Arteriovenous Access Graft Infection: Standards of Reporting and Implications for Comparative Data Analysis

Proposal of a classification of cannulation damage in vascular access grafts based on clinical, ultrasound, and microscopic observations

INTRODUCTION

Arteriovenous grafts (AVGs) serve as an alternative to native arteriovenous fistulas (AVFs) in the context of hemodialysis patient life planning. AVGs are more susceptible to developing outflow stenosis (due to intimal hyperplasia), thrombosis, and infections. However, an often overlooked contributor to AVG failure is cannulation damage. The objective of this paper is to assess the impact of cannulations on AVGs. We aim to establish a classification of AVG damage by comparing clinical data and ultrasound images with microscopic morphological findings obtained from explanted grafts.

MATERIALS AND METHODS

This study is conducted at a single center. We included all patients who underwent AVG creation between 2011 and 2019. Comprehensive data on clinical history, follow-up, and complications were collected and reviewed. Duplex ultrasound (DUS) characteristics were documented, and all grafts explanted during the analysis period underwent optical microscopy evaluation. Finally, clinical data, along with DUS and microscopic findings, were integrated to derive a damage classification.

RESULTS

During the study period, 247 patients underwent 334 early cannulation AVGs. The median follow-up duration was 714 days (IQR 392, 1195). One hundred eleven (33%) grafts were explanted. Clinical data and DUS findings were utilized to formulate a four-grade classification system indicating increasing damage.

CONCLUSION

Cannulation damage alone does not solely account for AVG failure. It results from a biological host-mediated process that promotes the growth of intimal hyperplasia at the cannulation sites. This process is not clinically significant within the initial 2 years after AVG creation.

Improving accuracy of vascular access quality classification in hemodialysis patients using deep learning with K highest score feature selection

OBJECTIVE

To develop and evaluate a novel feature selection technique, using photoplethysmography (PPG) sensors, for enhancing the performance of deep learning models in classifying vascular access quality in hemodialysis patients.

METHODS

This cross-sectional study involved creating a novel feature selection method based on SelectKBest principles, specifically designed to optimize deep learning models for PPG sensor data, in hemodialysis patients. The method effectiveness was assessed by comparing the performance of multiple deep learning models using the feature selection approach versus complete feature set. The model with the highest accuracy was then trained and tested using a 70:30 approach, respectively, with the full dataset and the SelectKBest dataset. Performance results were compared using Student's paired t-test.

RESULTS

Data from 398 hemodialysis patients were included. The 1-dimensional convolutional neural network (CNN1D) displayed the highest accuracy among different models. Implementation of the SelectKBest-based feature selection technique resulted in a statistically significant improvement in the CNN1D model's performance, achieving an accuracy of 92.05% (with feature selection) versus 90.79% (with full feature set).

CONCLUSION

These findings suggest that the newly developed feature selection approach might aid in accurately predicting vascular access quality in hemodialysis patients. This advancement may contribute to the development of reliable diagnostic tools for identifying vascular complications, such as stenosis, potentially improving patient outcomes and their quality of life.

Hemodialysis patients and complications management costs in Italy: Plastic cannulae a potentially cost-effective strategy

BACKGROUND

The treatment of end-stage chronic renal failure involves substantial costs for health care, which could be higher considering hemodialysis access complications management costs. Complications could be addressed by cannulation technique, but also by the needle. In particular, the use of a metal needle for cannulation is responsible for several complications that compromise dialysis delivery and require interventions. This analysis aims to evaluate, from a hospital perspective, the direct costs related to complications that may occur in hemodialysis patients in Italy.

METHODS

To identify the main complications to consider in our analysis and related patient pathway for their management, we conducted an international literature search on PubMed and validated the data for Italy with an Italian Key Opinion Leader (KOL). A micro-costing analysis was developed to precisely assess the economic costs of healthcare interventions to manage complications due to vascular access cannulation.

RESULTS

The major complications identified, and the average cost/per episode for their management are the following ones: Local infection € 1455 (min € 745 and max € 2160); Sepsis, that requires hospitalization in ward € 4401 (min € 3693 and max € 4623); Sepsis (ICU) € 17,190; Hematoma € 304 (min € 252 and max € 728); Aneurysm € 3632 (min € 3139 and max € 4014); Pseudoaneurysm € 3695 (min € 3615 and max € 4014); Stenosis € 2229 (min € 1874 and max € 4857); Thrombosis € 2151 (min € 1941 and max € 3395).

CONCLUSIONS

In making decisions, hospital administration, and payer should take into consideration, not just the price of devices, but the entire patient's pathway. The use of plastic cannulae in hemodialysis patients shows improved outcomes compared to traditional metal needles. Furthermore, combining it with accurate and efficient cannulation techniques reduces complication rates, improves patients' quality of life, and reduces healthcare resource consumption.

Surely you can't B. cereus: Bacillus cereus infection resulting in spontaneous pseudoaneurysm of a nonaccessed arteriovenous graft

Vascular graft infections are a well-described complication of loop arteriovenous grafts (AVGs) placed for hemodialysis access and are reported to occur in 0.5% to 6.0% of AVGs. The most common microorganisms implicated in these infections are the Staphylococcus species. We present a case of a chronically nonaccessed graft rupture caused by an indolent B. cereus colonization, which is usually a foodborne contaminant. The finding of this organism as the causal agent in an AVG infection warrants further research into the potential emergence of the Bacillus species as a contributing factor in the morbidity and mortality resulting from AVG infection.

Early-cannulation arteriovenous grafts: Multidisciplinary learning is essential to optimize outcomes

BACKGROUND

It is likely that there will be an increasing role for early-cannulation arteriovenous grafts (ecAVG) with a wider recognition of the need to tailor vascular access to avoid futile procedures and unnecessary TCVC. However, experience of these products is not common and limited to early surgical adopters, with little information on the systemic changes and multi-disciplinary care needed to optimize outcomes. The aim of this study was to report the impact of a multi-disciplinary approach on quantifiable outcomes.

METHODS

A retrospective analysis of a prospectively maintained database of 295 ecAVG implanted over an 8-year time-period was performed. Indicative outcomes were chosen to reflect nephrology (patient selection), nursing care (cannulation complications of infection and pseudoaneurysm) and radiology (thrombosis) on cumulative impact (functional patency) over three distinct time periods.

RESULTS

The incidence of ecAVG increased 10-fold over the three time periods. The use of ecAVG changed significantly from salvage tertiary access to TCVC avoidance and salvage of existing AVF. Nursing complications reduced markedly with significantly fewer over-cannulation episodes and pseudo-aneurysms. With an improved pro-active surveillance programme, the time to first thrombosis doubled and the risk of thrombosis halved. Ultimately this resulted in significantly improved functional patency with a risk of ecAVG loss less than one-third by the last time-period.

CONCLUSIONS

All aspects of ecAVG use require scrutiny and critical appraisal. Failure or success is not simply achieved by performing good technical surgery with an efficacious product, but by the care taken across a wide range of elements spanning case selection, implantation, use and maintenance.

Guidelines on vascular access for hemodialysis from the Brazilian Society of Angiology and Vascular Surgery

Chronic kidney disease is a worldwide public health problem, and end-stage renal disease requires dialysis. Most patients requiring renal replacement therapy have to undergo hemodialysis. Therefore, vascular access is extremely important for the dialysis population, directly affecting the quality of life and the morbidity and mortality of this patient population. Since making, managing and salvaging of vascular accesses falls within the purview of the vascular surgeon, developing guideline to help specialists better manage vascular accesses for hemodialysis if of great importance. Thus, the objective of this guideline is to present a set of recommendations to guide decisions involved in the referral, evaluation, choice, surveillance and management of complications of vascular accesses for hemodialysis.

Management of infected arteriovenous grafts for haemodialysis: Outcomes and strategies using a novel objective scoring system

BACKGROUND

In haemodialysis patients with exhausted autogenous options, prosthetic arteriovenous grafts (AVGs) are frequently utilised as tertiary vascular access. However, the prosthetic nature of AVGs precipitates an increased risk of infection which may translate to excess morbidity and life-threatening complications. The current evidence remains divided on the optimal treatment strategy for arteriovenous graft infections (AVGi) with arguments for conservative management by antibiotics, salvaging with graft revision or total/subtotal excision. To address this gap, we assessed the outcomes of AVGi patients treated in our institution, developing an AVGi severity classification model and a proposed treatment algorithm to guide AVGi management.

METHODS

We conducted a single centre retrospective review of outcomes of patients with AVGi managed either by sole antibiotics therapy, graft revision or surgical excision between June 2016 and May 2021. Outcomes of AVGi patients across differing treatment groups were compared, including 1-year mortality, 6-month and 1-year functional vascular access. We also analysed the outcomes of tunnelled haemodialysis lines (THL), which were used as a temporary vascular access in several AVGi patients in our study.

RESULTS

A total of 34 AVGi patients were managed within that time frame and included in the study (5 conservatively management by antibiotics, 5 graft revisions and 24 surgical excision) with a mean age of 60.4 ± 14.4 years (67.6% males). Overall 1-year mortality was 14.7%. A 6-month functional vascular access status across the three groups stood at 60%, 60% and 10% while 1-year functional vascular access status was 60%, 75% and 42% respectively.

CONCLUSIONS

When clinically appropriate, conservative management by antibiotics or salvage/graft revision can present as prudent AVGi treatment options. The adoption of our proposed severity classification system and treatment algorithm provides a more thorough objective assessment of the infection and helps guide the clinical decision-making process.

Meta-analysis of total versus partial graft excision: Which is the better choice to manage arteriovenous dialysis graft infection?

BACKGROUND

Arteriovenous graft infection (AVGI) is a major cause of hemodialysis access failure. Delayed diagnosis and inappropriate treatment may lead to increased morbidity (3-35%) and mortality up to 12%.

OBJECTIVES

Compare the postoperative outcomes of total graft excision (TGE) and partial graft excision (PGE) in the treatment of AVGI.

DESIGNS

Systematic review and meta-analysis METHODS: The dataset was defined by searching PubMed, EMBASE, Google Scholar, and the Cochrane database for articles outlining the terms arteriovenous graft infection, infected dialysis graft, TGE and PGE published between 1995-2020. The data analysis evaluated the outcomes of TGE and PGE in the management of AVGI. The meta-analysis was performed using Review Manager Software version 5.4.1.

MAIN OUTCOME MEASURES

30-day mortality, recurrent infection, and reoperation rate.

SAMPLE SIZE

Eight studies, including 555 AVGI, and 528 patients.

RESULTS

PGE showed a significant increase in recurrent graft infection rate (OR=0.23,95% CI=0.13-0.41, P<.00001) and re-operation rate for control of infection (OR=0.14,95% CI=0.03-0.58, P<.007). However, the 30-day mortality rate did not differ significantly between the groups (OR=0.92,95% CI=0.39-2.17, P=.85).

CONCLUSIONS

TGE remains a safe and effective surgical method for the management of AVGI. PGE is associated with a higher risk of graft infection and need for re-operation. As a result, PGE should only be considered in carefully selected patients.

LIMITATION

Risk of bias due to the differences in patient characteristics.

CONFLICT OF INTEREST

None.

Application and implications of a standardised reporting system for arteriovenous access graft infection

INTRODUCTION

The perception that arteriovenous graft infection (AVGi) is frequent and severe is not based on contemporary data from large units using modern AVG. Furthermore, older reports compounded misperceptions by using non-standardised reporting that prevents easy comparison against the alternative modalities. The aim of this article is to use a recently published reporting scheme to analyse the frequency, management and outcome of AVGi in a large series of sequential early-cannulation AVG with long-term follow-up.

METHODS

A single-center series analysis was performed of 277 early-cannulation AVG with minimum 1-year follow-up (total 120,082 days). Infections relating to the AVG were classified, root-cause analysed and the outcomes presented.

RESULTS

Sixteen percent of all AVG implanted (51 episodes) developed infection related to the AVG. Primary AVGi (related to the insertion procedure or within 28 days) occurred in 9 (3%); secondary AVGi (related to AVG in use) occurred 33 times (rate 0.27/1000 haemodialysis days), at a mean of 382 days, and tertiary AVGi (in AVG no longer in use) occurred nine times. Only 1/3 of all AVGi led to bacteraemia, and ½ did not lead to loss of functional access.

SUMMARY

AVG infection is not common, caused a systemic infection in only one-third, did not lead to metastatic infection, and importantly, was treatable without loss of access in one-half of all cases. Using an objective system that discriminates between aetiology and outcome allows a more complete objective understanding of relative infection risks and outcomes for AVG that can inform discussions with patients requiring vascular access for haemodialysis.

Arteriovenous Grafts' Types of Indications and Their Infection Rate

BACKGROUND

Arteriovenous graft infection is a well-known and frequent complication. The objective of this study was to compare infection rates of primary and secondary indicated arteriovenous grafts (AVGs).

SUBJECTS AND METHODS

Retrospectively, we evaluated the indications for AVGs created at our institution which became infected. One hundred forty AVGs were evaluated. Of these AVGs, 33 (23.6%) were primary and 107 (76.4%) secondary indicated.

RESULTS

Infection of a primary AVG was detected in 5 patients (15.2 %). Infection of a secondary AVG was detected in 30 patients (28.0%). Primary and secondary patency were significantly lower in patients with infected AVG (P = 0.006; P = 0.0001). The effect of diabetes mellitus and age on development of infection was not confirmed.

CONCLUSIONS

Indications for AVG creation clearly influence the future risk of infection. If the indication to use the AVG is to correct a complicated arteriovenous fistula, the risk of infection is 2 times higher.