Timing of first cannulation of arteriovenous fistula: are we waiting too long?

Practical guide of vascular ultrasound in arteriovenous fistulae

The use of vascular ultrasound, especially with the increasing prevalence of percutaneous arteriovenous fistulas, has taken a central role as a diagnostic and therapeutic imaging procedure in vascular access creation. The current review article stresses the importance of vascular ultrasound in arteriovenous fistula, from planning to creation to maintenance. It summarises and gives practical guidance regarding sonographic criteria for vascular access procedure planning, the application of vascular ultrasound intraoperatively and during follow-up. Ultrasound education and training modalities to meet high standards of patient care in hemodialysis are presented.

Evaluation of Factors Affecting Wrist Radio-Cephalic Arteriovenous Fistula Maturation: A Single Institutional Observational Study

Background: Chronic renal failure is the most common indication for which arterio-venous (AV) fistula creation surgery is being performed. Various studies have found that native arteriovenous fistulas are the best in long-term patency with lower complications. We conducted this study to find out the role of preprocedural duplex ultrasound (DUS) in predicting outcomes of radio-cephalic fistula in the wrist in the North-Karnataka population. Methods: This prospective study was conducted from May 2019 to July 2020 on 50 patients who were hemodialysis-dependent and underwent AV fistula creation with age from 20 to 70 years. All the patients underwent preoperative DUS and were followed up post-operatively after one, two, and six weeks. Hemodialysis was initiated through the constructed fistula once it was mature, and the maximum blood flow through the fistula was measured. SPSS version 20.0 was used for statistical analysis. Results: Among 50 subjects, the overall cumulative success of AVF maturation was 86% (43), and failure to mature rate was 14% (7). Logistic regression of maturation outcome in the wrist autologous arteriovenous fistula for individual factors showed statistically significant results (P < 0.05) for the diameter of the radial artery > 1.6 mm and the distensibility of the cephalic vein > 0.4 mm. Conclusions: Vein distensibility and radial artery diameter are key factors in predicting successful AVF maturation. The use of intraoperative papaverine instillation directly on vessels can improve arteriovenous fistula outcomes.

Predictors of time to first cannulation for arteriovenous fistula in pediatric hemodialysis patients: Midwest Pediatric Nephrology Consortium study

BACKGROUND

Permanent vascular access (PVA) is preferred for long-term hemodialysis. Arteriovenous fistulae (AVF) have the best patency and the lowest complication rates compared to arteriovenous grafts (AVG) and tunneled cuffed catheters (TCC). However, AVF need time to mature. This study aimed to investigate predictors of time to first cannulation for AVF in pediatric hemodialysis patients.

METHODS

Data on first AVF and AVG of patients at 20 pediatric dialysis centers were collected retrospectively, including demographics, clinical information, dialysis markers, and surgical data. Statistical modeling was used to investigate predictors of outcome.

RESULTS

First PVA was created in 117 children: 103 (88%) AVF and 14 (12%) AVG. Mean age at AVF creation was 15.0 ± 3.3 years. AVF successfully matured in 89 children (86.4%), and mean time to first cannulation was 3.6 ± 2.5 months. In a multivariable regression model, study center, age, duration of non-permanent vascular access (NPVA), and Kt/V at AVF creation predicted time to first cannulation, with study center as the strongest predictor (p < 0.01). Time to first cannulation decreased with increasing age (p = 0.03) and with increasing Kt/V (p = 0.01), and increased with duration of NPVA (p = 0.03). Secondary failure occurred in 10 AVF (11.8%). Time to first cannulation did not predict secondary failure (p = 0.29), but longer time to first cannulation tended towards longer secondary patency (p = 0.06).

CONCLUSIONS

Study center is the strongest predictor of time to first cannulation for AVF and deserves further investigation. Time to first cannulation is significantly shorter in older children, with more efficient dialysis treatments, and increases with longer NPVA duration.

Two weeks post-operative ultrasound examination of radio-cephalic arteriovenous fistulae to predict maturity in a Chinese population

AIM

The aim of this study was to assess the accuracy of post-operative ultrasound examination for predicting wrist radio-cephalic arteriovenous fistula maturity.

METHODS

All radio-cephalic arteriovenous fistulas performed in our hospital between October 2015 and December 2017 were included in this study. Ultrasound examination of radio-cephalic arteriovenous fistulas was performed 2 weeks post-surgery. Radio-cephalic arteriovenous fistula maturation was defined as successful cannulation of a fistula with two needles, delivery of blood via the access route at a flow rate ⩾200 mL/min for 4 h, and dialysis via fistulae in at least six consecutive sessions.

RESULTS

Eighty-two wrist radio-cephalic arteriovenous fistulas were analyzed, of which 13 failed. Cephalic vein diameter >4.285 mm and brachial artery peak systolic velocity >134.75 cm/s were the best post-operative ultrasound predictors of radio-cephalic arteriovenous fistula maturity (p < 0.001 and p = 0.011, respectively). Receiver-operating characteristic curve analysis showed that the sensitivity and specificity of predicting radio-cephalic arteriovenous fistula maturation were 88.4% and 92.3% for cephalic vein diameter (area under the curve = 0.939), respectively, and 82.9% and 76.9% for brachial artery peak systolic velocity (area under the curve = 0.830), respectively. All assessments predicted radio-cephalic arteriovenous fistula maturity (post-operative positive predictive values: cephalic vein diameter = 98.4%, brachial artery peak systolic velocity = 95%) much better than radio-cephalic arteriovenous fistula failure (post-operative negative predictive values: cephalic vein diameter = 60%, brachial artery peak systolic velocity = 45.5%).

CONCLUSION

Two weeks after surgery, a new wrist radio-cephalic arteriovenous fistula with a cephalic vein diameter >4.285 mm was considered suitable for dialysis. A high-risk arteriovenous fistula failure would benefit from early intervention.

Relationships Between Clinical Processes and Arteriovenous Fistula Cannulation and Maturation: A Multicenter Prospective Cohort Study

BACKGROUND

Half of surgically created arteriovenous fistulas (AVFs) require additional intervention to effectively support hemodialysis. Postoperative care and complications may affect clinical maturation.

STUDY DESIGN

Hemodialysis Fistula Maturation (HFM) Study, a 7-center prospective cohort study.

SETTING & PARTICIPANTS

491 patients with single-stage AVFs who had neither thrombosis nor AVF intervention before a 6-week postoperative ultrasonographic examination and who required maintenance hemodialysis.

PREDICTORS

Postoperative care processes and complications.

OUTCOMES

Attempted cannulation, successful cannulation, and unassisted and overall clinical maturation as defined by the HFM Study criteria.

RESULTS

AVF cannulation was attempted in 443 of 491 (90.2%) participants and was eventually successful in 430 of these 443 (97.1%) participants. 263 of these 430 (61.2%) reached unassisted and 118 (27.4%) reached assisted AVF maturation (overall maturation, 381/430 [88.6%]). Attempted cannulation was less likely in patients of surgeons with policies for routine 2-week versus later-than-2-week first postoperative visits (OR, 0.21; 95% CI, 0.06-0.70), routine second postoperative follow-up visits (OR, 0.39; 95% CI, 0.15-0.97), and a routine clinical postoperative ultrasound (OR, 0.28; 95% CI, 0.14-0.55). Attempted cannulation was also less likely among patients undergoing procedures to assist maturation (OR, 0.51; 95% CI, 0.27-0.98). Unassisted maturation was more likely for patients treated in facilities with access coordinators (OR, 1.91; 95% CI, 1.17-3.12), but less likely after precannulation nonstudy ultrasounds (OR per ultrasound, 0.42 [95% CI, 0.26-0.68]) and initial unsuccessful cannulation attempts (OR per each additional attempt, 0.90 [95% CI, 0.83-0.98]). Overall maturation was less likely with infiltration before successful cannulation (OR, 0.44; 95% CI, 0.22-0.89). Among participants receiving maintenance hemodialysis before AVF surgery, unassisted and overall maturation were less likely with longer intervals from surgery to initial cannulation (ORs for each additional month of 0.81 [95% CI, 0.76-0.88] and 0.93 [95% CI, 0.89-0.98], respectively) and from initial to successful cannulation (ORs for each additional week of 0.87 [95% CI, 0.81-0.94] and 0.88 [95% CI, 0.83-0.94], respectively).

LIMITATIONS

Surgeons' management policies were assessed only by questionnaire at study onset. Most participants received upper-arm AVFs, planned 2-stage AVFs were excluded, and maturation time windows were imposed. Some care processes may have been missed and the observational design limits causal attribution.

CONCLUSIONS

Multiple processes of care and complications are associated with AVF maturation outcomes.

Endovascular treatment to boost AV fistula maturation

Impaired fistula maturation is associated with puncture-related complications, insufficient dialysis and potential permanent access failure. Non-maturation is frequently initiated by stenotic vascular access vessels comprising the outflow veins, the arteriovenous anastomosis and infrequently the inflow artery. Further findings in maturation protraction are central venous stenoses or accessory outflow veins. Depending on the underlying pathology, several endovascular approaches to boost fistula maturation are possible. To date standard balloon angioplasty remains the primary proven treatment option.

Is early cannulation of an arteriovenous fistula associated with early failure of the fistula?

Objective

To study the effect of early cannulation of arteriovenous fistulas (AVF) on early AVF failure.

Methods

Analysis of two databases of access operations and dialysis sessions from 1/12/2002 till 1/4/2015. Follow-up until 1/4/2016. Functional dialysis use defined as six consecutive cannulations of the AVF with two needles. Early cannulation defined as needling of the AVF within 30 days of creation. Early failure was defined as abandonment for new form of access within 90 days of first cannulation. Machine blood-flow rates (BFR) of each dialysis session for the first 2 months collected from the dialysis database.

Results

We analysed 1167 AVFs with functional dialysis use. Some 148 AVFs (11%) were needled within 30 days. Early needling was not associated with increased early failure rates (p = 0.43). Early failure rates were lower in AVFs with six consecutive successful cannulations from the start (p = 0.002). There was a trend of reduced early failure rates (test for trend: p = 0.018) in the latter years of the study period, but no trend in early cannulation rates (p = 0.19). Failure to achieve six successful cannulations from the start was an independent predictor of early AVF failure but early needling was not an independent predictor in multivariate analysis. Average starting BFRs were higher in AVF that were needled early.

Conclusions

Early cannulation was not associated with early failure. Failure to achieve six successful cannulations from the start was an independent predictor of early failure. The trend in yearly variation of early failure rates suggests that evolving practices influenced early failure rates.

Early use of autogenous arteriovenous fistula in patients with urgent hemodialysis

PURPOSE

This study was designed to evaluate the long-term patency rate and complications associated with early use of the autogenous forearm arteriovenous fistula (AFAVF) in patients needing urgent hemodialysis.

METHODS

The clinical data of all patients undergoing AFAVFs for hemodialysis access between June 1996 and June 2016 were retrospectively evaluated. The primary and secondary patencies were estimated using the life table method.

RESULTS

A total of 104 AFAVFs were created for 102 patients. All patients had entered hemodialysis when fistulas were constructed. The mean time to the first cannulation of the AFAVF was 17.33 ± 4.60 (5-27 days). Four AFAVFs (3.8%) became occluded within 30 days of creation of the access, and five AFAVFs (4.8%) had hematomas after cannulation. There were no cases of infection of the wound or steal syndrome or prolonged arm edema. The primary patency rate was 77.81% at 1 year, 73.05% at 2 years, 64.64% at 3 years, 60.75% at 5 years and 47.48% at 10 years. The secondary patency rate was 96.78% at 1 year, 95.18% at 5 years and 85.81% at 10 years.

CONCLUSIONS

In this study, the patency rates following the early use of the AFAVFs were not inferior to the previously reported patency rates in the literature. For patients entering hemodialysis with an inserted central catheter, the early use of the AFAVFs decreases the complications associated with catheters.

Clinical Utility of a New Predicting Score for Radiocephalic Arteriovenous Fistula Survival

BACKGROUND

Radiocephalic arteriovenous fistula (RC-AVF) is the recommended first choice for vascular access (VA). The CAVeA₂T₂ scoring system was recently published (ipsilateral central venous catheter access, age >73 years, vein <2.2 mm, lower limb angioplasty, and absent intraoperative thrill). The aim of the present study was to assess the clinical utility of the CAVeA₂T₂ scoring system for predicting RC-AVFs survival in our center and its subsequent application in VA management.

MATERIAL AND METHODS

In this single-center retrospective study, all RC-AVFs performed from January 2010 to July 2014 were included. The CAVeA₂T₂ was applied. Primary, assisted primary, and secondary patency rates were measured.

RESULTS

Sixty RC-AVFs were analyzed. Mean age was 64.3 ± 14.7 years. Mean CAVeA₂T₂ score was 1.23 ± 1.2. The median fistula secondary patency was 13.7 ± 1.6 months. Secondary patency was at 6 weeks and at 6, 12, and 24 months: 88.3%, 66.7%, 55%, and 31.7%, respectively. Increasing score (≥2) was associated with a decrease in primary (log-rank, χ² = 16.7, dif = 1, P = 0.0001) and secondary patency rate survival (log-rank, χ² = 5.4, dif = 1, P = 0.0001). In addition, stratification of the CAVeA₂T₂ score into 3 groups (scores 0-1, 2, and 3+) retained its significance for primary (log-rank, χ² = 19.4, dif = 2, P = 0.0001) and secondary patency rate survival (log-rank, χ² = 5.5, dif = 2, P = 0.046) at the end of the study.

CONCLUSIONS

In the present study, the CAVeA₂T₂ scoring system has proved to be a useful, easy to apply tool that is highly predictive of RC-AVF survival. Based on our results, we should avoid perform RC-AVFs, in those patients with CAVeA₂T₂ score ≥2 and late nephrology referral. Prospective studies should be designed to establish the management of patients with a higher CAVeA₂T₂ score.

Is Brachial Artery Blood Flow Measured by Sonography During Early Postoperative Periods Predictive of Arteriovenous Fistula Failure in Hemodialysis Patients?

OBJECTIVES

The aim of our study was to determine a brachial artery blood flow level measured by sonography during early postoperative periods that is predictive of arteriovenous fistula failure in hemodialysis patients.

METHODS

Doppler sonography was used to estimate the blood flow in the brachial artery of 103 patients at 1 and 14 days after arteriovenous fistula creation. The performance of brachial artery blood flow during early postoperative periods for predicting fistula failure was evaluated, and optimal cutoff values were determined.

RESULTS

During a 6-month follow-up, 85 fistulas were classified as mature, and 18 were classified as failures. The reproducibility of blood flow measurements in the brachial artery was good (intraclass correlation coefficient, 0.912). The blood flow in the failure group was significantly lower than that in the mature group at both 1 and 14 days after fistula creation (P < .05). During the first 2 postoperative weeks, the blood flow increased by 40.7% in the failure group versus 78.3% in the mature group. The areas under the receiver operating characteristic curves of brachial artery blood flow for predicting failure were 0.77 (95% confidence interval, 0.66-0.87; optimal cutoff value, 310 mL/min)at 1 day and 0.91 (95% confidence interval, 0.83-0.99; 413 mL/min) at 14 days after fistula creation.

CONCLUSIONS

Brachial artery blood flow measured by sonography during early postoperative periods may be predictive of forearm fistula failure. Blood flow of less than 310 mL/min at 1 day and 413 mL/min at 14 days after fistula creation may indicate a risk of failure to mature.

Accuracy of Early Postoperative Clinical and Ultrasound Examination of Arteriovenous Fistulae to Predict Dialysis Use

Aim

The aim of this article is to assess the accuracy of early clinical and ultrasound (US) examination in terms of predicting arteriovenous fistula (AVF) dialysis use.

Methods

Physical and US examination of patent AVF was performed 4 weeks after fistula creation. AVF dialysis use was defined as subsequent use of an AVF for at least six consecutive dialysis sessions with two needles and a blood flow of more than 200 mL/min.

Results

Of 119 AVF patent at 4 weeks, 26 (22%) failed. Clinical examination was 96% sensitive for predicting successful dialysis, but only 21% specific for failure. Vein diameter above 5 mm and an arterial end-diastolic velocity above 110 cm/s were the best US predictors for dialysis use. Vein diameter was slightly better than arterial velocity in terms of predicting maturity (sensitivity: 83% vs 67%, specificity: 68% vs 65%). All assessments predicted AVF maturity (positive predictive value: clinical = 81%, US diameter = 90%, US velocity = 87%) much better than AVF failure (negative predictive value: clinical = 63%, US diameter = 53%, US velocity = 37%).

Conclusion

One month after surgery, a new AVF with a thrill or a vein diameter >5 mm is likely to be used for dialysis. An AVF not meeting these criteria has an increased risk of failure and further investigations may be required.

Morphologic and Functional Vessels Characteristics Assessed by Ultrasonography for Prediction of Radiocephalic Fistula Maturation

Purpose

Although native radiocephalic arteriovenous fistula (RCAVF) is the best vascular access for hemodialysis (HD), a major obstacle to increase its use is high frequency of fistulas that fail to mature. The aim of this study was to investigate and define cut-off values of morphologic and functional vessel parameters influencing successful RCAVF maturation using ultrasound.

Methods

A prospective, observational study was performed on 122 patients (66 men) who underwent primary RCAVF creation. Internal diameters of cephalic vein (CVd) and radial artery (ARd), venous distensibility (VD), resistance index (RI) and endothelial function by flow mediated dilatation (FMD) were determined by ultrasound examination before AVF placement. AVF maturation was observed by measuring blood flow (Qa) and CVd 0, 14 and 28 days after creation. Depending on the time when AVFs attained maturity (Qa ≥500 mL/min, CVd ≥5 mm), patients were divided into three groups: (i) successful maturation (after four weeks), (ii) prolonged maturation (within eight weeks) and (iii) failure to mature.

Results

Only 11% of patients failed to achieve a mature RCAVF. Successful AVF maturation occurred in 53% of patients and prolonged maturation in 36% of patients. ROC analysis defined the limits of variables relevant for RCAVF success (CVd >1.8 mm, ARd >1.6 mm, VD >0.4 mm). Female sex was associated with prolonged maturation (OR 0.35, 95% CI=0.17-0.72; P=0.005) having a significantly smaller ARd (1.83 vs. 2.01 mm, P=0.01) but better FMD (2981.5 vs. 2689.5, P=0.02) compared to men.

Conclusions

ARd ≤1.6 mm, CVd ≤1.8 mm and VD ≤0.4 mm are exact cut-off points, which best predict nonmaturation of RCAVF. Women need extended time for adequately matured AVF.

Avaliação da maturação das fístulas arteriovenosas para hemodiálise pelo eco-Doppler colorido

CONTEXTO: Quando se confecciona uma fístula arteriovenosa para hemodiálise (FAVH) autógena, é necessário que se aguarde a dilatação da veia em questão e o desenvolvimento de volume de fluxo mínimo, fenômeno chamado de maturação. Ainda hoje se discute qual o tempo necessário para ocorrer essa maturação. OBJETIVO: Avaliar a maturação de FAVH utilizando-se critérios ecográficos. MÉTODO: Entre maio de 2004 e 2005, 40 pacientes foram selecionados prospectivamente, sendo 23 homens (57,5%), com média de idade de 17,5±51,3 anos, com indicação de confecção de uma FAVH. Utilizou-se o aparelho Logic III® com transdutor de 10 MHz para a avaliação no pré-operatório e nos 7º, 14º, 21º e 28º dias de pós-operatório. Os critérios para a maturação após a cirurgia foram: veia com diâmetro médio maior que 4 mm e volume de fluxo maior que 400 mL/min. RESULTADOS: O diâmetro médio pré-operatório foi de 3,24±1,43 e 3,71±1,37 mm para fístulas de punho e de cotovelo, respectivamente. O diâmetro final foi de 5,01±0,87 mm para as FAVH de punho (p = 0,006) e de 6,15±1,16 mm para as FAVH de cotovelo (p = 0,95). O volume de fluxo no 7º dia pós-operatório foi de 493,63±257,49 mL/min e 976,33±332,90 mL/min para as FAVH de punho e cotovelo, respectivamente. Ao final do estudo, foi calculado o valor de 556,81±288,42 mL/min nas FAVH de punho (p < 0,05) e de 1031,62±614,812 mL/min nas FAVH de cotovelo. Baseados nos dois critérios, a maturação ocorreu em 57,1% das fístulas de punho e em 100% das fístulas de cotovelo após a 1ª semana. Após 4 semanas, 67,9% das fístulas de punho e 100% das fístulas de cotovelo apresentaram maturação. CONCLUSÃO: A maioria das FAVH de cotovelo apresentou diâmetro e fluxo adequados para punção logo após a 1ª semana de pós-operatório. Para as FAVH de punho, houve melhora progressiva dos padrões de maturação com o passar das semanas, sugerindo que essas FAVH devem ser puncionadas preferencialmente após a 4ª semana de pós-operatório.

Blood flow volume changes in the maturing arteriovenous access for hemodialysis

In our center, we start hemodialysis using arteriovenous accesses empirically 1 mo after surgery in nearly all patients, when the vein diameter reaches 5 mm and blood flow is assumed to be adequate. We measured blood flow and vessel diameter in the maturing autogenous and prosthetic access to determine if this approach can be justified by quantitative physiological parameters. Of 66 consecutive autogenous and prosthetic arteriovenous accesses created over 3 mo in 2004, 62 were prospectively examined by duplex ultrasonography preoperatively, immediately after surgery in the recovery room, at 10 d postoperatively and 1 mo after surgery before first cannulation. In the 20 forearm accesses, the immediate postoperative mean blood flow was 549 +/- 189 mL/min, 885 +/- 227 mL/min at 10 d and 934 +/- 260 mL/min at 1 mo. In the 22 upper-arm accesses, the immediate postoperative mean access blood flow was 858 +/- 292 mL/min, 1060 +/- 326 mL/min at 10 d and 1116 +/- 427 mL/min at 1 mo. In 20 prosthetic accesses, near maximal flow was attained immediately after surgery (990 +/- 256 mL/min). Most of the increased flow in autogenous accesses occurred early in the maturation process. This suggests that 1 mo is adequate for autogenous access maturation before use for hemodialysis. The process of access maturation appears to be less relevant in prosthetic accesses, where blood flow is high from the day of surgery and tissue incorporation is, therefore, more important.

Vascular access for hemodialysis

Establishing and maintaining adequate vascular access is essential to providing an appropriate dialysis dose in patients with end-stage renal disease. Complications related to vascular access have a significant role in dialysis-related morbidity and mortality. The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) clinical practice guideline for dialysis access was last updated in 2000 and provides a framework for the optimal establishment and maintenance of dialysis access, and treatment of complications related to dialysis access. This paper reviews the 2000 K/DOQI dialysis access guideline as well as updated information published subsequently.