Arteriovenous Fistula Blood Flow Research Articles

Primary Failure of the Arteriovenous Fistula in Patients with Chronic Kidney Disease Stage 4/5.

BACKGROUND:An Arteriovenous fistula (AVF) is a creation of the natural blood vessels. It is a “gate of life” for the patients on hemodialysis.AIM:The study aimed to analyze the predictors for primary failure of AVF such as gender, age, number and location of AVF, and primary renal disease in patients with chronic kidney disease (CKD) stage 4/5.MATERIAL AND METHODS:The medical records of 178 created arteriovenous fistulae in patients with CKD stage 4/5, were retrospectively studied. Primary failure of AVF was defined as thrombosis or inability for cannulation of AVF within 3 months. Adequate maturation of AVF was defined as successful cannulation of AVF treatment and blood flow of > 600 ml/min.RESULTS:The mean age of the patients was 59.75 ± 14.65 years, and 65.16% (116/178) were men. Adequate maturation of AVF was achieved in 83.71% (149/178). Primary failure of AVF occurred in 16.29% (29/178) of the created fistulae, while 10.11% (18/178) had early thrombosis. The distal arteriovenous fistulae were significantly more frequently created in male patients (51 vs 18; p = 0.015). The female patients were significantly older than the male patients (63.27 vs 57.86 years; p = 0.018).CONCLUSION:Male gender was associated with better maturation of AVF. The age, number and location of AVF, and primary renal disease in patients with CKD stage 4/5 were not associated with primary failure of AVF.

Effect of Blood Pump Flow and Arteriovenous Fistula Blood Flow on the Blood Pressure and Cardiac Function in Patients Undergoing Maintenance Hemodialysis.

The effect of blood pump flow rate on the cardiac functions of hemodialysis patients with arteriovenous fistula (AVF) is largely unknown. This study aimed to investigate if blood pump flow rate (Qb) and AVF access flow rate (Qa) can affect the cardiac function of Chinese hemodialysis patients. A total of 72 patients undergoing AVF hemodialysis were included from March 2010 to June 2014 and dichotomized into the high- and low-flow groups using the medians of Qb (220 mL/min) and Qa (1000 mL/min) as the cutoffs. The cardiac function parameters were measured by ultrasound dilution technique within the first (t + 30) and the last (t - 30) 30 min of dialysis. At t + 30, Qb-high group had significantly higher systolic blood pressure (SBP) and mean arterial pressure (MAP) than Qb-low group. At t - 30, Qb-high group had higher SBP, diastolic blood pressure (DBP), and MAP than Qb-low group. Qa-high group had higher SBP, MAP, cardiac output (CO), cardiac index (CI), central blood volume (CBV), and lower peripheral resistance than Qa-low group. Multiple linear regression showed that at t - 30, Qb was positively correlated with SBP and MAP. Qa was positively correlated with CO, CI, CBV, and PR but negatively correlated with heart rate. Although Qb > 220 mL/min and Qa >1000 mL/min would elevate some parameters, the means of SBP, DBP, MAP remain within the normal range, indicating that appropriate increase in blood pump flow rate has little effect on the cardiac function of hemodialysis patients.

Digital pressure in haemodialysis patients with brachial arteriovenous fistula.

Background & objectives:The pathophysiological mechanisms involved in distal pressure changes following arteriovenous fistula (AVF) creation in patients with end-stage renal disease (ESRD) are not completely understood. This study was aimed to assess digital pressure changes post-AVF creation and to identify the factors that might influence these changes in ESRD patients.Methods:In this prospective study, 41 patients with ESRD underwent AVF creation. Basal digital pressure (BDP), digital brachial index (DBI), calcium, phosphorus and blood urea levels were assessed preoperatively. BDP, DBI, vein and artery diameters, and AVF blood flow were also evaluated at one and two month(s) post-AVF creation.Results:Mean BDP significantly decreased from 131.64±25.86 mmHg (baseline) to 93.15±32.14 and 94.53±32.90 mmHg at one and two months post-AVF creation, respectively (P<0.001). Mean DBI significantly decreased one month post-AVF creation versus baseline (0.70±0.18 vs. 0.89±0.17 mm, P<0.001) and remained similar at two versus one month(s) postoperatively (0.70±0.23 vs. 0.70±0.18 mm). At both postoperative timepoints, no correlation between DBI decrease and increased artery and vein diameters or fistula blood flow was observed. Mean DBI difference between patients with previous ipsilateral access versus those without was not significant from pre to one month postoperatively. No correlation was observed between baseline phosphorus, calcium and blood urea nitrogen and DBI changes.Interpretation & conclusions:Our findings suggest that decrease in distal pressure following AVF creation may not be influenced by the arterial remodelling degree, vein diameter or fistula flow. In uraemic patients, those with low calcium and/or increased phosphorus, no association between these parameters and DBI changes could be observed.

Prediction of Arteriovenous Fistula Clinical Maturation from Postoperative Ultrasound Measurements: Findings from the Hemodialysis Fistula Maturation Study.

The utility of early postoperative ultrasound measurements in predicting arteriovenous fistula (AVF) clinical maturation is uncertain. We investigated the relationships of ultrasound parameters with AVF clinical maturation in newly created AVF, measured at 1 day and 2 and 6 weeks, in 602 participants of a multicenter, observational cohort study. A backward elimination algorithm identified ultrasound measurements that independently predicted unassisted and overall AVF maturation. Candidate variables included AVF blood flow, diameter, and depth, upper arm arterial diameter, presence of stenosis, presence of accessory veins, seven case-mix factors (age, sex, black race, AVF location, diabetes, dialysis status, and body mass index), and clinical center. We evaluated the accuracy of the resulting models for clinical prediction. At each ultrasound measurement time, AVF blood flow, diameter, and depth each predicted in a statistically significant manner both unassisted and overall clinical maturation. Moreover, neither the remaining ultrasound parameters nor case-mix factors were associated with clinical AVF maturation after accounting for blood flow, diameter, and depth, although maturation probabilities differed among clinical centers before and after accounting for these parameters. The crossvalidated area under the receiver operating characteristic curve for models constructed using these three ultrasound parameters was 0.69, 0.74, and 0.79 at 1 day and 2 and 6 weeks, respectively, for unassisted AVF clinical maturation and 0.69, 0.71, and 0.76, respectively, for overall AVF maturation. AVF blood flow, diameter, and depth moderately predicted unassisted and overall AVF clinical maturation. The other factors considered did not further improve AVF maturation prediction.

Association of Preexisting Arterial Intimal Hyperplasia with Arteriovenous Fistula Outcomes.

Preoperative arterial function is associated with arteriovenous fistula (AVF) development. Because arterial pathology may correlate with its function, preexisting arterial intimal hyperplasia may be associated with AVF development. Vascular specimens obtained from 125 patients (with minimal 2 mm arterial diameter and 2.5 mm venous diameter) undergoing AVF creation were quantified for arterial intimal hyperplasia, arterial medial fibrosis, arterial microcalcification, and venous intimal hyperplasia. A 6-week postoperative ultrasound quantified AVF diameter, blood flow, and stenosis. Clinical AVF maturation was assessed using a predefined protocol. In a prospective cohort study design, we investigated the association of preexisting arterial intimal hyperplasia with the postoperative AVF diameter, blood flow, stenosis, and clinical maturation failure, after controlling for baseline demographics, comorbidities, and preoperative vein diameter. Additional analyses evaluated whether other vascular pathologies interacted with arterial intimal hyperplasia in affecting AVF outcomes. The median intimal thickness of the native artery was 22.0 μm (interquartile range, 14.8-37.1 μm). The median postoperative AVF diameter was 4.8 (interquartile range, 3.7-6.8) mm, blood flow was 796 (interquartile range, 413-1036) ml/min, and stenosis was present in 37 out of 98 patients with ultrasound data (38%). AVF nonmaturation occurred in 37 out of 125 patients (30%). Preexisting arterial intimal thickness was not significantly associated with AVF blood flow (-12 ml/min; 95% confidence interval [95% CI], -55 to 30 ml/min), diameter (-0.04 mm; 95% CI, -0.21 to 0.14 mm), stenosis (odds ratio, 0.93; 95% CI, 0.75 to 1.14), or clinical maturation failure (odds ratio, 1.07; 95% CI, 0.90 to 1.28), all per 10 μm increase. There was no significant interaction of preexisting arterial intimal thickness and postoperative AVF outcomes with arterial medial fibrosis, arterial microcalcification, or venous intimal hyperplasia. Preexisting arterial intimal hyperplasia is not associated with the 6-week AVF blood flow, diameter or stenosis, or clinical maturation when the preoperative arterial diameter is ≥2 mm.

Effect of Anti-Hypertensive Medication History on Arteriovenous Fistula Maturation Outcomes

Background: The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis. However, approximately half of AVFs fail to mature. The use of angiotensin converting enzyme inhibitors (ACE-Is), angiotensin receptor blockers (ARBs), and calcium channel blockers (CCBs) exerts favorable endothelial effects and may promote AVF maturation. We tested associations of ACE-I and ARBs, CCBs, beta-blockers, and diuretics with the maturation of newly created AVFs. Methods: We evaluated 602 participants from the Hemodialysis Fistula Maturation Study, a multi-center, prospective cohort study of AVF maturation. We ascertained the use of each medication class within 45 days of AVF creation surgery. We defined maturation outcomes by clinical use within 9 months of surgery or 4 weeks of initiating hemodialysis. Results: Unassisted AVF maturation failure without intervention occurred in 54.0% of participants, and overall AVF maturation failure (with or without intervention) occurred in 30.1%. After covariate adjustment, CCB use was associated with a 25% lower risk of overall AVF maturation failure (95% CI 3%–41% lower) but a non-significant 10% lower risk of unassisted maturation failure (95% CI 23% lower to 5% higher). ACE-I/ARB, beta-blocker, and diuretic use was not significantly associated with AVF maturation outcomes. None of the antihypertensive medication classes were associated with changes in AVF diameter or blood flow over 6 weeks following surgery. Conclusions: CCB use may be associated with a lower risk of overall AVF maturation failure. Further studies are needed to determine whether CCBs might play a causal role in improving AVF maturation outcomes.

Comparison of hemodialysis arteriovenous fistula blood flow rates measured by Doppler ultrasound and phase-contrast magnetic resonance imaging

ObjectiveThe objective of this study was to compare blood flow rates measured by Doppler ultrasound (DUS) and phase-contrast magnetic resonance imaging (MRI) in patients having a hemodialysis arteriovenous fistula (AVF) and to identify scenarios in which there was significant discordance between these two approaches. MethodsBlood flow rates in the proximal artery (PA) and draining vein (DV) of newly created upper extremity AVFs were measured and compared using DUS and phase-contrast MRI at 1 day, 6 weeks, and 6 months postoperatively. ResultsBlood flow rates in the PA measured by DUS (1155 ± 907 mL/min, mean ± standard deviation) and by MRI (1170 ± 657 mL/min) were not statistically different (P = .812) based on 78 data pairs from 49 patients. DV DUS flow (1277 ± 995 mL/min) and MRI flow (1130 ± 655 mL/min) were also not statistically different (P = .071) based on 64 data pairs. In both PA and DV, the two methods substantially agreed with each other (Cohen κ: PA, 0.66; DV, 0.67) when flow rates were put into four clinically relevant categories (<300, 300-599, 600-1499, and ≥1500 mL/min). The Bland-Altman analyses of DUS and MRI flow identified six and four outliers for PA and DV, respectively. Seven outliers had higher DUS than MRI flow, with all DUS scan sites having a large lumen or significant local curvature; the other three had lower DUS flow, partly due to an underestimation of lumen diameter by DUS. ConclusionsDUS and MRI flow rates are generally comparable in both PA and DV. When DUS is used for flow measurements, careful attention to accurate lumen diameter measurements is needed and scan sites with marked curvature should be avoided. Our result may improve the accuracy of DUS-measured AVF blood flow rate.

Differential expression profile of long non-coding RNA in the stenosis tissue of arteriovenous fistula

ObjectiveTo analyze and preliminarily validate the lncRNA expression profiles in the stenosis tissue of arteriovenous fistula (AVF). MethodsA total of 54 uremic patients administered in the department of nephrology in the First Affiliated Hospital of Nanchang University between February 2017 and March 2017 were included in the study and subsequently categorized as experimental group, which included 12 patients with confirmed diagnosis of AVF, and control group which included 42 patients with no vascular stenosis. The experimental group inclusion criteria include: AVF used >3 months; The blood flow of AVF <200 mL/min; the degree of the stenosis was >50%, excluded obvious thrombosis; The ultrasonographic data of AVF stenosis is complete. The controls were randomly selected from uremic patients who were primary AVF operation, excluded obvious vascular stenosis and vascular diseases. Among them, 4 sample in the experimental group and 4 controls were used in LncRNA sequencing. RNA in vascular tissue was extracted by Trizol and IncRNA sequencing was used to establish the expression profiles of lncRNA in the stenosis tissue of AVF.9 difference expression lncRNA were collected for validating in AVF stenosis cases by using quantitative real-time polymerase chain reaction (qRT-PCR). Moreover, Cluster analysis, gene functional analysis and pathway analysis were used to explore the function of difference expression lncRNA. ResultsAmong the 27,692 lncRNA transcripts examined, 247 lncRNAs were found to be significantly differentially expressed (P < 0.05, fold change ≥2) in the experimental group and control group, with 141 being up-regulated and 106 down-regulated. The expression levels of 9 lncRNAs validated by subsequent qRT-PCR were shown to be highly consistent with the sequencing data. ConclusionOur study revealed lncRNAs expression profiles in the stenosis tissue of AVF by LncRNA sequencing. These lncRNAs and its related signaling pathways may play a key role in the occurrence and progression of AVF stenosis.

Post-operative arterio-venous fistula blood flow influences primary and secondary patency following access surgery.

Primary arteriovenous fistula arterio venous fistula (AVF) formation has proven to be the best and optimal vascular access for the majority of haemodialysis patients. At present there are limited data to suggest which haemodynamic parameters most correlate with the likelihood of early failure. The aim of this study is to identify the haemodynamic predictors of early failure, hence identify which fistulae may benefit from timely pre-emptive intervention. Retrospective analysis of data was performed of 201 patients undergoing native AVF creation over a one year period. Demographic details, co-morbidity, preoperative vessel calibre were collected. Flow was measured by duplex ultrasound post operatively. Preoperative vein calibre (p = 0.01) and fistula flow (p < 0.001) positively affected primary patency. Age, gender, ethnicity, type of fistula, hypertension and preoperative arterial calibre did not influence outcome. Regression analysis showed that the strength of correlation between early postoperative fistula flow and patency decreased progressively with time. Six week flow predicts early, but not late, failure. ROC analysis identified 300 ml/min flow as the best predictor of patency. Fistulae with flow above 300 ml/min were more likely to remain patent over the next 12 months (p < 0.001, HR = 7.4). Postoperative fistula flow of less than 300 ml/min identifies AVFs at high risk of early failure. These may be candidates for early intervention with balloon assisted maturation. The findings of this retrospective cohort study strongly support the need for a more robust prospectively designed trial identifying haemodynamic factors that can predict mid and long-term AVF patency.

High-flow arteriovenous fistula and heart failure: could the indexation of blood flow rate and echocardiography have a role in the identification of patients at higher risk?

Although only high-flow arteriovenous fistulas (AVFs) are postulated to cause high-output cardiac failure (HOCF), there are currently no universally accepted criteria defining a high-flow fistula. To verify if vascular access blood flow (Qa) ≥ 2000ml/min provides an accurate definition of high-flow fistula, we selected 29 consecutive patients with Qa ≥ 2000ml/min at color-duplex ultrasound examination and assessed them for the presence of cardiac failure symptoms; transthoracic echocardiography was also performed. Nineteen patients (65%) had heart failure symptoms and were classified with HOCF. At receiver operating characteristic (ROC) curve analysis, Qa ml/min values did not identify patients with heart failure symptoms but when AVF blood flow was indexed for height2.7, Qa ≥ 603ml/min/m2.7 detected the occurrence of HOCF with good accuracy (sensitivity 100%, specificity 60%, efficiency 86%, positive predictive value 83%, negative predictive value 100%, area under curve 0.75). At echocardiographic evaluation, patients with Qa ≥ 603ml/min/m2.7 had a more severe increase of left ventricular mass (63 ± 18 vs. 47 ± 7g/m2.7, p < 0.003), left ventricular diastolic volume (140 ± 42 vs. 109 ± 14ml, p < 0.007), left atrial volume (53 ± 23 vs. 39 ± 5ml/m2, p < 0.015), a higher incidence of diastolic dysfunction (70 vs. 17%, p < 0.019) and higher CO reduction after AVF manual compression (2151 ± 875 vs. 1292 ± 527ml/min, p < 0.009) than patients with Qa < 603ml/min/m2.7. Indexation of AVF blood flow should be considered in defining high-flow fistula because the effect of Qa may differ in individuals of different sizes. A Qa value ≥ 603ml/min/m2.7 and its association with some echocardiographic alterations could identify patients at higher risk for HOCF.

Reversible pulmonary hypertension in post -renaltransp lantation patient with longst anding arteriovenous fistula

Case report of reversible high pulmonary hypertension (PH) in patient with successful kidney transplantation (KT) is presented. The distinction of the case was the functioning arteriovenous fistula (AVF) with excessive blood flow during 15 years in the absence of indications for hemodialysis. Consequently, PH was complicated by serious congestive heart failure (CHF) with high cardiac output. Surgical closure of AVF resulted in complete regression of clinical, instrumental and laboratory signs and symptoms of PH and CHF within 2 weeks. The pathogenic role of excessive AVF blood flow in PH and CHF formation is a point of discussion. Surgical closure of AVF with excessive blood flow is recommended in cases of presence of symptomatic PH and CHF in patients after successful KT.

Impact of arteriovenous fistula blood flow on serum il-6, cardiovascular events and death: An ambispective cohort analysis of 64 Chinese hemodialysis patients

Flows (Qa) of arteriovenous fistula (AVF) impact the dialysis adequacy in hemodialysis (HD) patients. However, data for different access flow levels on outcomes related to long-term dialysis patients, especially in Chinese patients, are limited. Herein, we performed an ambispective, mono-centric cohort study investigating the association between the AVF flows and inflammation, cardiovascular events and deaths in Chinese hemodialysis patients bearing a radio-cephalic fistula (AVF) from 2009 to 2015. Twenty-three patients (35.9%) developed at least one episode of cardiovascular disease (CVD) in two years after AVF creation. AVF Qa, IL-6 and hsCRP were significantly higher in patients with CVD than in patients without CVD. Multi-factorial binary logistic regression analysis found that the independent and strongest risk factor for CVD in HD patients was serum IL-6, which showed a positive association with AVF Qa levels in patients. Therefore, the linkage between AVF Qa tertiles and adverse clinical outcomes (cardiovascular events and mortality) was examined over a median follow-up of five years. IL-6 was significantly increased in the high AVF Qa (>1027.13 ml/min) group. Patients with median AVF Qa showed the lowest morbidity and mortality of CVD according to the AVF Qa tertiles, whereas higher Qa was associated with a higher risk of CVD, and lower AVF Qa (600 ml/min ≤AVF Qa <821.12 ml/min) had a higher risk of non-CVD death. Therefore, keeping the AVF Qa at an optimal level (821.12 to 1027.13 ml/min) would benefit HD patients, improve long-term clinical outcomes and lower AVF-induced inflammation.

Protective effect of micro needle array drug delivery technology on the blood vessel of arteriovenous fistula

Objective To investigate the protective effect of mucopolysaccharide polysulfate cream(MPC) and micro needle array drug delivery technologarray(MNADDT) on the blood vessel of arteriovenous fistula. Methods Eighty cases maintenance hemodialysis patients with autogenous arteriovenous fistula were randomly divided into control group(with the treatment of MPC) and study group(with the treatment of MPC plus MNADDT), 40 patients in each group.Both groups were studied for the duration of 12 months.The vascular complications of puncture pain sense, puncture failure times, phlebitis, hardening of the arteries, internal fistula stenosis or embolism, pseudoaneurysm, swollen hands comprehensive syndrome of two groups were observed, and the changes of arteriovenous fistula blood flow, blood vessel diameter by Doppler ultrasound were observed in the two groups for 12 months. Results (1)The incidence of puncture pain(2.71±0.11 vs.2.76±0.14, t=2.21, P<0.05), puncture failure times(38 times vs.73 times, χ2=11.425, P<0.05), phlebitis(2 cases vs.8 cases, χ2=4.341, P<0.05) and blood vessel sclerosis(2 cases vs.9 cases, χ2=5.446, P<0.05) of the treatment group were significantly lower than that of the control group during the study(P<0.05). (2)Blood flow of arteriovenous fistulain of control group before and after treatment were (859.7±148.3) ml/min and ( 946.5±169.2) ml/min respectively, and the difference was significant(t=2.356, P<0.05). While blood flow of arteriovenous fistulain, cephalic vein diameter, head of venous flow velocity of study group before and after treatment were (824.6±171.5 ) ml/min and ( 1 218.1±241.9) ml/min, (5.59±0.74) mm and (6.02±0.57) mm, (94.23±27.35) cm/s and (115.85±36.63) cm/s, respectively, and the differences were significant(t=8.212, 2.382, 2.877, P<0.05), there were no significantly changes in the above indexes in the study group after treatment(t=5.3612, 2.152, 2.281, P<0.05). Conclusion MPC plus MNADDT can reduce the vascular complications of arteriovenous fistula, improve blood vessel diameter and increase blood flow. Key words: Hemodialysis; Arteriovenous fistula; Complication; Micro needle array administration; Doppler ultrasound

Evaluation of Long-Term Combination Therapy With Peritoneal Dialysis and Hemodialysis.

It is well known that a combination therapy with peritoneal dialysis (PD) and hemodialysis (HD) is feasible and may improve clinical status in patients for whom adequate solute and fluid removal is difficult to achieve with PD alone. The objective of the present study was to evaluate whether the therapy is useful in the likelihood of long-term peritoneal membrane and cardiac function. The therapy was 6days of PD and one session of HD per week. Physical, biochemical, dialysate-to-plasma ratio of creatinine (D/P Cr), arteriovenous fistula (AVF) blood flow, and left ventricular mass index (LVMI) data were prospectively analyzed in 30 patients with measurements performed at 0 and 6months, and for 21 patients, 12 or 18months after initiation of the therapy. The levels of hemoglobin (Hb) after therapy were significantly higher than those at the initiation of therapy. The levels of LVMI and human atrial natriuretic peptide (hANP) after therapy were significantly lower than those at the initiation of therapy, whereas AVF blood flow did not change significantly. D/P Cr levels at 6months after the therapy were significantly lower than those at the initiation of therapy. D/P Cr levels at 12 or 18months after the therapy were not aggravated. It appears that the therapy improves Hb levels and cardiac function because of adjusting body fluid status. It was indicated that peritoneal function after therapy may be improved. Therefore, combination therapy is useful from the lifestyle viewpoint of patients in the transition period of PD to HD with end-stage kidney disease.

Effects of Cardiac Function with Postoperative Arteriovenous Fistula Blood Flow in Patients with Hemodialysis

Background/Aims: This study was aimed at evaluating the effect of cardiac function with postoperative arteriovenous fistula (AVF) blood flow in hemodialysis (HD) patients. Methods: A total of 45 HD patients were examined at the Juntendo University Hospital. The AVF blood flow was measured using ultrasonography, and the cardiac function was measured using echocardiography. Correlation between these parameters and the rate of change in body weight (BW) was analyzed. Results: The number of postoperative days significantly correlated with the AVF blood flow, and it positively correlated with the stroke volume (SV). The postoperative AVF blood flow in patients with reduced ejection fraction (EF) was lower than that in patients with normal EF. The rate of change of BW negatively correlated with that of SV, positively correlated with cardiac output (CO), and positively correlated with CO in patients with an AVF blood flow of more than 1,000 mL/min. Conclusion: It appears that the cardiac function can be improved by controlling the BW even in patients with high AVF blood flow.

Ultrasound-guided axillary brachial plexus block versus local infiltration anesthesia for arteriovenous fistula creation at the forearm for hemodialysis in patients with chronic renal failure.

Background:The primary failure rate for arteriovenous fistula (AVF) creation under local anesthesia for hemodialysis is about 30%. Axillary brachial plexus block (BPB) may improve blood flow through blood vessels used in fistula creation; it may improve the AVF blood flow and thus may reduce the primary failure rate after 3 months.Methods:Hundred and forty patients with chronic renal failure scheduled for AVF creation for hemodialysis were divided into two equal groups; Group 1 (AxBP-G) received ultrasound (US) guided axillary BPB, and Group 2 (LI-G) received local infiltration. We recorded the measurements of the brachial and radial arteries before and after anesthesia and the AVF blood flow in both groups at three different time points. Furthermore, the primary failure rate was recorded in each group and compared.Results:After anesthesia, the mean radial artery blood flow in the AxBP-group was 3.52 ml/min more than the LI-group, and the brachial artery diameter was also 0.68 mm more than in the LI-group, both differences were statistically significant (P < 0.05). There were significant increases (P < 0.05) in the AVF blood flow in the AxBP-group more than the LI-group with mean differences of 29.6, 69.8, and 27.2 ml/min at 4 h, 1 week, and 3 months, respectively. The overall mean of AVF blood flow was 42.21 ml/min more in the AxBP group than the LI-group a difference which is statistically significant (P < 0.001). The primary failure rate was 17% in the AxBP group versus 30% in the LI-group; however, this difference is not significant statistically (P = 0.110).Conclusion:The US-guided axillary block increases AVF blood flow significantly more than local infiltration and nonsignificantly decreases the primary failure rate of the AVF after 3 months.

Impact of vascular access intervention therapy on cardiac load in hemodialysis patients.

Vascular access intervention therapy (VAIVT) has been positioned as the first choice of treatment for stenosis lesions frequently observed in arteriovenous fistula (AVF) for hemodialysis patients in Japan. Furthermore, increased blood flow can provide a stable dialysis. In contrast, it has been reported that excess blood flow of AVF causes high-output heart failure. Although VAIVT is used to increase blood flow of AVF, the impact of VAIVT on cardiac load has been rarely reported. We examined the factors associated with cardiac load in hemodialysis patients undergoing VAIVT by measuring levels of α human atrial natriuretic polypeptide (hANP) and brain natriuretic peptide (BNP) before and after VAIVT. Data were extracted on hemodialysis patients who underwent measurements of αhANP and BNP in before and after VAIVT at our facility and related facilities between February 2014 and December 2014. Nineteeen patients (median age, 73.0 [66.5-80.5] years; male, 52.6%; 36.8% with diabetes; median duration of dialysis treatment, 50.0 [21-109] months) were enrolled in this study. Flow volume of AVF was higher after VAIVT than that before VAIVT (442.0 vs. 758.0 mL/minute, P < 0.001). Moreover, resistance index (RI) of AVF after VAIVT was lower than that before VAIVT (0.61 vs. 0.53, P < 0.01). Although αhANP did not change before and after VAIVT (55.6 vs. 54.9 pg/mL, P = 0.099), BNP after VAIVT was significantly higher than that before VAIVT (145.2 vs. 175.0 pg/mL, P < 0.05). Factors correlated with the increase in BNP were flow volume of AVF before VAIVT (r = -0.458, P = 0.049) and levels of BNP before VAIVT (r = 0.472, P = 0.041). There was no significant correlation between the increase in αhANP with flow volume of AVF before VAIVT, levels of αhANP before VAIVT. Patients with high levels of BNP and low flow volume of AVF before VAIVT were considered to have a high risk of developing heart failure after VAIVT.

Preoperative Vascular Medial Fibrosis and Arteriovenous Fistula Development.

Arteriovenous fistula maturation requires an increase in the diameter and blood flow of the feeding artery and the draining vein after its creation. The structural properties of the native vessels may affect the magnitude of these changes. We hypothesized that an increase in the collagen content of the vascular media (medial fibrosis) preoperatively would impair vascular dilation and thereby, limit the postoperative increase in arteriovenous fistula diameter and blood flow and clinical arteriovenous fistula maturation. We enrolled 125 patients undergoing arteriovenous fistula creation between October of 2008 and April of 2012 and followed them prospectively. Any consenting subject was eligible. Arterial and venous specimens were sampled during arteriovenous fistula surgery. Masson's trichrome-stained samples were used to quantify medial fibrosis. Arteriovenous fistula diameter and blood flow were quantified using 6-week postoperative ultrasound. Clinical arteriovenous fistula maturation was assessed using a predefined protocol. The association of preexisting vascular medial fibrosis with arteriovenous fistula outcomes was evaluated after controlling for baseline demographics, comorbidities, and the preoperative venous diameter. The mean medial fibrosis was 69%±14% in the arteries and 63%±12% in the veins. Arterial medial fibrosis was associated with greater increases in arteriovenous fistula diameter (Δdiameter =0.58 mm; 95% confidence interval [95% CI], 0.27 to 0.89 mm; P<0.001) and arteriovenous fistula blood flow (Δblood flow =85 ml/min; 95% CI, 19 to 150 ml/min; P=0.01) and a lower risk of clinical arteriovenous fistula nonmaturation (odds ratio, 0.71; 95% CI, 0.51 to 0.99; P=0.04), all per 10% absolute difference in medial fibrosis. In contrast, venous medial fibrosis was not associated with the postoperative arteriovenous fistula diameter, blood flow, or clinical maturation. Preoperative arterial medial fibrosis was associated with greater arteriovenous fistula diameter and blood flow and a lower risk of clinical arteriovenous fistula nonmaturation. This unexpected observation suggests that medial fibrosis promotes arteriovenous fistula development by yet undefined mechanisms or alternatively, that a third factor promotes both medial fibrosis and arteriovenous fistula maturation.

Estimation of arterio-venous access blood flow in hemodialysis patients using video image processing technique.

Assessment of arterio-venous fistula (AVF) blood flow (ABF) is vital in hemodialysis (HD) patients. Currently, no non-invasive and contact-free technique is available to accurately measure ABF in routine clinical practice. In this study, we developed a novel approach using video image processing (VIP) to measure the change in optic flow in the skin. We the tested the hypothesis that the change in optical flow, expressed as the change in pixels between consecutive frames, is related to ABF. We recorded AVF videos in 40 HD patients using a digital camera and processed them by VIP technique. We then compared the actual ABF as measured by routine online clearance (ABFOLC) and the amplitude (AMP) of optical flow. Technical and procedural errors rendered VIP invalid in 13 patients. In the remaining 27 patients the optical flow AMP was significantly lower in patients with low (<;900 ml/min) ABFOLC compared to patients with normal (≥900 ml/min) ABFOLC (AMP 3.4±1*103 vs 5.2±1.4 *103 [pixels], p<;0.01). In these 27 patients AMP correlated with ABFOLC (R2=0.71, p<;0.0001). While more extensive research is necessary, these preliminary results indicate the potential usefulness of the VIP technique to identify low ABF.

Association between Preoperative Vascular Function and Postoperative Arteriovenous Fistula Development.

Arteriovenous fistula (AVF) maturation failure is the primary cause of dialysis vascular access dysfunction. To evaluate whether preoperative vascular functional properties predict postoperative AVF measurements, patients enrolled in the Hemodialysis Fistula Maturation Study underwent up to five preoperative vascular function tests (VFTs): flow-mediated dilation (FMD), nitroglycerin-mediated dilation (NMD), carotid-femoral pulse wave velocity, carotid-radial pulse wave velocity, and venous occlusion plethysmography. We used mixed effects multiple regression analyses to relate each preoperative VFT to ultrasound measurements of AVF blood flow rate and venous diameter at 1 day, 2 weeks, and 6 weeks after AVF placement. After controlling for AVF location, preoperative ultrasound measurements, and demographic factors (age, sex, race, and dialysis status), greater NMD associated with greater 6-week AVF blood flow rate and AVF diameter (per absolute 10% difference in NMD: change in blood flow rate =14.0%; 95% confidence interval [95% CI], 3.7% to 25.3%; P<0.01; change in diameter =0.45 mm; 95% CI, 0.25 to 0.65 mm; P<0.001). Greater FMD also associated with greater increases in 6-week AVF blood flow rate and AVF diameter (per absolute 10% difference in FMD: change in blood flow rate =11.6%; 95% CI, 0.6% to 23.9%; P=0.04; change in diameter =0.31 mm; 95% CI, 0.05 to 0.57 mm; P=0.02). None of the remaining VFT parameters exhibited consistent statistically significant relationships with both postoperative AVF blood flow rate and diameter. In conclusion, preoperative NMD and FMD positively associated with changes in 6-week AVF blood flow rate and diameter, suggesting that native functional arterial properties affect AVF development.