Vein diameter after intraoperative dilatation with vessel probes as a predictor of success of hemodialysis arteriovenous fistulas.

BACKGROUND: Vascular access is "the life line" for patients on chronic hemodialysis. The autogenous arteriovenous fistula provides the best access to the circulation because of low complication rate, long-term use, and lower cost, compared to arteriovenous graft and central venous catheter. The primary objective of this prospective study was to investigate the predictive value of vein diameter after intraoperative dilatation with vessel probes on hemodialysis fistula maturation. MATERIAL AND METHODS: Ninety-three fistulas were performed by a single surgeon from February 1, 2006 to January 31, 2009. Intraoperative vein dilatation with vessel probes was attempted in all fistulas. Measurements of the feeding artery diameter, vein diameter and the increased vein diameter after intraoperative dilatation were performed and immediate failure, early patency, early failure, primary patency, and fistula survival outcomes were recorded during 48-month follow-up. RESULTS: Early failure occurred in 20% of fistulas and 70% matured sufficiently for cannulation. Variables with significant impact on the failure to mature by univariate analysis were: body-mass index (P=0.041), artery diameter (P<0.001), vein diameter (P=0.004), and vein diameter after dilatation (P=0.002). However, but multivariate analysis showed that only body-mass index (P=0.038), artery diameter (P=0.001), and the diameter of the vein after dilatation (P=0.018) significantly affected maturation. In a group of 56 (60%) patients with vein diameter before dilatation ≤ 2 mm, among vessel characteristics found by multivariate analysis, only vein diameter after dilatation (P=0.004) significantly affected function. CONCLUSIONS: Artery diameter and vein diameter after intraoperative dilatation with vessel probes were the main predictors of fistula function.

Validation of a patient-specific hemodynamic computational model for surgical planning of vascular access in hemodialysis patients.

Vascular access dysfunction is one of the main causes of morbidity and hospitalization in hemodialysis patients. This major clinical problem points out the need for prediction of hemodynamic changes induced by vascular access surgery. Here we reviewed the potential of a patient-specific computational vascular network model that includes vessel wall remodeling to predict blood flow change within 6 weeks after surgery for different arteriovenous fistula configurations. For model validation, we performed a multicenter, prospective clinical study to collect longitudinal data on arm vasculature before and after surgery. Sixty-three patients with newly created arteriovenous fistula were included in the validation data set and divided into four groups based on fistula configuration. Predicted brachial artery blood flow volumes 40 days after surgery had a significantly high correlation with measured values. Deviation of predicted from measured brachial artery blood flow averaged 3% with a root mean squared error of 19.5%, showing that the computational tool reliably predicted patient-specific blood flow increase resulting from vascular access surgery and subsequent vascular adaptation. This innovative approach may help the surgeon to plan the most appropriate fistula configuration to optimize access blood flow for hemodialysis, potentially reducing the incidence of vascular access dysfunctions and the need of patient hospitalization.

The influence of need-based, continuous, low-dose iron replacement on hemoglobin levels in hemodialysis patients treated with erythropoiesis-stimulating agents.

Anemia is a common and important complication of chronic kidney disease. Treatment includes the use of erythropoiesis-stimulating agents (ESAs) and iron supplementation. However, the optimal schedule of iron supplementation remains to be defined. Thirty-one long-term hemodialysis patients were treated for 1 year (period 1) with ESAs and an intermittent pulse regimen consisting of 100 mg of iron sucrose administered after different dialysis sessions depending on serum ferritin and other laboratory values, but no more than once per week. During the next 3 years (period 2), patients were treated with ESAs and need-based, continuous, low-dose iron. Iron doses were determined on the basis of values and changes of serum ferritin and transferrin saturation every fourth week after the longest interdialysis time interval. Iron doses ranged from 10 to 60 mg of iron sucrose and were given 1-3 times per week. If grounded, we gradually reduced or even abolished the iron doses. A significant increase in the hemoglobin concentration and hematocrit during period 2 in comparison with period 1 was observed. The use of ESAs did not change significantly during period 2 in comparison with period 1, while the use of iron was significantly lower in period 2. Significantly lower values were obtained for serum ferritin, saturation of transferrin, serum iron, and total serum iron-binding capacity during period 2. A better response to ESA therapy (increase in hemoglobin and hematocrit) is achieved with need-based, continuous, low-dose iron replacement.

Quality assessment of vascular access procedures for hemodialysis: A position paper of the Vascular Access Society based on the analysis of existing guidelines.

Quality assessment in vascular access procedures for hemodialysis is not clearly defined. The aim of this article is to compare various guidelines regarding recommendation on quality control in angioaccess surgery. The overall population of end-stage renal disease patients and patients in need for hemodialysis treatment is growing every year. Chronic intermittent hemodialysis is still the main therapy. The formation of a functional angioaccess is the cornerstone in the management of those patients. Native (autologous) arteriovenous fistula is the best vascular access available. A relatively high percentage of primary failure and fistula abandonment increases the need for quality control in this field of surgery. There are very few recommendations of quality assessment on creation of a vascular access for hemodialysis in the searched guidelines. Some guidelines recommend the proportion of native arteriovenous fistula in incident and prevalent patients as well as the maximum tolerable percentage of central venous catheters and complications. According to some guidelines, surgeon's experience and expertise have a considerable influence on outcomes. There are no specific recommendations regarding surgeon's specialty, grade, level of skills, and experience. In conclusion, there is a weak recommendation in the guidelines on quality control in vascular access surgery. Quality assessment criteria should be defined in this field of surgery. According to these criteria, patients and nephrologists could choose the best vascular access center or surgeon. Centers with best results should be referral centers, and centers with poorer results should implement quality improvement programs.

Preoperative ultrasound still valuable for radio-cephalic arteriovenous fistula creation?

Radio-cephalic arteriovenous fistula is a prototype hemodialysis access with small incidences of infection and distal ischemia, it spares proximal veins for future access use and it helps in the maturation of veins that may be used for more proximal access creations. This access type is prone to higher early failure rates compared to more proximal fistulas and there are unsolved uncertainties regarding exact ultrasound parameters predictive of fistula outcome. Evolution of ultrasound use has yielded several functional parameters that can be measured in addition to anatomical lumen sizes, which remain core parameters on which the decision to construct fistula in radio-cephalic forearm position is based. We propose to use arterial hyperemic response and wall morphology to aid in this decision when radial artery diameter falls in the interval with predictive uncertainty of 1.6-1.9 mm and to use venous flow pattern, respiratory variation, radial artery status and possibly venous distensibility when cephalic vein augmented diameter lies in the borderline interval of 2-2.4 mm. Ultrasound preoperative mapping and planning should be followed by expert surgical technique and several technique modifications of the classical end-to-side approach are possible to enhance operation outcome and diminish the incidence of stenosis most often present at juxta-anastomotic location. In our experience radio-cephalic arteriovenous fistula remains the golden standard for hemodialysis access and preoperative ultrasound the single best imaging modality to plan the operation and predict its success.

Strategy for the maximal use of native arteriovenous fistulae for hemodialysis.

The long-term survival and quality of life of patients on hemodialysis is dependent on the adequacy of dialysis via an appropriately placed vascular access. The native arteriovenous fistula (AV fistula) at the wrist is generally accepted as the vascular access of choice in hemodialysis patients due to its low complication and high patency rates. It has been shown beyond doubt that an optimally functioning AV fistula is a good prognostic factor of patient morbidity and mortality in the dialysis phase. Recent clinical practice guidelines recommend the creation of a vascular access (native fistula or synthetic graft) before the start of chronic hemodialysis therapy to prevent the need for complication-prone dialysis catheters. A multidisciplinary approach, including nephrologists, surgeons, interventional radiologists, and nurses should improve the hemodialysis outcome by promoting the use of native AV fistulae. An important additional component of this program is the Doppler ultrasound for preoperative vascular mapping. This approach may be realized without unsuccessful surgical explorations, with a minimal early failure rate, and a high maturation, even in risk groups such as elderly and diabetic patients. Vascular access care is responsible for a significant proportion of health care costs in the first year of hemodialysis. These results also support clinical practice guidelines that recommend the preferential placement of a native fistula.

The importance of success prediction in angioaccess surgery.

Access to the circulation is an "Achilles' heel" of chronic hemodialysis. According to the current guidelines, autologous arteriovenous fistula is the best choice available. However, the impossibility of immediate use and the high rate of non-matured fistulas place fistula far from an ideal hemodialysis vascular access. The first attempt at constructing an angioaccess should result in functional access as much as possible. After failed attempts, patients and nephrologists lose their patience and confidence, which results in high percentage of central venous catheter use. Predictive models could help, but clinical judgment still remains crucial. Early referral to the nephrologist and vascular access surgeon, careful preoperative examinations, preparation of patients and duplex sonography mapping of the vessels are very important in the preoperative stage. In the operative stage, it is crucial to understand that angioaccess procedures should not be considered as minor procedures and these operations must be performed by surgeons with demonstrable interest and experience. In the postoperative stage, appropriate surveillance of the maturation process is also important, as well as good cannulation skills of the dialysis staff. The purpose of this review article is to stress the importance of success prediction in order to avoid unsuccessful attempts in angioaccess surgery.

Renal Replacement Therapy in Slovenia: Excerpts From 2013 Data.

This report provides a summary of the 2013 Slovenian renal replacement therapy (RRT) data, obtained from 24 renal centers: 23 dialysis and one transplant center, referring from 31 December 2013, with 100% response rate to individual patient questionnaires. Slovenia had a population of 2 061 085 on 1 January 2014. The total number of patients treated by RRT was 2077, i.e. 1008.3 per million of population (pmp); 1349 (65%) were treated by hemodialysis, 52 (2.5%) by peritoneal dialysis, and 676 (32.5%) had a functioning kidney graft. A total of 260 incident patients, 126.2 pmp (at day one), started RRT, their median age was 69 years, 59.8% were men,. 58.5% of hemodialysis patients were treated with on-line hemodiafiltration. Vascular access was arteriovenous fistula in 79%, polytetrafluoroethylene graft in 8%, and catheter in 13% of patients, mean blood flow 276 ± 41 mL/min, 5.5% dialyzed in a single-needle mode. The crude death rate was 11.4% in all RRT patients (incident patients day 1 included, 15.9% in hemodialysis, 12.3% in peritoneal dialysis, 2.1% in transplant recipients). 60 kidney transplantations were performed in 2013, from deceased donors.

Vascular access for hemodialysis: arteriovenous fistula.

The long-term survival and quality of life of patients on hemodialysis (HD) is dependant on the adequacy of dialysis via an appropriately placed vascular access. The optimal vascular access is unquestionably the autologous arteriovenous fistula (AVF), with the most common method being the conventional radio-cephalic fistula at the wrist. Recent clinical practice guidelines recommend the creation of native fistula or synthetic graft before the start of chronic HD therapy to prevent the need for complication-prone dialysis catheters. This could also have a beneficial effect on the rapidity of worsening kidney failure. A multidisciplinary approach (nephrologists, surgeons, radiologists and nurses) should improve the HD outcome by promoting the use of AVF. An important additional component of this program is the Doppler ultrasound for preoperative vascular mapping. Such an approach may be realized without unsuccessful surgical explorations, with a minimal early failure rate and a high maturation, even in patients with diabetes mellitus.

Subcutaneous compared with intravenous epoetin treatment in patients on hemodialysis: one center study.

The use of epoetin has, in Europe, been restricted to the intravenous (i.v.) route in patients on hemodialysis. This study is aimed at investigating impacts of this change in policy. We retrospectively compared 45 hemodialysis patients treated with epoetin (alpha, beta) subcutaneously (subcutaneous [s.c.] period) for 12 months before and 12 months after changing the route from s.c. to i.v., and 38 patients of the i.v. period who underwent long-term, i.v. low-dose iron therapy (i.v. iron period) for 6 months. During the study period, the dose of epoetin increased in the i.v. period compared to the s.c. period by 6.4% (7379 +/- 3556 IU/week [median 7846] vs 6907 +/- 3842 IU/week [median 5846], respectively [NS]). During the i.v. iron period, patients began to receive regular i.v. iron. The postiron epoetin dose was 5923 +/- 4779 IU/week (median 4500). The dose was decreased in comparison with the s.c. and i.v. periods by 14.2% and 19.7%, respectively. Hemoglobin decreased in the i.v. period compared to the s.c. period (120.4 +/- 8.0 g/L vs 123.5 +/- 6.7 g/L [P < 0.01]), and increased in the i.v. iron period compared to the s.c. and i.v. periods ([126.5 +/- 9.9 g/L vs 123.5 +/- 6.7 [P < 0.01]), and vs 120.4 +/- 8.0 (P < 0.01)]. Changing the route of administration of epoetin required an insignificant increase in dosage. Regular low-dose iron improves the response to epoetin and lowers the dose of epoetin, even in cases when the intravenously administration route is used.

Patients with chronic kidney disease: safety aspects in the preoperative management.

Chronic kidney disease (CKD) is a major public health problem worldwide. Early detection and treatment of CKD can often prevent or delay some of the negative outcomes of CKD. This chapter shows how treatment of hypertension, proteinuria and metabolic disorders slow down the deterioration of renal function. Irrespective of the mode of renal replacement therapy, maintaining the veins in the upper extremities is of vital importance. Below are suggestions on how to protect blood vessels of the upper limbs and when to start preparing for the construction of vascular access. In this chapter, it is also shown how necessary it is to conduct a clinical evaluation of the blood vessels, which is required before the start of vascular access management. The methodology of noninvasive evaluation of vessels by duplex sonography is also presented. This method is very useful, especially if the vessels are not clinically visible, as well as the information concerning the morphological and functional properties of blood vessels.

Vascular access creation and care should be provided by nephrologists.

The long-term survival and quality of life of patients on hemodialysis is dependent on the adequacy of dialysis via an appropriately placed vascular access. Recent clinical practice guidelines recommend the creation of native arteriovenous fistula or synthetic graft before start of chronic hemodialysis therapy to prevent the need for complication-prone dialysis catheters. The direct involvement of nephrologists in the management of referral patterns, predialysis follow-up, policy of venous preservation, preoperative evaluation, vascular access surgery and vascular access care seems to be important and productive targets for the quality of care delivered to the patients with end-stage renal disease. Early referral to nephrologists is important for delay progression of both kidney disease and its complications by specific and adequate treatment, for education program which should include modification of lifestyle, medication management, selection of treatment modality and instruction for vein preservation and vascular access. Nephrologists are responsible for on-time placement and adequate maturation of vascular access. The number of nephrologists around the world who create their own fistulas and grafts is growing, driven by a need for better patient outcomes on hemodialysis. Nephrologists have also a key role for care of vascular access during hemodialysis treatment by following vascular access function using clinical data, physical examination and additional ultrasound evaluation. Timely detection of malfunctioning vascular access means timely surgical or radiological intervention and increases the survival of vascular access.

Native arteriovenous fistula: preoperative evaluation.

Duplex sonography recently has been recognized as an objective and noninvasive method to assess morphological and functional parameters of vessels that could predict arteriovenous fistula (AVF) patency and time of adequate maturation. To prospectively study prognostic indicators of native AVFs, forearm arteries and veins of patients with end-stage renal disease were examined by duplex sonography before AVF construction. Several anatomic parameters, including feeding artery internal diameter (IDA), resistance index (RI), and arterial blood flow (Q(A)) before and at reactive hyperemia (RH) and internal diameter of the vein (IDV) before and after proximal vein compression (PVC), were measured. Measurements of the feeding artery were repeated at different periods after native AVF construction. One hundred sixteen patients were included on the study. The primary patency rate (successful constructed AVF) of native AVFs was 80.2%. In this group, mean values for IDA were 0.264 cm; RI at RH, 0.50; and Q(A), 54.5 mL/min. IDV increased after PVC for 59.3%. In the group with failed AVFs (19.8%), mean IDA was 0.162 cm; RI at RH, 0.70; and Q(A), 24.1 mL/min. IDV increased after PVC for only 12.4%. Patency rates after surgery in a group with IDAs greater than 0.16 cm was 93%, and with IDAs of 0.16 cm or less, 32%. In a group with RIs at RH less than 0.7, the patency rate was 95.3%, and with RIs of 0.7 or greater, 38.7%. An AVF feeding artery Q(A) of 300 mL/min was achieved in the group with IDAs greater than 0.16 cm, those with RIs at RH less than 0.7 after 1 week, those with IDAs of 0.16 cm or less between 3 and 8 weeks, and those with RIs of 0.7 or greater between 8 and 12 weeks. This study shows that duplex sonography may provide useful data on preoperative morphological and functional characteristics of vessels used for AVF construction. Increase in IDA, Q(A), RI at RH, and IDV after PVC are important to predict AVF primary patency rate. Based on these measurements, the most adequate location for AVF construction, as well as time of optimal AVF development, can be determined, particularly for patients at greater risk for primary failure, such as the elderly and patients with diabetes.

Postoperative assessment of vascular access.

Vascular access problems lead to increased patient morbidity and mortality. Autologous arteriovenous fistulas (AVFs) are preferred over grafts. An increase in utilization of AVFs results in an increased incidence of early AVF failure and nonmaturation. A thorough evaluation of a new AVF after 4-6 weeks after creation should be considered mandatory. Experienced persons can examine AVF and predict its utility as a dialysis access. Detailed physical examination of the access performed by educated and trained staff can provide, in most cases, adequate information about the main causes for AVF dysfunction in case of nonmaturation or in case of late access complications. Physical examination has been shown to be very accurate in assessing fistula and is not difficult to learn. Doppler ultrasound (DU) is an additional diagnostic method to predict the ultimate maturation of newly created AVFs and is also very useful in further defining problems that have been detected by physical examination. DU also provides additional information that is of the utmost importance for the surgical or interventional treatment.In this review, basic principles of physical examination and of DU examination of early and late AVF/graft complications are shown.

Renal replacement therapy in Slovenia: excerpts from 2011 data.

This report provides a summary of the 2011 Slovenian renal replacement therapy (RRT) data. Data were obtained from 24 renal centers: 23 dialysis and one transplant center, referred as of 31 December 2011, with 100% response rate to individual patient questionnaires. Slovenia has a population of approximately 2 million (2 052 496 in 2011). The total number of patients treated by RRT was 2011,that is, 980 per million of population (pmp); 0.4% decrease compared to 2010. 1347 (67.0%) were treated by hemodialysis, 60 (3.0%) by peritoneal dialysis, and 604 (30.0%) had a functioning kidney graft. A total of 236 incident patients, 115 pmp (at day one), started RRT, their median age was 68 years, 64.8% were men, 36.4% were diabetics. Regarding hemodialysis patients, 59.3% were treated with on-line hemodiafiltration, 86% with ultrapure dialysis fluid. Median weekly duration of hemodialysis was 12.5 h, median dry body weight 70 kg, mean blood flow 275 ± 46 mL/min, 7.1% were dialyzed in a single-needle mode. Vascular accesses were native arteriovenous fistula in 79%, polytetrafluoroethylene graft in 6%, and catheter in 15%. The crude death rate was 15.9% in dialysis patients, 1.9% in transplant recipients, and 12.0% in all RRT patients (both dialysis and transplant, incident patients at day 1 included). Slovenia has been a member of Eurotransplant since 2000. Forty-six kidney transplantations were performed in 2011, all from deceased donors. A slight decrease in prevalent number of RRT patients was observed in 2011, for the first time in 40 years. The number and proportion of patients with functioning kidney grafts is increasing, reaching 30% in 2011.

Non-matured arteriovenous fistulae for haemodialysis: diagnosis, endovascular and surgical treatment.

Non-maturation is a feature of autologous vascular access. The autologous arteriovenous fistula needs time to mature and for the vein to enlarge to a size where it can be needled for dialysis. A fistula that fails early is one that either never develops adequately to support dialysis or fails within the first three months of its use. Two variables are required for fistula maturation. Firstly, the fistula should have adequate blood flow to support dialysis and secondly, it should have enough size to allow for successful repetitive cannulation. Three main reasons for maturation failure are: arterial and venous problems and the presence of accessory veins. Early diagnostics and intervention for fistula maturation minimizes catheter use and its associated complications. The identification of immature fistulae is relatively simple. Physical examination has been highlighted to be a valuable tool in assessing fistula. Any fistula that fails to mature adequately and demonstrates abnormal physical findings should be studied aggressively. Ultrasonography can successfully identify candidates who fail to meet the recently developed criteria for immature fistulae. In recent years, digital subtraction angiography and contrast-enhanced magnetic resonance angiography has been introduced for assessment of dysfunctional haemodialysis conduits, including immature fistulae. A great majority of non-matured fistulae can be successfully salvaged using percutaneous techniques. In addition to endovascular techniques, surgical intervention can also be an option. This paper reviews the process of fistula maturation and presents information regarding how to obtain a mature fistula.

Expansion of blood volume increases the primary patency rate of arteriovenous fistulas for hemodialysis in patients with critical arterial quality.

The aim of our prospective study was to find out if the expansion of blood volume can improve early arteriovenous fistula (AVF) function after construction in patients with marginal vessel quality. Before AVF construction, the arteries of the upper arm were examined by duplex sonography. Patients with critical values of internal artery diameter (IDA) <1.6 mm, resistance index (RI) at reactive hyperemia (RH) >0.7 and feeding artery blood flow (ABF) <24 mL/min were divided into two groups by random sampling. One group received plasma expander (hydroxyethyl starch) during surgery and the other did not. During the surgical procedures to construct 43 AVFs in 37 patients with critical artery quality, the patients received a mean volume of 720 mL (range 320-1000 mL) of plasma expander. The primary patency rate in this group was 86% (37/43). In the other group of 37 patients with critical artery quality, 42 AVFs were constructed and no plasma expander was given during surgery. The primary patency rate was 26.2% (11/42, P > 0.001). The two-year survival of the AVF in the group given plasma expander was 66.3%, and in the other group it was 13.3%. In our study, the infusion of plasma expander in patients with critical artery quality increased the primary patency rate after AVF construction. Based on the morphological and functional characteristics of arteries determined by pre-operative duplex sonography, the need for blood volume expansion could be predicted.