Vascular Access Quality Research Articles

#1204 Measuring needling experience: development and validation of the Needling Patient Reported Experience Measure (NPREM)

Abstract Background and Aims Most people on haemodialysis rely on having reliable access to their vascular system, often via surgically created arteriovenous fistula or graft. At the beginning of each dialysis session, needles must be inserted. While ‘needling’ is a key step, an annual UK survey shows that needling is one of the lowest scoring areas of reported experience for individuals receiving haemodialysis in a kidney centre or satellite unit. Qualitative research indicates that needling can be painful and cause anxiety. Although an emerging area of research, no validated measures exist which assess patient reported experience of needling. We aimed to develop a questionnaire which reliably measures needling experience. The Needling Patient Reported Experience Measure (NPREM) was developed over multiple phases consisting of qualitative interviews with patients, item generation involving a multidisciplinary expert group including experts by experience, cognitive interviewing and pilot testing. Here we report the results of the final validation phase. Methods Seven NHS kidney centres participated in the validation phase (aiming for 500 participants). Between February-April 2023, participants completed either online or paper versions of the questionnaire. A subset of participants (aiming for 80-120) completed a follow-up questionnaire pack (NPREM, Change of Circumstances) 2-4 weeks after the first to assess the reliability of the scale over time. Analyses included a full evaluation of the scale psychometric properties and factor analyses to assess dimensional structure. Correlations with other validated measures (Vascular Access Quality of Life [VASQoL], EuroQol 5 Dimension [EQ5D-5L], and Patient Activation Measure [PAM]) were used to assess the convergent and divergent validity of the NPREM. Results 468 people participated (sample characteristics: male 66%, mean age 66 years (SD 14), White 75%, access via fistula 95%, first access 76%), of which 99 completed the follow-up. Overall, the NPREM showed good internal consistency (Cronbach's alpha = 0.94) and moderate to strong inter-item correlations. Factor analyses indicated that needling experience was a unidimensional construct, with one strong, main factor. Follow-up scores were strongly correlated (r = 0.89) with participants’ initial NPREM responses, demonstrating high reliability. Evidence of convergent validity was seen in the strong correlations between the NPREM and 1) the VASQoL (r = 0.60) and 2) the Overall Needling Experience question (r = 0.79). NPREM did not correlate with the EQ-5D (r = −0.31), the EQ-5D overall health (r = 0.24) or PAM (0.17), demonstrating divergent validity. The research team reviewed all items and themes reaching a consensus on items included, resulting in the validated 28-item NPREM (v 1.0), across five themes of care (Communicating with the Team, My Fistula/Graft and Needling, Steps in Needling, Working Together, My Personal Experience) plus Overall Needling Experience. Conclusion These results indicate that the NPREM offers a robust needling-specific tool to measure patient experience in those receiving haemodialysis. It addresses a gap by offering a way for kidney care providers to assess needling experience, both as a whole and across themes of care, which may facilitate meaningful service improvements. When published, the NPREM will be publicly available and free to use.

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

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. 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. 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). 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.

DeepVAQ : an adaptive deep learning for prediction of vascular access quality in hemodialysis patients

BackgroundChronic kidney disease is a prevalent global health issue, particularly in advanced stages requiring dialysis. Vascular access (VA) quality is crucial for the well-being of hemodialysis (HD) patients, ensuring optimal blood transfer through a dialyzer machine. The ultrasound dilution technique (UDT) is used as the gold standard for assessing VA quality; however, its limited availability due to high costs impedes its widespread adoption. We aimed to develop a novel deep learning model specifically designed to predict VA quality from Photoplethysmography (PPG) sensors.MethodsClinical data were retrospectively gathered from 398 HD patients, spanning from February 2021 to February 2022. The DeepVAQ model leverages a convolutional neural network (CNN) to process PPG sensor data, pinpointing specific frequencies and patterns that are indicative of VA quality. Meticulous training and fine-tuning were applied to ensure the model’s accuracy and reliability. Validation of the DeepVAQ model was carried out against established diagnostic standards using key performance metrics, including accuracy, specificity, precision, F-score, and area under the receiver operating characteristic curve (AUC).ResultDeepVAQ demonstrated superior performance, achieving an accuracy of 0.9213 and a specificity of 0.9614. Its precision and F-score stood at 0.8762 and 0.8364, respectively, with an AUC of 0.8605. In contrast, traditional models like Decision Tree, Naive Bayes, and kNN demonstrated significantly lower performance across these metrics. This comparison underscores DeepVAQ's enhanced capability in accurately predicting VA quality compared to existing methodologies.ConclusionExemplifying the potential of artificial intelligence in healthcare, particularly in the realm of deep learning, DeepVAQ represents a significant advancement in non-invasive diagnostics. Its precise multi-class classification ability for VA quality in hemodialysis patients holds substantial promise for improving patient outcomes, potentially leading to a reduction in mortality rates.

Understanding consumer preference for vascular access safety and quality measurement: an international survey.

Objectives The aim of this study was to examine patient perceptions regarding vascular access quality measurement. Methods A web-based, cross-sectional survey was performed using a convenience sample of healthcare consumers with vascular access experience, recruited from September 2019 to June 2020. Survey respondents were asked to rate the perceived importance of 50 vascular access data items, including patient demographics, clinical and device characteristics, and insertion, management and complication data. Data were ranked using a five-point Likert scale (1, least important; 5, most important), and are reported as median values. Respondents proposed additional items and explored broader perspectives using free-text responses, which were analysed using inductive thematic analysis. Results In all, 68 consumers completed the survey. Participants were primarily female (82%), aged 40-49 years (29%) and living in Australia or New Zealand (84%). All respondents indicated that measuring the quality of vascular access care was important. Of the 50 items, 37 (74%) were perceived as 'most important' (median score 5), with measures of quality (i.e. outcomes and complications) rated highly (e.g. thrombosis and primary blood stream infection). Participants proposed 16 additional items. 'Gender' received the lowest perceived importance score (median score 3). Two themes emerged from the qualitative analysis of broader perspectives: (1) measurement of vascular access device complication severity and associated factors; and (2) patient experience. Conclusion Measuring vascular access quality and safety is important to consumers. Outcome and complication measures were rated 'most important', with respondents identifying a need for increased monitoring of their overall vascular access journey through the health system. What is known about the topic? The use of vascular access devices is common among hospitalised patients. Quality surveillance is not standardised, with no incorporation of patient preference. What does this paper add? We identify the data items consumers perceive as valuable to measure related to their vascular access journey; most importantly, consumers perceived the collecting of vascular access data as important. What are the implications for practitioners? Health services can use these data to develop platforms to monitor the quality and safety of vascular access care.

A single centre experience of arteriovenous fistula creation for hemodialysis access in Dar es Salaam, Tanzania

Chronic kidney disease (CKD) is increasingly diagnosed and thus more patients are in need of hemodialysis (HD) to sustain their life. The quality of vascular access for HD should be suitable for repeated puncture and allow a fast blood flow rate for high-efficiency dialysis with minimal complications. Our study aimed to document local experience and early outcomes after arteriovenous fistula (AVF) creation for hemodialysis access including complications related to AVF creation.This was a hospital based clinical audit in which case notes of patients who had undergone AVF creation between May, 2017 and March, 2018 at Muhimbili National Hospital (MNH) were reviewed using a structured data collection tool. Information regarding preoperative assessment for AVF creation, outcome of AVF, and age of the patients were collected. Descriptive statistics were prepared and summarized as tables. A total of 57 case notes of patients who underwent AVF creation for HD access with males contributing majority of patients (77.2%) were reviewed. The predominant age group was 41 to 60 years of age (56.2%) with mean age 47 years and age range of 18 -69 years. Three patients had procedure abandoned on the table due to sclerotic vein. The functional maturation rate was found to be 64.9% and post AVF complications in 15 patients (26.3%). Recorded post AVF creation complications were fistula stenosis/revision (27.8%), bleeding/haematoma (22.2%), limb oedema (22.2%), aneurysm (11.1%), surgical site infection [SSI] (11.1%) and thrombus formation (5.6%).AVF creation for HD access is common at MNH with a functional maturation rate of 64.9%, which is an acceptable rate. The preoperative vascular assessment in this survey was mainly found to be physical examination while preoperative vascular imaging was not commonly done to assess suitability of veins and arteries for AVF creation although post AVF complications are relatively few.

Building a Global, Pediatric Vascular Access Registry: A Scoping Review of Trial Outcomes and Quality Indicators to Inform Evidence-Based Practice.

Internationally, there is a lack of comparative vascular access (VA) data for pediatric clinicians and organizations to benchmark outcomes, evaluate quality initiatives, and improve practice. A VA registry is needed to address these knowledge and data capture gaps. To determine the range and heterogeneity of VA outcome measures or quality indicators reported in randomized controlled trials (RCTs) and clinical registries, to inform development of a homogeneous, reliable, minimum dataset for a pediatric VA registry. Scoping review framework. A systematic search for RCTs reporting VA outcomes in pediatrics and neonates was undertaken in the Cochrane library, EMBASE, CINAHL, PubMed, MEDLINE, and EBSCO using a medical subject headings and key words related to VA and pediatrics. We included RCTs of children (0-18years) reporting any VA outcome. We identified clinical registries reporting VA data in children (0-18) through web-based searches using key words related to VA and clinical or quality registries. Additional registries were identified through peer consultation. The frequency and scope of outcome measures and quality indicators were extracted from trials and registries and evaluated. From 93 RCTs included, 214 different VA measures were reported, reflecting 14 outcome domains. The most commonly reported outcome domains were insertion (44 RCTs; 47%), noninfectious complications (33 RCTs; 35%), and infectious complications (30 RCTs; 32%). Of the 22 registries identified, VA-associated infection was the main quality indicator routinely collected (12 registries; 55%). Outcomes such as mechanical complications and patient-reported outcomes were infrequently collected. Vascular access outcomes reported in pediatric and neonatal RCTs are highly heterogeneous. Internationally, clinical registries currently collect minimal VA data with the exception of infection outcomes. A core dataset of reliable, relevant measures to children and clinicians for VA device quality is needed. This will enable a VA registry that facilitates inter-institutional and international benchmarking.

Successful multidisciplinary interventions for arterio-venous fistula creation by the Pacific Northwest Renal Network 16 vascular access quality improvement program

In December 2001, 44.2% of hemodialysis (HD) patients in the Northwest Renal Network (NWRN 16) received dialysis using an arteriovenous fistula (AVF). Substantial differences were noted in percentages of patients with AVF, ranging from 5% to 90% of the facility population, suggesting wide variation in physician practice patterns within the Network. To address the needs of facilities having < 40% AVF, NWRN 16 provided education and tools for their vascular access decision-makers to promote AVF creation. In 2002, the Network sponsored 4 regional workshops targeted to nephrologists, vascular surgeons, dialysis nurses, and interventional radiologists. 46 facilities (43% of all Network facilities) had <40% AVF in use in December, 2001, dialyzing 2940 patients (Invited Units). Percent AVF in use in all the Invited Facilities increased from 31.3% pre-intervention to 39.8% at 1 year (p<0.001 vs pre) to 56.2% at four years: 79.8% increase in the prevalent AVF rate over a four-year period (95% confidence interval: 77.8% to 81.7%). Low prevalent AVF rates in many NWRN 16 facilities may have resulted from differences in physician practice patterns. The success of Network 16 AVF Intervention demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, innovative strategies to increase AVF rates among dialysis patients.

Successful AV fistula creation does not lead to higher catheter use: the experience by the Northwest Renal Network 16 Vascular Access Quality Improvement Program. Four years follow-up.

In 2002, the Center for Medicare and Medicaid Services (CMS) required all 18 Renal Networks to participate in a Vascular Access Quality Improvement Program (QIP). The Northwest Renal Network (NWRN 16) chose to increase arteriovenous fistula (AVF) use. NWRN 16 hypothesized that strategies which targeted the improvement of AVF rate and the reduction of catheter use were the same. In December 2001, 44.2% of hemodialysis (HD) patients in the NWRN 16 received HD using an AVF which met the Dialysis Outcome Quality Initiative (K/DOQI) 40% AVF guideline for prevalent patients. However, 43% of HD facilities (2869 patients) had less than 40% of AVF and higher HD catheter rates than the average Network catheter rates (25.0 vs. 20.3%). To address the needs of underperforming facilities, NWRN 16 provided education and tools for their vascular access decision makers to promote AVF creation and catheter reduction. In 2002, NWRN 16 sponsored four regional workshops targeted at nephrologists, vascular surgeons, HD nurses, and interventional radiologists. Percentage of AVFs in use in invited facilities increased from 31.3% pre-intervention to 56.2% at 4 yrs: 78% increase (99% confidence interval: 77.8% to 81.5%). Percentage of catheters increased from 25% to 25.8%: 3.2% change over 4 yrs (99% confidence interval: 2.5% to 4%). The success of Network 16's AVF interventions demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, and innovative strategies to increase dramatically AVF use without substantial increase in catheter use.

Vascular Access Quality Improvement

The aim of this study was to compare the clinical outcomes of different treatment strategies for children with partial-thickness scalds at two burn centers. At the first burn center, these burns were treated with a hydrofiber dressing (Aquacel®, Convatec, Inc.®, Princeton, NJ, USA) or silver sulfadiazine (SSD, Flammazine®, Sinclair IS Pharma, London, UK Pharmaceuticals), while at the second burn center, cerium nitrate-silver sulfadiazine (CN-SSD, Flammacerium®, Sinclair IS Pharma, London, UK Pharmaceuticals) was used.A two-center retrospective study was conducted of children admitted between January 2009 and December 2013 for partial-thickness scalds up to 10% TBSA who were treated primarily with a hydrofiber dressing or silver sulfadiazine (Burn Center Rotterdam) vs. cerium nitrate-silver sulfadiazine (Burn Center Groningen). The Dutch Burn Repository R3 and the electronic medical records of the study population were used for data extraction. The primary outcome was the time to wound healing. The secondary outcomes were the length of hospital stay, wound infection, and surgical treatment.The time to wound healing differed between the groups (HR = 1.46, 95%CI 1.17–1.82); the shortest time to wound healing was observed in the patients treated with CN-SSD (median 13 days), compared with 15 days for the patients treated with hydrofiber and 16 days for the patients treated with SSD (p < 0.01). The length of stay was significantly shorter for the hydrofiber patients (medians: hydrofiber 3 days, SSD 10 days and CN-SSD 7 days; p < 0.01), but their outpatient treatment period was significantly longer (medians: hydrofiber 12 days, SSD 6 and CN-SSD 4 days; p < 0.01). The proportion of surgeries and the mean time to surgery was similar between the burn centers.This study compared different burn centers’ treatment strategies for children with partial-thickness scalds and found a shorter time to wound healing in the CN-SSD group. Patients treated with hydrofiber had a shorter clinical period in comparison with the SSD and CN-SSD patients. The results of CN-SSD are promising and warrant further study. A prospective study is needed to gain full insight into the merits and drawbacks of the treatment strategies. This will allow clinicians to make full use of the strengths of particular treatments to benefit specific patients.

Implantación de la técnica del “ojal” o “buttonhole” en una unidad de hemodiálisis hospitalaria: satisfacción del paciente

Por los profesionales del campo de la Nefrología y la Diálisis es conocida la vital importancia de contar con un acceso vascular óptimo desde que en 1945 se realizase el primer tratamiento renal sustitutivo con hemodiálisis. Esto es debido a que la calidad del acceso vascular (AV) condiciona la eficiencia y efectividad de dicha técnica, así como la morbilidad y calidad de vida de los pacientes sometidos a esta terapia1. Para que un AV sea considerado óptimo debe reunir varias características: permitir el abordaje seguro y continuado al sistema vascular, proporcionar flujos suficientes que permitan suministrar la dosis de diálisis requerida y carecer de complicaciones. Sin embargo, a pesar de que, en la actualidad, este tipo de AV no existe, el que más se acerca a estos requisitos es la fístula arteriovenosa interna (FAVI)1. Por ello, se considera el acceso vascular de elección en los pacientes con insuficiencia renal crónica terminal que requieren hemodiálisis. La evidencia científica coincide en la importancia de los cuidados enfermeros efectivos de la FAVI y de una técnica de punción adecuada para conseguir el correcto desarrollo y permeabilidad, prolongar su supervivencia y minimizar las complicaciones relacionadas con la disfunción (estenosis, aneurismas, trombosis, infección...). El correcto uso y mantenimiento de este acceso vascular (AV) va a ser la piedra angular relacionada con el aspecto técnico de la hemodiálisis en el que la enfermería puede incidir. Se ha comprobado que la técnica de punción de la FAVI es motivo de ansiedad y disconfort para el paciente y, secundariamente para el personal del enfermería2. Además de influir en la supervivencia de la FAVI, dado que las punciones repetidas acaban alterando la morfología y características del vaso sanguíneo3, como ya enunció Kronung en 1984 con su análisis de las consecuencias de las múltiples punciones, y la mejor técnica para evitar su daño4, debido a la elongación de la pared frontal del vaso provocada por el desplazamiento del tejido y al posterior llenado con un trombo del hueco generado tras la retirada de la aguja.

How to improve vascular access care.

Preservation of a well-functioning vascular access (VA) is one of the most important and problematic areas in the care of dialysis patients. Providing high quality of care can reduce morbidity, improve quality of life and reduces costs. Given the increased complexity and the multidisciplinary character of VA care, it is a prerequisite to establish a dedicated multidisciplinary approach. An essential part of VA care is the management of the process before, during and after cannulation. A lack of knowledge and skills can have major implications for dialysis patients and may be related to VA outcome. Therefore, VA care requires continuous education of staff and patients, timely referral, adequate planning, and early identification or prevention of complications with elective treatment. Furthermore, access care data should be measured to continuously improve VA quality and measure the effects of the performance and effort.

Does the extracorporeal blood flow affect survival of the arteriovenous vascular access?

Hemodiafiltration with high-convective volumes is associated with improved patient survival, whereby practical realization is contingent on high extracorporeal blood flow (Qb) and dialysis treatment time. However, Qb is restricted by vascular access (VA) quality and/or concerns that high Qb could damage the VA. Taking VA quality into consideration, one can investigate the relationship between Qb and VA survival. We analyzed data from 1039 patients treated by hemodiafiltration over a 21-month period where access blood flow (Qa) measurements were also available at baseline. VA failure was defined as a surgical intervention resulting in the generation of a new VA. Qa was included as a stratification variable within a Cox regression model. A second Cox proportional hazard model with a penalized spline was used to describe the association between Qb and VA survival. Compared with Qb in the 350-357 mL/min range, a significantly higher hazard ratio (HR) for VA failure was detected for fistula only, and then only for Qb < 312 mL/min (HR: 2.361, 95% confidence interval [CI]: 1.251-4.453), Qb = 387-397 mL/min (HR: 1.920, 95% CI: 1.007-3.660) and Qb >414 mL/min (HR: 2.207, 95% CI: 1.101-4.424). Age, gender, diabetes, VA vintage, position of the VA, and arterial pressure were not significantly associated with outcome. The form of the penalized spline confirmed higher risk for VA failure for the lowest and the highest values of Qb. Taking Qa into consideration, no association was found between VA failure and Qb up to flows as high as approximately 390 mL/min.

The Effect of Type and Vascular Access Quality on the Outcome of Chronic Hemodialysis Treatment

The function of vascular access has a key significance in hemodialysis treatment results. An overview of factors contributing to successful arteriovenous fistula (AVF) constructions and the effect of vascular access quality on the outcome of renal replacement therapy were analyzed, including our study observations. On the basis of the data obtained in the study, the creation of autogenous AVF was reported to be possible in 92.9% of the 213 investigated patients. In 81.2% of the patients, vascular access was found to be located on the forearm. Comorbidities, especially congestive heart failure and peripheral vascular disease, were the main factors that had a negative effect on AVF construction and quality. AVF abnormalities were detected on physical examination in 37% of the patients. Results from the physical examination were found to be consistent with those obtained from Doppler ultrasound, thermodilution, and intra-access pressure measurement. AVF stenosis significantly increased the risk for access thrombosis, catheter insertion, and vascular access-related hospitalization.

Successful AV Fistula Creation does not Lead to Higher Catheter Use: The Experience by the Northwest Renal Network 16 Vascular access Quality Improvement Program. Four Years follow-up

Background In 2002, the Center for Medicare and Medicaid Services (CMS) required all 18 Renal Networks to participate in a Vascular Access Quality Improvement Program (QIP). The Northwest Renal Network (NWRN 16) chose to increase arteriovenous fistula (AVF) use. NWRN 16 hypothesized that strategies which targeted the improvement of AVF rate and the reduction of catheter use were the same. In December 2001, 44.2% of hemodialysis (HD) patients in the NWRN 16 received HD using an AVF which met the Dialysis Outcome Quality Initiative (K/DOQI) 40% AVF guideline for prevalent patients. However, 43% of HD facilities (2869 patients) had less than 40% of AVF and higher HD catheter rates than the average Network catheter rates (25.0 vs. 20.3%). To address the needs of underperforming facilities, NWRN 16 provided education and tools for their vascular access decision makers to promote AVF creation and catheter reduction. Methods In 2002, NWRN 16 sponsored four regional workshops targeted at nephrologists, vascular surgeons, HD nurses, and interventional radiologists. Results Percentage of AVFs in use in invited facilities increased from 31.3% pre-intervention to 56.2% at 4 yrs: 78% increase (99% confidence interval: 77.8% to 81.5%). Percentage of catheters increased from 25% to 25.8%: 3.2% change over 4 yrs (99% confidence interval: 2.5% to 4%). Conclusion The success of Network 16's AVF interventions demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, and innovative strategies to increase dramatically AVF use without substantial increase in catheter use.

Implementation of a vascular access quality programme improves vascular access care

In the Netherlands an access quality improvement plan (QIP) was introduced by vascular access coordinators (VAC) with the aim to decrease vascular access-related complications by preemptive intervention of malfunctioning accesses. A vascular access QIP was established in 24 centres (46% of all Dutch facilities) and a structural multidisciplinary vascular access meeting was instituted. In these centres, including 2300 patients, a protocol for enhancement of fistula creation and access surveillance programme was implemented, with instruction of physicians and nurses, and rounds to discuss complications and evaluate vascular access interventions. The number and type of vascular access, permanent catheters, thrombosis rates and number of interventions were evaluated at the start and end of the study period. After the surveillance programme, the number of autogenous arterio-venous fistulas (AVFs) had increased significantly from 69 to 77% (P < 0.01), while the use of temporary subclavian vein catheters declined (34% vs 11%) (P < 0.01), with a substantially higher percentage of jugular vein catheters (from 23 to 35%). Interventional treatment of malfunctioning accesses by percutaneous transluminal angioplasty (PTA) (from 0.39 to 0.50 patient/year; P < 0.001)) and surgical revisions (from 0.06 to 0.12 per patient/year; P < 0.001) also increased. These data demonstrate that a vascular access QIP resulted in placement of more autogenous AVFs, increased number of PTAs and surgical interventions. These findings suggest that a vascular access care QIP is worthwhile to improve dialysis patients' care and access morbidity.

Successful Multidisciplinary Interventions for Arterio-Venous Fistula Creation by the Pacific Northwest Renal Network 16 Vascular access Quality Improvement Program

Background In December 2001, 44.2% of hemodialysis (HD) patients in the Northwest Renal Network (NWRN 16) received dialysis using an arteriovenous fistula (AVF). Substantial differences were noted in percentages of patients with AVF, ranging from 5% to 90% of the facility population, suggesting wide variation in physician practice patterns within the Network. To address the needs of facilities having &lt;40% AVF, NWRN 16 provided education and tools for their vascular access decision-makers to promote AVF creation. Methods In 2002, the Network sponsored 4 regional workshops targeted to nephrologists, vascular surgeons, dialysis nurses, and interventional radiologists. Results 46 facilities (43% of all Network facilities) had &lt;40% AVF in use in December, 2001, dialyzing 2940 patients (Invited Units). Percent AVF in use in all the Invited Facilities increased from 31.3% pre-intervention to 39.8% at 1 year (p&lt;0.001 vs pre) to 56.2% at four years: 79.8% increase in the prevalent AVF rate over a four-year period (95% confidence interval: 77.8% to 81.7%). Conclusion Low prevalent AVF rates in many NWRN 16 facilities may have resulted from differences in physician practice patterns. The success of Network 16 AVF Intervention demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, innovative strategies to increase AVF rates among dialysis patients.

SIMPLE PRESSURE MEASUREMENT IS NOT RELIABLE IN DETECTION OF ACCESS STENOSIS IN NATIVE AV FISTULAS

Dynamic arterial and venous pressures (PA, PV) are used as the simplest tools to assess vascular access quality (VAQ). An increased PV over three consecutive dialyses is believed to indicate a stenosis, a rule devised for synthetic grafts (AVG) but not adequately validated for AV fistulas (AVF). In this study dynamic PV and static intra-access pressure (calculated by means of the simplified formula PIA=(PA+PV)/2) changes were evaluated in 46 accesses in which balloon angioplasty had to eventually be performed. The whole group consisted of 30 forearm AVF, 5 upper arm AVF and 11 AVG. Pressures were compared in each patient at a time of satisfactory access flow (QVA) and immediately before the angioplasty and pressure difference over that period (deltaPV, deltaPIA) evaluated. Despite a significant drop in QVA over the follow-up interval in both AVF and AVG, the mean deltaPV and deltaPIA in AVF were only several mm Hg and the chosen threshold limit of 20 mmHg was exceeded in approximately 10% of patients only. The results in the AVG group were, however, very different: The mean deltaPV and deltaPIA were close to 20 mmHg and almost 60% of patients in the AVG group exceeded this limit. Evaluation of PIA did not improve stenosis detection in either group. It is concluded that PV and/or PIA monitoring may be useful to detect a stenosis in AVG but not in AVF.

Comparison of Different Techniques of Hemodialysis Vascular Access Flow Evaluation

Measurement of vascular access flow (QVA) has been suggested as a method of choice for vascular access quality (VAQ) monitoring. Besides traditional duplex Doppler, a number of bedside methods based mostly on the Krivitski principle of QVA evaluation from recirculation at reversed needles (RX), have been developed. This work compares ultrasonic dilution (UD), taken as a reference, HD01, Transonic Systems; duplex Doppler (DD); thermodilution (TD), BTM, Fresenius; optodilutional RX measurement (ORX), Critline III, R-mode, HemaMetrics; direct optodilutional QVA evaluation from jumpwise changes in ultrafiltration rate at both normal and reversed needles connection (OABF), Critline III, ABF-mode; and direct transcutaneous optodilutional QVA evaluation (TQA), Critline III TQA. Firstly, reproducibility of each method was assessed by duplicate measurement at unchanged conditions. This was followed by paired measurement with each method performed at controlled change in relevant measurement condition (two different extracorporeal blood flows in UD and TD, changed sensor position in TQA). Finally paired measurements by each method and the reference method performed at identical conditions were evaluated to assess accuracy of each method. The simple Krivitski formula QVA= QB(1-RX)/RX was used wherever manual QVA calculation was needed. Very high reproducibility was seen in UD, both for measurement at the same extra corporeal blood flow (QB) (correlation coefficient of duplicate measurement r= 0.9702, n= 58) and for measurement at two different QB (r= 0.9735, n= 24), justifying its current status of a reference method in QVA evaluation. Slightly lower reproducibility of TD measurement at the same QB (r= 0.9197, n= 40) and at two different QB (r= 0.8508, n= 168) can be easily overcome by duplicate measurement with averaging. High correlation of TD vs. UD (r= 0.9543, n= 54) makes TD a viable clinical alternative in QVA evaluation. Consistently different QVA obtained at two different QB should prompt closer investigation of anatomical conditions of the access. Use of the simple Krivitski formula in TD (which measures total recirculation, i.e. sum of access recirculation and cardiopulmonary recirculation) brings about underestimation of QVA, which progressively increases from QVA of about 600 ml/min up. Good correlation, although with significant scatter (r= 0.8691, n= 27) was found between the DD- and UD-based QVA. By far the worst reproducibility at the same QB from among the investigated methods was found in ORX (0.6430, n= 23). Also the correlation of ORX vs. UD was lower than in other methods (r= 0.702, n=33) and general overestimation of QVA by about 25% was noted. Correlation of OABF vs. UD (r= 0.6957, n= 26) was slightly better than that of ORX and it gave less overestimated values. The TQA method showed very high reproducibility (r= 0.9712, n= 85), however only for unchanged sensor position. Correlation of QVA measured at two different sensor positions was much worse (r= 0.7255, n= 22). Correspondence of TQA vs. UD was satisfactory (r= 0.8077, n= 36). Skilled and experienced operators are a must with this method.

Vascular access quality monitoring.

Access dysfunction presents a risk for haemodialysis patients and is costly for health care providers. Regular vascular access quality (VAQ) monitoring enables the detection of adverse access conditions early allowing timely interventions, which will presumably be less invasive, more successful and cheaper. This paper reviews all currently used assessment parameters: dynamic and static pressures, recirculation and blood flow through the access--and analyses pros and cons of each of them. Based on this overview it is concluded that access flow monitoring should be the method of choice, possibly combined with monitoring of another parameter to further enlarge diagnostic possibilities of the monitoring. The VAQ monitoring system developed and used currently in the author's dialysis centre is briefly described as an example. The issue of access flow related to haemodynamics is briefly mentioned. With the introduction of any VAQ monitoring system, one has to acknowledge a change in structure of interventions and that the demand for surgical procedures decreases with a concurrent increase in percutaneous interventions.

Improving Quality of Vascular Access Care for Hemodialysis Patients

Because quality of care for patients with end-stage renal disease (ESRD) has improved, they require long-term vascular access for hemodialysis. Construction of a native vein arteriovenous fistula (AVF) on the arm is considered best practice; a prosthetic graft (PG) AVF on the arm is a good alternative, although insertion of a central venous catheter (CVC), the third choice, is sometimes necessary. A quality improvement project was initiated at the dialysis unit of Rijnland Hospital (The Netherlands) to improve quality of vascular access care. Seventy-four patients were treated from January 2001 through June 2002. The list of preferred access operations was adapted from evidence-based guidelines. The percentages of CVCs and PGs were chosen as quality indicators. Twelve of 19 patients (34%) appeared to be using CVCs unnecessarily. Actions were taken, and the CVC indicator decreased by 11%. The PG indicator decreased gradually from 24% to 8%. Reductions in the use of CVCs and PGs suggest that the vascular access improvement project resulted in improvement of long-term vascular access for hemodialysis patients. A considerable decrease in the use of PGs and CVCs was achieved in 2001. However, a decrease of CVCs to < 20% has still not been realized, perhaps because new hemodialysis patients referred to the dialysis unit have already had CVCs inserted. Considerable improvement, as reflected in the number of hemodialysis patients with CVCs or PGs, can be achieved with a minimum of costs.