has 2 silicone catheters that are inserted into the superior vena cava or the right atrium. Clinical results so far have been satisfactory. However, use of this device is not free from the complications of infection and thrombosis. In our pilot study a total of 2203 hemodialysis sessions have been performed in 12 end-stage renal disease patients who received 13 Dialock devices. A total of 12 septicemia episodes have been successfully treated with a combination of intravenous antibiotic therapy and topical antibiotic therapy (the latter achieved by introducing high concentrations of antibiotic solutions into the catheters). This combination therapy was first used in 2 septicemic patients after they had failed to respond adequately to intravenous antibiotic therapy alone. After adjunctive use of the lock technique, the septicemia in these patients promptly resolved. In the 12 episodes of septicemia that responded to the combination therapy, S. Epidermidis was the responsible microbe on 5 occasions. In the remaining episodes, the micro-organisms involved included: S. Aureus, S. Capitus, S. Saccharolyticus, S. Lugdenensis, A. Xylosoxidans, E. Coli and Propionibacterium Acnes. The lock approach entailed the instillation of 200 or more units/ml heparin in conjunction with 1-2 mg/ml Vancomycin, 100 mg/ml Piperacillin or 50’000 units/ml Penicillin G. We suggest that the antibiotic lock technique may be useful as an adjunctive therapeutic modality in the treatment of infections related to the use of indwelling vascular access devices.

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ASAIO Journal 2000; 46: 767-770

Adjunctive Antibiotic/Anticoagulant Lock Therapy in the Treatment of Bacteremia Associated with the Use of a Subcutaneously Implanted Hemodialysis Access DeviceR. Boorgu et al.

To improve vascular access for hemodialysis, a new device (Dialock Hemodialysis Access System, Biolink Corp. Middleboro, MA) has been developed. Implanted subcutaneously, the device is accessed by percutaneous puncture. Attached to the device are two catheters that are implanted into the superior vena cava or right atrium. Clinical results thus fas have been promising. However, use of this device is not free from infectious complications. In the present pilot study, 25 maintenance hemodialysis patients were implanted with 26 Dialock Devices. The incidences of bacteremia was 2.9/1000 catheter days. In 14 episodes of bacteremia in 8 patients the infection was successfully treated with a combination of systemic antibiotic treatment and adjunctivee antibiotic/anticoagulant lock therapy. The lock therapy entailed the instillation of both an antibiotic and an anticoagulant into the device. We believe that the antibiotic/anticoagulant lock technique is an effective, adjunctiv therapeutic modality in the treatment of infections related to the use of indwelling vascular access devices.

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ASN 2000 (abs); 11:180A

Incidence of Clotting and Infection with Dialock, a New Vascular Access Device, Compared to Grafts, Fistulas and Catheter.K. Bansal et al.

Vascular access remains a major problem in the delivery of adequate hemodialysis (HD) treatments. The purpose of this study was to compare the incidence of clotting and infection over a 12-month period in 1999 for all HD patients according to type of vascular access used: graft (G), fistula (F), internal jugular catheter (C) and Dialock (D). The Dialock ( Biolink Corp., Middleboro MA), currently under clinical investigation in the USA, is a titanium port that is implanted subcutaneously below the level of the clavicle. Two tunneled silicone catheters inserted via the internal jugular vein are staggered within the right atrium. A mechanical valve is opened when special 15-gauge needles are inserted percutaneously to establish vascular access. Vascular access distribution in our patients was 37%G, 15%F, 45%C and 3%D respectively. During the 12-month period there was a total of 1377 patient months with 84 episodes of complications in the form of clotting of infection.

Type of Access Clotting Infection Incidence per Pat.Year #Pt % #Pt % Clotting Infection BothGraft 25 29.7 2 0.22 0.02 0.24Fistula 7 8.3 0 0.06 0.00 0.06Catheter 35 41.7 9 0.31 0.08 0.38Dialock 1 1.1 5 0.01 0.04 0.05

68 16 0.59 0.14 0.73

Incidence of clotting was significantly lower for D when compared to G,F and C. Incidence of infection was lower for D when compared to G,F, and higher for D when compared to C. 4 of the 5 D infections occurred in the same calendar month. This cluster of infecions is

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believed to habe originated from a single healthcare provider who had contact with all D patients. The Dialock device offers a reduced rate of clotting while maintaining HD adequacy.

Kidney International, Vol. 58 (2000), pp 2221-2227

Initial clinical results with the LifeSite Hemodialysis Access SystemGerald A. Beathard and Gerald A. Posen

Background: The LifeSite Hemodialysis Access System is a subcutaneous valve with an internal pinch clamp that is actuated with a standard 14-gauge dialysis needle, connected to a single lumen cannula placed in the central venous circulation for hemodialysis (HD).Methods: The LifeSite System (2valves) was implanted in 23 patients with immediate dual-needle HD use. The cannulas were placed in either the jugular or the sublavian veins and were connected to the subcutaneous valves located in the upper chest area.Results: The mean duration of device survival for the LifeSite System was 6.8 0.97 months. During this period, the device achieved precription HD flow rates averaging 384.7 78.5 ml/min with a venous pressure of 223.2 60.3 mm Hg. After 125 patient monts, device removal because of infection was at a rate of 2.5 per 1000 days, and there were no devices removed because of poor flow. The average Kf/V for these patients was 1.51.Conclusion: The preliminary clinical study has validated the applicability of the LifeSite Hemodialysis Access System as an access for HD. It is easily implanted and easily used, provides safe and effective dialysis, and is well accepted by patients. It should be especially useful as a bridge device to allow for maturation of a native fistula and will provide an alternative for long-term use in patients in whom a peripheral dialysis access in not feasible.

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Artif Organs 1998 Nov; 22 (11):945-7

Filling hemodialysis catheters in the interdialytic period: heparin vs. citrat vs. polygerine: a prospective randomized study.Buturovic J; Ponkivar R. Kandus A; Boh M; Klinkmann J; Ivanovich PDept of Nephrology, University Medical Center, Ljubljana, Slovenia

Heparin and saline are commonly used to fill hemodialysis central venous catheters to prevent their thrombosis during the interdialytic period. The purpose of this prospective clinical study was to evaluate whether replacing heparin with citrat or polygeline could ensure satisfactory catheter funvtion without exposing patients to the risk of systemic heparinization. 30 end-stage renal disease (ESRD) patients with subclavian or jugular single lumen catheters as temporary vascular access for hemodialysis were enrolled. After the insertion of the catheters, the patients were randomly assigned to one of the following three filling groups: Group A, heparin; Group B, citrate; Group C, polygeline. Before each dialysis, the filling solution was aspirated and clot volume, if present, was measured. The catheter usage time and the clot volume were 23 24 days and 0.052 0.035 ml in Group A, 51 36 days and 0.059 0.032 ml in Group B, and 32 10 days and 0.056 0.038 ml in Group C, respectively. Our results indicate that citrate or polygeline can replace heparin effectively as a filling solution for single lumen temporary hemodialysis catheters.

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ASN (abs) Vol 10, Sep 1999; pp 218-219

Clinical Results of the German DIALOCK Access Study; A New Subcutaneous Port System and a Novel Antimicrobial Lock Solution.Klaus Sodemann1, Beate Feldmer1, Hans D. Polaschegg3, Peter Thon2, Iris Lubrich-Birkner1, Joerg Baumert1.1Dialysis Center Lahr/Ettenheim, Lahr, Germany; 2Bad Hersfeld, Germany; 3Kostenberg, Austria

Since 1997 a subcutaneous port system has been available (DIALOCK, Biolink Corp., USA). The device has tow silastic catheters. A pilot trial started in Germany to examine the reliability of the device and avoidance of infection by prophylactic use of an antimicrobial “lock” solution. The composition was developed by one of the authors (K.S.). It contains Taurolidine, which is a safe antimicrobial and does not induce bacterial resistance.From June 1998 thru May 1999, 38 patients were recruited in 14 dialysis centers (20 female, 18 male) with a mean age of 65 12 yr. The implantation was done by nephrologists. The preferred vessel for insertion was the right int. jugular vein, but all other large veins were used. All patients had a high co-morbidity, 18/38 were diabetics. Since the start of the trial 3 patients died of cardiac causes, 1 patient had recovery of renal function, 1 patient had the port electively removed after maturation of an AV fistula.The DIALOCK is punctured with 2 special needles. After skin disinfection with alcohol the general procedure is similar to the punctue of a graft. When removing the needles the bleeding time is less than 3 minutes.The total duration of DIALOCK use is 6’612 days. The device was able to be used for all planned HD sessions (n=2’991). In 5 patients we ovserved episodes of bloodstream related catheter infections. 4 out of these 5 had a secondary wound healing, 2 out of these 4 had the device removed because of subcutaneous pocket infection. The rate of infection was 0.75/1000 days.The prophylactic antimicrobial lock seems to reduce the rate of infection. Even the salvage of the port was possible 3/5 septicaemic patients. Compared to implanted catheters, the innovative DIALOCK system is an improvement in the care of hemodialysis patients.

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EDTNA/ERCA Abstracts 1999 XXV; 53

Flow dynamics and safety aspects of a novel transcutaneous blood access deviceH.D. Polaschegg (1), F. Prosl (2)1 Medical Devices Consultant, Köstenberg, Austria; 2 Biolink Corp., Middleboro,MA, USA.

A novel blood access device that connects to central venous catheters has been developed. A metal port is placed under the skin similar to the ports already in use for drug infusion. The port consist of a titanium body ~50 x 30 x 12 mm and weighs 38g. For dialysis the port is accessed with special cannulas. Valves in the port are opened when the cannulas are inserted and close automatically when the cannulas are removed. The flow path created by the cannulas, the port, and the catheter is smooth without dead space, sharp bends and turbulent zones. Measured flow pressure curves corrobate the theoretical prediction of smooth flow. In-vitro endurance tests show valve lifetimes of more than 5 years. Risk analysis shows that most risks common with catheters but also with fistulas and grafts are avoided or significantly reduced. The risk of undetected blood loss to environment related to cannulas slipping from fistulas is largely reduced because of the pressure drop in the catheter. Because of the locking mechanism cannulation is similar with all patients and the risk of puncturing through a vessel is avoided. A mix up of arterial and venous puncture sites does not result in high recirculation because the catheter Ups are placed in the right atrium. The risk of air embolism and blood loss related to catheters is avoided because of the transcutaneous placement of the port and because of the integrated valves. The smooth flow path can be completely rinsed with saline after use and filled precisely with a locking solution. Risk analysis and in-vitro evaluation show that the common mechanical failures leading to a blood loss or air embolism and to clotting are avoided and that the port described is a safe and reliable device. Clinical experience so far is exellent and will be presented in another paper.

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EDTNA/ERCA ABSTRACTS 1999 XXV;27

Preliminary results of a new subcutaneous port-system for haemodialysis combined with heparin-free antibacterial lock solutionKlaus Sodemann, Beate Feldmer, Hans D. Polaschegg, E. Keller, H. Löffler, B. Friedrich, Iris Lubrich-Birkner, Joerg BaumertDialysis Center Lahr/Ettenheim, Lahr, Germany.

An increasing number of haemodialysis (HD) patients need an implantable permanent venous catheter due to peripheral vessel exhaustion. In addition to the risk of tunnel infection the disadvantage of body hygiene is obvious. A new implantable port-system is an innovative approach to vascular access. The subcutaneously implanted titanium device is connected with two 12 French silastic catheters introduced with the tips into right atrium. The valves of the port are opened by two special needles allowing a blood flow af about 300 ml/min. In a prospective multi centre pilot trail with approval of the ethics committee starting June 1998 16 ports were implanted by an experienced nephrologist after informed consent in 10 female and 6 male patients (mean age 68 9yr) until November 1998. 9/16 patients were diabetics, the inclusion criterion for the study was vessel exhaustion. 8/16 patient suffered from severe congestive heart failure, all had a high comorbidity. 9 patients started HD just after implantation, the other patients were on chronic HD and switched from catheter to port ( 4 pat. Exchange by guide wire). No peri-operative complications occurred. Preferred vessel was the right int.jug. vein(IJV, n=11), the other were: left IJV (n=4), left (n=2) and right (n=1) subclavian vein. Total duration of the device use is 1528 days; in 4 pat. 5 months. The ports could be used for all planned HD sessions (n=776).To avoid intraluminal contamination of the device a recently developed mixture of an antibacterial lock was applied between the sessions and removed before next treatment. This solution consists of taurolidine, a unique antiseptic substance with efficacy even against fungi and multi resistant germs. Combined with citric acid and sodium citrate, clotting of the catheters is prohibited and application of heparin unnecessary.2 Episodes of bacteriaemia (staph. Aureus) were obseerved during the study period and successfully treated without loss of the device (1.3 infections/1000 days). Due to deterioration of blood flow 10’000 units of urokinase were applied as a lock after treatment (n=34, resp. 4.4%) with good efficacy.

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This innovative vascular access is well accepted by the patients and seems to be superior to implanted catheters. It could even be an alternative to grafts and patients on home-HD due to its safety.

EDTA Meeting June 2001 Poster Presentation

FROM TUNNELED CATHETERS TO DIALOCK PORT, A FURTHER STEP IN DEALING WITH VASCULAR ACCESS PROBLEMS.Quarello F., Forneris G., Pozzato M., Formica M., Vallero A., Cesano G.Nephrology & Dialysis Unit. Giovanni Bosco Hospital, Torino, Italy

Tunneled central venous catheters (TCVC) have become an important new vascular access (VA) alternative for chronic hemodialysis (HD). Since 1993 we implanted 281 TCVC with satisfactory results. Nevertheless, infections and thromboses led to failure of 7.5% abd 5.5% of the catheters, respectively. From 1.Feb 2000 up to 31. Jan 2001 we chose a Dialock Port (Biolinlk Corp., USA), a new totally implanted VA, for 21 HD patients [12M/9F, mean age 626yrs (37-78)], in 5 cases as first VA. On average, the devices were punctured 3.54 days after implantation (0-19) and used thereafter for 170102 days (29-365). The lock solution was 3.8% citrate. One chamber was removed after 1 month due to central vein thrombosis. The QB prescribed was obtained in 95.2% of the sessions. To restore an optimal blood flow, a shortening of the catheter was carried out in 3 cases. Mean venous and arterial pressures at Qb 300 ml/min.130.9 and –151.9 mmHg, respectively. 4 episodes of bacteremia (1.1 per 1000 pt-days) occurred in 2 patients: 1 patient developed an endocarditis and vertebral osteomyelitis, but recovered completely after 4 months of antibiotic therapy and catheters exchange, while maintaining the device; in the other a severe sepsis resulted in the removal of the Dialock. 3 positive lock cultures occurred in other pts and were treated by lock antibiotic therapy. Slight difficulties in needle placement were recorded in 6.4% of the sessions but only in 2 cases the dialysis was delayed. Local skin over the chamber is free of lesion in all cases but one. 3 patients were started on nocturnal HD (7hrsX3) and felt it was easier to sleep with their arms free and both needles safely anchored to their chest. 1 patient was able to restart home dialysis after a short training with his new device. In conclusion, besides the reduction of infection and thrombosis rates with respect to TCVC, a totally implantable device could offer an advantageous alternative in particular settings (i.e. nocturnal, daily and home HD), where a reliable vascular access is of critical importance.

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ANGIOACCESS FOR HEMODIALYSIS ABSTRACT, 1999,208.

A NEW ANTI-INFECTIVE LOCK SOLUTION APPLIED TOGETHER WITH A SUBCUTANEOUS PORT SYSTEMKlaus Sodemann, Beate Feldmer, Hans D. Polaschegg, Thon P., E. Keller, H. Löffler, Wizemann V., Iris Lubrich-Birkner, Joerg BaumertDialysis Center Lahr/Ettenheim, Lahr, Germany.

The risk of sepsis is the Achilles’ heel of implanted permanent venous catheters. The lock technique with antibiotics is not widespread until now and cannot avoid fungal infections. Recently an anti-infective lock solution was developed for the application together with a new port-system. The suvcutaneously implanted titanium device is connected with two 12 French silastic catheters introduced with the tips into the right atrium. The valves of the port are opened by two special needles allowing a blood flow up to 300 ml/min.The new filling solution consists of taurolidine, a unique antiseptic substance even with efficacy against fungi and multiresistant germs. Combined with citric acid and sodium citrate clotting of the catheters is prohibited and application of heparin unnecessary. The mixture is absolutely atoxic and even can be injected intravenously without any harm. In order to avoid intraluminal contamination of the device and catheters the anti-infective lock is applied between dialysis sessions and removed before next treatment by aspiration.In a prospective multicenter pilot trial with approval of the ethics committee starting June 1998, 28 ports were implanted by 3 experienced nephrologists after informed consent in 18 female and 10 male patients (mean age 68 (yr.) until January 1999. 8 dialysis centers are participating in the study. The inclusion criterion was vessel exhaustion. 8128 pat. Suffered from severe congestive heart failure, all had a high comorbidity. Start of hemodialysis (HD) just after implantation was in 13 patients, the other patients were on chronic HD, and 5 pat. switched from catheter to port (exchange by guidewire). Preferred vessel was the right int. jug. Vein (IJV, n=16), other were: left IJV (n=4), both subclavian veins (n=8), and the ext. jug. Vein in 1 pat. Total duration of the device use is 3,068 days, in 9 patients more than 6 months. The puncture of the port was done without any special procedure after skin disinfection with alcohol. Despite the fact that 4 pats. had a septicaemic episode due to catheter infections just before or during the time of implantation no infection of the device occurred in the further course. 2 episodes of blood stream related infections with Staph. aureus were observed during the study period and successfully treated without loss of the device ( 0.65) infections 11’000 days). The one patient developed a spondylitis and had an implanted catheter 4 months before the start of the study, the other pat. with the positive blood culture had an immuno-suppressive therapy due to M.Crohn.

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The low infection rate without loss of this innovative vascular access seems to be a progress in the treatment of patients with vessel exhaustion compared to implanted catheters.

ANGIOACCESS FOR HEMODIALYSIS ABSTRACT, 1999.195.

INVESTIGATION OF THE EFFECT OF CATHETER SIDE HOLES ON FLOW PROPERTIES AND OUTWASH OF THE LOCKING SOLUTIONPolaschegg HD., Sodemann K., Estabrook B.Medical Devices Consultant, Köstenberg, Austria; Dialysis Center Lahr/Ettenheim, Germany; Biolink Corp. Duxbury, MA, USA

Clinical observation, motivated us to investigate the flow properties of the Canaud catheter. The Canaud catheter investigated is a soft silicon catheter with 2.1 mm inner diameter and 6 side holes of approx. 1.3 mm diameter spaced at equal distances 1.3 mm and 60 apart in a screw like fashion. Clinically, clots of up to 3 cm length are found during aspiration ot the locking solution from the catheter. We suspected that this lot comes from the catheter tip the length being the distance between the first side hole and the catheter tip. Also, clinically high pressure drops are recorded occasionally and the arose if closure of the catheter tip or of one or more side holes could be the cause. Two different in-vitro and one in-vivo experiment were done to study the problem: 1. In-vitro pressure-flow with one or more side holes and/or the catheter tip closed. From this curves the directional pressure-flow asymmetry was calculated.2. In-vitro tests of the influence of density and osmolarity of the locking solution on the loss of the locking solution from the catheter tip. This experiment was repeated in-vivo by injecting a contrast solution under X-ray observation. Results: 1. A rapid loss of the locking solution occurs if the density is different from the density of the blood. This can be observed in-vitro even without flow outside the catheter. No influence of the osmolarity has been found.2. The catheter side holes do not contribute to flow. There is no relevant increase of the pressure drop as long as either the tip hole or at least 2 side holes remain open. With one side hole only open the pressure drop increases by 20% compared to any other combination. The flow direction asymmetry of the pressure drops is lowest when all side holed are closed. This indicates that the side holes cause some turbulence in aspiration mode.Conclusion: 1. Side holes facilitate the loss of the locking solution from the catheter tip. This process takes a few minutes only. The Tip is therefore not protected against clotting and biofilm growth. 2. Side holes do not reduce the pressure drop. The high pressure drops

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observed occasionally are the result of the almost complete occlusion of all holes and/or of other causes, e.g. clots in other parts, fibrin, fleets or kinks.This conclusion and initial good clinical results with two parallel single lumen catheters without side holes motivate us to use catheters without side holes for patients who have no other alternative for blood access.

ERA/EDTA 1999, ABSTRACT

FEMORAL VEIN AS AN UNUSUAL PERMANENT ACCESS WITH A NEW SUBCUTANEOUS PORT SYSTEMK. Sodemann, A. Sodemann, B. Feldmer; Community Hosp. Ettenheim, GermanyH. Polaschegg, Köstenberg, AustriaW. Erd; Community Hosp. Zell a. See, Austria

Introduction: Obstruction of the upper vena cava is an increasing problem after long term cannulation by indwelling catheters. Failure of vascular access even in young patients may limit the survival with kidney transplantation of CAPD.Due to the risk of infection the insertion of permanent catheters into the femoral vein is unusual. This desperate case describes the successful implantation of a titanium Port (Dialock) in the thigh.Conclusion: The Dialock in this placement may be an alternative in patients with an obstruction of the vena cava superior. Now, in the German Dialock pilot trial 5 patients have got an access in this position.

ERA/EDTA 1999; Abstract

AVOIDANCE OF INFECTION OF A NEW SUBCUTANEOUS PORT SYSTEM BY AN ANTI-INFECTIVE LOCK SOLUTIONKlaus Sodemann, Beate Feldmer, Hans D. Polaschegg, Thon P., E. Keller, H. Löffler, Wizemann V., Iris Lubrich-Birkner, Joerg Baumert, D. KissDialysis Center Lahr/Ettenheim, Lahr, Germany.

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Conclusion: Compared to the disadvantages of catheters the port system allows bathing and is very safe. Combined with the new lock solution the risk of infection is low and allows a puncture technique similar to a graft. Lifetime of the device needs to be established.

Blood Purification 2001; 19:251-254

Two Years’ Experience with Dialock and CLS (A New Antimicrobial Lock Solution)K. Sodemann, B. Feldmer; Community Hosp. Ettenheim, GermanyH. Polaschegg, Köstenberg, Austria

Discussion: Safety concerns and high complication rates have caused catheters to be regarded as temporary or last resort blood access. Potentially fatal risks related to central venous catheters include air embolisme, severe blood loss and electric shock. These specific risks have been substantially eliminated by the inherent design and implantation of Dialock.The complications of infection have been quite low in this study. Catheter-related infection or bacteremia was less than 0.3 episodes per 1000 catheter days of usse, which is considerably below recent reviews of catheter studies. Schwab and Beathard reported rates of 4 episodes per 1000 days and Canaud reported 3.5 episodes per 1000 days with permanent catheters.Pocket infection in this study were 0.8 episodes per 1000 days. This rate is lower than analogous catheter exit site infections reported as 1.8 episodes per 1000 days when the site is protected with mupirocin in the treatment group and 14.3 in the control group.We have observed that the incidence of pocket infection has been reduced in the last 10 months of the study following greater attention to accessing technique. Currently, we strive to treat all infections to avoid removal of Dialock and now have a 77% eradication of infection over the full study. In addition, we have instituted an infection prevention strategy that has eliminated pocket infections in all of the currently enrolled patients over the last 4 months.Our experience with the Dialock/CLS has been gratifying. We believe the Dialock system is ready for widespread evaluation by clinicians to further elucidate its role in hemodialysis access.

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Klinische Erfahrungen mit DIALOCK

Sabine Zitta, K. Tiesenhausen, J. Roob, S. Horn, G. Wimsberger, G. Enzinger, G. Leitner, P. Krisper, J. Horina, H. HolzerKl. Abt. für Nephrologie, Medizinische Universitätsklinik und Kl. Abt. für Gefässchirurgie, Chir. Universitätsklinik, Graz, Austria

Aufgrund des immer älteren und multimorbideren Patientengutes werden weltweit zunehmend zentrale Venenkatheter als permanente Gefässzugänge für die chronische Dialysebehandlung verwendet.Seit 1996 stehen subcutan implantierte Dialyse-Portsysteme zur Verfügung. Am 2. November 1999 wurde in Oesterreich der erste Dialock in Graz implantiert. Insgesamt konnten bisher 7 Patienten mit diesem Portsystem in unserem Klinikum versorgt werden. Entscheidend für die Wahl des Dialocks als zentraler Gefässzugang bei diesen chronischen Dialysenpatienten waren:- Progredienz einer dilatativen Cardiomyopathie (n=2)- Rezidivierende Shuntthrombosen (n=2)- Ausgeprägtes Steal-Syndrom mit Fingernekrosen (n=1)- Paranoia mit mehrmaliger Entfernung der Dialysekatheter durch den Patienten (n=1)- Diab. Spätsyndrom mit schwerster diabetischer Mikro- und Makroangiopathie, St. n. Oberschenkelamputaion beidseits (n=1)

An 3 Patienten musste innerhalb einer Woche nach Port-Implantation eine chirurgische Revision vorgenommen werden: Einmal aufgrund eines ausgedehnten Hämatoms in der Port-Tasche, in einem Fall war wegen Dialock-Dysfunktion aufgrund zu langer Katheter die Kürzung derselben notwendig. Bei einer besonders adipösen weiblichen Patientin musste der lege artis implantierte Port aufgrund technischer Schwierigkeiten bei der Punktion in seiner Lage korrigiert werden. Davon abgesehen war die Funktion der Ports in Hinblick auf Blutfluss und Dialysequalität als ausgezeichnet zu beurteilen.Im Lauf des Beobachtungzeitraums von 768 Dialock-Behandlungstagen traten 5 mal vorübergehende Dysfunitionen auf, die sich mittels Lyse (Urokinase) beheben liessen. In einem Fall musste der Dialock nach 6 Monaten wegen Portinfektion und Sepsis innerhalb

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von 24 Stunden entfernt werden. Die Akzeptanz dieses Zugangs wurde von den Dialysepatienten als sehr gut (n=2), gut (n=4) oder befriedigend (n=1) bewertet.Nach unseren bisherigen Erfahrungen bewährte sich der Dialock im Einsatz bei chronischen Dialysepatienten mit schlechtem Gefässstatus und Herzinsuffizienz.

International Conference on Nosocomial and Healthcare-Associated Infections, March 5-9 2000, Atlanta, GA. Poster

EFFICACY OF THE BIOLINK CATHETER LOCK SOLUTION (CLS) FOR DIALOCK HEMODIALYSIS ACCESS PORT AND CATHETERS- AN IN VITRO MODELLeonard Mermel, DO, ScM, AM (Hon); Stephen Parenteau, MS, MT (ASCP)

Conclusions: The Biolink Catheter Lock Solution containing taurolidine prevents colonization of Dialock hemodialysis access ports and catheters after overnight incubation of ports and catheters inoculated with 50-600 CFU/ml of gram-positive bacteria, gram-negative bacteria or Candida. Preservative-containing heparin flush solution was unable to inhibit growth in the ports and catheters under the study conditions. The Biolink catheter lock solution hold great promise as a novel strategy to prevent serious intravascular catheter related infections.

101st General Meeting of the American Society of Microbiology, May 20-24, 2001, Orlando, Florida

ERADICATION OF MICROBIAL BIOFILMS WITH AN ANTIMICROBIAL CATHETER-LOCK SOLUTIONM.W. Mittelman, M. Pelak; Altran Corp., Boston ; C. Shah, Biolink Corp., MA; J.W. Costeron, Montana State Univers., Bozeman, MT

Abstract: Infections associated with vascular access systems lead to increased morbidity and mortality rates among patients suffering from end stage renal failure and other conditions requiring long-term indwelling catheterization. As with many kinds of implantable devices, the development of bacterial and fungal biofilms recalcitrant to antibiotic therapyies often leads to the loss of otherwise patent vascular access systems. We evaluated the efficacy of a new antimicrobial catheter-lock solution, CLS, against bacteria and a yeast colonizing silicone catheter material. Biofilms were developed under dynamic-flow conditions in modified Robbins devices with Mueller-Hinton broth containing 6% newborn calf serum. Following a 72h colonization period, axenic biofilms were treated for 24h with either CLS, or 5000 units/ml heparin under static conditions, then quantitatively recovered. The viability of bloodstream isolates of

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Staphylococcus aureus, Staphylococcus epidermidis, or Enterococcus faecalis biofilm bacteria exposed to the CLS solution decreased significantly ( P< 0.001 ) compared to the heparin solution, with log reduction values of 6.0, 4.8, and 4.6, respectively. Significant reductions in viable biofilm numbers were also seen with Pseudomonas aeruginosa and Candida albicans. This novel catheter-lock solution was effective at killing a significant microbial biofilm challenge under in vitro conditions designed to simulate the in situ catheter environment. The data suggest that CLS will prevent microbial colonization of silicone surfaces.

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