Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Hemodialysis vascular access flow measurements by the novel DMed NephroFlow® device: A comparative study with Transonic®

INTRODUCTION

The current Spanish Clinical Guidelines on Vascular Access for Hemodialysis support the need for surveillance and monitoring of vascular access (VA) to avoid complications. Ultrasound dilution (UD) methods are accepted for the evaluation of VA flow and Transonic® has established the gold standard method for the measurement. The DMed NephroFlow (NIPRO®) device, based on UD method has recently been incorporated. We report a comparative study between the classic Transonic® versus the new NephroFlow® device.

MATERIAL AND METHODS

For two consecutive months, measurements of VA flow using both referred systems were performed in patients with a native arteriovenous fistula (AVF) or a graft (AVG) on hemodialysis (HD) in our unit. Both studies were undertaken according to the usual recommendations: VA flow of 250 ml/min, ultrafiltration rate without modifications, both needles in the same vein, and always in the first hour of the HD session.

RESULTS

Forty-five patients were included: 17 women and 28 men, mean age of 67 ± 12 years. Thirty patients were diabetic. The baseline meantime on HD was 51 ± 39 months (range: 3-163). Type of VA was: 17 patients radio-cephalic AVF, 17 brachiocephalic AVF, 7 brachiobasilic AVF, and 3 with a graft. The mean flow estimated by the Transonic® was 1222 ± 805 ml/min and the estimated flow by the NephroFlow® device was 1252 ± 975 ml/min. Good reliability between Transonic® and NephroFlow® was observed, with a reliability index of Cronbach's Alpha of 0.927 and an Intraclass Correlation Index of 0.928.

CONCLUSIONS

The NephroFlow® device seems comparable with the accepted gold standard UD method for estimating VA flow. More studies must be performed to verify these results. However, they should be considered for the surveillance and monitoring of VA flow, in agreement with the Spanish Guidelines.

A meta-analysis of vascular access outcomes in hemodialysis patients aged 75 years or older

BACKGROUND

Several existing guidelines advocate the access creation without any specific recommendations for those patients over 75 years of age. The aim of this meta-analysis is to compare the outcomes of different vascular access procedures in the sub-group of elderly ESRD patients ⩾75 years of age.

METHODS

A literature search was performed using the MEDLINE and SCOPUS electronic databases. The analysis focused on studies with subgroups of elderly patients ⩾75 years of age with different vascular access procedures, and compared the failure rates of autologous versus prosthetic vascular access. Articles comparing patency rates of distal (forearm) versus proximal upper arm AVFs were also investigated.

RESULTS

Twelve relevant studies were identified and included in the meta-analysis. The pooled results revealed a statistically significant unassisted (primary) failure rate at 24 months in favor of autologous AVFs [odds ratio (OR): 0.56, 95% CI: 0.38-0.83, p = 0.003]. A secondary analysis revealed significantly higher 12 months unassisted (primary) and secondary failure rates of forearm AVFs compared with proximal upper arm AVFs (OR: 2.14, 95% CI: 1.53-2.97, p < 0.00001 and OR: 1.76, 95% CI: 1.12-2.78, p < 0.01 respectively).

CONCLUSION

An increased risk of failure of prosthetic vascular access procedures was found compared with autologous AVFs in patients ⩾75 years of age. Elderly patients ⩾75 years should not be excluded from creation of an autologous access, with proximal upper arm AVFs having better patency rates.

Lipectomy as an alternative for superficialization of autologous AVF in obese patients: experience of a referral center in Amazon

Background

The preferred vascular access for hemodialysis is a native arteriovenous fistula (AVF) because it offers the best results in the short and long terms, lower morbidity and mortality, and has additional advantages in relation to central venous catheters or arteriovenous grafts. However, obesity can present an additional challenge because of the barrier of subcutaneous cellular tissue covering the surface of the vein to be punctured.

Objectives

The authors review their experience with excision of subcutaneous tissue (lipectomy) overlying upper arm cephalic vein arteriovenous fistulas in obese patients.

Methods

Consecutive vascular access patients undergoing lipectomy for cannulation with difficult access because of vein depth were reviewed. Cephalic vein depth was measured by ultrasound in all cases.

Results

Twenty-two patients were reviewed (15 men and 7 women), with a mean body mass index of 34.0 kg/m2 (range: 28-40 kg/m2). Mean age was 58.4 years. The mean preoperative vein depth of 7.9 mm (range: 7.0-10.0 mm) was reduced to 4.7 mm (range: 3.0-6.0 mm) (P 0.01). The mean follow-up period for patients was 13.2 months. Four patients were lost to follow-up and four died during the period due to causes unrelated to vascular access.

Conclusions

Obesity should not be a limiting factor to creation of a native AVF, since lipectomy is a relatively simple option for superficialization, enabling functioning native and deep arteriovenous fistulas in obese patients.

The error of estimated GFR in predialysis care

The error of estimated glomerular filtration rate (eGFR) and its consequences in predialysis are unknown. In this prospective multicentre study, 315 predialysis patients underwent measured GFR (mGFR) by the clearance of iohexol and eGFR by 52 formulas. Agreement between eGFR and mGFR was evaluated by concordance correlation coefficient (CCC), total deviation index (TDI) and coverage probability (CP). In a sub-analysis we assessed the impact of eGFR error on decision-making as (i) initiating dialysis, (ii) preparation for renal replacement therapy (RRT) and (iii) continuing clinical follow-up. For this sub-analysis, patients who started RRT due to clinical indications (uremia, fluid overload, etc.) were excluded. eGFR had scarce precision and accuracy in reflecting mGFR (average CCC 0.6, TDI 70% and cp 22%) both in creatinine- and cystatin-based formulas. Variations -larger than 10 ml/min- between mGFR and eGFR were frequent. The error of formulas would have suggested (a) premature preparation for RTT in 14% of stable patients evaluated by mGFR; (b) to continue clinical follow-up in 59% of subjects with indication for RTT preparation due to low GFRm and (c) to delay dialysis in all asymptomatic patients (n = 6) in whom RRT was indicated based on very low mGFR. The error of formulas in predialysis was frequent and large and may have consequences in clinical care.

Hemodialysis vascular access coordinator: Three-level model for access management

Management of vascular access is a challenge for the dialysis team, particularly to keep the arteriovenous access working. The vascular access coordinator can positively contribute to increase the number of arteriovenous fistulas and reduce central venous catheters. In this article, we introduce a new approach to vascular access management centered on (the results of setting up) the role of vascular access coordinator. We described the three-level model (3Level_M) for vascular access management organized in three levels: vascular access nurse manager, vascular access coordinator, and vascular access consultant. We defined the instrumental skills and training required to be developed by each element and clarify the articulation between the model and all members of the dialysis team related to vascular access.

The hand grip training device: A new therapeutic option in arteriovenous fistula maturation

INTRODUCTION

Postoperative exercise improves arteriovenous fistula maturation for hemodialysis. However, scarce evidence exists about hand grip device on fistula maturation process.

OBJECTIVE

To evaluate the efficacy of a hand grip training program on arteriovenous fistula maturation in population with Chronic Kidney Disease 5-5D.

METHODOLOGY

Prospective study (15 months). Patients were randomized to handgrip (HG) or control group (CG) postoperatively. HG performed a training program using a hand grip device. CG received conventional care. Upper limb muscle strength (ULMS), Duplex ultrasonography, and clinical arteriovenous fistula maturation were assessed at 4 and 8 weeks postoperatively.

RESULTS

At 8 weeks after fistula creation, upper limb muscle strength was increased only in the handgrip group (from 18 ± 6 to 23 ± 9 kg, p = 0.023). Clinical maturation was significantly greater in handgrip group versus control group, both at 4 weeks after intervention (62% vs 23%, p = 0.004) and at 8 weeks (65% vs 27%, p = 0.004). Similarly, the Doppler ultrasonography maturation rates were significantly greater in the HG, both at 4 weeks (HG: 84% vs CG: 47%; p = 0.004) and at 8 weeks (HG: 89% vs CG: 50%; p = 0.002).

CONCLUSIONS

The hand grip is a useful and safety training device to improve the arteriovenous fistula maturation. This device results a new therapeutic option for maturation in arteriovenous fistula, particularly in distal arteriovenous fistula. Further studies are required to support these results.

Assessment of the performance of vascular access for hemodialysis

BACKGROUND

Life and quality of life on hemodialysis depends on adequate vascular access. An autogenous arteriovenous fistula (AVF) has the best performance, while the use of a central venous catheter (CVC) may have a negative impact on fistula performance and may be associated with increased systemic inflammation. Our objective is to evaluate the performance of vascular accesses in patients undergoing a chronic hemodialysis program.

METHODS

This is an observational, cross-sectional, and descriptive study that included patients on chronic hemodialysis for more than 90 days. Patients with an acute systemic inflammatory disease and those with acute cardiovascular illness were excluded. Clinical data, dialysis session parameters, and serum levels of inflammatory markers were evaluated.

RESULTS

A total of 91 patients were evaluated, 59 (65%) had an AVF and 32 patients (35%) had a CVC. The adequacy rate was 67%; being 67.8% with AVF and 65.6% with CVC. Among the causes of AVF inadequacy, the ones that presented the highest prevalence ratio (PR) were non-mature AVF (PR: 4.055; 95% CI: 2.017-8.151), pseudoaneurysm (PR: 6.580; 95% CI: 3.723-11.629) and presence of hematoma (PR: 4.360; 95% CI: 2.125-8.946), p < 0.001. Among the catheter group, the causes of inadequacy with the highest PR were the presence of access thrombosis, indicating the use of thrombolytics (PR: 11.103; 95% CI: 4.746-25.977; p < 0.001) and infection (PR: 2.984; 95% CI: 1.293-6.889; p = 0.010). Median primary AVF patency was 72 months compared to 7 months of catheters (p < 0.001). There was no significant difference in serum inflammatory markers between the two groups.

CONCLUSIONS

Adequacy rates of vascular accesses did not differ between the groups, but the primary and functional patency of AVF is 10 times higher than that of catheters. Infection in dialysis catheters is associated with worse access performance. There was no association between systemic inflammation and vascular access.

Endovascular tools for vascular access stenosis: Flow-chart proposal

Stenosis represents the most relevant arteriovenous fistula (AVF) pathology and can affects the entire conduit forming the fistula, from afferent artery to central venous vessels. Correction of vascular access stenosis significantly affects the survival and quality of life for end stage renal disease patients (ESRD) dependent on hemodialysis. Guidelines consider the procedure of percutaneous transluminal angioplasty (PTA) relevant for the primary treatment of these lesions with excellent results in restoring AVF immediately at the end of the procedure. From first AVF angioplasty in 1981 to now, wide scientific innovation has led to development of new devices, composed by different materials and technologies, specific for the site and the type of stenosis to be treated, able to manage resistant stenotic lesion and to reduce stenosis recurrences. International guidelines do not clearly specify all treatment possibilities in the individual case. In this review the authors want to provide specific information on most used devices for stenosis treatment based on literature evidence, showing when and where to use the various tools available with flow-chart treatment proposal.

Vascular access challenges in hemodialysis patients with superior vena cava syndrome

BACKGROUND

Superior vena cava syndrome in hemodialysis patients resulting from previous or current use of a tunneled central vein catheter is a rare but potentially severe condition. Two aspects have to be addressed during management and treatment: the restoration of central venous flow and the creation of an alternative vascular access to guarantee hemodialysis.

RESEARCH DESIGN

Conforming to the current guidelines and literature, we present a stepwise approach and discuss therapeutic options. The removal of the tunneled central vein catheter should be attempted and a native vascular access created whenever feasible.

RESULTS

First, an upper extremity AVF should be preserved or, as in our case, made functional. Endovascular treatment of CVSO should primarily consist of balloon dilatation. Placement of a stent or stent graft should be considered as a secondary option. HeRO graft placement may be considered in recurrent CVSO and recanalization with a Surfacer. LL-AVF or AVG need to be discussed and may be an alternative for certain HD patients when the risk of lower limb ischemia and infection is considered.

CONCLUSION

Several therapeutic options are available and the basic principles are well established in the literature, although the level of evidence is not high. Therefore, we propose a stepwise and interdisciplinary approach to guide the challenging decision-making process in SVC.

Vascular access for hemodialysis in Italy: What a national survey reveals

BACKGROUND

Since in Italy there are no official data on vascular access (VA) for hemodialysis the Vascular Access Project Group (VAPG) of the Italian Society of Nephrology (SIN) designed a national survey.

METHODS

A 35-question survey was designed and sent it to the Italian facilities through the SIN website. The basic questions were the prevalence, the location, and the surveillance of VA, the bedside use of ultrasound, the use of fluoroscopy for central venous catheter (CVC) placement, and of buttonhole technique, the role of nephrologist in the access creation.

RESULT

The questionnaire was completed in June 2022 by 161 facilities. The survey registered 15,499 patients, approximately one-third of the Italian dialysis population. The prevalence of arteriovenous fistula (AVF), arteriovenous Graft (AVG), and CVC were 61.8%, 3.7%, and 34.5% respectively. The AVF location was 50% in distal forearm, 20% in meanproximal forearm, 30% in upper arm. For AVF creation, nephrologists were involved in 72% of facilities while for CVC placement in 62%. As regards VA monitoring, 21% of the facilities did not have a surveillance protocol; 60% did not register AVF thrombosis and 53% did not register CVC infections. Most of facilities use the fluoroscope during CVC placement, 37% when needed, and 22% never. Ultrasound-guided puncture of complex AVFs was used by 80% of facilities. Buttonhole puncture was used in 5% of patients.

CONCLUSIONS

Some considerations emerge from the survey data: (1) The increasing CVC prevalence compared to DOPPS 5 study. (2) The low rate of AVG prevalence. (3) The nephrologist is the operator in many VA procedures. (4) The fluoroscopy for CVC placement and the US-guide puncture of the complex AVF are widely used in most facilities. (5) The practice of the buttonhole is not widespread. (6) When the operator is the nephrologist more distal fistulas are performed.

Dialysis for older adults: why should the targets be different?

The number of patients aged > 75-years treated by dialysis continues to increase, particularly in developed countries. Haemodialysis is a well-established treatment with national and international clinical guidelines designed to provide patients with optimal treatment. However, these were developed when the dialysis population was younger, and less co-morbid. This change in patient demographics questions whether these guideline targets still apply to older patients. More patients now start dialysis with residual kidney function and could benefit from a less frequent dialysis schedule. Older patients have a lower thirst drive, so lower interdialytic gains, reduced appetite, muscle mass and physical activity would potentially allow starting dialysis with less frequent sessions a practical option. Similarly, patients with residual kidney function and lower metabolic activity may not need to meet current dialyser Kt/Vurea clearance targets to remain healthy. Instead, some elderly patients may be at risk of malnutrition and might need liberalisation of the low salt, potassium and phosphate dietary restrictions, or even additional supplements to ensure adequate protein intake. Although a fistula is the preferred vascular access, a forearm fistula may not be an option due to vascular disease, while a brachial fistula can potentially compromise cardiovascular reserve, so a dialysis catheter becomes the de facto access, especially in patients with limited life expectancy. Thus, clinical guideline targets designed for a younger less co-morbid dialysis population may not be equally applicable to the older patient initiating dialysis, and so a more individualised approach to dialysis prescription and vascular access is required.

Hemodialysis vascular access in elderly patients: A comprehensive review

The number of elderly patients initiating hemodialysis (HD) increased considerably over the past decade. Arteriovenous fistulas (AVFs) are the preferred vascular access (VA) type in most HD patients. Choice of VA for older hemodialysis patients presents a challenge. The higher incidence of comorbidities, longer AVF maturation times, risk of primary failure, risk of patency loss, and shorter life expectancy are important factors to consider. In this review we provide a comprehensive analysis on maturation rates, primary failure, patency, and mortality regarding vascular access in patients older than 75 years of age.

Results of a hemodialysis vascular access routine ultrasound surveillance protocol and frequency of surveillance guided pre-emptive access maintenance interventions

BACKGROUND

To evaluate the implementation of routine surveillance using ultrasound on hemodialysis vascular access (VA) outcomes and determine the number and frequency of corrective, surveillance-guided procedures performed.

METHODS

Multicenter, prospective, observational study that includes consecutive hemodialysis patients receiving therapy from native arteriovenous fistulae (AVF) or grafts (AVG). Participants were assigned to a routine VA Color Doppler ultrasound surveillance (DUS) protocol from January 2019 to December 2021. Patients were referred for corrective procedures (endovascular or surgical) based on clinical or DUS findings (pre-emptive procedures; PEP). Primary endpoint was the estimation of primary unassisted (PUP) and secondary patency (SP) rates. Secondary endpoints were the determination of the number and frequency of PEP and VA survival rates.

RESULTS

In total, 223 patients with 243 VA (192 AVF and 51 AVG) were included. Access PUP and SP rates were 83% and 93% at 12 months, 75% and 88% at 24 months, and 72% and 83% at 36 months follow-up. Autologous fistulae PUP and SP were 89% and 96% at 12 months, 81% and 93% at 24 months, and 80% and 89% at 36 months, respectively. Graft PUP and SP were 56% and 80% at 12 months, 44% and 65% at 24 months, and 39% and 54% at 36 months, respectively. In total, 56 corrective procedures (38/56 PEP; 65.5%) were performed (0.13 procedures/year), of which 34 were in AVF patients (0.09 procedures/year) and 22 in AVG patients (0.40 procedures/year). Overall, 33 VA losses occurred (0.06 failures/year), 17 in AVF (0.04 failures/year), and 16 in AVG patients (0.20 failures/year).

CONCLUSION

The use of DUS resulted in the timely diagnosis of dysfunction, satisfactory overall VA survival, and patency rates, with a low PEP frequency. Randomized controlled trials are required to establish the value of DUS surveillance on access patency and whether DUS-guided interventions could improve VA outcomes.

Autologous forearm arteriovenous loop vascular access, an option to be considered

BACKGROUND

Autologous arteriovenous fistula is usually the vascular access of choice for hemodialysis in patients with chronic kidney disease. Autologous forearm loops with cephalic or basilic vein are an alternative in those cases with a suitable forearm vein but with an unsuitable radial artery; however they are rarely used and there is little reported evidence of their usefulness. Our objective is to report our results on the creation of autogenous forearm loops as vascular access for hemodialysis.

METHODS

We present a prospective cohort study of autogenous forearm loop arteriovenous fistula created between 2010 and 2022, in patients with stage 4-5 chronic kidney disease. Demographic data, surgical details, vein used, follow up to 24 months, maturation, utilization, primary, assisted, and secondary patency estimations with Kaplan-Meier curves, as well as complications during follow-up, were recorded.

RESULTS

During the study period, 22 autologous forearm loops were created, 14 of them with cephalic, and 8 with basilic vein. Most (59%) of the patients were men, 19 were already on dialysis and the rest started during follow-up. Sixteen patients had previous vascular accesses. One patient was lost during follow-up. Six-week maturation rate was 61.9% and utilization rate was 57.1%. 6, 12, and 24 months primary and secondary patencies were 75.4%, 59.2%, 41.5% and 85.0%, 69.5%, 56.9% respectively. In five patients an access-induced distal ischemia was diagnosed, four successfully treated and only one patient lost the access. No cases of infection or other major complications were reported.

CONCLUSION

Autologous forearm loops have acceptable maturation (61.9%) and patency rates at follow-up (56.9% 2-years secondary patency). Although rarely used, they are a vascular access alternative that should be considered to preserve the proximal vasculature of the arm for future accesses.

Clinical characteristics and preoperative ultrasound parameters related to low patency in radio-cephalic arteriovenous fistulas

INTRODUCTION

Our objective is to describe the clinical characteristics and preoperative ultrasound mapping parameters associated with primary and secondary patency of radio-cephalic arteriovenous fistulas (RCF).

METHODS

A retrospective, single-center, descriptive study, including patients undergoing a RCF creation between 2015 and 2019. Socio-demographic data and ultrasound parameters were collected and an analysis of primary and secondary patency was performed.

RESULTS

Eighty-four patients were included in this study. Mean age was 65.6 (±13.9) years; 76.6% were male. Mean preoperative ultrasound parameters: forearm cephalic vein diameter was 2.8 (±0.57) mm, radial artery diameter was 2.6 (±0.42) mm, radial artery systolic peak velocity was 68 (±14.3) cm/s radial artery resistance index was 0.76 (±0.9). At the end of the 4 years the follow-up, the mean primary and secondary patency were 47.2% and 80% respectively. Only female sex was significantly associated with a decrease in both primary patency (p = 0.043, HR = 0.48) and secondary patency (p = 0.021, HR = 0.023). Furthermore, radial artery systolic peak velocity (p = 0.007, HR = 2.6) showed a significant association with decreased primary patency and forearm cephalic vein diameter showed a borderline significant association with decreased secondary patency (p = 0.046, HR = 8.2).

CONCLUSIONS

A standardized evaluation by a vascular surgeon or nephrologist represent a key in the preoperative assessment of AVF candidates. Based on our results, we will consider to avoid distal vascular access in both female patients with lower radial artery systolic peak velocity (less than 68 cm/s) and borderline forearm cephalic vein diameter (less than 2.8 mm) after initial assessment in our clinical practice. Our results could encourage new studies in order to stablish the potential role of these parameters in the RCFs patency rates.

Effect of kidney transplantation activity on arteriovenous fistula use in prevalent haemodialysis patients: A registry-based study

BACKGROUND

Kidney transplantation (KT) is considered to be the best kidney replacement therapy (KRT) option for most end-stage kidney disease (ESKD) patients. Arteriovenous fistula (AVF) is considered to be the best vascular access (VA) for most haemodialysis (HD) patients. In this study, we investigated the effect of KT activity on AVF use in prevalent HD patients. The probability of receiving a kidney graft (KTx) over time, depending on the first VA used to start the HD program, was also evaluated.

METHODS

Data from the Catalan Registry of prevalent patients on KRT by either KT or HD were examined over a 20-year period (1997-2017).

RESULTS

The percentage of prevalent ESKD patients with a functioning KTx increased from 40.5% in 1997 to 57.0% in 2017 and, conversely, the percentage of AVF utilisation in HD patients decreased from 86.0% to 63.2% during the same period (for both comparisons, p < 0.001). This inverse relationship was also demonstrated in other countries and regions worldwide by performing a simple linear regression analysis (R2 = 0.4974, p = 0.002). The probability of prevalent patients dialysed through an AVF in Catalonia was independently associated with the percentage of functioning KTx among KRT population, after adjusting by age, gender, primary kidney disease, time on KRT, cardiovascular disease and type of HD Unit. Incident patients starting HD through an AVF had a significantly higher probability of receiving a KTx over time in comparison to patients who initiated HD through a catheter (hazard ratio 1.68 [95% confidence interval: 1.41-2.00], p < 0.001).

CONCLUSIONS

In addition to some demographical and clinical characteristics of patients and type of HD Unit, KT activity can be a determining factor in AVF use in prevalent HD patients. Starting an HD programme through an AVF is independently associated with a greater probability of receiving a KTx as compared to starting HD through a catheter.

Arteriovenous fistula self-care behaviors in patients receiving hemodialysis treatment: Association with health literacy and self-care agency

BACKGROUND

Arteriovenous fistula-related self-care behaviors, self-care agency and health literacy are important for vascular access patency, which is vital in the continuation of hemodialysis treatment. The purpose of this study was to determine the arteriovenous fistula-related self-care behaviors of patients receiving chronic hemodialysis treatment and the relationship between these behaviors and their health literacy and self-care agency levels.

METHODS

In this descriptive correlational study, the data were collected from 216 chronic hemodialysis patients.

RESULTS

The rate of the patients who had good self-care behaviors levels was 83.96%. The sociodemographic variables that were significantly related to AVF-related self-care behaviors were education, employment status and age. It was found that the patients who had had AVF for a longer time had better self-care behaviors regarding their management of symptoms and findings (p < 0.05). As the self-care agency of the patients (r = 0.612, p < 0.001) and their health literacy (r = 0.421, p < 0.001) increased, their AVF-related self-care behaviors also increased.

CONCLUSION

Age, education status, health literacy and self-care agency were identified to affect AVF-related self-care behaviors.

Cannulation Technique of Vascular Access in Hemodialysis and the Impact on the Arteriovenous Fistula Survival: Systematic Review and Meta-Analysis

Adequate cannulation technique (CT) methods and successful puncture are essential for hemodialysis (HD) and arteriovenous fistula (AVF) maintenance. This systematic review and meta-analysis was designed to identify which CT allows better AVF primary patency and lower rates of complications in HD patients. The search was carried out on the CINAHL, MEDLINE, Cochrane Library, and Joanna Briggs Institute Library databases to identify all randomized controlled trials (RCTs) and observational studies comparing clinical outcomes of buttonhole (BH) versus rope ladder cannulation (RL) from 2010 to 2022. The Risk-of-Bias (Rob 2) tool was used for RCTs and the ROBINS-I was used for non-randomized studies. RevMan 5.4 was used for the meta-analysis. A total of five RCTs, one quasi-randomized controlled trial, and six observational studies were included. When compared with RL cannulation, BH cannulation significantly increased bacteremia (RR, 2.76, 95% CI (1.14, 6.67), p = 0.02) but showed no differences in AVF primary patency (HR, 1.06, 95% CI (0.45, 4.21), p = 0.90). There was no thrombosis reduction (RR, 0.51, 95% CI (0.23, 1.14), p = 0.10) or intervention number reduction (RR, 0.93, 95% CI (0.49, 1.80), p = 0.84) with BH. Outcomes like pain, hematoma, and aneurism could not be merged due to a lack of data, reported as medians, as well as due to different definitions. The quality in general was poor and the heterogeneity among the studies prevented us from merging the outcomes.

Skin pigmentation as landmark for arteriovenous fistula cannulation in hemodialysis

BACKGROUND

The cannulation of the arteriovenous fistula (AVF) for hemodialysis (HD) has traditionally depended on the nurse's tactile sensation, which has been associated with suboptimal needle placement and detrimental effects on vascular access (VA) longevity. While the introduction of ultrasound (US) has proven beneficial in mapping the AVF outflow vein and assisting in cannulation planning, aneurysmal deformations remain a common occurrence resulting from various factors, including inadequate cannulation techniques. Within this context, the utilization of skin pigmentation as a clinical landmark has emerged as a potential approach to enhance cannulation planning in HD.

METHODS

A prospective longitudinal study was undertaken to investigate the correlation between the occurrence of venous morphological deformations and the cannulation technique guided by skin pigmentation after a 2-month period of implementation.

RESULTS

Thirty patients were enrolled in the study with 433 cannulations being described within the first 2 months of AVF use. The overall rate of cannulation-related adverse events was 21.9%. Comparative analysis demonstrated a statistically significant relationship (p < 0.001) between aneurysmal deformation and non-compliance with the proposed cannulation technique, resulting in cannulation outside the designated points. Non-compliance was primarily attributed to nurse's decision (57.1%).

CONCLUSION

The integration of US mapping of the AVF outflow vein and the utilization of skin pigmentation as a guiding tool have shown promising results in enhancing cannulation planning over time. Consistent adherence to a cannulation technique other than the area technique has been found to reduce the risk of AVF morphological deformation. These findings underscore the potential benefits of incorporating skin pigmentation as a clinical landmark in cannulation practices, highlighting its ability to impact positively cannulation outcomes.

Impact of preoperative exercise in not initially candidates to native arteriovenous fistulas

BACKGROUND

Native autologous arteriovenous fistula (AVFn) is the preferred vascular access for hemodialysis due to its long term patency and low complication rate. A challenging limitation is the anatomical inability to perform AVFn and failure of maturation. Preoperative isometric exercise (PIE) can increase vascular calibers and improve the rate of distal AVF. However, it is unknown whether PIE might enhance the performance of AVFn in patients who are not initially candidates.

METHODS

A retrospective observational study was conducted over a population of 45 patients evaluated in vascular access clinic, 23 were not initially candidates for radiocephalic (NRC-AVF) and 22 were not candidates for autologous fistula at all (NA-AVF). They were assigned to perform PIE with handgrip device and revaluated.

RESULTS

After 4-8 weeks of PIE, a AVFn was performed in 16 patients from NA-AVF group and a radiocephalic AVFn was performed in 21 patients from NRC-AVF group. Both groups experienced a significant and similar increase in venous caliber 0.91 ± 0.43 mm in NA-AVF versus 0.76 ± 0.47 mm in NRC-AVF (p = 0.336) and arterial caliber 0.18 ± 0.24 mm versus 0.18 ± 0.21 mm (p = 0.928), respectively. Nevertheless, primary failure rate was significantly higher in NA-AVF (n = 8, 50%) than in NRC-AVF group (n = 3, 14.3%) (p = 0.030). After 6 months, the fistula usability for dialysis was only 50% in NA-AVF, while 86.7% were dialyzed by fistula in NRC-AVF group (p = 0.038).

CONCLUSIONS

PIE allowed the allocation of an AVFn in patients not initially candidates, but entailed a high rate of maturation failure. Patients not candidates to radiocephalic AVF benefited from PIE and preserved a long term usability of AVF for dialysis.

Valoración de la seguridad del paciente en la práctica clínica de terapia renal sustitutiva en las unidades de vigilancia intensiva

Introducción: La seguridad del paciente en unidades de vigilancia intensiva, con terapia renal sustitutiva intermitente, está influenciada por diversos factores: los inherentes al paciente, humanos y técnicos. Objetivo: Identificar los factores de riesgo y principales incidencias presentes en la práctica clínica, que interfieren en la seguridad del paciente al que se le realiza terapia sustantiva renal intermitente. Material y Método: Estudio descriptivo y retrospectivo de 413 sesiones de terapia sustitutiva renal intermitente. Se obtuvieron datos demográficos, clínicos, complicaciones clínicas, técnicas, controles de monitores, medidas correctivas y factores de riesgo relacionados con las enfermeras mediante un cuestionario de experteza en diálisis. Resultados: 413 sesiones; (52,1%) hemodiálisis intermitente. Edad media 65 años; 78,7% sexo masculino; motivo de ingreso shock séptico (35,1%).Incidencias: error en la asignación de la modalidad (33,2%), pautas sin actualizar (30,5%), disfunción del acceso vascular (15,7%). Complicaciones clínicas: 47,6 en hemodiálisis intermitente, destacando hipotensión en 41,2%.Complicaciones técnicas en el 37,7% de las sesiones, coagulación total o parcial del circuito extracorpóreo (16,7%). Relacionados con el personal: falta de un programa estandarizado de formación (57,1%), variabilidad de personal (81%) y no asistencia a la capacitación programada (52,4%). Conclusión: La seguridad del paciente con terapia sustitución renal en unidades de vigilancia intensiva, es un proceso multifactorial: relacionados con aspectos no modificables (asociados al paciente), incidencias durante el procedimiento y complicaciones. Aunque no se produjeron efectos adversos mayores en la evolución clínica del paciente, éstos son considerados potenciales y algunos previsibles, controlables y evitables.

Análisis de la influencia de la pandemia por el virus SARS-CoV-2 sobre la tasa de bacteriemia en catéteres venosos tunelizados en una unidad de hemodiálisis

Antecedentes: La infección relacionada con catéter venoso central (CVC) está asociada a una elevada morbimortalidad y se ha relacionado con la bacteriemia asociada a CVC, disfunciones de catéter, la manipulación y las medidas higiénicas tomadas durante la misma. Objetivo: El objetivo del presente estudio fue comparar la tasa de bacteriemia entre los años 2019 y 2020, primer año de pandemia por el virus SARS-CoV-2, en una unidad de hemodiálisis de un hospital de la Comunidad Autónoma de Madrid. Material y Método: Se ha llevado a cabo un estudio observacional retrospectivo transversal en el que se compararon datos relativos a la manipulación y al funcionamiento del catéter, y tasa de bacteriemias relacionadas con el catéter entre los años 2019 y 2020 a través de la base de datos de la unidad. Resultados: En 2019 se incluyeron 35 pacientes, que presentaron una tasa de bacteriemia de 1,42/1000 días de catéter y 29 pacientes en 2020, con una tasa de bacteriemia de 1,82/1000 días de catéter, no encontrándose diferencias significativas (p=0,54), no encontrando un riesgo de bacteriemia incrementado o disminuido durante el primer año de pandemia producida por el virus SARS-CoV-2. Conclusiones: Como principal conclusión de este estudio, podemos afirmar que no se ha evidenciado que la llegada de la pandemia producida por la enfermedad del coronavirus y las medidas adoptadas frente al virus SARS-CoV-2, tanto organizacionales como de prevención, sean un factor de riesgo o protección respecto a la tasa de bacteriemia, probablemente debido al bajo número de eventos encontrados.

Valoración de la seguridad del paciente en la práctica clínica de terapia renal sustitutiva en las unidades de vigilancia intensiva

Introducción: La seguridad del paciente en unidades de vigilancia intensiva, con terapia renal sustitutiva intermitente, está influenciada por diversos factores: los inherentes al paciente, humanos y técnicos. Objetivo: Identificar los factores de riesgo y principales incidencias presentes en la práctica clínica, que interfieren en la seguridad del paciente al que se le realiza terapia sustantiva renal intermitente. Material y Método: Estudio descriptivo y retrospectivo de 413 sesiones de terapia sustitutiva renal intermitente. Se obtuvieron datos demográficos, clínicos, complicaciones clínicas, técnicas, controles de monitores, medidas correctivas y factores de riesgo relacionados con las enfermeras mediante un cuestionario de experteza en diálisis. Resultados: 413 sesiones; (52,1%) hemodiálisis intermitente. Edad media 65 años; 78,7% sexo masculino; motivo de ingreso shock séptico (35,1%).Incidencias: error en la asignación de la modalidad (33,2%), pautas sin actualizar (30,5%), disfunción del acceso vascular (15,7%). Complicaciones clínicas: 47,6 en hemodiálisis intermitente, destacando hipotensión en 41,2%.Complicaciones técnicas en el 37,7% de las sesiones, coagulación total o parcial del circuito extracorpóreo (16,7%). Relacionados con el personal: falta de un programa estandarizado de formación (57,1%), variabilidad de personal (81%) y no asistencia a la capacitación programada (52,4%). Conclusión: La seguridad del paciente con terapia sustitución renal en unidades de vigilancia intensiva, es un proceso multifactorial: relacionados con aspectos no modificables (asociados al paciente), incidencias durante el procedimiento y complicaciones. Aunque no se produjeron efectos adversos mayores en la evolución clínica del paciente, éstos son considerados potenciales y algunos previsibles, controlables y evitables.

Análisis de la influencia de la pandemia por el virus SARS-CoV-2 sobre la tasa de bacteriemia en catéteres venosos tunelizados en una unidad de hemodiálisis

Antecedentes: La infección relacionada con catéter venoso central (CVC) está asociada a una elevada morbimortalidad y se ha relacionado con la bacteriemia asociada a CVC, disfunciones de catéter, la manipulación y las medidas higiénicas tomadas durante la misma. Objetivo: El objetivo del presente estudio fue comparar la tasa de bacteriemia entre los años 2019 y 2020, primer año de pandemia por el virus SARS-CoV-2, en una unidad de hemodiálisis de un hospital de la Comunidad Autónoma de Madrid. Material y Método: Se ha llevado a cabo un estudio observacional retrospectivo transversal en el que se compararon datos relativos a la manipulación y al funcionamiento del catéter, y tasa de bacteriemias relacionadas con el catéter entre los años 2019 y 2020 a través de la base de datos de la unidad. Resultados: En 2019 se incluyeron 35 pacientes, que presentaron una tasa de bacteriemia de 1,42/1000 días de catéter y 29 pacientes en 2020, con una tasa de bacteriemia de 1,82/1000 días de catéter, no encontrándose diferencias significativas (p=0,54), no encontrando un riesgo de bacteriemia incrementado o disminuido durante el primer año de pandemia producida por el virus SARS-CoV-2. Conclusiones: Como principal conclusión de este estudio, podemos afirmar que no se ha evidenciado que la llegada de la pandemia producida por la enfermedad del coronavirus y las medidas adoptadas frente al virus SARS-CoV-2, tanto organizacionales como de prevención, sean un factor de riesgo o protección respecto a la tasa de bacteriemia, probablemente debido al bajo número de eventos encontrados.

Non-tunneled catheter tip depth position in urgent hemodialysis: a randomized controlled trial

BACKGROUND

The average accepted depth for non-tunneled catheters (NTC) insertion does not guarantee its correct position, so controversy exists. The aim of this study was to assess the effect of two NTC placement depths on the number of NTC complication episodes.

METHODS

We designed a triple blind, parallel group, randomized controlled trial in a single Hemodialysis Center in Mexico (Registry: ACTRN12619000774123). We included patients in urgent need of hemodialysis via internal right jugular vein NTC. The length of the NTC tip placement depth was randomized to second intercostal space (2ICS) or fourth intercostal space (4ICS), using physical landmarks. The primary outcome was to compare the composite number of NTC dysfunction, repositioning, and relocation episodes for 48 hours post-procedure.

RESULTS

One hundred and sixty-five patients were included, 86 and 79 patients to NTC placement in the 2ICS and 4ICS, respectively. All patients underwent intention-to-treat analysis. The incidence of the composite outcome was lower in the 2ICS group compared to the 4ICS group, 4 (4.6%) and 50 (63%) combined episodes, respectively (P<0.001). Compared to the 4ICS group, the 2ICS group presented a relative risk of 0.06 (CI: 0.02-0.21, P<0.001) and number needed to treat (NNT) of 2.1. No adverse events occurred, derived from the NTC placement.

CONCLUSIONS

NTC tip placement in the 2ICS compared to 4ICS decreases the incidence of the combined number of dysfunctions, repositioning and relocation episodes, with a NNT of 2 for its prevention.

In Vivo Effectiveness of Several Antimicrobial Locks To Eradicate Intravascular Catheter Coagulase-Negative Staphylococci Biofilms

Tunneled central venous catheter (TCVC) related infection remains a challenge in the care of hemodialysis patients. We aimed to determine the best antimicrobial lock therapy (ALT) to eradicate coagulase-negative staphylococci (CoNS) biofilms. We studied the colonization status of the catheter every 30 days by quantitative blood cultures (QBC) drawn through all catheter lumens. Those patients with a significant culture (i.e.,100 to 1,000 CFU/mL) of a CoNS were classified as patients with a high risk of developing catheter-related bloodstream infections (CRBSI). They were assigned to receive daptomycin, vancomycin, teicoplanin lock solution, or the standard of care (SoC) (i.e., heparin lock). The primary endpoint was to compare eradication ability (i.e., negative QBC for 30 days after ending ALT) rates between different locks and the SoC. A second objective was to analyze the correlation between ALT exposure and isolation of CoNS with antimicrobial resistance. Daptomycin lock was associated with a significant higher eradication success than with the SoC: 85% versus 30% (relative risk [RR] = 14, 95% confidence interval [CI] = 2.4 - 82.7); followed by teicoplanin locks with a 83.3% success (RR = 11.7; 95% CI = 2 - 70.2). We observed CoNs isolates with a higher teicoplanin MIC in patients with repeated teicoplanin locks exposure (coefficient = 0.3; 95% CI = 0.11 - 0.47). However, teicoplanin MICs decreased in patients treated with vancomycin locks (coefficient = -0.56; 95% CI = -0.85 - -0.02). Methicillin-resistance decreased with accumulative ALT (RR = 0.82; 95% CI = 0.69 - 0.98). In this study, daptomycin locks achieve the highest eradication rate of CoNS from hemodialysis catheters in vivo.

Tunneled catheter-related bacteremia in hemodialysis patients: incidence, risk factors and outcomes. A 14-year observational study

BACKGROUND

Tunneled catheter-related bacteremia represents one of the major complications in patients on hemodialysis, and is associated with increased morbidity and mortality. This study aimed to evaluate the incidence of tunneled catheter-related bacteremia and, secondly, to identify possible factors involved in the first episode of bacteremia.

METHODS

This is a retrospective study of all tunneled catheters inserted between 1 January, 2005 and 31 December, 2019. Data on patients with a tunneled catheter were analyzed for comorbidities, catheter characteristics, microbiological culture results and variables related to the first episode of bacteremia. Patient outcomes were also assessed.

RESULTS

In the 14-year period under study, 406 tunneled catheters were implanted in 325 patients. A total of 85 cases of tunneled catheter-related bacteremia were diagnosed, resulting in an incidence of 0.40 per 1000 catheter days (81.1% after 6 months of implantation). The predominant microorganisms isolated were Gram-positive organisms: Staphylococcus epidermidis (48.4%); Staphylococcus aureus (28.0%). We found no significant differences in time to catheter removal for infections or non-infection-related reasons. The jugular vein, the Palindrome® catheter, and being the first vascular access were protective factors for the first episode of bacteremia. The 30-day mortality rate from the first tunneled catheter-related bacteremia was 8.7%.

CONCLUSIONS

The incidence of bacteremia in our study was low and did not seem to have a relevant impact on catheter survival. S. epidermidis was the most frequently isolated microorganism, followed by S. aureus. We identified Palindrome® catheter, jugular vein, and being the first vascular access as significant protective factors against tunneled catheter-related bacteremia.

Pre-Emptive Antimicrobial Locks Decrease Long-Term Catheter-Related Bloodstream Infections in Hemodialysis Patients

This study aimed to prove that pre-emptive antimicrobial locks in patients at risk of bacteremia decrease infection. We performed a non-randomized prospective pilot study of hemodialysis patients with tunneled central venous catheters. We drew quantitative blood cultures monthly to detect colonization. Patients with a critical catheter colonization by coagulase-negative staphylococci (defined as counts of 100−999 CFU/mL) were at high risk of developing a catheter-related bloodstream infection. We recommended antimicrobial lock for this set of patients. The nephrologist in charge of the patient decided whether to follow the recommendation or not (i.e., standard of care). We compared bloodstream infection rates between patients treated with antimicrobial lock therapy versus patients treated with the standard of care (i.e., heparin). We enrolled 149 patients and diagnosed 86 episodes of critical catheter colonization by coagulase-negative staphylococci. Patients treated with antimicrobial lock had a relative risk of bloodstream infection of 0.19 when compared with heparin lock (CI 95%, 0.11−0.33, p < 0.001) within three months of treatment. We avoided one catheter-related bloodstream infection for every ten catheter-critical colonizations treated with antimicrobial lock [number needed to treat 10, 95% CI, 5.26−100, p = 0.046]. In conclusion, pre-emptive antimicrobial locks decrease bloodstream infection rates in hemodialysis patients with critical catheter colonization.

Sistema percutáneo de creación de fistulas arteriovenosas en pacientes con hemodiálisis: nuestra experiencia inicial

Introducción: La fístula arteriovenosa es considerada el acceso de elección para los pacientes en hemodiálisis; en los últimos años emerge una alternativa a la creación quirúrgica de esta: la fístula arteriovenosa endovascular. Esta nueva tecnología conlleva un método menos agresivo y sin cirugía.Objetivo: Describir los datos preliminares de nuestra unidad tras la implantación de este sistema novedoso, así como su implicación para enfermería.Material y Método: Análisis descriptivo retrospectivo de las FAV-endovasculares realizadas a cinco pacientes mediante técnica percutánea. Se consideraron las características de los pacientes, de las FAV-endovasculares realizadas y la dificultad para su punción (escala EVA).Resultados: La edad media fue de 63 (47-77) años, 100% hombres, dializándose con catéter tunelizado, a 4 de los pacientes se les había realizado al menos una fístula arteriovenosa quirúrgica sin éxito. La creación de la FAV-endovascular fue exitosa en 4 de los 5 pacientes, todas con localización radio-radial. No hubo complicaciones durante el procedimiento. De las 4 FAV-endovasculares 3 precisaron intervención endovascular posterior para su maduración. La media de tiempo de maduración 4,5 (4-5) meses; las 4 continuaron permeables al año.Puntuada por 9 enfermeras experimentadas, la mediana de dificultad fue: punción inicial: 7, a partir del mes: 5 y comparada con las FAV quirúrgicas: 5.Conclusiones: La FAV-endovascular supuso un procedimiento mínimamente invasivo con menor impacto para los pacientes, elevado éxito inicial, pero precisó intervención endovascular posterior para su maduración. La dificultad para la punción fue más elevada inicialmente. La ausencia de cicatriz  supuso realizar una exploración más exhaustiva.

How to needle: A mixed methods study on choice of cannulation technique for arteriovenous fistula

AIMS AND OBJECTIVES

The aim of this study was to describe the basis for choosing a cannulation technique for arteriovenous fistula.

BACKGROUND

Four cannulation techniques are relevant to cannulating an arteriovenous fistula: rope ladder, area puncture and buttonhole using blunt or sharp needles. The chosen technique may affect both the patency and number of complications.

DESIGN

The study used a convergent mixed methods design and inductive approach.

METHODS

A questionnaire and an inquiry of local guidelines were sent to nurses in all dialysis units in Sweden. Questionnaires were answered by nurses from 37 units, and 29 units included their local guidelines. The questionnaires were analysed using descriptive statistics and qualitative content analysis, and the guidelines were analysed using qualitative content analysis. The different analyses were combined in a final result. The study is based on GRAMMS guidelines.

RESULTS

Local guidelines, patients' and nurses' own judgement, and consultation with colleagues were found to greatly influence the choice of cannulation technique. Buttonhole was the most preferred cannulation technique in the participating units and was favoured by nurses when choosing a cannulation technique. The process of choosing a cannulation technique was found to be influenced by the dedication to good cannulation technique and healthy arteriovenous fistulas, whether the technique is perceived as being easy to use and is expected to prevent complications and based on the experienced-based knowledge of each dialysis unit.

CONCLUSIONS

Choosing a cannulation technique is a process based on the nurse, local guidelines and the patient. Most dialysis nurses and units in Sweden consider buttonhole to be a good cannulation technique and use it as their standard technique.

RELEVANCE TO CLINICAL PRACTICE

The results provide insight into why cannulation techniques are chosen differently in different units. The results also show the importance of evidence in making decisions on cannulation technique.

Results of endovascular treatment of venous anastomotic stenosis in prosthetic arteriovenous for hemodialysis PTFE grafts. Comparative analysis between patent and occluded grafts

OBJECTIVE

To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG.

MATERIAL AND METHODS

A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed.

STATISTICAL ANALYSIS

Survival analysis was performed for time-to-event data to assess patency.

RESULTS

Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in group B and 94.5% and 91% respectively in group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% y 15.7% respectively. Group B: 100%, 85.9%, 76,4% (p < 0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% y 31.3% respectively. Group B 100%, 95.3%, 95.2% (p < 0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 IC 95% 1.146-6.216, p = 0.010).

CONCLUSION

A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.

Prone Position Facilitates Creation of Ulnar-Basilic Arteriovenous Fistula

Background: The distal ulnar-basilic arteriovenous fistula (UBAVF) is a rarely used alternative type of vascular access for haemodialysis. The location of the vein on the back aspect of the forearm forces an extremely uncomfortable external rotation of the upper limb during surgery when the patient is in a supine position. Methods: We present a new approach towards creating UBAVF, which involves placing the patient in the prone position, thus eliminating the aforementioned inconvenience. The procedure was performed and described in a 46-year-old patient with chronic kidney disease (CKD) due to diabetic nephropathy. In the period from September 2021 to December 2021, we created an additional three UBAVFs with such modifications. Results: All fistulas were patent both immediately after the procedure and 2 weeks after surgery. Conclusions: The prone position may improve the comfort of both the operator and the patient during the procedure. On top of this, it may have a positive impact on the quality of the arteriovenous anastomosis.

Hemodialysis Arteriovenous Fistula Dysfunction: Retrospective Comparison of Post-thrombotic Percutaneous Endovascular Interventions with Pre-emptive Angioplasty

OBJECTIVES

We aimed to compare the clinical outcomes of pre-emptive angioplasty versus post-thrombotic percutaneous endovascular restoration of dysfunctional arteriovenous fistula (AVF).

METHODS

This retrospective study reviewed data from 80 patients who underwent 114 endovascular interventions for a malfunctioning AVF from July 2016 to August 2019. Stenotic AVFs were treated with pre-emptive angioplasty. Thrombosed AVFs were treated with percutaneous pharmacomechanical fibrinolysis with urokinase used only during the operation or continuously infused. The differences in patency rates were evaluated using Kaplan-Meier method. In addition, univariate and multivariate regression Cox models were used to determine influential factors on the post-intervention primary patency.

RESULTS

Post-thrombotic interventions and pre-emptive angioplasty yielded statistically similar rates in clinical success (100% vs 100%), anatomic success (94% vs 89%; p = .52), complication (4% vs 11%; p = .29), as well as postintervention primary, assisted primary and secondary patency (p = .80; .57; .57). The use of pre-emptive angioplasty was associated with reduced total cost (¥25108 vs ¥30833, p< .001). The patients who used urokinase only during the operation prolonged both the primary and assisted primary patency (p = .02; .002), while those with continuous infusion of urokinase had worst patency rates and high costs (¥39275 vs ¥25108 vs ¥27140, p< .001). Compared with the other locations, dysfunction in the anastomotic or juxta-anastomotic segment (HR = .41, p = .001) was associated with prolonged postintervention primary patency.

CONCLUSIONS

No clinical outcome differences was found between the post-thrombotic percutaneous endovascular interventions and pre-emptive angioplasty. However, pre-emptive angioplasty decreased access expenditure.

Atypical presentation of fistula dysfunction due to brachial arterial embolization mimicking stroke

Vascular access thrombosis is an important complication with great impact on access patency and, consequently, on a patient's quality of life and survival. We report the case of a 73-year-old woman with chronic kidney disease on hemodialysis with a radiocephalic arteriovenous fistula on the right arm that was brought to the emergency department with decreased strength in her right arm, ipsilateral hypoesthesia and facial hemi-hypoesthesia. The patient was given a brain computed tomographic scan that did not confirm suspicion of stroke. On re-examination, the patient had new-onset pain at arteriovenous fistula level, and her right arm was cold and pale. The nephrology department was called for arteriovenous fistula evaluation. On physical examination, her forearm fistula had a decreased thrill and arm elevation exacerbated its paleness. A bedside ultrasound was performed for arteriovenous fistula assessment. Doppler ultrasound revealed: partial thrombosis at brachial bifurcation, a flow of 80-105 mL/min at brachial artery level and a radial artery with a damped waveform. Anastomosis and draining vein were permeable. In this case, the diagnosis of acute embolic brachial artery occlusion was made by a fast bedside ultrasound evaluation. The patient underwent thromboembolectomy with Fogarty technique, recovering fistula thrill, radial and cubital pulses. Thromboembolism of the fistula feeding artery is a rare cause of vascular access thrombosis and it is rarely mentioned in the literature. In this report, failure to recognize the upper limb ischemia would have led to delayed treatment, potentially resulting in the fistula's complete thrombosis and further limb ischemia. We highlight the importance of a diagnosis method like Doppler ultrasound, which allows for rapid evaluation at the patient's bedside.

Validation of the inverse method for the determination of the access flow with thermodilution

INTRODUCTION

Thermodiluction is a widely used method for measuring vascular access flow (Q_A). Among the possibilities of TD, the reverse method (MI) can be beneficial in the execution time, without impact on the dialysis efficacy (Kt). However, it is not a sufficiently studied technique.

METHOD

Transversal study of 117 arteriovenous fistulas (AVF). Two Q_A measurements were taken with the method described by the manufacturer (MR) and another with MI. MI is bases in the obtention of an inverted recirculation registry at the beginning of the session and a single subsequent recirculation measurement with the lines in normal position. In the concordance analysis, the Bland-Altman method and Cohen's Kappa index were used.

RESULTS

Very good concordance between MR and MI was evidenced for QA below 700 ml/min, but it worsens as flow increases. The median variability between the MR measurements (intra-method variability) was 3.4% (-17.13). This value did not differ from the median variability generated between MR and MI (inter-method variability), which was 2% (-14, 12) (P = 0.287). The degree of agreement between the two to identify AVFs susceptible to intervention was very good (K = 0.834). The time spent using the MI was significantly shorter (P = 0.000) without evidence of variations in the Kt of the measurement sessions (P = 0.201).

CONCLUSIONS

The thermodiluction MI is valid to determine the flow of the vascular access, especially in Qa lower than 700 ml/min, with great time savings, simplification of the procedure and without modifying the dialysis efficiency. The variability between the measurement by MR and MI is similar to that of MR. The concordance between methods in identifying potentially pathological AVFs is very good.

Development and Validation of a Machine Learning Model Predicting Arteriovenous Fistula Failure in a Large Network of Dialysis Clinics

Background: Vascular access surveillance of dialysis patients is a challenging task for clinicians. We derived and validated an arteriovenous fistula failure model (AVF-FM) based on machine learning. Methods: The AVF-FM is an XG-Boost algorithm aimed at predicting AVF failure within three months among in-centre dialysis patients. The model was trained in the derivation set (70% of initial cohort) by exploiting the information routinely collected in the Nephrocare European Clinical Database (EuCliD^®). Model performance was tested by concordance statistic and calibration charts in the remaining 30% of records. Features importance was computed using the SHAP method. Results: We included 13,369 patients, overall. The Area Under the ROC Curve (AUC-ROC) of AVF-FM was 0.80 (95% CI 0.79–0.81). Model calibration showed excellent representation of observed failure risk. Variables associated with the greatest impact on risk estimates were previous history of AVF complications, followed by access recirculation and other functional parameters including metrics describing temporal pattern of dialysis dose, blood flow, dynamic venous and arterial pressures. Conclusions: The AVF-FM achieved good discrimination and calibration properties by combining routinely collected clinical and sensor data that require no additional effort by healthcare staff. Therefore, it can potentially enable risk-based personalization of AVF surveillance strategies.

Ultrasound guided cannulation of dialysis access

Vascular access is the key part of haemodialysis (HD) treatment, as this is not possible without a functioning access. The use of the arteriovenous fistula (AVF) has fewer complications, lower mortality and fewer hospital admissions compared to central venous catheter (CVC). However, although guidelines recommend AVF as the access of choice, access-related cannulation complications may lead to greater morbidity. Most guidelines recommend using Doppler ultrasound (DU) to surveil the AVF for HD, but its use must not only be limited to surveillance as it can also be used for needling. Therefore, among those techniques at our disposal today, one of the best tools for AVF needling is Doppler ultrasound (DU). Despite the lack of evidence regarding ultrasound-guided needling of AVF, it is becoming part of our usual practice arsenal in many HD centres. Its use has allowed needling results to improve and the number of complications to be reduced versus traditional ‘blind’ needling. It should be remembered that even though it is very useful for the daily work of dialysis nurses, as in the case of other techniques, it requires adequate, specialised and long-term training to acquire competence in using it. For example, it is important to learn some concepts and terminology that should be known and, at the same time, be highly familiar with different techniques available. Two types of needling techniques are described using US assistance: US-guided needling, where DU is used to make a map of the vessels which can be utilised and to mark the best site to insert the needles once the mapping is done; and real-time US-guided needling, the simultaneous manipulation of the probe and the insertion of the puncture needle through the slice plane of the ultrasound device. Regarding the real-time technique, there are two approaches: out of plane (the probe takes a transversal image of the needle) and in plane (vessel axis aligned with the probe and the needle in the same plane) To ensure successful needling and to maximise reproducibility, especially with tight deadlines and staff resources, nursing staff need to follow some important recommendations that include safety and the use of the method, both for them and the patient. In this way, ultrasound-guided needling becomes a tool with enormous potential utility, but practical training is as important as knowing the technique.

Upper limb anatomy and preoperative mapping

Vascular access is absolutely essential for haemodialysis due to its relationship with quality of dialysis and associated morbidity. Therefore, it must be monitored and continuously surveilled from the moment it is created to prevent failure in maturation and thrombosis. Multidisciplinary collaboration is necessary when the main aim is to achieve the adequate vascular access flow with the fewest possible complications. The starting point, and probably the main one, is vascular access planning. This planning requires both a deep understanding of the anatomy of the upper limb and enough skill to examine it by Doppler ultrasound. The aim of this article is to review the anatomical and haemodynamical concepts of the arterial and venous vascular tree and explain how to perform ultrasound mapping, optimising the technical resources provided by this tool. Likewise, adequate access creation criteria that minimise the risk of failure and associated complications will be discussed.

Results of endovascular treatment of venous anastomotic stenosis in prosthetic arteriovenous for hemodialysis PTFE grafts. Comparative analysis between patent and occluded grafts

OBJECTIVE

To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG.

MATERIAL AND METHODS

A retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed.

STATISTICAL ANALYSIS

Survival analysis was performed for time-to-event data to assess patency.

RESULTS

Group A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups. Technical and clinical success were 100% in Group B and 94.5% and 91% respectively in Group A. Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% and 15.7% respectively. Group B: 100%, 85.9%, 76.4% (p<0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% and 31.3% respectively. Group B 100%, 95.3%, 95.2% (p<0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 95% CI 1.146-6.216, p=0.010).

CONCLUSION

A higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion.

Ultrasound evaluation of access complications: Thrombosis, aneurysms, pseudoaneurysms and infections

Arteriovenous fistula (AVF) complications are classified based on fistula outcomes. This review aims to update colour Doppler (CD) and pulse wave Doppler (PWD) roles in managing early and late complications of the native and prosthetic AVF. Vascular access (VA) failure occurs because inflow or outflow stenosis activates Wirchow's triad inducing thrombosis. Therefore, the diagnosis of the tributary artery and outgoing vein stenosis will be the first topic considered. Post-implantation complications occur from the inability to achieve AVF maturation and dialysis suitability due to inflow/outflow stenosis. Late stenosis is usually a sequence of early defects repaired to maintain patency. Less frequently, in the mature AVF or graft, complications are acquired 'de novo'. They derive either from incorrect management of vascular access (haematoma, pseudoaneurysm, prosthesis infection) or wall pathologies (aneurysm, myxoid valve degeneration, kinking, coiling, abnormal dilation from defects of elastic structures). High-resolution transducers (10-20 MHz) allow the characterization of the wall damage, haemodynamic dysfunctions, early and late complications even if phlebography remains the gold standard for the diagnosis for its sensitivity and specificity.

Current role of ultrasound in hemodialysis access evaluation

Physical examination (PE) is considered the backbone before vascular access (VA) placement, during maturation period and for follow-up. However, it may be inadequate in identifying suitable vasculature, mainly in comorbid patients, or in detecting complications. This review highlights the advantages of ultrasound imaging to manage VA before placement, during maturation and follow-up. Furthermore, it analyses the future perspectives in evaluating early and late VA complications thank to the availability of multiparametric platforms, point of care of ultrasound, and portable/wireless systems. Technical improvements and low-cost systems should favor the widespread ultrasound-based VA surveillance programs. This significant turning point needs an adequate training of nephrologists and dialysis nurses and the standardization of exams, parameters, and procedures.