Vascular access - 1

POSITIVE QB STRESS TEST EARLY DETECTS INFLOW STENOSIS OF NATIVE ARTERIOVENOUS FISTULAS AND PREVENTS VASCULAR ACCESS FAILURE

Abstract

INTRODUCTION AND AIMS:

The gold standard method to assess vascular access function is monitoring its blood flow to prevent access thrombosis. Several methods are available for measuring the access flow: ultrasound dilution technique and Doppler imaging are the most used, but they are often time expensive and not always available as first line tests. Bonforte et al proposed the QB stress test (QBST) to monitor A-V fistula blood flow. This standardized simple test is performed raising patients' arm from the normal (0°) to the up position (90°) during hemodialysis treatment at different pump blood flow: 400, 300, 200 and 100 ml/min. In the raised position, the A-V blood flow decreases of about 300 ml/min (range 250-400 ml/min). Positive test occurs when the aspiration pressure falls below -300 mmHg at pump blood flows of 200 and 100 ml/min, suggesting that the access blood flow is decreased probably because of an inflow stenosis.The aim of our study was to validate in a cohort of 90 hemodialysed patients (M/F= 53/37, aged 69 ± 1.26 years) the efficacy of QBST to monitor native A-V fistulas blood flow in a surveillance period of 2 years (2007-2008).

METHODS:

We tested 20 distal, 44 middle arm and 26 proximal A-V fistulas. QBST were regularly performed bimonthly for each patient. The surveillance consisted of the early detection of an inflow stenosis before A-V failure to prevent thrombosis. Positive QBST patients were submitted to a Doppler ultrasound.

RESULTS:

The group of patients with a negative QBST had an events incidence rate of 2.5/100 pz/year (4 thrombosis, 4.4% in two years), while those with a positive QBST had an events incidence rate of 42/100 pz/years (11 stenosis, 12.2 % in two years); Chi²= 50.5, p<0.00001. Figure 1 shows that the fistulas with a positive QBST had a free events survival of 5% at 24 months, while negative QBST fistulas had an events free survival of 87% at 24 months.

The Cox regression analysis showed that the Hazard ratio risk of an inflow stenosis in positive QBST fistulas was 50 (z= 3.73, pz<0.001). In all positive QBST patients, Doppler ultrasound always confirmed the presence of an inflow stenosis. All the stenosis were hemodinamically significative, except one, and required angioplasty or surgical intervention.

CONCLUSIONS:

Our observational study shows that QB ST is an usefull, low cost, simple and efficient method for A-V fistula surveillance. It could be used routinely as a first line test for the early screening of inflow AV fistulas stenosis to prevent vascular access failure.

THE ROLE OF HYPERINSULINISM IN PRIMARY ARTERIOVENOUS FISTULA FAILURE

Abstract

INTRODUCTION AND AIMS:

Increasing fistula maturation rates is still a challenge for nephrologists. A major problem with the arteriovenous fistula (AVF) is the high frequency of primary failure, either due to early thrombosis or lack of maturation. Because placing fistulae in more patients is recommended by the guidelines, it is expected to increase the risk of primary failure. Therefore we aimed to investigate the role of hyperinsulinism as a new factor in primary AVF failure which is strongly related atherosclerotic vascular disease.

METHODS:

Totally 75 patients (44 M, 31 F) with a recent diagnosis of ESRD uderwent a AVF creation by the same surgeon. The causes of ESRD were: DM(33.3%), HT(18.7%), urologic disorders (14.7%), unkonown (13.3%), and others (20%). The presence of thrill were recorded on first postoperative day. Functioning access was defined as successful cannulation with a minimum blood flow of 250 ml/min for at least a complete dialysis treatment after 4 weeks of AVF creation. Fat Mass were measured by leg-to-leg bioimpedance. The significant factors differed between patients with and without primary AVF failure, were included in logistic regression analysis to demonstrate independent predictors of primary AVF failure.

RESULTS:

Primary AVF failure (pAVFF) was detected in 18 (24%) of patients. Patients with and without primary AVF failure were compared in Table 1. The remaining parameters (age, sex, lipids, BMI, waist circumfence, serum calcium, phosphorus, Parathyroid hormone, hemoglobin, blood pressure, arterial and and vein diameter, site of AVF were similar).

The logistic regression analysis of preoprative parameters revealed following OR and 95% CI values: HOMA-IR 1.423 (1.120-1.808) (p=0.004), serum albumin 0.134 (0.021-0.843) (p=0.032), Fat mass 1.090 (0.870-1.367) (p=0.45), Daily proteinuria 1.745 (1.042-2.924) (p=0.034). When presence of postoperative thrill on AVF was added to analysis we found that HOMA-IR and serum albumin remained as independent predictor of primary AVF Failure.

CONCLUSIONS:

To our knowledge, there is no previous study investigating the role of hyperinsulinism in pAVF failure. This study indicates that insulin resistance may be a metabolic reason of pAVFF. We also observed that hypoalbuminemia is an undetermined risk factor and warrants further investigations.

SAFETY AND EFFICACY OF PRIMARY THROMBO PROPHYLAXIS PROTOCAL (PTPP) WITH HEPARIN AND CLOPIDOGREL FOR ARTERIO VENOUS FISTULA (AVF) FAILURE IN ADULT DIALYSIS PATIENTS WITH MULTIPLE RISK FACTORS

Abstract

INTRODUCTION AND AIMS:

Native AVF are widely recognized and recommended as the preferred primary vascular access (VA) for dialysis due to their long term patency and low of complication rate. How ever this kind of VA has a relatively high early failure (early thrombosis or non maturation) especially in certain high-risk groups. The aim of our study is to examine the safety and efficacy of PTPP in such patients.

METHODS:

In this prospective study from 2001 to 2007, a total of 76 patients with clinical conditions recognized as risk factors for primary failure of AVF were analyzed. Risk factors identified were – Diabetes mellitus, age >60 years, left ventricular dysfunction with EF <40%, orthostatic hypotension, peripheral vascular disease, dialysis dependency at the time of AVF construction, hyperhomocystenemia and erythropoitin usage. Patients were divided in to 2 groups. Group 1(G1) -Historical group i.e. no treatment, with 35 patients and Group 2(G2) –on PTPP, with 36 patients. Our PTPP was – unfractionated heparin 100 IU /Kg subcutaneously 2 hours prior to the surgery followed by 50 IU/Kg/Day for 4 weeks (not given on the day of dialysis) and Tab.Clopidogrel 75 mg per day, starting 48 hours before surgery and to continue for 1 year. Histopathological (HPE) of the specimens from the radial artery (RA), brachial artery (BA) and venous segment was done in all. Primary out come measure was fistula patency with adequate blood flow at 1 year and secondary out come measure were AVF maturation time and new onset gastro intestinal (GI) bleeding during the study period. Standard statistical methods were used.

RESULTS:

The average age, number of males, and percentage of diabetics in G1 and in G 2 respectively were -65.97 years (60-72) & 66.02 years (60-72), 25&s24 and 21 (60%)&23 (63.89%).Five (14.28%) from G1 and 7 (19.45%) from G2 had at least one previous AVF failure. HPE of vascular specimens – severe atherosclerosis with calcified plaques and pre-existing intimal hyperpalsia (IH) in 71.42% of G1 and 72.23% of specimens of G2.Severe eccentric neo intimal hyperpalsia of venous segment specimen was present in all redo AVFs. Thirty-one patients of G1 and 33 from patients G2 completed the study.Fistula patency with adequate blood flow at 1 year in G1 was 29.03% and that of G2 was 84.84%. The average fistula maturation time in-G1 was 12.45 weeks (range 10-17) while in-G2 was 9.58(range 6-14). New on set GI bleeding during the study period noticed in 5.7% (n-2) of G1 and 8.34%(n-3) of G2 patients.

CONCLUSIONS:

This study showed that our PTPP is highly effective in prevention of early AVF failure in high-risk groups [Fistula patency with adequate blood flow at 1 year- 84.84%(PTPP group) Vs29.03% (No treatment group)]. It also reduces the fistula maturation time significantly[9.58 weeks (PTPP group) Vs11.42 weeks (No treatment group)].PTPP is also safe as there age no sibnificant bleeding coplications [New onset GI bleeding 8.33% (PTPP group) Vs 5.7% (No treatment group)].

THE INTERACTIVE EFFECT BETWEEN LENGTH POLYMORPHISM OF HEME OXYGENASE-1 GENE AND FAR INFRARED THERAPY ON ACCESS FLOW AND UNASSISTED PATENCY OF AV FISTULA IN HD PATIENTS

Abstract

INTRODUCTION AND AIMS:

A longer length polymorphism with GT repeat number [(GT)_n] <30 in the heme oxygenase-1 (HO-1) gene and far infrared therapy (FIR) were associated with better prognosis of arteriovenous fistula (AVF) in hemodialysis (HD) patients. This study is aimed to determine the interaction between HO-1 genotype polymorphism and FIR therapy on access flow (Qa) and patency of AVF in HD patients.

METHODS:

HD patients were randomized into the control group and the FIR group who received 40 minutes of FIR therapy during HD thrice a week. Hemodynamic parameters were measured by the Transonic HD₀₂ monitor during HD. The Qa₁/Qa₂ and Qa₃/Qa₄ were defined as the Qa measured at the beginning/ at 40 minutes later in the HD session prior to the initiation and at the end of the 1-year study respectively. A WS^TM TY101 FIR emitter was used for FIR therapy. Its generated wavelengths range between 3 and 25 μm (a peak between 5 and 6 μm). The (GT)_n repeat at the promoter region of the HO-1 gene was determined by PCR. L (long) allele means [(GT)_n] ≥30 and S (short) allele means [(GT)_n] <30, therefore contributing to S/S, S/L and L/L genotypes.

RESULTS:

Totally 127 patients finished the study and the data are listed in table 1. (1) [Δ(Qa₄-Qa₂) - Δ(Qa₃-Qa₁)] represents the thermal effect of 40 minutes of FIR on the change of Qa. (2) Δ(Qa₃-Qa₁) represents the non-thermal effect of one year of FIR on the change of Qa. (3) Δ(Qa₄-Qa₂) represents the sum of the thermal effect (for 40 minutes) and the non-thermal effect (for one year) by FIR on Qa.

CONCLUSIONS:

FIR therapy can improve the function of AVF in HD patients, with the best protective effect in those with S/S genotype of HO-1.

SYMPTOMATIC CENTRAL VEIN STENOSIS SYNDROME ASSOCIATED TO CUFFED TUNNELED HEMODIALYSIS CATHETERS: A CANADIAN SINGLE CENTER EXPERIENCE

Abstract

INTRODUCTION AND AIMS:

Cuffed tunneled catheters are one of the vascular accesses frequently used in hemodialysis. Symptomatic central vein stenosis remains one of the feared complications associated with such catheters.The aim of our study was to describe the occurrence of symptomatic central vein stenosis in our hemodialysis center and identify some factors involved.

METHODS:

From January 2008 to November 2008, all cases of symptomatic central vein stenosis that occurred in our facility were retrospectively identified and evaluated. The exact position and length of stay of previous and actual tunneled catheters were noted. Location of fistulae and grafts and their relation to the development of symptoms were also recorded.

RESULTS:

Two hundred and sixty-five patients are currently undergoing hemodialysis in our center. Out of these, 86 (32%) patients are chronically using cuffed tunneled catheters for several reasons. During the observation period, 12 (14%) patients presented with a symptomatic central venous syndrome. Internal jugular tunneled catheters have been implicated in 8 (67%) of these patients while subclavian tunneled catheters were responsible in 4 (33%) patients. For 9 (75%) patients, the symptoms developed within weeks following the creation of an ipsilateral peripheral hemodialysis access. Brachiocephalic and radiocephalic fistulae were responsible in 6 (67%) and 1 (11%) cases respectively. A brachioaxillary graft was involved in the 2 (22%) other cases.

CONCLUSIONS:

As reported in the literature, symptomatic central vein stenosis syndrome in hemodialysis is a relatively frequent complication of the use of cuffed tunneled catheters.Although the internal jugular approach is preferred for catheter placement over subclavian route, this approach was linked, in our study, to significant symptomatic stenosis complications. Moreover, in most cases, the creation of a peripheral access, whether fistula or graft, predisposed to the development of symptoms in an otherwise occult ipsilateral central stenosis.

A NOVEL VENOUS DIALYSIS NEEDLE IMPROVES THE ADEQUACY OF DIALYSIS

Abstract

INTRODUCTION AND AIMS:

We have previously demonstrated in vitro that the jet that exits the current venous dialysis needle (CVN) increases the velocity (Ve) of the flow post needle 100 times and creates high turbulence (Tu), that a new venous needle (NVN) decreases the Ve of the flow threefold and the Tu sixfold in vitro, that in sheep the NVN causes less damage to circulating blood cells (CBC) than the CVN during hemodialysis(HD) and that the NVN causes less damage to circulating blood cells in humans. The NVN has three jets: two through lateral openings and one through the distal end, unlike the CVN which has one jet. The <Ve and <Tu caused by the NVN is expected to decrease endothelial damage, intimal hyperplasia, stenosis and thrombosis of the vascular access, and damage to CBC in patients.

METHODS:

The current study in which 16 patients with ESRD were studied was performed to demonstrate whether the NVN causes equal changes in venous needle pressure and urea reduction ratio (URR) than the CVN. Each patient received two similar HD, one using a CVN 15G and the other using a NVN 15G. The mean duration of dialysis, blood flow rate, and venous pressure were measured and the urea reduction ratio (pre BUN-post BUN/pre BUN x 100) were calculated. Paired Student t test was used to compare the means of the difference between the needles.

RESULTS:

CONCLUSIONS:

This study demonstrated that the hemodynamic changes caused by the NVN cause a higher URR than the CVN which is a significant clinical advantage over the CVN. Additional patients are under study.

DISCLOSURE:

Shareholder: Biomedical Enterprises Inc,

ROLE OF ULTRASONOGRAPHY IN INSERTION OF FEMORAL DIALYSIS CATHETERS – A SINGLE-CENTER PROSPECTIVE RANDOMIZED TRIAL

Abstract

INTRODUCTION AND AIMS:

Insertion of dialysis catheters (DC) is an integral part of management of renal failure patients. We aimed to study the role of ultrasonography (USG) in improving success rates and minimising complications during femoral vein dialysis catheter insertion.

METHODS:

This was a randomized prospective study on 110 patients requiring femoral dialysis access placement, in a tertiary care hospital. Patients were randomized into two groups(55 patients each) based on technique of access placement- USG guided and landmark (blind) technique. Data were collected on patient demographics, operator experience, and side of insertion. Outcome measures included successful insertion of the catheter, number of attempts, and complications.

RESULTS:

Both the groups were comparable regarding age and sex of patients, operator experience and side of cannulation. Femoral vein cannulation was successful in 98/110 patients (89.1%) with success rate of 80% (44/55) using landmark technique and 98.2% (54/55) under USG guidance (p = 0.002). In the landmark group 54.5% catheterizations could be accomplished in first attempt as compared with 85.5% in the USG group (p = 0.000). Complication rate was 13/110 (11.8%), with 10 (18.2%) complications in the landmark group and 3 (5.5%) in the USG group (p=0.039).

CONCLUSIONS:

Ultrasound guidance can improve success rate, reduce number of attempts and decrease the complications related to femoral DC insertion.This technique should become standard practice,in the view of its obvious benefits in improving patient safety and reducing complications.

INTERVENTIONS TO PROMOTE ARTERIOVENOUS FISTULA MATURATION WORSEN SHORT AND LONG TERM FISTULA OUTCOMES

Abstract

INTRODUCTION AND AIMS:

Primary failures due to thrombosis or inadequate maturation remains a significant barrier in improving prevalence of AVF use. With the significant emphasis to improve the incidence and prevalence of AVFs, more interventions are required to promote AVF maturation and maintain patency of previously functional AVFs. The objective of this study is to study both short-term and long-term survival among AVFs which require interventions to promote maturation and maintain patency compared to those that did not require interventions to promote maturation.

METHODS:

A retrospective review of University of Cincinnati hemodialysis patients who received autologous AVFs from January 2002 to March 2008 was performed. In total, we identified 127 patients during this period. 74.8% were male, 69.3% blacks, 53.5% diabetics, 24.4% had peripheral vascular disease, 70.1% with upper arm accesses, and 42.5% requiring intervention before AVF maturation. Cumulative survival was defined as the time from AVF creation to complete AVF failure. Primary (unassisted) patency was defined from the time of AVF creation until first AVF intervention to maintain patency. Postintervention secondary patency was defined as the interval from the time of intervention until complete AVF failure. Kaplan-Meier survival analysis was used to model access patency, and log rank test used to compare the patency of patient subgroups.

RESULTS:

There were no demographic differences between patients who had an intervention before AVF maturation and those who did not. Patients with interventions prior to AVF maturation compared to those without interventions had worse cumulative survival (mean survival 797 vs 970 days, p= 0.0044), postintervention secondary patency (median survival 390 vs 630 days, p= 0.036) and primary (unassisted) patency (median survival 96 vs 605 days, p=0.004), and longer time to first AVF use (median time 127 vs 85 days, p=0.0068).

CONCLUSIONS:

Patients with interventions prior to AVF maturation had worse short and long term outcomes, and required longer maturation time before first use. Interventions (surgical or endovascular) prior to AVF maturation may induce endothelial injury, inflammation, and oxidative stress, resulting in worse short and long-term AVF survival.

LIPECTOMY AS A NEW APPROACH TO SUPERFICIALIZATION OF DIRECT AUTOGENOUS FOREARM RADIAL-CEPHALIC ARTERIO-VENOUS FISTULAS FOR HEMODIALYSIS

Abstract

INTRODUCTION AND AIMS:

The depth of veins can discourage surgeons from creating radial-cephalic fistulas in obese patients. Elevation and tunnelization are the two techniques that have been described to superficialize these veins and make them accessible for cannulation. Unfortunately, such manipulation of veins has potential drawbacks. We report lipectomy, a new technique which removes subcutaneous fat and does not mobilize the vein.

METHODS:

This single center prospective study included 49 consecutive patients who underwent second-stage lipectomy after creation of a radial-cephalic fistula. The male/female ratio was 17/32, mean age was 54 years, 36% had diabetes, and the mean body mass index (BMI) was 31 ± 5.6 kg/m². Subcutaneous fatty tissues were removed after two transverse skin incisions under regional anesthesia and preventive hemostasis. Cannulation was first possible one month later, after clinical and color duplex ultrasound evaluation. All patients were then checked systematically every six months by the surgeon. Success rates were defined according to the ability to cannulate the vein in the lipectomy area within 3 months.

RESULTS:

Technical and clinical success rates were 96% (47/49). Mean vein depth decreased from 8 mm ± 2 mm to 3 mm ± 1mm according to duplex ultrasound follow-up. The mean vein diameter increased from 6 mm ± 1 mm to 8 mm ± 2 mm. In one patient tortuosity of the vein that was overlooked required conventional retunneling of the vein. One extensive subcutaneous hematoma resulted in fibrosis and loss of the fistula. One patient died before the fistula could be used.Primary patency rates were 71% ± 7% and 63% ± 8% at 1 and 3 years, respectively, and secondary patency rates were 98% ± 2% and 88% ± 7%.

Delayed complications were treated by surgery (n=8) or by endovascular procedures (n=10).

CONCLUSIONS:

Lipectomy is a safe, effective and durable approach to make deep arterialized forearm veins accessible for routine cannulation for hemodialysis in obese patients. It might even be hypothesized that incident obese dialysis patients will eventually have the highest proportion of radial-cephalic fistulas, since they often have distal veins that have been preserved from previous attempts at cannulation for blood sampling or infusion by their fat.

ALTEPLASE IN THE TREATMENT OF AV VASCULAR ACCESS THROMBOSIS

Abstract

INTRODUCTION AND AIMS:

The maintenance of vascular access patency is of major importance for achieving long-term survival and quality of life in patients on chronic hemodialysis (HD). Access failure is primarily due to thrombosis, which, when uncorrectable, leads to access loss. Thrombolysis with alteplase (recombinant tissue-type plasminogen activator; tPA) has been successfully used in occluded central venous catheters and arteriovenous (AV) grafts, but there are limited data regarding its efficacy in occluded autologous AV fistulas.Aim of our study was to retrospectively evaluate thrombolysis with tPA in the salvage of permanent vascular access.

METHODS:

All cases of thombosed AV grafts or fistulas that were thrombolysed with tPA in two HD units that use the same treatment protocols were recorded within the last 3 years. Thrombolysis outcome, patency time and re-occlusion were also recorded and analyzed in relation to patients' characteristics, laboratory parameters and pharmaceutical treatment.

RESULTS:

Thombolysis with tPA was applied in 40 cases, 13 fistulas and 27 grafts. Pain and local hematomas were the most common complications that were noted in less than 10% of cases. There was no statistically significant difference in thrombolysis outcome between AV fistulas or grafts; successful thrombolysis was recorded in 61.5% of fistulas and 51.8% of grafts. Elevated C-reactive protein (Odds Ratio per unit increase in log: 9.26, p=0.014) and early vascular thrombosis (Odds Ratio per month of functioning access in log: 0.1, p=0.016) were identified as independent risk factors for thrombolysis failure in multiple logistic regression analysis. In 54.5% of successfully thrombolysed accesses re-occlusion occured after a median functioning time of 6 months.

CONCLUSIONS:

Thrombolysis with tPA is a safe, non-invasive and effective method for the management of AV access occlusion that can preserve access patency or gain time until surgical repair minimizing the need for central venous catheters. However, more studies need to confirm our findings.

THE ARTERIOVENOUS "BI-FLOW" PTFE GRAFT FOR HAEMODIALYSIS

Abstract

INTRODUCTION AND AIMS:

The failure rates of arteriovenous (AV) polytetrafluroethylene (PTFE) haemodialysis grafts are very high, causing significant morbidity and costs. Within the first two years after implantation, stenotic occlusions occur in up to 97 %, mainly at the venous site of the anastomosis.The two main mechanisms of stenotic development comprise both intimal hyperplasia on the venous floor and pseudointimal development near the hood and toe regions of the graft. We invented a new venous anastomic graft design to potentially increase long-term patency. The new design comprises the combination of a flow diffusor (gradual widening) at the venous anastomic site with a separation of the widened part by application of a suture (called “bi-flow” graft). This results in an 8-shaped configuration providing two consecutive flow channels, lower shear stress and inhibition of the development of separation areas. The design was tested in-vitro.

METHODS:

In-vitro experiments have been performed using siliastic models of four different anastomic configurations (straight, cuffed (Venaflo® type), diffusor, and “bi-flow”® type) inserted into a pulsatile flow 'Berlin Heart' circuit. By means of Particle Image Velocimetry (PIV) - a high resolution laser flow visualization method – velocity, shear rates and shear stress have been computed and the different anastomic models have been compared.

RESULTS:

Venous wall shear stress levels were highest in the straight graft. Cuffed and diffusor grafts showed significantly lower shear stress, but still led to large separation areas. In the "bi-flow" graft there was a significant reduction of wall shear stress compared with the straight graft. Due to the flow separation of the two flow channels in the "bi-flow" graft; no separation areas were detected. In addition to these findings, the flow rates increased by about 25% compared to the other anastomic models.

CONCLUSIONS:

The new anastomic "bi-flow" design addresses the two main problems of stenotic development in haemodialysis grafts in vitro. Further animal experiments are in progress.

THE EFFECTIVENESS OF FOLIC ACID AND VITAMIN B-6 SUPPLEMENT ON HOMOCYSTEINE LEVELS AND ON VASCULAR ACCESS FUNCTION IN HAEMODIALYSIS PATIENTS: A THREE YEARS FOLLOW UP

Abstract

INTRODUCTION AND AIMS:

An elevated total homocysteine (tHcy) plasma concentration is an independent risk factor for atherosclerosis and is associated with increased morbidity and mortality due to cardiovascular disease in the general population. In addition, it plays a main role in the development of atherogenesis and thrombosis, particularly in end-stage renal disease and haemodialysis (HD) patients. Folic acid has been found an efficient therapeutic approach in lowering tHcy but the effectiveness of a combination of folic acid and vitamin B- 6 supplement on tHcy and on vascular access function is not yet well known.Our purpose was 1) to assess the tHcy lowering effect of a combination of folate and vitamin B-6 supplement and 2) to determine their impact on vascular access (VA) function in un-supplemented HD patients.

METHODS:

The study was conducted in 78 HD patients (43 male and 35 female) mean age 63.4±14.4, mean duration on HD 96.4±24.8 months. Levels of tHcy were measured in 75 healthy controls mean age 69.4±13.4. The occurrence of a VA failure was defined as any dysfunction of VA, which required any kind of a surgical intervention or a temporary placement of a catheter. The data were analysed retrospectively on each patient over the period of the last two years and were then prospectively compared after a three years follow up treatment of a combination of folate and vitamin B-6 supplement. All patients were given 5 mg of folic acid and 250 mg of vitamin B-6 after the end of each HD session 3 times a week. During the study a number of parameters were close monitored: Hemoglobin, urea, CRP, creatinine, albumin, status of nutrition, body mass index, total cholesterol, calcium (Ca), phosphorus (P), Ca X P, PTH, mean arterial pressure, hypotensive episodes, VA recirculation rate.

RESULTS:

Initial mean tHcy plasma concentrations were high in all HD patients 48.78±22.58 micromol/l compared to controls 11.81±3.22 P<0.001. The mean tHcy plasma concentrations decreased significantly to 27.98±11.18 micromol/l, P<0.001 at the end of the three years. The VA failure was observed in 3 patients (3.84%) during the three years treatment follow up compared to 14 patients (17.94%) in the last two years before the treatment. There was no statistical difference in mean age and time of HD in patients with VA failure before or after the treatment or in the forementioned parameters.

CONCLUSIONS:

The combination of folate and vitamin B-6 supplement decreased significantly tHcy plasma concentrations in all un-supplemented HD patients. During the treatment period the correction of hyper-homocysteinemia was also associated with a significant decrease in the rate of VA failure. Folate and vitamin B-6 supplement seem to be very useful in HD patients and their VA function. Although our results are encouraging they should be tested in a larger HD group.

VENOGRAPHY USING SMALL DOSE OF RADIOCONTRAST AS A VENOUS MAPPING IN PRE-DIALYSIS PATIENTS

Abstract

INTRODUCTION AND AIMS:

Venous mapping using venography is essential to detect poor vascularity and to choose type of adequate vascular access before the operation. However, venography may induce contrast dye induced nephrotoxicity, which is dose dependent. This study was designed to evaluate nephrotoxicity and imaging quality and findings of venography using small dose of radiocontrast as a venous mapping in pre-dialysis patients.

METHODS:

We enrolled 16 consecutive patients with stage 4 and 5 chronic kidney disease undergoing venography. We used 10-15 ml of contrast dye diluted with 5-15 ml of saline for venography and evaluated cephalic vein of upper arm to central vein. Radiocontrast-induced acute renal failure (ARF) was defined as more than 20% decreases in glomerular filtration rate (GFR) from the baseline value at 4 days after the study. In cases of ARF, GFR was re-measured in 1 week after the study. GFR was calculated using MDRD-GFR.

RESULTS:

Patient's mean age was 58±16 years and 11 patients (68.8%) had diabetes mellitus. Mean GFR was 18.8±5 ml/min/1.73 m² (7-30 ml/min/1.73 m²). Image quality of venography was good in all patients. Of the 16 patients, 2 patients showed total obstruction of cephalic vein. And 2 patients showed too small sized cephalic vein without obvious stenosis to create AVF. There was no significant difference in GFR between the pre- and post-study (18.8±5 vs. 18.3±6 ml/min/1.73 m², p=0.229) (Fig. 1). Radiocontrast-induced acute renal failure developed (GFR: 17 to 13 ml/min/1.73 m²) in only one patient. But it completely recovered to baseline level seven days after the study with conservative treatment.

CONCLUSIONS:

This study suggests that venography using small dose of radiocontrast is effective in venous mapping to detect veins suitable for AVF in pre-dialysis patients.

A PROSPECTIVE ITALIAN SURVEY ON ARTERIOVENOUS FISTULA (AVF) STENOSIS SURVEILLANCE AND OUTCOMES: AN INTERIM ANALYSIS

Abstract

INTRODUCTION AND AIMS:

Practice patterns in AVF stenosis detection and repair vary widely, but little is known on their outcomes.

METHODS:

In January 2008, a questionnaire was sent to 25 hemodialysis facilities in the Veneto Region to assess prospectively surveillance criteria for stenosis and outcomes (elective stenosis revision, thrombosis, access loss) in patients (pts) with mature AVFs. An interim analysis was performed for the initial 7 months (mo) of follow-up. Thirteen facilities (52%) provided preliminary data on 900 mature AVFs.

RESULTS:

All participating facilities routinely screened for stenosis by multiple methods by monitoring dialysis arterial pressure and blood pump flow rate (Qb) (100%), dialysis venous pressure (92%), physical exam (92%), measuring Kt/V (77%), recirculation (69%) and access blood flow rate (Qa) (38%).Sixtyfive significant (>50%) stenoses were identified electively in patent AVFs, because of elevated arterial dialysis pressure and inability to achieve the prescribed Qb (42%), abnormal physical findings (29%), elevated dialysis venous pressure (9%), reduced Kt/V (9%), low Qa (6%), or presence of recirculation (5%).Fifteen stenosed AVF (23%) were left untreated (8 remained patent and 7 thrombosed during follow-up); 20 (31%) underwent angioplasty (PTA) and 30 (48%) surgery, which led to the placement of a new access in 19 cases (29%)(14 more proximal AVFs, 4 PTFE grafts, 1 permanent CVC). Initial success rate of PTA and surgery was 90% (range 67-100) and 37% (range 0-100), respectively.Median thrombosis and access loss rates were 3.8 (range 0-9) and 4.4/100 AVF-7 mo (range 0-13), respectively. Most of the thrombosed AVFs were deemed unsalvageable and were abandoned (30/39).Thrombectomy was usually performed by surgery (6/9), with a cumulative success rate of surgical and endovascular techniques of 22% only.

CONCLUSIONS:

Our interim analysis shows that in the Veneto Region: 1) all participating facilities adopt a median of 5 stenosis surveillance tools; 2) in AVFs, stenosis is largely identified by clinical criteria and abnormal dialysis parameters (pressures, Qb,Kt/V); 3) surgery is the preferred method of elective stenosis revision, though many stenosed AVFs are deemed unrepairable and substituted by a new access; 4) these practice patterns are associated with a low thrombosis rate and acceptably low access loss rate; 5) thrombosed AVFs are usually abandoned, an approach that can be partially justified by the low thrombosis rate and success of thrombectomy.Participating nephrologists: Bedogna V (Verona), Borin A (Legnago), Cascone C (Treviso), Cavallini L (Caprino, Villafranca), Loschiavo C (Verona), Marchini P (Venezia), Naso A (Padova), Pellanda V (Bassano), Piva M (Rovigo), Teodori T (Portogruaro, San Donà), Vianello A (Feltre).

FAILED HEMODIALYSIS ARTERIOVENOUS FISTULA – IS THERE A ROLE FOR MULTIDETECTOR CT? OUR EXPERIENCE

Abstract

INTRODUCTION AND AIMS:

To evaluate the diagnostic impact of multidetector CT in the evaluation of patient with failed arteriovenous fistula.

METHODS:

Between September 2007 and July 2008, 72 patients have been evaluated with arteriovenous fistula for hemodialysis. The patients have been enrolled basing on clinical evaluation and on echocolordoppler findings positive or suspicion for failed A-V fistula. The examinations were performed with 16 mulitidetector-row CT using a specific acquisiton protocol after contrast media intravenous injection, with Smart-Prep function. The CT axial data were integrated with 3D MIP and volume rendering reconstructions. The entire examination time, door to door, was about 10 minutes.

RESULTS:

The technique identified 42 cases of variable degree stenosis with preferential localization in perianastomotic site: 19 in arterial compartment and 23 in venous), 18 cases of aneurysm dilatations, 4 cases of thrombosis in superior cava system.

Identified 8 cases of graft pathology (occlusion or perianastomotic hematoma). All cases were confirmed by conventional phlebography or arteriography.

CONCLUSIONS:

The technique shows good diagnostic accuracy particularly if the patients evaluated are positive and or suspicious in preventive clinical or cdus examination. Moreover evaluate specifically the arteriovenous anastomosis and graft situation with optimal management of patient in less time and without NSF risk; for this reason may be preferred to MR. For these reasons it may be added in protocol fistula evaluation with diagnostic time reduction.

TRANSPOSITION OF RADIAL ARTERY FOR REDUCTION OF EXCESSIVE HIGH-FLOW IN ELBOW HEMODIALYSIS AVFs

Abstract

INTRODUCTION AND AIMS:

Transposition of the radial artery to the elbow level is a new surgical approach to flow reduction.

METHODS:

From 1992 to 2008, 47 consecutive patients (22 women) with brachial artery to elbow vein autogenous fistula underwent flow reduction via replacement of brachial artery by transposed distal radial artery inflow.

Fistulas were side-to-end either brachial-cephalic (19) or brachial-basilic (28). The indications were hand ischemia (4), cardiac failure (13), concerns about future cardiac dysfunction (23), and chronic venous hypertension resulting in aneurysmal degeneration of the vein (7). Mean patient age was 44 years, 11% were diabetic, 17% were smokers, and mean BMI was 22. Mean fistula age before flow reduction was 2.5 years.

RESULTS:

Technical success was 91% (43 of 47 pts). The mean flow rate dropped by 66% ± 14%. Clinical success in symptomatic patients was 75% (18 of 24). The fistula eventually had to be ligated in three cases of cardiac failure because of insufficient clinical improvement. All four patients with hand ischemia were cured, with no recurrence during follow-up.Primary patency rates at one and three years were 61% ± 7% and 40% ± 8%. Secondary patency rates at one and three years were 89% ± 5% and 70% ± 8%.

CONCLUSIONS:

Transposition of the radial artery is a safe and effective technique for flow reduction in proximal AVFs.

TUNNELLED CUFFED FEMORAL VENOUS TWIN CATHETERS FOR CHRONIC HEMODIALYSIS: A PILOT EXPERIENCE

Abstract

INTRODUCTION AND AIMS:

Hemodialysis vascular access is a challenging problem in old patients with several comorbidities, in which the cannulation of the internal jugular vein may have a high complication risk. The femoral access to central veins has been proposed with either coaxial central venous catheters (CVC) or twin Tesio CVC with the tips in the lower inferior vena cava (IVC).The aim of this study is to evaluate the use and complication rate of 70 cm long tunnelled cuffed femoral twin Tesio catheters (fCVC) for hemodialysis.

METHODS:

From May 2007, fCVC were placed in 21 patients with exhausted thoracic access or old pts with several comorbidities.Two single lumen carbotane fCVC (70 cm long, 10 Fr diameter) with a Dacron cuff at 45 cm from the tip were placed in each patient using Seldinger technique under fluoroscopic guidance and tunnelized in a straight 10 cm long tunnel in the tight. Tips were positioned at the high IVC or at the junction of the IVC and right atrium.All the CVCs underwent an infection surveillance program which includes a sterile protocol of CVC connection and disconnection during hemodialysis.

RESULTS:

During 18 months (May 2007-November 2008), 21 fCVCs (5 Left, 16 Right) have been inserted in 21 patients (12 males, 9 females, 78.5±9.3 yrs), with a total follow up of 4501 pt-day.The mean session Kt/V was 1.50 ± 0.17 (range 1.22-1.85) and the blood flow was 270 ± 17 ml/min.During the follow up, 4 fCVCs have been removed: one for the making of AV fistula, one for limb swelling and tunnel infection in absence of venous thrombosis, one was accidentally damaged and in one patient only one of the two fCVC was substituted for malfunction.The main complications were 2 inferior vena cava thrombosis of which one with pulmonary embolism, both during an infective episode. There have been 2 tunnel infections, 1 needing fCVC removal; 4 pts had 10 local infections in the site of venipuncture; 10 fCVC-related sepsis in 7 pts, with a sepsis incidence of 2.22 episodes/1000-CVC-day. There have been 6 deaths (mean follow up 6.7 months): 2 sudden deaths, 1 sepsis from inferior limb gangrene, 1 vascular cachexia after dialysis suspension, 1 heart failure from gastrointestinal hemorragy and 1 disseminated prostate adenocarcinoma.

CONCLUSIONS:

The placement of twin fCVC with their tip at the high IVC or at the junction of the IVC and right atrium is a feasible option as a vascular access for selected patients and guarantees an adequate dialysis. This is possible only if the tip of the CVC is in a sufficiently large vein, even it implies the use of long fCVC.Among the main complications, the two caval thrombosis rise the problem if an anticoagulant therapy is useful in every patient. Local infections are a main complication and a better attention to local disinfeciton and bacterial prophylaxis may be helpful.Concluding, this access may be used in pts with exhausted thoracic access and as a bridge waiting for a definitive access to be ready; moreover negatively selected pts may benefit from the use of fCVC.

PERCUTANEOUS DUPLEX-GUIDED BALLOON CRYOPLASTY: A NEW THERAPY FOR RAPIDLY RECURRENT ANASTOMOTIC VENOUS STENOSES OF HEMODIALYSIS GRAFTS

Abstract

INTRODUCTION AND AIMS:

The functional ability and patency of arteriovenous (AV) hemodialysis access have a major impact on survival and quality of life for patients with chronic renal failure. Prosthetic grafts are predisposed to dysfunction and eventual failure due to multiple stenoses developing during their lifetime. Frequent stenosis formation and thrombosis complicate this form of access. Patients may have a rapidly forming and recurrent venous stenosis at the graft-vein anastomosis to be the results of neointimal hyperplasia. This venous lesion is particularly resistant and sometimes intractable to conventional angioplasty. As a result, new therapies have been developed to reduced the formation and/or recurrence of neointimal hyperplasia. A new endovascular therapy combining cold treatment with balloon dilation (cryoplasty) has been proposed to prevent neointimal hyperplasia.

METHODS:

Twelwe patients met the criteria of recurrent venous stenosis in AV. Six patients had a loop in PTFE and six in mesenteric bovine vein. Surveillance criteria utilized to identify clinically significant venous stenosis was Doppler ultrasound monitoring for each patients every 20-50 days. Doppler ultrasound criteria defining compromised AV access included severe stenosis (>70%) measured on color image and confirmed by peak systolic velocity (PSV) ratio of >3 in the stenosis and the decrease of volume flow.

RESULTS:

The mean age was 67 ± 19 years, on hemodialyis from 114 ± 84 months. Mean follow up of the patients' VA were 4.15 ± 1.4 years. We performed in these patients 18 cryotheraphy with cryoballoon (cryoplasty). Cryoplasty allowed to increase the time to restenosis in VA from a mean of 179 ± 163 days to a mean of 235 ± 194 days. AV blood flow was 799 ± 270 ml/min before the procedure and 1093 ± 290 ml/min after one month from it. Stenosis was 0.2 ± 0.02 cm before and 0.34 ± 0.07 cm after one month.

CONCLUSIONS:

The positive results obtained are promising; cryoplasty increased time to restenosis of venous lesions, but didn't eliminate them completely as seen by recurrence.

ASSESSMENT OF DISTAL UPPER LIMB CIRCULATION IN HEMODIALYSIS PATIENTS WITH LASER DOPPLER SKIN PERFUSION PRESSURE; INFLUENCE OF VASCULAR ACCESS

Abstract

INTRODUCTION AND AIMS:

The patients with chronic kidney disease are susceptible to various atherosclerotic lesions, including peripheral arteries. Arterio-venous fistula (AVF), a common vascular access for hemodialysis (HD), may deteriorate upper limb circulation. Laser Doppler skin perfusion pressure (SPP) has been known as a useful method to evaluate peripheral arterial disease in HD and/or diabetic patients. We investigate the upper limbs circulation and influence of AVF with SPP in HD patients.

METHODS:

Finger SPP (FSPP) was measured at the distal middle finger. FSPP in HD patients were compared with those in healthy subjects. FSPP was measured before and 14 days after constructing AVF. According to the type of AVF, patients were divided into 3 groups (radio-cephalic AVF on the forearm, brachio-basilic AVF, PTFE graft on the elbow). The change of FSPP after construction of AVF in each group was investigated.

RESULTS:

FSPP in 105 HD patients (84mmHg) was significantly lower than those in 10 healthy controls (112mmHg). FSPP significantly decreased after HD (n=5). FSPP positively correlated with SPP of lower limbs (r=0.80), not with ankle brachial pressure index, age nor HD duration. FSPP on the arms with AVF (69mmHg) was significant lower than those without AVF (104mmHg, p<0.01). In 22 cases with construction of primary radio-cephalic AVF, FSPP decreased from 101mmHg to 67mmHg after the surgery (p<0.05). In type of AVF, FSPP with brachio-basilic AVF (56mmHg) or PTFE graft (51mmHg) on the elbow were lower than those with radio-cephalic AVF on the forearm (80mmHg).

CONCLUSIONS:

SPP is a useful tool to evaluate quantitatively upper limb circulation in the HD patients. Measuring upper limb SPP may be helpful to decide the treatment for AVF problems.

FUNCTIONAL PROFILE OF VASCULAR ACCESS (VA) IN ELDERLY PATIENTS (EP) UNDERGOING CHRONIC HEMODIALYSIS (HD)

Abstract

INTRODUCTION AND AIMS:

The best method of VA surveillance is periodic blood flow (Q_A) measurement. The aim of this prospective study is to report a five-year experience of VA stenosis surveillance by Q_A measurements in EP (aged ≥ 75 years), and to compare the results with patients (pts) under 75 years.

METHODS:

We monitored Q_A of 145 VA (arteriovenous fistula AVF 84.1% or graft AVG 15.9%) in 131 ESRD pts over 5 yr period. Of them, we analyzed 30 VA in 28 EP (prevalence 20.7%). Q_A was measured during the first hour of the HD session at least every 4 months by Delta-H method. Baseline Q_A was calculated from two consecutive HD sessions (the values were averaged). All VA with absolute Q_A<700 ml/min or ∇Q_A >20% from baseline over time met the positive evaluation (PE) criteria and were referred for angiography plus subsequent elective intervention if VA stenosis ≥50%. Mean arterial pressure (MAP) was measured simultaneous with Q_A.

RESULTS:

EP showed higher mean age compared with the remaining pts: 78.7 ± 2.7 versus58.4 ± 11.9 yr (p < 0.001). Mean time on HD (40.1 ± 60.7 versus 29.1 ± 41.3 months) and prevalence of diabetic nephropathy (14.3 versus 20.4) were similar in both groups of pts (p=0.74 and 0.59, respectively). Type of VA in EP (%): radial AVF 50, brachial AVF 23.3, brachial AVG 10, femoral AVG 16.7. EP have lower prevalence of AVF (73.3% versus 87.0%) and higher prevalence of AVG (26.7% versus 13.0%) compared with the remaining pts, although this differences did not reach statistical significance (p=0.069). Ratio number VA/pts (2.07 ± 1.28 versus 1.94 ± 1.64) and mean VA duration (33.9 ± 56.4 versus 26.1 ± 53.9 months) were similar in both groups of pts (p=0.19 and 0.97, respectively). VA of EP showed lower baseline (812.6 ± 290.8 ml/min) and overall (867.9 ± 292.8 ml/min) mean Q_A compared to the remaining VA (1171.3 ± 436.9 and 1244.6 ± 481.0 ml/min, respectively) (for both comparisons, p < 0.001). No differences in baseline and overall MAP (mmHg) were found when comparing elderly (92.6 ± 14.4 and 92.2 ± 13.3, respectively) and “young” (95.8 ± 12.6 and 94.8 ± 12.3, respectively) pts (p=0.14 and 0.16, respectively). Prevalence of VA with PE (43.3% versus 29.6%), significant stenosis (36.7% versus24.3%) and elective treatment (20% versus 13%) were similar in both groups of VA (p=0.11, 0.13 and 0.24, respectively). No difference in mean increase of Q_A (ml/min) after preventive VA intervention were found when comparing EP (265.2 ± 231.6) and the remaining pts (513.2 ± 317.4) (p=0.25). VA thrombosis rate: similar when comparing both groups of pts (0.11 versus 0.10 episodes/patient/year, p=0.93). Primary (12.0 ± 4.2 versus20.0 ± 3.6 months) and secondary (20.0 ± 1.4 versus28.0 ± 4.2 months) VA patency: no difference between both groups of pts (p=0.09 and 0.82, respectively). Mortality was higher in EP (43.3% versus 16.5%, p=0.003).

CONCLUSIONS:

1) EP have a different distribution of AVF and AVG. 2) The functional VA profile is worse in EP. 3) The functional results obtained after elective VA intervention are similar when comparing EP and "young" pts.

ENDOVASCULAR REPAIR OF LARGE HAEMODIALYSIS FISTULA ANEURYSMS WITH POLYTETRAFLUOROETHYLENE-COVERED STENTS

Abstract

INTRODUCTION AND AIMS:

Since the initial description of the technique by Brescia et al in 1966 [1] native arteriovenous fistulae (AVF) remain the first choice for haemodialysis access and are the most common vascular access in the Australian haemodialysis population [2]. Patients with end stage kidney disease have limited sites for creation of AVF, and these accesses have a finite life expectancy. Endovascular procedures such as angioplasty and stent placement are being increasingly used by nephrologists to treat vascular access dysfunction and avoid access abandonment [3]. Aneurysms within AVF may occur as a result of repeated trauma from dialysis needling or repeated angioplasty to areas of recurrent stenosis. Their occurrence threatens the function of AVF, limits the potential areas of access needling and large aneurysms may ultimately rupture with catastrophic sequelae. Surgical options to repair such large aneurysms are limited and often involve loss of the fistula and insertion of temporary access catheters.Endovascular stent placement is the standard of care in most percutaneous coronary and peripheral artery interventions, however there is a paucity of current literature on the use of polytetrafluoroethylene (PTFE)-covered stents to repair AVF. The aim of this study was to retrospectively review the patency and safety of PTFE covered stents for repair large AVF aneurysms.

METHODS:

A single centre retrospective review of all patients who underwent endovascular intervention to repair large AVF true aneurysms was performed between August 2008 and October 2008. The study group consisted of 3 patients (1M, 2F) with ages 39, 45 and 62 years (1 left forearm transposed saphenous vein loop, 1 left brachiocephalic and 1 right brachiocephalic) who required 5 PTFE covered stents (4 nitinol (Fluency-Plus, Bard) (1 stainless steel (Advanta V12, Atrium Medical)). The indication for intervention was a rapidly enlarging true aneurysm not otherwise amenable to surgical revision.

RESULTS:

All patients were treated as a day procedure under local anaesthetic which was well tolerated without any immediate post procedure complications. The maximal diameter of the aneurysmal segments stented was 35-40 mm. PTFE covered stainless steel stents may be inadvertently crushed as occurred to our first patient. The stainless steel stent was angioplastied and a nitinol stent placed in the adjacent aneurysmal segment that developed. We have subsequently only used nitinol PTFE covered stents. Four months post intervention all AVF were patent, with resolution of the aneurysmal segments.

CONCLUSIONS:

In our single centre experience PTFE covered nitinol stenting of AVF aneurysms appears to be safe with the potential to extend the life of a dialysis access. Long term data on the patency and complications of insertion of PTFE covered nitinol stents will be needed before this can be recommended as a treatment for AVF aneurysms.

ANTIBIOTIC LOCK SOLUTIONS FOR THE PREVENTION OF CATHETER-RELATED BACTERAEMIA IN HAEMODIALYSIS PATIENTS

Abstract

INTRODUCTION AND AIMS:

Catheter-related bacteraemia remains an important cause of morbidity and mortality in haemodialysis patients. Antibiotic catheter lock solutions show promise in preventing the catheter infections.

METHODS:

In this observational study, we retrospectively studied 75 catheters with heparin solution alone and 74 catheters with gentamicin antibiotic lock. The majority of catheters were non-tunneled (95%). Cumulative catheter survival free of catheter-related bacteraemia was compared between the groups.

RESULTS:

Baseline characteristics between the two groups were similar, except a slightly lower albumin level in the gentamicin lock solution group. There were 18 and 5 catheter-related bacteraemia episodes before and after gentamicin antibiotic lock respectively. Staphylococcus aureus contributed to over half (65%) of the total bacteraemia episodes. Gentamicin antibiotic lock significantly reduced the catheter-related bacteraemia rates per 1,000 catheter-days from 4.6 to 1.5 episodes (P= 0.002). Kaplan-Meier survival analysis using log rank test showed significantly better bloodstream infection-free survival in the treatment group with gentamicin antibiotic lock (P = 0.023).

Similar survival advantage of the gentamicin antibiotic lock was demonstrated in the analysis restricted to non-tunneled catheters. Otherwise, we found no significant association of catheter-related bacteraemia with patient age, obesity, gender, baseline serum albumin level, obesity and diabetes mellitus. No serious adverse events were attributable to gentamicin antibiotic lock.

CONCLUSIONS:

Gentamicin lock solutions effectively reduce the catheter-related bacteraemia in haemodialysis patients, including patients with non-tunneled catheters.

FACTORS RELATED TO BLOOD FLOW RATE (Q_A) IN ARTERIOVENOUS FISTULA (AVF) OF PATIENTS UNDERGOING CHRONIC HEMODIALYSIS (HD)

Abstract

INTRODUCTION AND AIMS:

The best method of vascular access (VA) surveillance is periodic Q_A measurement. The aim of this cross-sectional study is to investigate the relationship between Q_A and clinical parameters in ESRD patients (pts) undergoing HD by AVF.

METHODS:

We measured Q_A non invasively in 50 AVF (54% radial and 46% brachial AVF; AVF duration 57.7 ± 76.8 months) without evidence of significant stenosis in 50 stable ESRD (age 62.1 ± 15.4 yr, time on HD 44.6 ± 50.5 months, 16% diabetes, ratio number VA/pts: 1.5 ± 0.9) pts. Sixteen pts (32%) had history of another comorbidity (coronary artery or cerebrovascular or peripheral vascular diseases) different to diabetes. Other sixteen pts had history of previous VA that were ipsilateral to the AVF under study in most cases (87.5 %). Q_A was calculated by Delta-H method (ABF-mode) using Crit Line III monitor within the first hour of the HD session (78%) or by Doppler ultrasound (22 %) performed by the same radiologist using a 5-8 MHz linear transducer. Mean arterial pressure MAP and Kt/V index: determined simultaneous with Q_A. Laboratory parameters: measured the same week of Q_A measurement. Variables analyzed: age of pts, sex, height, body mass index (BMI), time on HD, diabetes mellitus, history of another comorbidity, systolic blood pressure (SBP), diastolic blood pressure (DBP), MAP, Kt/V index, type of AVF, AVF duration, history of previous VA, haemoglobin, total cholesterol, HDL-cholesterol, LDL-cholesterol, C-reactive protein (CRP), albumin.

RESULTS:

Mean Q_A was 1262.9 ± 548.2 ml/min (range, 576-2596 ml/min). Functional AVF classification depending on the different segments of Q_A (ml/min) considered: < 700: 10%, 700-1000: 32%, 1000-1500: 28%, 1500-2000: 16%, > 2000: 14%. Pts with history of any comorbidity different to diabetes had higher mean Q_A (1458.3 ± 600.7 ml/min) compared to pts without comorbidities (1171.0 ± 504.9 ml/min), although this difference did not reach statistical significance (p=0.09). Pts with history of previous VA showed higher mean Q_A (1538.0 ± 637.7 ml/min) compared with the remaining pts (1133.5 ± 455.4 ml/min) (p=0.029). Mean Q_A was similar for pts with mean MAP<100 mmHg (n=26, 1346.4 ± 626.7 ml/min) and for pts with mean MAP≥100 mmHg (n=24, 1172.5 ± 443.7 ml/min) (p=0.49). Radial AVF had lower mean Q_A (1060.3 ± 468.5 ml/min) compared to brachial AVF (1500.9 ± 548.0 ml/min) (p=0.002). No correlation was found between mean Q_A and: mean age (r=0.009, p=0.95), height (r=-0.14, p=0.34), BMI (r=-0.084, p=0.56), time on HD (r=0.15, p=0.29), SBP (r=0.023, p=0.87), DBP (r=-0.114, p=0.43), MAP (r=-0.082, p=0.57), Kt/V index (r=-0.010, p=0.95), AVF duration (r=0.073, p=0.62), haemoglobin (r=0.077, p=0.59), total cholesterol (r=0.043, p=0.76), HDL-cholesterol (r=0.17, p=0.24), LDL-cholesterol (r=0.067, p=0.64), CRP (r=-0.041, p=0.78) and albumin (r=-0.016, p=0.91).

CONCLUSIONS:

1) Most AVF (60 %) showed mean Q_Abetween 700 and 1500 ml/min. 2) Mean Q_Ais not influenced by blood pressure. 3) The functional profile of AVF is worse in pts without history of previous VA and is related to AVF location.

PRIMARY ARTERIOVENOUS FISTULA WITH A SMALL SKIN INCISION (SMALLER THAN 1 cm): SURGICAL TECHNIQUE AND RESULT (A REPORT FROM ONE OF THE FACILITIES IN THE DIALYSIS OUTCOMES AND PRACTICE PATTERNS STUDY [DOPPS] II-IV)

Abstract

INTRODUCTION AND AIMS:

Thus far, many surgical techniques related to native arteriovenous fistula (AVF) in chronic hemodialysis patients have been reported. In cases of plastic surgery, it goes without saying that minimal invasiveness is definitely desirable.We believe that a 1-cm skin incision would be adequate for creating a primary arteriovenous fistula. Here, we report our surgical procedure and the obtained cumulative patency rate.

METHODS:

From April 2000 to December 2007, 120 AVFs were created using the technique described herein; these cases were analyzed in the present study. Under local anesthesia with 1% lidocaine, an approximately 1-cm-long transverse skin incision was made between the antebrachial cephalic vein and the radial artery at the junction of the dorsal venous branch. The subcutaneous space was exposed as much as possible to achieve a good working space. First, the dorsal venous branch was ligated and separated. Thereafter, the cephalic vein and radial artery were freed and mobilized, and side-to-side arteriovenous anastomosis was created using 7-0 Prolene suture. The anastomosis was approximately 4 mm in diameter, and it appeared to function well after the ligation of the vein distal to the anastomosis. The cumulative patency rate was determined by the Kaplan-Meier analysis method.

RESULTS:

The average duration of operation was 48.7 ± 10.3 min; the shortest operation was 29-min long, while the longest one went on for 71 min. No complications were noted. The primary patency rates at 12, 24, and 36 months were 84.9, 75.6, and 63.9%, respectively, while the corresponding secondary patency rates were 83.6, 75.6, and 67.1%. The functional accuracy of the AVF created with a minimum skin incision was identical to that of a standard AVF.

CONCLUSIONS:

By using the above-described surgical procedure, we could create a primary AVF through a 1-cm skin incision. We showed that such a small skin incision was wide enough for vascular anastomosis in some cases.The patency rate shown in our study is thought neither a past report nor inferiority. Although our method may not always be applicable, it does have aesthetic benefits for women and younger patients. In fact, we thought that the surgical scars in these patients were cosmetically acceptable. Restricting the area for surgery may render the procedure tedious for the surgeon. However, as expected, a smaller surgical field did not have an unfavorable effect on the surgical outcome.

ASYMMETRIC DIMETHYLARGININE IN CHRONIC HEMODIALYSIS PATIENTS WITH NATIVE ARTERIO-VENOUS FISTULA FAILURE

Abstract

INTRODUCTION AND AIMS:

Asymmetric dimethylarginine (ADMA), endogenous inhibitor of nitric oxide synthase is associated with endothelial dysfunction and promotion arteriosclerosis in general population and in patients with end stage kidney disease. We have hypothesized that serum level of ADMA in patients on chronic hemodialysis (HD) treatment would have a destructive influence on the native arterio-venous fistula (AVF). The aim of our study conducted in HD patients was to investigate any influence between ADMA and AVF failure. Moreover we analyzed possible relations between ADMA and some biochemical parameters of nutritional status, inflammation and cardiac failure in patients with AVF complications.

METHODS:

98 chronic HD patients, means age 65.4 years, mean duration of HD treatment 41.5 ± 43.4 months were considered for the study. We retrospectively selected 28 patients (Group I) who in the previous 12 months had diagnosed various incidents of AVF complications (thrombosis, stenosis, pseudoaneurysmatosis, infection) and compared with remaining 70 patients who had uncomplicated function of AVF during the same period (Group II). In both groups we measured ADMA and biochemical parameters of inflammation (IL-6), status nutrition (albumin, normalized proteins catabolic rate), and cardiac function (N-terminal pro brain natriuretic peptide (NT- pro BNP). In both groups of patients blood flow, comorbidity score and adequace of HD were evaluated. For comparison serum ADMA and NT- pro BNP levels measured by ELISA method were also analyzed in control group (CG; n = 30, mean age 47.5 years.

RESULTS:

We found that mean serum ADMA concentration was significantly higher in HD patients that in CG (0.51 ± 0.3 umol/L vs 0.39 ± 0.1 umol/L; p < 0.03). We did not find any relationship diabetes and AVF failure. We did not observe any differences between mean serum ADMA levels in both seperates patients groups (0.6 ± 0.4 umol/L vs. 0.5 ± 0.3 umol/L). In Group I we found that mean IL-6 level was significantly higher (p < 0.03), and blood flow significantly lower (p < 0.0006) than in Group II. There were no correlations between ADMA and all measured parameters in both groups of HD patients.

CONCLUSIONS:

Our results suggest that ADMA levels were not associated with observed complications in AVF of HD patients. In both groups of HD patients ADMA level had no association with inflammation, status nutrition and cardiac function expressed by significantly higher than in CG serum NT-pro BNP level.

CATHETER-RELATED INFECTION, DOES THE PLACE OF INSERTION MATTERS?

Abstract

INTRODUCTION AND AIMS:

In our country during the last years the number of patients treated with hemodialysis is increased very much thanks to positive reimbursement policies. We had to use widely untunneled central venous catheters as a vascular access. The rate of infection is much higher using untunneled catheters compared to patients that are dialysed with tunneled catheters or moreover with native fistulas. Infection is the most common cause of morbidity and the second most common cause of death next to cardiovascular disease in HD patients. The majority of the deaths due to infection are secondary to bacteremia. Interdialytic locking with antibiotics has shown to reduce risk of infection and bacteremia. Based on concerns about the risk of infection, the jugular site is often preferred over the femoral site for dialysis vascular access.

METHODS:

We performed a prospective, randomized, open label clinical trial comparing the rate of catheter infection in two groups of patients those who were dialysed using a femoral untunneled catheter with those who used jugular or subclavian untunneled catheter. We used the same catheter lock solution in both groups (10mg/ml cefazolin plus 5000U/ml heparin).

RESULTS:

During a 2-year period we followed 236 untunneled catheters newly implanted in 106 consecutive patients. Patients were randomized to receive femoral vein (Group A) or jugular otherwise subclavian (Group B) catheterization by operators experienced in placement at three sites. We found that the incidence of catheter infection rate was similar in both groups [Group A 3.2 episodes/1000 catheter-days and Group B 2.7 episodes/1000 catheter-days (p<0.45)]. The mean duration of infection free-days in Group A catheters did not differ significantly compared with Group B catheters (respectively, 85.5 days vs 94.3 days (p<0.19). Furthermore hematomas in the Group B occurred more than in the group A [(5/116 catheters [4.3%] vs 2/120 catheters [1.6%], respectively; p =0.028].

CONCLUSIONS:

Using the same lock solution, jugular or subclavian venous catheterization access does not seem to decrease the risk of infection compared with femoral access.