Hemodialysis access failure: a call to action

Radial artery deviation and reimplantation technique vs classical technique in arterio-venous fistula: A randomised control trial

BACKGROUND

Surgically created arterio-venous fistulas (AVFs) are the gold standard for haemodialysis access for patients with end-stage renal disease. Standard practice of AVF creation involves selecting the non-dominant upper limb and starting with most distally with radio-cephalic arterio-venous fistula. The primary patency rate of radio-cephalic arterio-venous fistula varies from 20%-25%. It has been suggested the neointimal hyperplasia at the mobilized venous segment causes stenosis of the anastomosis. Therefore, the radial artery deviation and reimplantation (RADAR) technique, in which the vein is minimally mobilized, should result in a higher success rate.

AIM

To compare the RADAR technique with classical technique in creation of AVF including: (1) Success rate; (2) Time to maturation; (3) Duration of surgery; and (4) Complication rate.

METHODS

In our study we recruited 94 patients in two randomized groups and performed the AVF by the classical method or the RADAR method.

RESULTS

The RADAR group had higher primary success rate (P = 0.007), less rate of complications (P = 0.04), shorter duration of surgery (P = 0.00) and early time to maturation (0.001) when compared with the classical group. The RADAR procedure is a safe and a more efficient alternative to the current classical method of AVF creation. Longer duration of follow-up is required to assess the long-term outcomes in the future.

CONCLUSION

The RADAR procedure is a safe and more efficient alternative to the current classical method of AVF creation. Longer duration of follow-up is required to assess the long-term outcomes in the future.

Improving vascular access knowledge and assessment skill of hemodialysis staff

CONTEXT

Vascular access malfunction and failure contribute to morbidity and hospitalization in hemodialysis populations. Although controversy still exists over the identification and appropriate management of access malfunction, recognition of sentinel signs during physical examination remains an efficient way to screen for access malfunction. Dialysis staff are on the front line of providing quality care to dialysis patients, often being the first ones who could detect early physical signs of access malfunction.

OBJECTIVES

The study's purpose is to determine the effect of an advanced vascular access educational module presented to hemodialysis nurses and technicians, focusing on physical examination findings to identify a dialysis access at risk for malfunction.

METHODS

Utilizing a quasi-experimental pretest and posttest group design with a nonequivalent comparison control group, the effect of an advanced vascular access education module to improve vascular access knowledge and skill in recognition of sentinel signs of access malfunction was studied in a group of hemodialysis nurses (registered nurses [RNs]) and certified patient care technicians (PCTs).

RESULTS

Knowledge post-test scores (RN, M=94.44, SD=7.05; PCT, M=90.83, SD=7.93) were significantly higher than pretest scores (RN, M=79.54, SD=12.47; PCT M=80.67, SD=7.99) in the intervention group (p<0.001) but not in the comparison group. There were no statistically significant differences in mean skill scores between dialysis nurses (p=0.38) and PCTs (p=0.826) or between intervention and comparison groups (p=0.332).

CONCLUSIONS

This study exposes a critical gap in the transition of vascular access knowledge to the practical skill of access assessment. The findings suggest the need for restructuring the clinical training of dialysis nurses and PCTs in vascular access management and care. Newer active learning educational strategies in physical assessment of hemodialysis vascular access should be explored to further support dialysis nurses and PCTs in providing optimal patient care.

Prediction of Vascular Access Stenosis by Lightweight Convolutional Neural Network Using Blood Flow Sound Signals

This research examines the application of non-invasive acoustic analysis for detecting obstructions in vascular access (fistulas) used by kidney dialysis patients. Obstructions in these fistulas can interrupt essential dialysis treatment. In this study, we utilized a condenser microphone to capture the blood flow sounds before and after angioplasty surgery, analyzing 3819 sound samples from 119 dialysis patients. These sound signals were transformed into spectrogram images to classify obstructed and unobstructed vascular accesses, that is fistula conditions before and after the angioplasty procedure. A novel lightweight two-dimension convolutional neural network (CNN) was developed and benchmarked against pretrained CNN models such as ResNet50 and VGG16. The proposed model achieved a prediction accuracy of 100%, surpassing the ResNet50 and VGG16 models, which recorded 99% and 95% accuracy, respectively. Additionally, the study highlighted the significantly smaller memory size of the proposed model (2.37 MB) compared to ResNet50 (91.3 MB) and VGG16 (57.9 MB), suggesting its suitability for edge computing environments. This study underscores the efficacy of diverse deep-learning approaches in the obstructed detection of dialysis fistulas, presenting a scalable solution that combines high accuracy with reduced computational demands.

Reassessing the utility of access recirculation and Kt/V for the prediction of arteriovenous fistula failure using online clearance monitoring: the SHUNT STUDY

BACKGROUND

The arteriovenous fistula (AVF) is prone to thrombosis which can be avoided by use of monitoring and surveillance programmes. Although surveillance imaging techniques have been shown to be more sensitive and specific than clinical monitoring during dialysis, monitoring may have significant advantages in terms of cost and time saving. In this study we evaluate the yield of two monitoring techniques [blood temperature monitoring (BTM) access recirculation (AR) and Kt/V via online-clearance-monitoring (OCM)].

METHODS

In this single-centre prospective observational study, 101 patients were followed-up for one year. The primary outcome measure was a composite of AVF failure. OCM-Kt/V and BTM-AR were recorded at every dialysis session.

RESULTS

Of all baseline characteristics only a prior history of percutaneous transluminal angioplasty (PTA) to the AVF conferred a significant change in AVF survival (failure events/100 pt years with prior PTA vs. without = 64.0 vs. 17.3, log-rank p = 0.0014; unadjusted hazard ratio (HR) 3.74 (95% CI 1.56-8.94) p = 0.003). Participants with baseline AR < 10% vs. > 15% had poorer AVF survival (p = 0.0002) and HR for baseline AR 10-15% group vs. AR > 15% group = 4.5 (95% CI 1.55-13.05). There was no combination of change in (Δ) AR, ΔKt/V or its presence over any number of dialysis sessions that provided an acceptable combination of sensitivity and specificity or discrimination for AVF failure.

CONCLUSIONS

BTM-AR and OCM-Kt/V are specific but insufficiently sensitive tools for the prediction of AVF failure. BTM-AR and OCM-Kt/V use at every dialysis session appears to add little to the traditional, infrequent use of these evaluations.

Study protocol for Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID)

Background

A functioning vascular access (VA) is crucial to providing adequate hemodialysis (HD) and considered a critically important outcome by patients and healthcare professionals. A validated, patient-important outcome measure for VA function that can be easily measured in research and practice to harvest reliable and relevant evidence for informing patient-centered HD care is lacking. Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID) aims to assess the accuracy and feasibility of measuring a core outcome for VA function established by the international Standardized Outcomes in Nephrology (SONG) initiative.

Methods

VALID is a prospective, multi-center, multinational validation study that will assess the accuracy and feasibility of measuring VA function, defined as the need for interventions to enable and maintain the use of a VA for HD.

The primary objective is to determine whether VA function can be measured accurately by clinical staff as part of routine clinical practice (Assessor 1) compared to the reference standard of documented VA procedures collected by a VA expert (Assessor 2) during a 6-month follow-up period. Secondary outcomes include feasibility and acceptability of measuring VA function and the time to, rate of, and type of VA interventions.

An estimated 612 participants will be recruited from approximately 10 dialysis units of different size, type (home-, in-center and satellite), governance (private versus public), and location (rural versus urban) across Australia, Canada, Europe, and Malaysia.

Validity will be measured by the sensitivity and specificity of the data acquisition process. The sensitivity corresponds to the proportion of correctly identified interventions by Assessor 1, among the interventions identified by Assessor 2 (reference standard). The feasibility of measuring VA function will be assessed by the average data collection time, data completeness, feasibility questionnaires and semi-structured interviews on key feasibility aspects with the assessors.

Discussion

Accuracy, acceptability, and feasibility of measuring VA function as part of routine clinical practice are required to facilitate global implementation of this core outcome across all HD trials. Global use of a standardized, patient-centered outcome measure for VA function in HD research will enhance the consistency and relevance of trial evidence to guide patient-centered care.

Trial registration

Clinicaltrials.gov: NCT03969225. Registered on 31st May 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02987-1.

Arteriovenous fistulas for hemodialysis: Brief review and current problems

The number of people worldwide living with end-stage renal disease is increasing. Arteriovenous fistulas are the preferred method of vascular access in patients who will require hemodialysis. As the number of patients with arteriovenous fistulas grows, the role of physicians who intervene who maintain and salvage these fistulas will grow in importance. This review aims to familiarize practitioners with the rationale for arteriovenous fistula creation, the detection of fistula dysfunction, and the state of the art on fistula maintenance and preservation. Current controversies are briefly reviewed.

Getting the basics right: the monitoring of arteriovenous fistulae, a review of the evidence

PURPOSE OF REVIEW

Despite being the preferred vascular access for haemodialysis, the arteriovenous fistula (AVF) remains prone to a number of complications, the most common of these being thrombosis secondary to stenosis. This has resulted in the widespread use of monitoring and surveillance programmes. Surveillance uses more resources than monitoring and has not been convincingly shown to improve outcomes. The evidence supporting the use of the various monitoring tools has been relatively neglected and has not been the focus of literature review. This narrative review is the first to appraise the evidence for the use of physical examination, access recirculation, Kt/V and dynamic venous pressures (DVP) as monitoring tools in mature AVF.

RECENT FINDINGS

The vastly increased number of data points for access recirculation, Kt/V and DVP produced as standard by online clearance monitoring (OCM) on modern dialysis machines is likely to have significantly changed the utility of these metrics in the prediction of AVF failure. Algorithms have been developed to highlight those of highest risk of failure.

SUMMARY

The evidence supporting the use of monitoring in the prediction of AVF failure is predominantly observational, underpowered and more than 20 years old. Access recirculation and Kt/V appears to have higher utility in AVF than in arteriovenous grafts. We suggest that the development of OCM necessitates the reevaluation of these tools.

The Role of Peritoneal Dialysis as the First-Line Renal Replacement Modality

Twenty years after its introduction, peritoneal dialysis (PD) is a well-established alternative to hemodialysis (HD) as a modality of renal replacement therapy. Much debate and research is apparent in the literature, comparing hemodialysis and PD as “opposite” modalities and trying to ascertain which modality should be more optimal.

In our opinion, HD and PD are two distinct modalities, each with its own advantages and disadvantages. In addition, it is clear that for both HD and PD, rates of technique failure are high, causing patients to transfer between modalities. The question is thus not which modality is best, but rather, which flow-chart of modalities makes best use of the advantages of each modality, while avoiding its disadvantages. In this respect, HD and PD appear to be complementary modalities.

The better preservation of residual renal function, lower risk of infection with hepatitis B and C, better outcome after transplantation, preservation of vascular access, and lower costs are arguments to promote PD as a good initial treatment. When PD-related problems arise (adequacy, ultrafiltration, peritonitis, patient burnout), a timely transfer to HD has to be planned.

This editorial tries to review arguments supporting the complementary nature of both modalities, and especially the role of PD as the first-line renal replacement therapy.

Utilization of Peritoneal Dialysis in the Acute Setting

Peritoneal dialysis (PD), although classically described and utilized in the treatment of patients with end-stage renal disease, can also be utilized in the acute setting in different clinical situations. Recent studies showed that, in patients with acute renal failure, it is possible to obtain reasonable dialysis doses with adequate metabolic and electrolytic control and low incidence of complications by utilizing continuous PD through a cycler at high volume. In patients with congestive heart failure without end-stage renal disease, PD is capable of promoting clinical improvement with slow removal of liquids, becoming an attractive alternative for situations of rapidly or slowly worsening cardiac function. In patients submitted to chronic hemodialysis but who have vascular access difficulties, PD can also be utilized as a “bridge,” thereby avoiding the use of central venous catheters, which can be associated with infectious complications such as bacterial endocarditis. New studies must be realized showing other indications for PD.

Complications of arteriovenous fistula in dialysis patients: Incidence and risk factors in Taif city, KSA

AIM

The aim of this study was to measure the prevalence of arteriovenous fistula (AVF) and its complications in patients undergoing hemodialysis (HD) in Taif Region, Saudi Arabia.

METHODS

This was a prospective hospital-based study conducted on 196 patients aged above 18 years who were undergoing dialysis in two hospital Taif City. Data collected and documented using a pretested questionnaire, which included sociodemographic details and also information about fistula-related complications. Hospital records were also reviewed to match the complication and related risk factors. Appropriate statistical tests were used and analyzed with SPSS software ver. 23.

RESULTS

Majority of the study patients were in the age group of 41-60 years and the prevalence in male and female were 49.5% and 50.5%, respectively. The most prevalent chronic illness in the patients was hypertension (41.7%) and more than 30.6% had multiple chronic illness. The most common type of AVF was radiocephalic fistula (RCF). The most common complication associated with the patients with AVF was ischemic neuropathy (29.6%). Smokers had significant history of myocardial infarction than non smokers.

CONCLUSION

Early and timely detection of complications in AVF is essential for proper management. Health professional should have thorough knowledge regarding the complications related to AVF. Early diagnosis and appropriate treatment are essential to improve the quality of life in patients on HD.

Effects of aspirin resistance and mean platelet volume on vascular access failure in hemodialysis patients

BACKGROUND/AIMS

Maintaining the patency of vascular access (VA) in hemodialysis (HD) patients is important and can be life-saving. We investigated the effects of aspirin resistance and mean platelet volume (MPV) on VA failure in HD patients.

METHODS

We enrolled 163 patients on maintenance HD. VA failure was defined as thrombosis or a decrease of > 50% of the normal vessel diameter, as revealed by angiography.

RESULTS

Aspirin resistance was observed in 17 of 109 patients in whom this parameter was measured, and was not significantly associated with VA failure (p = 0.051). The mean MPV was 9.15 ± 0.05 fL. The 163 patients were grouped by the median MPV value (9.08 fL) at baseline; patients with higher MPVs (n = 82) had lower platelet counts (p = 0.002) and albumin levels (p = 0.009). During 34 months of follow-up, 65 VA failures (39.9%) occurred. The Kaplan-Meier curve revealed significant differences between the two groups in terms of cumulative VA failure (54.1% vs. 35.3%, p = 0.018). On multivariate analysis, the MPV (hazard ratio [HR], 1.794; 95% confidence interval [CI], 1.066 to 3.020; p = 0.028), platelet count (HR, 1.003; 95% CI, 1.001 to 1.006; p = 0.01), and smoking status (HR, 1.894; 95% CI, 1.019 to 3.519; p = 0.043) independently predicted VA failure.

CONCLUSION

A high MPV was associated with an increased risk of VA failure, whereas aspirin resistance showed only a weak association. The MPV may predict VA survival in HD patients.

High-Urgency Renal Transplantation for Patients With Vascular Access Failure: A Single-Center Experience

In the face of access failure for renal replacement therapy or severe complications despite or due to dialysis, high-urgency renal transplant (HU-RT) allocation is possible. Vascular access failure patients have multiple comorbidities and a higher risk of cardiovascular and thrombotic events. Thus, it is presumed that graft and patient survivals might be worse for these patients. The aim of this paper was to analyze the characteristics and outcomes of HU-RT patients due to access failure for renal replacement therapy when comparing them to a population of deceased-donor renal transplant (DDRT) patients. We analyzed data from our Renal Transplantation Unit from January 2006 to April 2017. In this period, 374 patients had a renal transplant. Of these, 11 patients received a high-urgency deceased-donor renal transplant (HU-DDRT). Compared with patients who had a DDRT, HU-DDRT patients were predominantly female (54.5% vs 43.5%, P = .007) and younger (41.6 ± 7.9 vs 49.4 ± 11.8, P = .031). HU-DDRT patients were not significantly more sensitized than DDRT (14.1 ± 27.4 vs 13.5 ± 24.1, P = .935), and had a comparable number of HLA mismatches (3.4 ± 1.4 vs 3.6 ± 1.2, P = .343). Despite the higher incidence in hypertensive (90.9 vs 73.5%, P = .196) and diabetic patients (27.3% vs 15.7%, P = .305) in the HU-DDRT group, this difference was not statistically significant. The percentage of retransplantation was similar in both groups (9.1% vs 7.2%, P = .808). Donor sex, age, and baseline serum creatinine were similar between the groups. There was an increased proportion of expanded criteria donors in HU-DDRT (54.5% vs 25.1%, P = .028). There were no differences in cold or warm ischemia time nor in serum creatinine at discharge or during the first 2 years of follow-up. In both groups, a similar proportion of patients experienced acute rejection episodes. Comparable to DDRT patients, HU-DDRT patients had a high proportion of graft survival at the 1-year follow-up (90.9% vs 93.1%, P = .777). At a 2-year follow-up, graft survival was lower in the HU-DDRT group (81.8% vs 91.5%, P = .267). Mean follow-up for both groups was comparable (78.5 ± 46.7 vs 68.4 ± 40.8 months, P = .424). Overall, graft loss occurred in approximately 36.4% of HU-DDRT patients and 20.9% of DDRT patients (P = .219). Both groups had an overall mortality rate of around 9%. The differences were not statistically significant due to the limited number of patients. More comorbidities and reportedly worse cardiovascular prognosis of access failure (AF) patients and use of expanded criteria donors did not negatively reflect in worse short-term outcomes in our cohort, which highlights the importance of HU-RT in prolonging the survival of AF patients.

Patency and outcomes of tunneled hemodialysis catheter via femoral versus jugular vein access

The design of a suitable catheter to achieve a permanent, economical, and efficient vascular pathway for hemodialysis has been always accompanied by difficult and potential complications. Various strategies have been adopted to minimize the use of tunneled catheters that are used for dialysis. Regarding this, the present study aimed to assess the success, patency, as well as early and late complications of cuffed femoral and jugular hemodialysis catheters. This case–control study was performed on 145 hemodialysis patients who were candidates for the insertion of tunneled hemodialysis catheters at Rasoul-e-Akram Hospital in Tehran, Iran, during 2015–2016. The data were collected retrospectively by reviewing the patients' medical records. The participants were divided into two groups of femoral and jugular accesses, based on the type of catheter they had. To determine the procedure-related outcomes, they were assessed 1 week, 1 month, and 6 months after catheterization. According to the results, the mean times of catheter efficacy (patency) were 4.43 ± 3.11 and 5.65 ± 4.57 months in the femoral and jugular access groups, respectively, showing no significant difference between the two groups (P = 0.095). Furthermore, the femoral and jugular access groups had the infection prevalence of 23.2% and 16.2%, thrombosis prevalence of 28.6% and 20.9%, and mortality rates of 3.5% and 1.4%, respectively. According to the multivariable linear regression model, the history of catheterization could predict reduced catheter patency. In addition, catheter-related infection could be predicted among females based on the multivariate logistic regression analysis. As the findings indicated, femoral and jugular hemodialysis catheter insertions showed no significant difference in terms of the mean patency, complications (e.g., infection and thrombosis), and mortality rate.

Comparison of alteplase and urokinase for pharmacomechanical thrombolysis of clotted hemodialysis access

BACKGROUND

Percutaneous pharmacomechanical thrombolysis is increasingly used to salvage thrombosed hemodialysis access. We aim to evaluate the effectiveness of alteplase compared to urokinase in percutaneous pharmacomechanical thrombolysis clotted access.

METHODS

Records of patients who underwent pharmacomechanical thrombolysis at Interventional Nephrology Suite in a tertiary teaching hospital from 1 January 2016 to 31 December 2016 were reviewed. Technical and clinical success rates, thrombosis-free and cumulative survivals, procedure time, and radiation dose imparted to patients were compared for pharmacomechanical thrombolysis with urokinase versus alteplase.

RESULTS

A total of 122 incident patients underwent pharmacothrombolysis (n = 53 for urokinase, n = 69 for alteplase) during the study period. The mean dose of urokinase and alteplase used was 176,897 ± 73,418 units and 3.7 ± 0.8 mg, respectively. Pharmacomechnical thrombolysis using urokinase versus alteplase has similar technical success rate (98.1% vs 97.1%, p = 0.599), clinical success rate (88.7% vs 97.1%, p = 0.068), complication rate (9.4% vs 13.0%, p = 0.373), and primary patency rates at 3 months (57.1% vs 70.1%, p = 0.106). Thrombosis-free survivals of the vascular access were 113.2 (35.3, 196) days versus 122 (84, 239) days (p = 0.168). Cumulative survivals were 239 (116, 320) vs 213 (110.5, 316.5) days (p = 0.801). Procedure time, fluoroscopy time, skin dose, and dose were significantly lower for pharmacomechanical thrombolysis using alteplase compared to urokinase (p = 0.045, p < 0.0001, p = 0.006, p = 0.001, respectively). Stenting was found to be associated with successful dialysis following thrombolysis on univariate analysis (odds ratio: 9.167, 95% confidence interval: 1.391-19.846, p = 0.021), although this was no longer significant in multivariate analysis (p = 0.078).

CONCLUSION

Alteplase is an effective and safe alternative to urokinase for pharmacomechanical thrombolysis of clotted vascular access.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

A Meta-analysis of Preoperative Duplex Ultrasound Vessel Diameters for Successful Radiocephalic Fistula Placement

Background

The Kidney Dialysis Outcomes Quality Initiative (K/DOQI) guidelines for vascular access recommend the use of radiocephalic wrist arteriovenous fistulas (RCAVFs) as the initial option for dialysis access. The survival rate of a successfully placed fistula is excellent. However, 10–24% of RCAVFs fail to reach functional status as the result of early thrombosis or maturation failure. Many authors have investigated the utility of preoperative vascular mapping by Duplex ultrasound to predict adequate vessel size for successful fistula placement. This meta-analysis is the first in which preoperative radial arterial (RAD) and cephalic venous diameters (CVD) required for favorable fistula outcomes are reviewed.

Methods

A literature search was performed by use of the MEDLINE electronic base for “arteriovenous, fistula, ultrasound, and hemodialysis.” The analysis yielded 166 studies, of which 20 studies included preoperative duplex data. Meta-analysis was performed by applying the statistical test of comparing two proportions, assuming equal variances.

Results

A total of 433 patients were duplexed for preoperative evaluation of the RAD and 386 for CVD. The total number of subjects ranged from 21 to 91, mean age 58.7 years. The subjects were 55.5% male, 39.0% with diabetes mellitus. Meta-analysis yielded 2.0 mm for RAD and 2.0 mm for CVD as designated cutoff vessel diameters. Our study showed the mean fistula success rate was significantly different between RAD >2.0 mm (59%) and RAD >2.0 mm (40%). The mean fistula success rate was also significantly different between CVD > 2.0 mm (71%) and >2.0 mm (29%). Successful fistula placement was defined as a functional fistula at least 4–6 weeks after creation.

Conclusion

On the basis of our study, the use of Duplex ultrasound is important in determining preoperative vessel diameter size, and subsequent functional success rate of fistula placement.

Dialysis arteriovenous access monitoring and surveillance according to the 2017 Spanish Guidelines

The Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology (S.E.N.), vascular surgery (SEACV), interventional radiology (SERAM-SERVEI), infectious diseases (SEIMC), and nephrology nursing (SEDEN)), along with the methodological support of the Iberoamerican Cochrane Centre, has developed the Spanish Clinical Guidelines on Vascular Access for Hemodialysis. This article summarizes the main issues from the guideline's chapter entitled "Monitoring and surveillance of arteriovenous access." We will analyze the current evidence on conflicting topics such as the value of the flow-based screening methods for the arteriovenous access surveillance or the role of Doppler ultrasound as the imaging exploration to confirm suspected stenosis. In addition, the concept of significant stenosis and the criteria to perform the elective intervention for stenosis were reviewed. The adoption of these guidelines will hopefully translate into a reduced risk of thrombosis and increased patency rates for both arteriovenous fistulas and grafts.

Evaluation of Gore-Tex Graft Patency in Hemodialysis Access

Aim

The purpose of this retrospective study was to analyze the patency and complications of Gore-Tex grafts used in hemodialysis (HD) access.

Methods

In the last 16 years, 1649 surgical procedures were performed on 655 patients to ensure and maintain permanent HD access. The study group consisted of 64 HD patients on whom 81 vascular synthetic PTFE Goretex grafts were performed. There were 28 males and 36 females, 3 of them were children (4.7%). Mean age was 54.2 years (range 15–77). Two types of Gore-Tex prosthesis were used: Diastat and Stretch. All grafts were implanted in the upper extremities. Kaplan-Meier survival curves were calculated to determine primary and secondary patency. Log-rank analysis was used to determine differences between curves.

Results

Primary and secondary patency at 12 months was 52.5% and 67.5%, and at 18 months respectively 41.5% and 58.2%. The Diastat graft had a lower primary and secondary patency compared with the Stretch graft (respectively p = 0.02 and p = 0.008). Factors such as gender, coexisting diabetes and hypertension did not determine graft patency. Thrombosis was one of the most frequent complications. The remaining complications included stenosis, pseudoaneurysms, infection, steal syndrome and seroma.

Conclusion

On the basis of our experience Stretch grafts appear a better option for creating vascular access for HD than Diastat grafts.

Primary Thromboprophylaxis with Heparins for Arteriovenous Fistula Failure in Pediatric Patients

Background

To reduce the incidence of early arteriovenous fistula failure (AVF) due to thrombosis in pediatric hemodialysis (HD) patients, a primary thromboprophylaxis (PTP) protocol was initiated at author's institution in June 2005. The goal of this study is to report author's experience with this protocol one year later.

Methods and Results

19 AVFs (14 patients, Historical group) and 8 AVFs (7 patients, PTP group) were created prior to and after initiation of PTP respectively. PTP consisted of unfractionated heparin (5–10 units/kg/hr) infusion postoperatively, followed by subcutaneous low molecular weigh heparin (LMWH) until AVF was matured. LMWH dosing was “Prophylactic” (0.5 mg/kg/d, anti-factor Xa levels: peak 0.25–0.5 and trough < 0.3 units/mL) and “Therapeutic” (1 mg/kg/d, anti-factor Xa level: peak 0.5-1 and trough < 0.5 units/mL) based on thrombosis predisposition. In Historical group, 12 AVFs did not receive thromboprophylaxis (No-treatment group), 5 received 81 mg aspirin/day (Aspirin group), and 2 received LMWH. In No-treatment group 10/12 AVFs failed: 9 thromboses and 1 stenosis. In Aspirin group 1/5 AVFs failed due to thrombosis. In PTP group 1/8 AVFs failed due to stenosis; the first 2 AVFs developed hematoma prompting a reduction in LMWH dose and monitoring trough anti-factor Xa levels, one AVF required thrombectomy after LMWH was transiently held. The incidence of thrombosis was less in PTP group (12.5%) when comparing to No-treatment group (83%) (p < 0.05).

Conclusion

PTP is a feasible option to prevent early thrombosis at AVF. Close clinical and laboratory monitoring including trough anti-factor Xa levels is required to adjust optimum anticoagulation. Larger studies are needed to clarify safety and efficacy of our PTP protocol.

A porcine Model of Intimal-Medial Hyperplasia in Polytetrafluoroethylene Arteriovenous Grafts

Purpose

Vascular access polytetrafluoroethylene (PTFE) graft failure is a major cause of morbidity in the hemodialysis population. The most common cause of graft failure is thrombosis secondary to stenosis at the venous outflow tract. Venous outflow stenosis is characterized by intimal-medial hyperplasia. We have developed a porcine arteriovenous (AV) graft model that may be used to investigate this proliferative response and aid in the development of new therapies to prevent intimal-medial hyperplasia and improve graft patency.

Methods

Left carotid to right external jugular vein PTFE (6 mm) grafts were implanted in the necks of swine. Immediately following anatomosis, flow rates were recorded. In one group of animals (n = 4) the venous outflow tract was harvested after 7 days and morphometric analysis of intimal and medial area was performed. In a second group (n = 8) the graft patency was monitored until 28 days.

Results

All porcine PTFE fistula grafts were patent at 7 days and 100% patency was maintained until 14 days. After 28 days, 75% of the grafts failed due to thrombosis. The venous outflow tract developed a significant proliferative response. After 7 days the intimal and medial areas were 469 ± 9 μm2 and 875 ± 26 μm2 respectively. At 28 days the intimal and medial areas were 913 ± 55 μm2 and 1437 ± 182 μm2 respectively. Luminal flow rate of the venous outflow tract was reduced significantly (344 ± 11 ml/min at Day 0 to 129 ± 14 ml/min at Day 7, p < 0.05).

Conclusions

This porcine model rapidly, reliably and robustly reproduces the flow reducing stenosis and intimal-medial hyperplasia at the venous outflow tract of PTFE arteriovenous fistula. It represents a promising tool for investigating the mechanisms of intimal-medial hyperplasia, evaluating therapeutic interventions and new graft materials.

Improved Measurement of Vascular Access Pressure

Vascular access stenosis and thrombosis is one of the key problems for hemodialysis patients. Prospective monitoring of static venous dialysis pressures can be applied to detect outflow stenoses in a vascular access. However, the location of stenoses within the access may influence the diagnostic value of venous pressure measurements. Whereas a decrease in access flow occurs with all types of stenosis, strictures within the arterial anastomosis or between arterial and venous dialysis needle cannot be detected with venous pressure measurements alone.

A new approach is discussed, which bases on the improved measurement of static venous and arterial extracorporeal pressures. Extracorporeal pressure at zero blood flow depends on both the position of the heart relative to the extracorporeal blood circuit and the vertical offset between access site and fluid level in the bloodline. After hydrostatic correction of each pressure signal the normalized arterial and venous intra-access pressure ratio AP/MAP can be calculated. A venous stenosis leads to an increase in both arterial and venous pressure ratio. In case of access stenosis between arterial and venous needle the ratio of venous pressure to mean arterial pressure is normal, and only the arterial pressure ratio is elevated. In summary, a combination of arterial and venous pressure measurement is more sensitive and allows differentiation between mid-access and venous stenosis. Hydrostatic correction of the dialysis pressure signal is inevitable. To minimize the rate of access thrombosis, venous and arterial intra-access pressure should be considered when evaluating dialysis pressures as part of any access monitoring program.

Ultrasound Guided Brachial Arterial Angioplasty during the Creation of a Radio-Cephalic Arteriovenous Fistula: A Case Report

To prevent arteriovenous fistula (AVF) early failure, due to radial or brachial artery stenosis, ultrasound guided angioplasty performed while surgically creating the AVF could be an effective procedure.

Case report

A 76-year-old diabetic male patient, on hemodialysis (HD) for 15 months, presented extensive thrombosis of the radio-cephalic AVF at the right arm, which had lasted for about 10 days. Ultrasound examination showed a 40% brachial artery stenosis with eccentric calcified plaque. The stenosis was localized about 1.5 cm before the artery bifurcation. The brachial artery diameter was 0.45 cm before and 0.26 cm at the level of the stenosis, the latter being 0.45 cm long. At the left wrist, under local anesthesia, the radial artery and the cephalic vein were exposed; the radial artery was then longitudinally incised for 7–8 mm in the area selected to create the AVF. A 6 Fr introducer, a metallic guide wire and a catheter for angioplasty were inserted one after the other in the radial artery. When the correct position of the angioplasty catheter in the stenotic area was established by ultrasound examination, the balloon was blown up to 13 atm for 35 sec, reducing the stenosis from 40–20%. Finally, a side-to-side radio-cephalic fistula was created, legating the distal vein. The AVF was used for HD after 3 weeks. The follow-up at 6 months demonstrated fair access performance and it was used without problems. Our satisfactory experience suggests that ultrasound guided angioplasty of brachial artery stenosis, performed simultaneously with surgical AVF creation, is possibly a successful procedure. This technique reduces the risk of early AVF failure and also allows, when required, stent implantation.

A comparison of efficacy of endovascular versus surgical repair for the treatment of arteriovenous fistula stenosis in Taiwan

BACKGROUND

Percutaneous transluminal angioplasty (PTA) and fistula reconstruction surgery are therapeutic options for vascular access occlusion in hemodialysis patients. However, owing to its convenience, PTA has gradually become the preferred therapeutic option for fistula stenosis or occlusion. This study investigated the effects of the two therapeutic methods on the vascular access maintenance duration (number of days) and maintenance costs of fistula in dialysis patients from different dialysis units.

METHODOLOGY

In this study, 544 hemodialysis patients from 2 dialysis units in a teaching hospital in the southern area of Taiwan were included in the analysis of the frequency of PTA or revascularization surgery and the use of related medical resources by conducting a retrospective chart review.

RESULTS

The frequency of PTA in the patients undergoing long-term hemodialysis was not significantly associated with their demographic characteristics. The efficacy of PTA has declined with shorter maintenance duration with increasing PTA frequency. The cost profile of PTA was more expensive than that of fistula revascularization surgery.

CONCLUSIONS

In this study, PTA was found to be just a temporary solution for fistula thrombosis, whereas fistula reconstruction surgery is inexpensive and improves survival time. Therefore, dialysis units should establish an appropriate standard of care to avoid over-reliance on PTA in order to reduce the fistula failure rate, improve the dialysis efficacy, and reduce the psychological stress in patients, as well as to reduce the maintenance costs and rationalize the medical expenses.

Clinical Course of Hemodialysis Access After Initial Endovascular Intervention for Stenosis in Asian Renal Failure Patients

BACKGROUND

Arteriovenous fistula (AVF) and arteriovenous fistula graft (AVG) access for hemodialysis can develop stenosis, eventually leading to thrombosis and access failure. Prompt endovascular intervention can salvage the access but restenosis does occur. Clinical course, restenosis pattern, and risk factors associated with initial stenosis of AVFs/AVGs in Asian hemodialysis patients were studied.

METHOD

A retrospective study was conducted (January 2009-June 2012) on consecutive patients with renal failure who developed the first-time stenosis in the vascular access and were managed with endovascular intervention. One hundred fourteen patients (54 AVFs and 60 AVGs) were studied, and all clinical outcomes were recorded until October 2013.

RESULTS

The mean time from access creation to endovascular intervention for the first-time stenosis for patients with AVF and AVG was 23.5 (32.7 standard deviation [SD]) months and 12.5 (11.0) months, respectively. An average of 1.7 (range, 1-5) interventions were performed for AVFs, whereas 2.4 (range, 1-11) for AVGs ( P = .008). Upon conclusion of the study, 23 patients with AVF survived with functional index access, whereas 10 passed away with a functional original access. The remaining 21 patients with AVFs failed, requiring new access, tunneled catheter, or peritoneal dialysis. Of the 60 patients with AVG, 6 survived and 8 died with functional index access; 46 required new access or other forms of dialysis ( P = .000). Kaplan-Meier estimated that access patency and survival with functional access were significantly lower for AVGs than for AVFs after the first salvage intervention. Female patients had an increased risk of restenosis with both univariate ( P = .016) and multivariate ( P = .013) analysis. With univariate analysis ( P = .039), patients with hyperlipidemia had a higher risk of developing restenosis in the vascular access.

CONCLUSION

The clinical course and prognosis of failing AVFs and AVGs are distinct. The information on access prognosis and stenosis recurrence patterns will be helpful for patient counseling and planning of follow-up intervals, after the first-time intervention for access stenosis.

Economic Impact of the Beneficial Effect of Changing Vascular Anastomotic Technique in Hemodialysis Access

There is an urgent and compelling need to reduce the morbidity and expense of maintaining hemodialysis vascular access patency. We previously reported the beneficial effects of altering anastomotic technique on vascular access patency from a multicenter clinical trial. Interrupted anastomoses created with nonpenetrating clips showed significant improvement in primary, assisted primary, and secondary patencies of native vein fistulae (AVF) and synthetic arteriovenous grafts (AVG). In the current report, we provide an analysis of the economic impact of these procedures. The economic analysis is based on a subgroup of patients who underwent access procedures as outpatients during years 1998–1999 at a university-affiliated hospital that contributed 23% of procedures described in the multicenter clinical trial. Hospital charges and payments received were determined for fistula placement and for commonly performed surgical and endovascular procedures (thrombectomy and angioplasty) that maintain patency. Financial comparisons were based on the hospital's average accumulative charges and actual payments calculated on a daily basis. Cost curves were generated by using charge and payment data. Financial information was extrapolated to the entire study population to estimate the cost savings for the larger group. Both charge and payment calculations indicated financial benefit with the use of clips. When financial estimates were extrapolated to reflect the national volume, clip usage projected significant savings of $20 million for AVF and $30.8 million for AVG for every 1,000 days of access patency. Replacing conventional sutures with clips can reduce the morbidity and cost associated with maintaining permanent hemodialysis vascular accesses. This beneficial effect may be due to the biologic advantages of interrupted, nonpenetrating vascular anastomoses.

The importance of success prediction in angioaccess surgery

Access to the circulation is an "Achilles' heel" of chronic hemodialysis. According to the current guidelines, autologous arteriovenous fistula is the best choice available. However, the impossibility of immediate use and the high rate of non-matured fistulas place fistula far from an ideal hemodialysis vascular access. The first attempt at constructing an angioaccess should result in functional access as much as possible. After failed attempts, patients and nephrologists lose their patience and confidence, which results in high percentage of central venous catheter use. Predictive models could help, but clinical judgment still remains crucial. Early referral to the nephrologist and vascular access surgeon, careful preoperative examinations, preparation of patients and duplex sonography mapping of the vessels are very important in the preoperative stage. In the operative stage, it is crucial to understand that angioaccess procedures should not be considered as minor procedures and these operations must be performed by surgeons with demonstrable interest and experience. In the postoperative stage, appropriate surveillance of the maturation process is also important, as well as good cannulation skills of the dialysis staff. The purpose of this review article is to stress the importance of success prediction in order to avoid unsuccessful attempts in angioaccess surgery.

Effect of a Rapid Clinical Protocol to the Conversion from Central Venous Hemodialysis Catheter to Arteriovenous Access

Purpose

Evaluation of the rapid conversion protocol that includes an ambulatory dialysis access center (DAC), and a three-step clinical pathway, to the conversion rate from central venous hemodialysis (HD) catheter to functioning arteriovenous (AV) access.

Methods

Prospective data were collected on 97 consecutive catheter-dependent HD patients. DAC is defined as an ambulatory unit, able to accommodate clinic visits, ultrasound examinations, surgical, interventional and hybrid procedures. Step I: initial evaluation, vein mapping and creation of AV access. Step II: clinical evaluation in two weeks and if failure identified, secondary procedure to restore function. Step III: evaluation in four weeks after creation, and additional procedure to promote maturation if indicated. The success rate, time to conversion and time to catheter removal were recorded.

Results

From the 97 consecutive referred patients, eight patients were excluded. From the remaining 89 patients, 99% were successfully converted to AV access. Seventy-three percent of the patients were converted to native arteriovenous fistulae and 27% of the patients to prosthetic arteriovenous shunts. The median time from creation to HD catheter removal was 63 (SD 41) days. Fifty-two percent of the patients required at least one additional secondary procedure to accomplish successful conversion

Conclusions

High rates of timely conversion from catheter to AV access, primarily AV fistulae, can be accomplished within the context of the rapid conversion protocol.

Early Experience With a Novel Hybrid Vascular Graft for Hemodialysis Access Creation in Patients With Disadvantaged Anatomy

Purpose: To describe the use of the Hybrid vascular graft in disadvantaged anatomy for hemodialysis access creation and compare outcomes to standard-wall polytetrafluoroethylene (PTFE) grafts. Methods: In a retrospective analysis, 25 patients (mean age 65±14 years; 13 men) who received the Hybrid graft were compared with 35 contemporaneous patients (mean age 63±12 years; 20 men) who received a standard PTFE graft for hemodialysis access over a 2-year period. Criteria for Hybrid graft placement were (1) exhausted or inadequate peripheral veins for arteriovenous fistula (AVF) creation and concomitant small target veins that precluded conventional PTFE graft placement, (2) previous graft anastomosis or a stent in the venous target at the level of the axilla, or (3) failed brachial-basilic or brachial-brachial upper arm transposition AVF with a small target vein at the axilla. Efficacy, anatomic and clinical considerations, and technique were reviewed; patency rates, complications, and reinterventions were examined. Results: Technical success was achieved in all cases, and all grafts were usable for hemodialysis. Seven of 25 Hybrid patients required stent-graft extensions and 3 patients required angioplasty to improve venous outflow at the time of Hybrid graft insertion. Three of 35 standard PTFE graft patients required angioplasty to improve venous outflow at the time of graft insertion. There was no perioperative mortality or procedure-related morbidity in either group. Median follow-up was 21 months. The patient survival estimate was 66% at 2 years. Estimated primary patency (24% vs 18%, p>0.05), assisted primary patency (34% vs 28%; p>0.05), and secondary patency rates (40% vs 38%, p≥0.05) at 24 months were equivalent for Hybrid vs PTFE grafts, respectively. Venous hypertension was not a complication following Hybrid graft implantation but was seen in 2 patients with the standard PTFE graft. Conclusion: The Hybrid graft offers a safe, technically effective alternative for patients with disadvantaged anatomy requiring hemodialysis access and has comparable outcomes to standard PTFE grafts. Further clinical experience and long-term data are required for determining the proper utility of this device in chronic dialysis-dependent patients.

Association Between Vascular Access Dysfunction and Subsequent Major Adverse Cardiovascular Events in Patients on Hemodialysis: A Population-Based Nested Case-Control Study

The association between dialysis vascular access dysfunction and the risk of developing major adverse cardiovascular events (MACE) in hemodialysis patients is unclear and has not yet been investigated. We analyzed data from the National Health Insurance Research Database of Taiwan to quantify this association. Adopting a case-control design nested within a cohort of patients who received hemodialysis from 2001 to 2010, we identified 9711 incident cases of MACE during the stage of stable maintenance dialysis and 19,422 randomly selected controls matched to cases on age, gender, and duration of dialysis. Events of vascular access dysfunction in the 6-month period before the date of MACE onset (ie, index date) for cases and before index dates for controls were evaluated retrospectively. The presence of vascular access dysfunction was associated with a 1.385-fold higher odds of developing MACE as estimated from the logistic regression analysis. This represents a significantly increased adjusted odds ratio (OR) at 1.268 (95% confidence interval [CI] = 1.186-1.355) after adjustment for comorbidities and calendar years of initiating dialysis. We also noted a significant exposure-response trend (P < 0.001) between the frequency of vascular access dysfunction and MACE, with the greatest risk (adjusted OR = 1.840, 95% CI = 1.549-2.186) noted in patients with ≥3 vascular access events. We concluded that dialysis vascular access dysfunction was significantly associated with an increased risk of MACE. Hence, vascular access failure can be an early sign for MACE in patients receiving maintenance hemodialysis. Active monitoring and treatment of cardiovascular risk factors and related diseases, not merely managing vascular access dysfunction, would be required to reduce the risk of MACE.

Oral prostacycline analog and clopidogrel combination provides early maturation and long-term survival after arteriovenous fistula creation: A randomized controlled study

Vascular access is used as a lifeline for hemodialysis in patients with end stage renal disease failure (ESRD). Failure of arteriovenous fistula (AVF) maturation is still high. The purpose of this study was to research the effects of clopidogrel in combination with oral iloprost, a synthetic analog of prostacyclin PGI2. Ninety-six diabetic ESRD patients were divided into two groups. In the first group (Group 1, N = 50), clopidogrel (75 mg daily dose) and an oral prostacycline analog (200 mg daily dose) were administered. In the second group (Group 2, N = 46), placebo was given. All patients took study medication 7-10 days prior to surgery. A Doppler ultrasound (USG) was performed for measurement of arterial and venous diameters, and peak systolic velocity of arterial flow based on subsequent fistula adequacy. Autogenous AVFs were constructed in forearm as distally as possible in all patients. Both groups were followed-up for a year. In the placebo group, early AVF thrombosis was detected in two patients (4.3%). AVF maturation failure was noted in 14 patients (30.4%) in placebo group and in four patients (8%) in clopidogrel plus oral prostacycline analog group in the early postoperative period (P = 0.001). The mean maturation time was 38 ± 6.5 and 53 ± 12.8 days in study and placebo groups, respectively (P = 0.023). The mean blood flow was 352 ± 94 mL/min in placebo group and 604 ± 125 mL/min in study group (P = 0.001). The arterial end diastolic velocity was 116 ± 14 cm/s in study group and 72 ± 21 cm/s in placebo group (P = 0.036) 1 year after the surgery. Our data indicated that clopidogrel and oral prostacycline analog combination is effective and safe for the prevention of primary AVF failure in hemodialysis patients and decreased acute and chronic thrombotic events.

Outcomes of initial hemodialysis access surgery in an Asian population

PURPOSE

Access-related morbidity contributes substantially to the costs of hemodialysis. The aim of this study was to examine the outcomes of initial hemodialysis access surgery at a single center in Singapore and to analyze factors which might influence survival of the surgically-created access.

METHODS

Patients undergoing their first hemodialysis access operations between January 2003 and December 2007 were retrospectively identified. Primary and assisted primary patency rates were determined by the Kaplan-Meier method. Data on age, sex, diabetic status, and prior tunneled central venous catheter (CVC) use were analyzed against the outcome of arteriovenous fistulas (AVF).

RESULTS

During the study period, 410 primary upper limb access operations were performed: 297 forearm AVF (72.4%), 91 upper arm AVF (22.2%), and 22 arteriovenous grafts (AVG; 5.4%). Men comprised 55.4%, 271 (66.1%) had diabetes, and 316 patients (77.1%) came to surgery with pre-existing CVC. Sixty-two percent of forearm AVF and 67% of arm AVF were used successfully. Age, sex, diabetes, and prior use of a CVC did not significantly affect the ability to use an AVF. Only in the female diabetic subgroup was an earlier loss of primary assisted patency of AVF recorded.

CONCLUSIONS

In our Asian population, we have demonstrated AVF patency rates equivalent to those of international centers. We now face the challenge of achieving a higher rate of pre-emptive AVF placement with a subsequent reduction in CVC use.

The effect of two different hand exercises on grip strength, forearm circumference, and vascular maturation in patients who underwent arteriovenous fistula surgery

Objective

To compare the effect of two different hand exercises on hand strength and vascular maturation in patients who underwent arteriovenous fistula surgery.

Methods

We recruited 18 patients who had chronic kidney disease and had undergone arteriovenous fistula surgery for hemodialysis. After the surgery, 10 subjects performed hand-squeezing exercise with GD Grip, and other 8 subjects used Soft Ball. The subjects continued the exercises for 4 weeks. The hand grip strength, pinch strength (tip, palmar and lateral pinch), and forearm circumference of the subjects were assessed before and after the hand-squeezing exercise. The cephalic vein size, blood flow velocity and volume were also measured by ultrasonography in the operated limb.

Results

All of the 3 types of pinch strengths, grip strength, and forearm circumference were significantly increased in the group using GD Grip. Cephalic vein size and blood flow volume were also significantly increased. However, blood flow velocity showed no difference after the exercise. The group using Soft Ball showed a significant increase in the tip and lateral pinch strength and forearm circumference. The cephalic vein size and blood flow volume were also significantly increased. On comparing the effect of the two different hand exercises, hand-squeezing exercise with GD Grip had a significantly better effect on the tip and palmar pinch strength than hand-squeezing exercise with Soft Ball. The effect on cephalic vein size was not significantly different between the two groups.

Conclusion

The results showed that hand squeezing exercise with GD Grip was more effective in increasing the tip and palmar pinch strength compared to hand squeezing exercise with soft ball.

Angioplasty of communicating veins to the brachial vein in haemodialysis patients with obliterated superficial veins of the upper arm

AIM

To evaluate the outcomes of angioplasty of the communicating veins when superficial veins of the upper arm were almost totally obliterated in haemodialysis patients.

MATERIALS AND METHODS

Twenty-one angioplasties of the communicating veins that were performed for failing haemodialysis fistulas in patients with almost totally obliterated superficial veins of the upper arm from December 2006 to March 2011 were retrospectively reviewed. Fistulas were of the following types: native radiocephalic fistulas (n = 20) and radio-antecubital fistulas (n = 1). All angioplasties were performed using 5-8 mm conventional balloons. Cutting balloon angioplasty was additionally performed in five patients. The primary, secondary, and target lesion patency rate was calculated using Kaplan-Meier analysis.

RESULTS

The communicating vein was located in the antecubital fossa. Technical and clinical success rates were 100% and 95.2%, respectively. Follow-up duration was 1-52 months (mean 20 months). The primary patency rates were 76%, 43%, and 29% at 3, 6, and 12 months, respectively, and target lesion patency rates were 81%, 62%, and 43% at 3, 6, and 12 months, respectively. The secondary patency rates were 81%, 76%, and 57% at 3, 6, and 12 months, respectively. There were no major or minor complications.

CONCLUSION

Angioplasty of the communicating vein is effective in restoring function in failing haemodialysis fistula in patients with obliterated superficial veins of the upper arm.

Clinical analysis of pulmonary infection in hemodialysis patients

The present study aimed to investigate the pathogen distribution and drug resistance of lung infections in hemodialysis to guide clinical empirical pharmacy. The clinical data of 116 hemodialysis patients with pulmonary infection were analyzed. The majority of the 82 pathogens isolated from the sputa of patients were Gram-negative bacteria (accounting for 71.95%). The results of the drug sensitivity test suggested that Gram-negative bacilli had low resistance rates to piperacillin and tazobactam, imipenem and amikacin, while Gram-positive cocci had a low resistance rate to vancomycin. All resistance rates of the pathogens to other common antimicrobials were >50%. The pathogens resulting in lung infections in hemodialysis patients were mainly Gram-negative bacteria and were significantly resistant to various antibacterials. Results of the this study demonstrate that pathological examination should be performed as early as possible and effective antimicrobial agents should be chosen according to drug sensitivity test results.

Thrombin-anti-thrombin levels and patency of arterio-venous fistula in patients undergoing haemodialysis compared to healthy volunteers: a prospective analysis

Background

Patients on haemodialysis (HD) are at an increased risk of sustaining thrombotic events especially to their vascular access which is essential for maintenance of HD.

Objectives

To assess whether 1) markers of coagulation, fibrinolysis or endothelial activation are increased in patients on HD compared to controls and 2) if measurement of any of these factors could help to identify patients at increased risk of arteriovenous (AVF) access occlusion.

Patients/Methods

Venous blood samples were taken from 70 patients immediately before a session of HD and from 78 resting healthy volunteers. Thrombin-antithrombin (TAT), D-dimer, von Willebrand factor (vWF), plasminogen activator inhibitor-1 antigen (PAI-1) and soluble p-selectin were measured by ELISA. C-reactive protein (hsCRP) was measured by an immunonephelometric kinetic assay. Determination of the patency of the AVF was based upon international standards and was prospectively followed up for a minimum of four years or until the AVF was non-functioning.

Results

A total of 70 patients were studied with a median follow-up of 740 days (range 72-1788 days). TAT, D-dimer, vWF, p-selectin and hsCRP were elevated in patients on HD compared with controls. At one year follow-up, primary patency was 66% (46 patients). In multivariate analysis TAT was inversely associated with primary assisted patency (r= -0.250, p= 0.044) and secondary patency (r = -0.267, p= 0.031).

Conclusions

The novel finding of this study is that in patients on haemodialysis, TAT levels were increased and inversely correlated with primary assisted patency and secondary patency. Further evaluation is required into the possible role of TAT as a biomarker of AVF occlusion.

Pre Dialysis care and types of Vascular Access Employed in Incident Hemodialysis Patients: A study from Pakistan

OBJECTIVE

To determine frequency of different vascular access use in Incident hemodialysis (HD) patients and determine whether predialysis care in terms of timely advice for vascular access placement was better in the hands of nephrologist.

METHODS

A cross sectional study was conducted. Data was collected on the type of access used for first HD, including temporary Central venous catheters (CVC), permanent CVC (Permacath), arteriovenous fistula (AVF), or arteriovenous graft (AVG). In addition, information was also gathered if patients were aware of their renal disease and was followed by other physicians or nephrologist.

RESULTS

A total of 120 patients were enrolled in the study, 80% required CVC as their first access for HD (96/120 patients) out of which 74.2% were dialyzed through temporary catheter and 5.8% through Permacath. About 20% of patients were dialyzed through mature Arteriovenous (AV) access. Majority (95.8%) of patients were being followed by any health care provider. 68% of them were aware of their renal disease. About 55.8% were referred to nephrologist and 40% were followed by other physicians. About 83.5% of patients followed by nephrologist were advised AV access prior to commencing HD, compared to only 10.4% followed by other physicians (p<0.05). 24/61 (39.3%) patients that were advised AV access by both groups had timely made AV access and underwent HD by it.

CONCLUSION

Very high incidence of temporary HD catheter was used in Incident HD patients. Moreover, pre dialysis care in terms of placement of AV access prior to initiating HD is better in the hands of nephrologist and patients should be timely referred to nephrologist especially when they have Stage 4 chronic kidney disease (CKD).

Interventional nephrology: Novel devices that will one day change our practice

There is increasing awareness of vascular access dysfunction as a significant contributor to the morbidity associated with chronic hemodialysis. Over the last several years, interventional nephrologists, in conjunction with our colleagues in vascular surgery, have led the way in the creation of novel devices that are designed to help solve the vascular access problem. The purpose of this review is to describe novel devices in the precommercial stage of development that have the potential to revolutionize the field of dialysis vascular access. These devices include bioengineered blood vessels, access monitoring technology, and advanced anastomotic connectors.

Effectiveness of aspirin on double lumen permanent catheter efficacy in ESRD

BACKGROUND

The complications of vascular access are the most imperative etiology for hospitalization, morbidity and mortality in chronic hemodialysis. The most prevalent complication of central catheter is dysfunction due to thrombosis. Aspirin is an anti-aggregative platelet drug that may increase the patency of permanent catheters (perm-cath).

OBJECTIVES

The aim of this study was to evaluate the role of Aspirin in perm-cath survival.

PATIENTS AND METHODS

This study included a total of 185 ESRD cases according to the inclusion criteria for perm-cath insertion in hemodialysis. One hundred and eighty patients following perm-cath insertion had proper blood flow through perm-cath during hemodialysis. Patients were randomly divided between intervention (80 mg/day Aspirin initiated a day following catheter insertion) and control (placebo) groups. The average time that the perm-cath was functional was noted. Demographic characteristics included comorbidities and past history were also used to address probable influence on perm-cath function and patency.

RESULTS

The mean survival time of the catheter in Aspirin group was significantly higher than the control group (5.3 ± 4.7 month versus 3.9 ± 2.7 month, P = 0.012). No significant difference in major complications of Aspirin use (such as GI bleeding) was noted between two groups (P = 0.52). In terms of the patient's demographic characteristics, those of the female gender and a history of diabetes mellitus were found to have significant influence on median survival rate of the catheters (P = 0.021, 0.043 respectively).

CONCLUSIONS

These results suggest that Aspirin use following perm-cath insertion might be beneficial for catheter survival. This increased survival time might enable patient's use of AVF maturation for long term dialysis access.

Increased production of superoxide anion contributes to dysfunction of the arteriovenous fistula

Vascular access dysfunction causes morbidity in hemodialysis patients. This study examined the generation and pathobiological significance of superoxide anion in a rat femoral arteriovenous fistula (AVF). One week after AVF creation, there was increased production of superoxide anion accompanied by decreased total superoxide dismutase (SOD) and Cu/Zn SOD activities and induction of the redox-sensitive gene heme oxygenase-1. Immunohistochemical studies of nitrotyrosine formation demonstrated that peroxynitrite, a product of superoxide anion and nitric oxide, was present in increased amounts in endothelial and smooth muscle cells in the AVF. Because uncoupled NOS isoforms generate superoxide anion, and NOS coupling requires tetrahydrobiopterin (BH(4)) as a cofactor, we assessed NOS uncoupling by determining the ratio of BH(4) to dihydrobiopterin (BH(2)); the BH(4)-to-BH(2) ratio was markedly attenuated in the AVF. Because Src is a vasculopathic signaling species upstream and downstream of superoxide anion, such expression was evaluated; expression of Src and phosphorylated Src was both markedly increased in the AVF. Expression of NADPH oxidase (NOX) 1, NOX2, NOX4, cyclooxygenase (COX) 1, COX2, p47(phox), and p67(phox) was all unchanged, as assessed by Western analyses, thereby suggesting that these proteins may not be involved in increased production of superoxide anion. Finally, administration of tempol, a superoxide anion scavenger, decreased neointima formation in the juxta-anastomotic venous segment and improved AVF blood flow. We conclude that the AVF exhibits increased superoxide anion generation that may reflect the combined effects of decreased scavenging by SOD and increased generation by uncoupled NOS, and that enhanced superoxide anion production promotes juxta-anastomotic stenosis and impairs AVF function.