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Colombo A, Provenzano M, Rivoli L, Donato C, Capria M, Leonardi G, Chiarella S, Andreucci M, Fuiano G, Bolignano D, Coppolino G. Utility of Blood Flow/Resistance Index Ratio (Q x) as a Marker of Stenosis and Future Thrombotic Events in Native Arteriovenous Fistulas. Front Surg 2021; 7:604347. [PMID: 33569388 PMCID: PMC7868551 DOI: 10.3389/fsurg.2020.604347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 09/09/2020] [Accepted: 12/31/2020] [Indexed: 11/21/2022] Open
Abstract
Objective: The resistance index (RI) and the blood flow volume (Qa) are the most used Doppler ultrasound (DUS) parameters to identify the presence of stenosis in arteriovenous fistula (AVF). However, the reliability of these indexes is now matter of concern, particularly in predicting subsequent thrombosis. In this study, we aimed at testing the diagnostic capacity of the Qa/RI ratio (Qx) for the early identification of AVF stenosis and for thrombosis risk stratification. Methods: From a multicentre source population of 336 HD patients, we identified 119 patients presenting at least one “alarm sign” for clinical suspicious of stenosis. Patients were therefore categorized by DUS as stenotic (n = 60) or not-stenotic (n = 59) and prospectively followed. Qa, RI, and QX, together with various clinical and laboratory parameters, were recorded. Results: Qa and Qx were significantly higher while RI was significantly lower in non-stenotic vs. stenotic patients (p < 0.001 for each comparison). At ROC analyses, Qx had the best discriminatory power in identifying the presence of stenosis as compared to Qa and RI (AUCs 0.976 vs. 0.953 and 0.804; p = 0.037 and p < 0.0001, respectively). During follow-up, we registered 30 thrombotic events with an incidence rate of 12.65 (95% CI 8.54–18.06) per 100 patients/year. In Cox-regression proportional hazard models, Qx showed a better capacity to predict thrombosis occurrence as compared to Qa (difference between c-indexes: 0.012; 95% CI 0.004–0.01). Conclusions: In chronic haemodialysis patients, Qx might represent a more reliable and valid indicator for the early identification of stenotic AVFs and for predicting the risk of following thrombosis.
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Affiliation(s)
| | | | - Laura Rivoli
- Unit of Nephrology, Department of Internal Medicine, Chivasso Hospital, Turin, Italy
| | - Cinzia Donato
- Renal Unit, "Pugliese-Ciaccio" Hospital of Catanzaro, Catanzaro, Italy
| | | | | | | | | | - Giorgio Fuiano
- Renal Unit, "Magna Graecia" University, Catanzaro, Italy
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Lopot F, Malík J, Švára F, Polakovič V. Changes in vascular access blood flow: Etiological factors and clinical implications. J Vasc Access 2020; 22:575-584. [PMID: 32873115 DOI: 10.1177/1129729820953021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/17/2022] Open
Abstract
METHODS Records of 10,000 QVA measurement performed in 549 patients over 20 years were used as retrospective and anonymized data source, making ethical commission involvement unnecessary. Two approaches are used to elucidate association of QVA changes with different factors: analyses of smaller cohorts in which both the QVA and the respective factor were measured (e.g. association of QVA with cardiac output (CO)), or-in case of rare phenomena-a form of a well illustrated case reports was used (e.g. association of QVA and Kt/V). RESULTS Significant increase in CO after permanent VA creation (3-4-fold of the QVA value) was found. Impact of intradialytic CO changes on QVA is attenuated by relatively stable VA resistance compared to systemic resistance. Blood pressure impact is much stronger and it should therefore be noted at each QVA measurement. As reproducibility of different QVA measurement methods varies, use of the same method should be preferred. Direction of the arterial needle insertion in VA affects the QVA measured, especially in synthetic grafts, too. Also patient's own QVA variability may be quite high. All this makes KDOQI/EBPG recommended acceptable QVA drops too strict, they should be revised. In re-stenoses prone patients, measurement intervals should be shortened, too. CONCLUSION QVA values are significantly affected by many factors. Their knowledge appears essential for safe and effective VA surveillance and management.
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Affiliation(s)
- František Lopot
- General University Hospital, Department of Medicine, Prague - Strahov, Czech Republic.,First Medical Faculty, Charles University, Institute of biophysics, Prague, Czech Republic
| | - Jan Malík
- First Medical Faculty, Charles University, 3rd Clinic of Internal Medicine, Prague, Czech Republic
| | - František Švára
- General University Hospital, Department of Medicine, Prague - Strahov, Czech Republic
| | - Vladimír Polakovič
- General University Hospital, Department of Medicine, Prague - Strahov, Czech Republic
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Panda B, Mandal S, Majerus SJA. Flexible, Skin Coupled Microphone Array for Point of Care Vascular Access Monitoring. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2019; 13:1494-1505. [PMID: 31634844 PMCID: PMC6944775 DOI: 10.1109/tbcas.2019.2948303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 06/10/2023]
Abstract
Point-of-care screening for hemodialysis vascular access dysfunction requires tools that are objective and efficient. Listening for bruits during physical exam is a subjective examination which can detect stenosis (vascular narrowing) when properly performed. Phonoangiograms (PAGs)-mathematical analysis of bruits-increases the objectivity and sensitivity and permits quantification of stenosis location and degree of stenosis (DOS). This work describes a flexible and body-conformal multi-channel sensor and associated signal processing methods for automated DOS characterization of vascular access. The sensor used an array of thin-film PVDF microphones integrated on polyimide to record bruits at multiple sites along a vascular access. Nonlinear signal processing was used to extract spectral features, and cardiac cycle segmentation was used to improve sensitivity. PAG signal processing algorithms to detect stenosis location and severity are also presented. Experimental results using microphone arrays on a vascular access phantom demonstrated that stenotic lesions were detected within 1 cm of the actual location and graded to three levels (mild, moderate, or severe). Additional PAG features were also used to define a simple binary classifier aimed at patients with failing vascular accesses. The classifier achieved 90% accuracy, 92% specificity, and 91% sensitivity at detecting stenosis greater than 50%. These results suggest that point-of-care screening using microphone arrays can identify at-risk patients using automated signal analysis.
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Chen MCY, Weng MJ, Wu MYW, Liu YC, Chi WC. Measuring the palpable pulsatility length as a physical examination test in defining the severity of inflow stenosis for hemodialysis fistulas. BMC Nephrol 2019; 20:356. [PMID: 31519166 PMCID: PMC6743188 DOI: 10.1186/s12882-019-1536-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 06/12/2019] [Accepted: 08/27/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pulsatility is an important property of hemodialysis arteriovenous fistulas (AVF) and can be perceived by the fingers as a gradual decrease in strength downstream from the anastomosis along the main trunk of the fistula. The distance from the point at which the pulse becomes imperceptible to the anastomosis is termed the palpable pulsatility length (PPL); we considered this length may play a role in assessing the severity of inflow stenosis for hemodialysis fistulas. METHODS This study was performed by retrospective analysis of routinely collected data. Physical examinations and fistula measurements were performed in a selected population of 76 hemodialysis patients with mature fistulas during half a year. Fistula measurements included the PPL before and after treatment and the distance between the anastomosis and the arterial cannulation site (aPump length). The aPump index (API) was calculated by dividing the PPL by the aPump length. Angiograms were reviewed to determine the location and severity of stenosis. PPL and API were used to detect the critical inflow stenosis, which indicates severe inflow stenosis of an AVF. RESULTS Receiver operating characteristic analysis showed that the area under the curve was 0.895 for API and 0.878 for PPL. A cutoff value of API < 1.29 and PPL < 11.0 cm were selected to detect the critical inflow stenosis. The sensitivity was 96.0% versus 80.0% and specificity was 84.31% versus 84.31% for API and PPL, respectively. CONCLUSIONS PPL and API are useful tools in defining the severity of pure inflow stenosis for mature AVFs in the hands of trained examiners with high sensitivity and specificity.
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Affiliation(s)
- Matt Chiung-Yu Chen
- Department of Interventional Radiology, Yuan's General Hospital, No.162, Cheng-gong 1st Rd., Lingya District, Kaohsiung City, 802, Taiwan.
| | - Mei-Jui Weng
- Department of Radiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Misoso Yi-Wen Wu
- Department of Interventional Nursing, Yuan's General Hospital, Kaohsiung, Taiwan
| | - Yi-Chun Liu
- Department of Nephrology, Yuan's General Hospital, Kaohsiung, Taiwan
| | - Wen-Che Chi
- Department of Nephrology, Yuan's General Hospital, Kaohsiung, Taiwan
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Spanish Clinical Guidelines on Vascular Access for Haemodialysis. Nefrologia 2018; 37 Suppl 1:1-191. [PMID: 29248052 DOI: 10.1016/j.nefro.2017.11.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 05/10/2017] [Accepted: 06/21/2017] [Indexed: 12/26/2022] Open
Abstract
Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.
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Hwang SD, Lee JH, Lee SW, Kim JK, Kim MJ, Song JH. Comparison of ultrasound scan blood flow measurement versus other forms of surveillance in the thrombosis rate of hemodialysis access: A systemic review and meta-analysis. Medicine (Baltimore) 2018; 97:e11194. [PMID: 30045249 PMCID: PMC6078674 DOI: 10.1097/md.0000000000011194] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The benefit of access flow surveillance in preventing vascular access thrombosis and failure remains controversial, as many randomized clinical trials (RCTs) have failed to demonstrate consistent results. The aim of this study was to perform a meta-analysis including newly published RCTs with a subgroup analysis for arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs). METHODS A systematic review of the available literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. An electronic search was conducted using the MEDLINE, EMBASE, and Cochrane Library databases of RCTs conducted from 1970 to 2017 that involved access flow surveillance. As a result, 9 RCTs met our criteria. The control group was defined by indirect and various surveillance methods such as dynamic venous pressure measurement and physical examination. Conversely, the interventional group was defined as a noninvasive duplex ultrasound scan (USS) or ultrasound dilution that directly measured the flow of vascular access. RESULTS The studies included 990 patients comprising 658 native AVFs and 332 AVGs. The prevalence of diabetes was 29.3%and 30.5% in the interventional and control groups, respectively. The estimated overall pooled risk ratio (RR) of thrombosis was 0.782 [95% confidence interval (95% CI), 0.553-1.107; P = .17], favoring interventional group, although this was not statistically significant. In the subgroup analysis, the pooled RR of thrombosis was .562 (95% CI, 0.346-0.915; P = .02) for AVFs, which significantly favored the interventional group. Conversely, the pooled RR for AVGs was 1.104 (95% CI, 0.672-1.816; P = .70). CONCLUSION The surveillance method to measure access flow through USS showed a significant benefit for reducing thrombosis in AVFs. The result encourages adherence to the current guidelines for AVFs. However, no benefit was found regarding AVGs. Recent guidelines with a "one-size-fits-all" approach may be revised to a "tailored-to-risk" approach.
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Affiliation(s)
- Seun Deuk Hwang
- Division of Nephrology and Hypertension, Department of Internal Medicine, Inha University School of Medicine, Incheon
| | - Jin Ho Lee
- Division of Nephrology, Department of Internal Medicine, Bongseng-Memorial Hospital, Busan, Korea
| | - Seoung Woo Lee
- Division of Nephrology and Hypertension, Department of Internal Medicine, Inha University School of Medicine, Incheon
| | - Joong kyung Kim
- Division of Nephrology, Department of Internal Medicine, Bongseng-Memorial Hospital, Busan, Korea
| | - Moon-Jae Kim
- Division of Nephrology and Hypertension, Department of Internal Medicine, Inha University School of Medicine, Incheon
| | - Joon Ho Song
- Division of Nephrology and Hypertension, Department of Internal Medicine, Inha University School of Medicine, Incheon
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Castro A, Moreira C, Almeida P, de Matos N, Loureiro L, Teixeira G, Rego D, Teixeira S, Pinheiro J, Carvalho T, Fonseca I, Queirós J. The Role of Doppler Ultrassonography in Significant and Borderline Stenosis Definition. Blood Purif 2018; 46:94-102. [DOI: 10.1159/000488442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 09/05/2017] [Accepted: 03/15/2018] [Indexed: 02/02/2023]
Abstract
Background: The definition of significant stenosis (SS) remains controversial. Methods: We retrospectively reviewed 1,040 consultations. SS was defined in the presence of clinical and echo-Doppler (DDU) criteria: Qa <500 mL/min or Qa decrease >25%; RI >0.7 in the feeding artery or absolute minimal luminal stenosis diameter <2.0 mm. Stenosis without any additional criteria were considered borderline stenosis (BS). Results: Two hundred twenty-one arteriovenous fistulas (AVFs) were included: 58.8% had SS, 18.6% had BS, and 22.6% had no dysfunctional access (ND). SS had a significantly higher thrombotic events than BS and ND (13.1 vs. 4.4%, p = 0.018). The annual thrombosis rate was 0.007, 0.037, and 0.004 in the ND, SS, and BS, respectively. AVF cumulative survival at 5 years was significantly lower in SS (89.5%) compared to BS (100%) and ND (97.4%; p = 0.03). BS had an HR for AVF failure of 1.1, p = 0.955, while the SS presented an HR of 5.9, p = 0.09. Conclusion: AVF clinical monitoring with additional DDU criteria appear to be appropriate for therapeutic referral.
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Roca-Tey R, Ibeas J, Moreno T, Gruss E, Merino JL, Vallespín J, Hernán D, Arribas P. Dialysis arteriovenous access monitoring and surveillance according to the 2017 Spanish Guidelines. J Vasc Access 2018; 19:422-429. [PMID: 29544403 DOI: 10.1177/1129729818761307] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/15/2022] Open
Abstract
The Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology (S.E.N.), vascular surgery (SEACV), interventional radiology (SERAM-SERVEI), infectious diseases (SEIMC), and nephrology nursing (SEDEN)), along with the methodological support of the Iberoamerican Cochrane Centre, has developed the Spanish Clinical Guidelines on Vascular Access for Hemodialysis. This article summarizes the main issues from the guideline's chapter entitled "Monitoring and surveillance of arteriovenous access." We will analyze the current evidence on conflicting topics such as the value of the flow-based screening methods for the arteriovenous access surveillance or the role of Doppler ultrasound as the imaging exploration to confirm suspected stenosis. In addition, the concept of significant stenosis and the criteria to perform the elective intervention for stenosis were reviewed. The adoption of these guidelines will hopefully translate into a reduced risk of thrombosis and increased patency rates for both arteriovenous fistulas and grafts.
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Affiliation(s)
- Ramon Roca-Tey
- 1 Department of Nephrology, Hospital de Mollet, Fundació Sanitària Mollet, Barcelona, Spain
| | - José Ibeas
- 2 Department of Nephrology, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Teresa Moreno
- 3 Department of Radiology, Hospital Juan Ramón Jiménez, Complejo Hospitalario Universitario de Huelva, Huelva, Spain
| | - Enrique Gruss
- 4 Department of Nephrology, Hospital Universitario Fundación de Alcorcón, Alcorcón, Spain
| | - José Luis Merino
- 5 Department of Nephrology, Hospital Universitario del Henares, Coslada, Spain
| | - Joaquín Vallespín
- 6 Department of Vascular Surgery, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - David Hernán
- 7 Fundación Renal Íñigo Álvarez de Toledo, Madrid, Spain
| | - Patricia Arribas
- 8 Department of Nephrology, Hospital Infanta Leonor, Madrid, Spain
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Bastola S, Paulson WD, Jones SA. Applicability of an entry flow model of the brachial artery for flow models of the hemodialysis fistula. Proc Inst Mech Eng H 2017; 231:766-773. [PMID: 28466757 DOI: 10.1177/0954411917705910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/16/2022]
Abstract
The native arteriovenous fistula creates a shunt that provides the high blood flow that is needed for dialysis. Lumped parameter hemodynamic models of the arteriovenous fistula can be used to predict shear stresses and pressure losses and can be applied to help understand unsolved problems such as the high rate of arteriovenous fistula maturation failure. These models combine together flow components, such as arteries, stenosis, anastomoses, arterial compliance, and blood inertia, and each component must be modeled with an appropriate pressure-flow relationship. Poiseuille flow is generally assumed for straight vessels, but the unique high flow rates within the brachial artery of an arteriovenous fistula are expected to induce entry flow effects that are neglected in this model. To estimate the importance of these effects, brachial artery flow was modeled in a low-resistance network, such as the one that occurs when an arteriovenous fistula is constructed, through the lumped parameter model, and the predicted flow rates and pressures were compared to those predicted by computational fluid dynamics. When Poiseuille flow was assumed, the flow rate from the lumped parameter model was consistently larger than that from computational fluid dynamics, with a cycle-averaged error of 36.8%. When an entry flow model (Shah) was assumed, the lumped parameter-based flow was 6% lower than the computational fluid dynamics model at the peak of the flow waveform, and the cycle-averaged error was reduced to 7.8%. Thus, in a low-resistance (high flow) arteriovenous fistula circuit, an entry flow model can account for steeper near-wall velocity gradients. This result can provide a useful guide for designing engineering models of the arteriovenous fistula.
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Affiliation(s)
- Sulav Bastola
- 1 Biomedical Engineering Program, Louisiana Tech University, Ruston, LA, USA
| | - William D Paulson
- 2 Division of Nephrology, Augusta University Medical Center, Augusta, GA, USA
| | - Steven A Jones
- 1 Biomedical Engineering Program, Louisiana Tech University, Ruston, LA, USA
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Poort LJ, Ludlage JH, Lie N, Böckmann RA, Odekerken JC, Hoebers FJ, Kessler PA. The histological and histomorphometric changes in the mandible after radiotherapy: An animal model. J Craniomaxillofac Surg 2017; 45:716-721. [DOI: 10.1016/j.jcms.2017.02.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 10/19/2016] [Revised: 01/15/2017] [Accepted: 02/13/2017] [Indexed: 02/07/2023] Open
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Dariushnia SR, Walker TG, Silberzweig JE, Annamalai G, Krishnamurthy V, Mitchell JW, Swan TL, Wojak JC, Nikolic B, Midia M. Quality Improvement Guidelines for Percutaneous Image-Guided Management of the Thrombosed or Dysfunctional Dialysis Circuit. J Vasc Interv Radiol 2016; 27:1518-30. [DOI: 10.1016/j.jvir.2016.07.015] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 12/29/2015] [Revised: 07/12/2016] [Accepted: 07/14/2016] [Indexed: 01/20/2023] Open
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Volume blood flow, static pressure ratio and venous conductance in native arterio-venous fistulae: three surveillance methods compared. J Vasc Access 2015; 16:211-7. [PMID: 25656259 DOI: 10.5301/jva.5000324] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Accepted: 10/06/2014] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Dialysis venous pressure monitoring has been widely recommended as a surveillance method but has not been shown to improve access outcomes in randomised controlled trials. The method has been impaired by the need to either turn off the blood pump or to derive the static venous pressure from the venous pressure measured with the dialysis pump running. We have developed a unique algorithm which converts Doppler-shifted spectral information derived from unscaled pulsatile blood flow waveforms into an estimate of mean blood pressure (MBP) at the point of ultrasound insonation. METHODS We have devised the unique expression shown here: MBP = MAP/(1 + Pff/Vff) where MAP is the mean arterial pressure, Pff = (systolic - diastolic)/MAP measured on the contralateral arm and Vff = spectral maximum - minimum/mean. Venous conductance (VC) can be measured by combining this pressure data with Duplex ultrasound blood flow data. A new device BlueDop™ has been used to illustrate the potential clinical value of non-invasive static pressure ratio (SPRn) in a monitoring role. Duplex and BlueDop™ technology were tested in an arterio-venous fistula (AVF) study in which VC, Q and SPRn were compared. Thresholds used for detection of ≥60% venous stenosis were VC <10 mL min-1 mm Hg-1, Q <500 mL min-1, SPRn >0.56. RESULTS The following accuracy was achieved: VC = 96%, Q = 92%, SPRn = 76% with similar accuracy in predicting premature thrombosis. CONCLUSIONS A new algorithm has been described and its in vivo accuracy in estimating mean 'pressure from flow' has been confirmed. Two new variables and a new dedicated instrument BlueDop™ have been demonstrated in clinical use.
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Rajabi-Jaghargh E, Banerjee RK. Combined functional and anatomical diagnostic endpoints for assessing arteriovenous fistula dysfunction. World J Nephrol 2015; 4:6-18. [PMID: 25664243 PMCID: PMC4317629 DOI: 10.5527/wjn.v4.i1.6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Received: 07/19/2014] [Revised: 08/26/2014] [Accepted: 11/19/2014] [Indexed: 02/06/2023] Open
Abstract
Failure of arteriovenous fistulas (AVF) to mature and thrombosis in matured fistulas have been the major causes of morbidity and mortality in hemodialysis patients. Stenosis, which occurs due to adverse remodeling in AVFs, is one of the major underlying factors under both scenarios. Early diagnosis of a stenosis in an AVF can provide an opportunity to intervene in a timely manner for either assisting the maturation process or avoiding the thrombosis. The goal of surveillance strategies was to supplement the clinical evaluation (i.e., physical examination) of the AVF for better and earlier diagnosis of a developing stenosis. Surveillance strategies were mainly based on measurement of functional hemodynamic endpoints, including blood flow (Qa) to the vascular access and venous access pressure (VAP). As the changes in arterial pressure (MAP) affects the level of VAP, the ratio of VAP to MAP (VAPR = VAP/MAP) was used for diagnosis. A Qa < 400-500 mL/min or a VAPR > 0.55 is considered sign of significant stenosis, which requires immediate intervention. However, due to the complex nature of AVFs, the surveillance strategies have failed to consistently detect stenosis under different scenarios. VAPR has been primarily developed to detect outflow stenosis in arteriovenous grafts, and it hasn’t been successful in accurate diagnosis of outflow lesions in AVFs. Similarly, AVFs can maintain relatively high blood flow despite the presence of a significant outflow stenosis and thus, Qa has been found to be a better predictor of only inflow lesions. Similar shortcomings have been reported in the detection of functional severity of coronary stenosis using diagnostic endpoints that were based on either flow or pressure. This limitation has been associated with the fact that both pressure and flow change in the presence of a stenosis and thus, hemodynamic diagnostic endpoints that employ only one of these parameters are inherently prone to inaccuracies. Recent attempts have resulted in development of new diagnostic endpoints that can combine the effects of pressure and flow. These new hemodynamic diagnostic endpoints have shown to be better predictors of functional severity of lesions as compared to either flow or pressure based counterparts. In this review article, we discussed the advantages and limitations of current functional and anatomical diagnostic endpoints in AVFs.
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Dwivedi AJ, Roy-Chaudhury P, Peden EK, Browne BJ, Ladenheim ED, Scavo VA, Gustafson PN, Wong MD, Magill M, Lindow F, Blair AT, Jaff MR, Franano FN, Burke SK. Application of human type I pancreatic elastase (PRT-201) to the venous anastomosis of arteriovenous grafts in patients with chronic kidney disease. J Vasc Access 2014; 15:376-84. [PMID: 24811601 PMCID: PMC6159820 DOI: 10.5301/jva.5000235] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Accepted: 02/13/2014] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To explore the safety and efficacy of PRT-201 applied to the outflow vein of a newly created arteriovenous graft (AVG). METHODS Randomized, double-blind, placebo-controlled, single-dose escalation study of PRT-201 (0.01 to 9 mg) applied to the graft-vein anastomosis and adjacent outflow vein immediately after AVG placement. The primary outcome measure was safety. The efficacy measures were intraoperative increases in outflow vein diameter and blood flow rate, primary unassisted patency, and secondary patency by dose groups (placebo, low, medium, high and All PRT-201). RESULTS A total of 89 patients were treated (28 placebo and 61 PRT-201). There were no significant differences in the proportion of placebo and PRT-201 patients reporting adverse events. Intraoperative outflow vein diameter increased 5% (p=0.14) in the placebo group compared with 13% (p=0.01), 15% (p=0.07) and 12% (p<0.001), in the low, medium and high groups, respectively. The comparison between the high and placebo groups was marginally statistically significant (p=0.06). The intraoperative blood flow did not change in the placebo group, and increased in the low, medium and high groups by 19% (p=0.34), 36% (p=0.09) and 46% (p=0.02), respectively. The low group had the longest primary unassisted and secondary patency and the fewest procedures to restore or maintain patency; however, the differences between groups were not statistically significant. CONCLUSIONS PRT-201 was well tolerated and increased AVG intraoperative outflow vein diameter and blood flow. Low dose tended to increase secondary patency and decrease the rate of procedures to restore or maintain patency. Larger studies with these doses will be necessary to confirm these results.
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Affiliation(s)
- Amit J. Dwivedi
- Department of Surgery, University of Louisville, Louisville, KY - USA
| | | | - Eric K. Peden
- Department of Cardiovascular Surgery, The Methodist Hospital, Houston, TX - USA
| | | | | | - Vincent A. Scavo
- Department of Cardiovascular and Thoracic Surgery, Indiana/Ohio Heart, Fort Wayne, IN - USA
| | | | - Marco D. Wong
- Research and Development, Proteon Therapeutics, Waltham, MA - USA
| | - Marianne Magill
- Research and Development, Proteon Therapeutics, Waltham, MA - USA
| | - Francesca Lindow
- Research and Development, Proteon Therapeutics, Waltham, MA - USA
| | - Andrew T. Blair
- Research and Development, Proteon Therapeutics, Waltham, MA - USA
| | - Michael R. Jaff
- VasCore, the Vascular Ultrasound Core Laboratory, Massachusetts General Hospital, Boston, MA - USA
| | | | - Steven K. Burke
- Research and Development, Proteon Therapeutics, Waltham, MA - USA
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15
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Agarwal AK, Shah R, Haddad NJ. Access blood flow testing. Semin Dial 2014; 27:595-8. [PMID: 25039319 DOI: 10.1111/sdi.12259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/26/2022]
Affiliation(s)
- Anil K Agarwal
- Department of Medicine, Nephrology Division, The Ohio State University Wexner Medical Center, Columbus, Ohio
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16
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17
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Cheong JH, Ng SSY, Liu X, Xue RF, Lim HJ, Khannur PB, Chan KL, Lee AA, Kang K, Lim LS, He C, Singh P, Park WT, Je M. An inductively powered implantable blood flow sensor microsystem for vascular grafts. IEEE Trans Biomed Eng 2012; 59:2466-75. [PMID: 22692871 DOI: 10.1109/tbme.2012.2203131] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/06/2022]
Abstract
Monitoring blood flow rate inside prosthetic vascular grafts enables an early detection of the graft degradation, followed by the timely intervention and prevention of the graft failure. This paper presents an inductively powered implantable blood flow sensor microsystem with bidirectional telemetry. The microsystem integrates silicon nanowire (SiNW) sensors with tunable piezoresistivity, an ultralow-power application-specific integrated circuit (ASIC), and two miniature coils that are coupled with a larger coil in an external monitoring unit to form a passive wireless link. Operating at 13.56-MHz carrier frequency, the implantable microsystem receives power and command from the external unit and backscatters digitized sensor readout through the coupling coils. The ASIC fabricated in 0.18-μm CMOS process occupies an active area of 1.5 × 1.78 mm (2) and consumes 21.6 μW only. The sensors based on the SiNW and diaphragm structure provide a gauge factor higher than 300 when a small negative tuning voltage (-0.5-0 V) is applied. The measured performance of the pressure sensor and ASIC has demonstrated 0.176 mmHg/√Hz sensing resolution.
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Affiliation(s)
- Jia Hao Cheong
- Institute of Microelectronics, Agency for Science, Technology and Research, Singapore.
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18
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More Precise Diagnosis of Access Stenosis: Ultrasonography versus Angiography. J Vasc Access 2012; 13:310-4. [DOI: 10.5301/jva.5000047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Accepted: 11/28/2011] [Indexed: 11/20/2022] Open
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19
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Kumbar L, Karim J, Besarab A. Surveillance and monitoring of dialysis access. Int J Nephrol 2011; 2012:649735. [PMID: 22164333 PMCID: PMC3227464 DOI: 10.1155/2012/649735] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 09/04/2011] [Accepted: 10/04/2011] [Indexed: 12/17/2022] Open
Abstract
Vascular access is the lifeline of a hemodialysis patient. Currently arteriovenous fistula and graft are considered the permanent options for vascular access. Monitoring and surveillance of vascular access are an integral part of the care of hemodialysis patient. Although different techniques and methods are available for identifying access dysfunction, the scientific evidence for the optimal methodology is lacking. A small number of randomized controlled trials have been performed evaluating different surveillance techniques. We performed a study of the recent literature published in the PUBMED, to review the scientific evidence on different methodologies currently being used for surveillance and monitoring and their impact on the care of the dialysis access. The limited randomized studies especially involving fistulae and small sample size of the published studies with conflicting results highlight the need for a larger multicentered randomized study with hard clinical end points to evaluate the optimal surveillance strategy for both fistula and graft.
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Affiliation(s)
- Lalathaksha Kumbar
- Division of Nephrology and Hypertension, Henry Ford Hospital, Detroit, MI 48202, USA
| | - Jariatul Karim
- Division of Nephrology and Hypertension, Henry Ford Hospital, Detroit, MI 48202, USA
| | - Anatole Besarab
- Division of Nephrology and Hypertension, Henry Ford Hospital, Detroit, MI 48202, USA
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20
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Abstract
Hemodialysis vascular access surveillance continues to be widely recommended despite ongoing controversy as to its benefit in prolonging access patency compared with clinical monitoring alone. The most common screening tests are access blood flow and dialysis venous pressure measurements. When surveillance test results cross a predetermined threshold, accesses are referred for intervention with correction of stenosis to reduce future thrombosis and prolong access survival. Current surveillance strategies have four components: (1) underlying condition; (2) screening test; (3) intervention; and (4) outcomes. However, limitations exist within each component that may prevent achieving the desired outcomes. This review discusses these limitations and their consequences. To date, randomized controlled trials have not consistently shown that surveillance improves outcomes in grafts, and there is limited evidence that surveillance reduces thrombosis without prolonging the life of native fistulae. In conclusion, current evidence does not support the concept that all accesses should undergo routine surveillance with intervention.
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Affiliation(s)
- William D Paulson
- Charlie Norwood VA Medical Center and Nephrology Section, Department of Medicine, Georgia Health Sciences University, Augusta, Georgia, USA
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21
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Catheter-based flow measurements in hemodialysis fistulas - bench testing and clinical performance. J Vasc Access 2011; 13:45-50. [PMID: 21725955 DOI: 10.5301/jva.2011.8443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Accepted: 03/14/2011] [Indexed: 11/20/2022] Open
Abstract
PURPOSE The purpose of this study was to perform bench and clinical testing of a catheter-based intravascular system capable of measuring blood flow in hemodialysis vascular accesses during endovascular procedures. METHODS We tested the Transonic ReoCath Flow Catheter System which uses the thermodilution method. A simulated vascular access model was constructed for the bench test. In total, 1960 measurements were conducted and the results were used to determine the accuracy and precision of the catheters, the effects of external factors (e.g., catheter placement, injection duration), and to test for systematic bias. In the clinical study, two interventional radiologists conducted a total of 250 measurements in 14 patients with arteriovenous fistulas to determine clinical precision and enable testing for bias between measurers. RESULTS Accuracy was excellent for both catheters with a high level of agreement between results from the ReoCath Flow Catheter System and the reference flowmeter. Clinical precision, expressed as the mean coefficient of variation, was 5.9% and 4.7% for the antegrade and retrograde catheters, respectively. Flow measurements were significantly affected by the distance between a stenosis and the tip of a retrograde catheter with the effect being proportional to the degree of stenosis. There was no systematic bias between measurers. CONCLUSIONS The Reocath Flow Catheter System was found to be accurate and precise. Reliable results require careful attention to catheter placement. Blood flow measurements provide unique information on the hemodynamic status of a vascular access and have the potential to optimize results of interventions.
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22
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Zasuwa G, Frinak S, Besarab A, Peterson E, Yee J. Automated intravascular access pressure surveillance reduces thrombosis rates. Semin Dial 2010; 23:527-35. [PMID: 20723160 DOI: 10.1111/j.1525-139x.2010.00755.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/27/2022]
Abstract
Although monitoring of vascular accesses by physical examination is nearly as sensitive as surveillance measurements by vascular access pressure when performed by examiners, the frequency of examinations is limited by time. We developed intravascular access pressure surveillance as a surrogate to physical examination. Using real-time data from hemodialysis machines, we derived intravascular access pressure ratios for each dialytic procedure. An automated, noninvasive surveillance algorithm that generated a "warning" list of patients at risk for thrombosis was formulated. We hypothesized that this algorithm would reduce access thrombosis frequency. We designed a study comparing thrombosis rates during a baseline 6-month interval to three subsequent 6-month periods of active surveillance. Referrals for interventions during this 18-month period were based on persistently abnormal elevated vascular access pressure ratio tests (VAPRT) >0.55. Thrombosis rates declined progressively for arteriovenous grafts (AVG) during the intervention period compared with the baseline period. Arteriovenous fistula (AVF) thrombosis rates decreased during postintervention months 13-18 during employment of the VAPRT. We conclude that use of VAPRT can reduce thrombosis rates in vascular accesses, and the magnitude of the effect is larger and more consistent in arteriovenous grafts (AVGs) than autologous AVFs.
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Affiliation(s)
- Gerard Zasuwa
- Division of Nephrology and Hypertension, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan 48202, USA.
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Abstract
The Centers for Medicare and Medicaid Services (CMS) recently revised the requirements that end-stage renal disease (ESRD) dialysis facilities must meet to be certified under Medicare. The CMS ESRD Interpretive Guidance Update states that the dialysis facility must now have an ongoing program of hemodialysis vascular access surveillance. Surveillance usually refers to monthly access blood flow or static dialysis venous pressure measurements combined with preemptive correction of stenosis. However, surveillance as currently practiced does not accurately predict synthetic graft thrombosis or prolong graft life. There is limited evidence that monthly surveillance may reduce native arteriovenous fistula thrombosis without prolonging fistula life, but the effect on thrombosis awaits further confirmation. Thus, the CMS surveillance requirement is not evidence based. We recommend the following changes to the ESRD Interpretive Guidance Update: only monitoring (e.g., physical examination) is required, whereas the proper role of surveillance awaits the results of further research. Such changes would allow nephrologists to apply the clinical judgment and individualized care that is most beneficial to their patients.
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24
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Kheda MF, Brenner LE, Patel MJ, Wynn JJ, White JJ, Prisant LM, Jones SA, Paulson WD. Influence of arterial elasticity and vessel dilatation on arteriovenous fistula maturation: a prospective cohort study. Nephrol Dial Transplant 2009; 25:525-31. [DOI: 10.1093/ndt/gfp462] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/14/2022] Open
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25
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Ponce P, Mateus A, Santos L. Anatomical correlation of a well-functioning access graft for haemodialysis. Nephrol Dial Transplant 2008; 24:535-8. [DOI: 10.1093/ndt/gfn512] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/14/2022] Open
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26
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Ram SJ, Nassar R, Work J, Abreo K, Dossabhoy NR, Paulson WD. Risk of Hemodialysis Graft Thrombosis: Analysis of Monthly Flow Surveillance. Am J Kidney Dis 2008; 52:930-8. [DOI: 10.1053/j.ajkd.2008.07.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 10/10/2007] [Accepted: 07/22/2008] [Indexed: 11/11/2022]
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Wijnen E, van der Sande FM, Tordoir JHM, Kooman JP, Leunissen KML. Effect of online haemodialysis vascular access flow evaluation and pre-emptive intervention on the frequency of access thrombosis. Clin Kidney J 2008; 1:279-84. [PMID: 25983912 PMCID: PMC4421281 DOI: 10.1093/ndtplus/sfn136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 11/22/2007] [Accepted: 08/01/2008] [Indexed: 11/17/2022] Open
Abstract
Introduction. Guidelines advocate surveillance of vascular access to reduce incidences of thrombosis. However, the value of online vascular access flow monitoring is still under debate. Methods. Through a systematic literature search, the effect of online access flow surveillance combined with pre-emptive intervention on thrombosis frequency is reviewed. Results. Due to methodological differences, adequate comparison of the individual study results is not possible. Moreover, the methodological quality of most of the included studies is not suitable for an adequate statistical analysis of the results. Conclusion. Until now, there is no conclusive evidence that online access flow evaluation has a significant effect on the rate of thrombosis. Future large-scale studies with adequate study design, adequate surveillance and intervention protocols and, possibly, better pre-emptive intervention alternative(s) are necessary.
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Affiliation(s)
- Edwin Wijnen
- Department of Internal Medicine, Division of Nephrology
| | | | - Jan H M Tordoir
- Department of Surgery , University Hospital Maastricht , Maastricht , The Netherlands
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28
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Paulson WD, Ram SJ, Work J, Conrad SA, Jones SA. Inflow stenosis obscures recognition of outflow stenosis by dialysis venous pressure: analysis by a mathematical model. Nephrol Dial Transplant 2008; 23:3966-71. [DOI: 10.1093/ndt/gfn400] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/12/2022] Open
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29
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Should arteriovenous fistulas and synthetic grafts undergo surveillance with pre-emptive correction of stenosis? ACTA ACUST UNITED AC 2008; 4:480-1. [DOI: 10.1038/ncpneph0878] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 04/29/2008] [Accepted: 06/03/2008] [Indexed: 11/09/2022]
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30
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White JJ, Jones SA, Ram SJ, Schwab SJ, Paulson WD. Mathematical model demonstrates influence of luminal diameters on venous pressure surveillance. Clin J Am Soc Nephrol 2007; 2:681-7. [PMID: 17699482 DOI: 10.2215/cjn.01070307] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND The reliability of dialysis venous pressure (VP) in detecting stenosis is controversial. A mathematical model may help to resolve the controversy by providing insight into the factors that influence static VP. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS This study used inflow artery and outflow vein luminal diameters from duplex ultrasound studies of 94 patients. These diameters were applied to a mathematical model, and how they affect the relation among VP, mean arterial pressure (MAP), blood flow, and stenosis was determined. Whether VP/MAP is a valid adjustment for the influence of MAP on VP, and whether the standard VP/MAP referral threshold of 0.50 is valid, were also determined. RESULTS It was found that there is an approximate one-to-one relation between MAP and VP, so VP/MAP is a valid adjustment. Also, the 0.50 threshold successfully identifies most grafts with stenosis of 65% or more. However, the ratio of artery/vein diameters varied widely between patients, and the ratio independently influences VP/MAP. When the inflow artery is relatively narrow, the VP/MAP increase is delayed followed by a more rapid increase as critical stenosis is reached. CONCLUSIONS VP/MAP is a valid adjustment for the influence of MAP on VP, and the standard VP/MAP threshold of 0.50 warns of the transition to critical stenosis. However, relatively narrow arteries cause a delay followed by a rapid increase in VP/MAP that may not be detected before thrombosis unless measurements are very frequent. Clinical trials that emphasize trend analysis with frequent measurements are needed to evaluate the efficacy of VP surveillance.
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Affiliation(s)
- John J White
- Augusta VA Medical Center, and Section of Nephrology, Hypertension, and Renal Transplantation, Medical College of Georgia, Augusta, Georgia 30912, USA
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