Venous Needle Research Articles

Automation and innovation in home hemodialysis machines.

In this review, we discuss the timeline of innovation and technologic development in home hemodialysis (HHD) in the United States and the legislative approvals that accompanied them. The most recently FDA-approved home hemodialysis devices provide features that include on-demand and batch dialysate generation, access disconnect for venous needle dislodgement, touchscreen interface with visual and auditory prompts and animations, drop-in sterilized cartridges with prestrung tubing, hot water disinfection of tubing allowing extended-use, dialysate flow rates as high as 500 ml/min, as well as remote treatment monitoring capabilities. Furthermore, wearable/portable dialysis devices are currently under development to simplify dialysis delivery to patients with end-stage kidney disease. Home hemodialysis devices providing longitudinal hemodialysis across different clinical settings, virtual reality headsets for more personalized training, automated patient support, as well as wearable device development and innovations give hope for a future where home hemodialysis is more accessible and seamless.

#1129 Systematic reporting of extracorporeal blood losses in a large dialysis provider organization

Abstract Background and Aims The assessment of adverse safety events is important for the risk assessment of major blood loss from the extracorporeal blood circuit during hemodialysis (HD). Such blood loss has been proven to result in a low double-digit number of fatal events per year in the USA. The frequency in Europe is not mandatorily recorded. The mechanisms of blood loss in the venous leg of the system, undetected by the alarm system of the dialysis machines, are not generally known and further patient and structure-related risks are not yet systematically recorded, evaluated and improved. Method We set up a web-based intranet database (“Event Management”) to record serious adverse events affecting patients during or around dialysis treatments in all 174 kidney centers of the Kuratorium für Dialyse und Nierentranspantation in Germany (KfH). This system is accessed via intranet within the KfH organization. Nursing and medical staff are regularly trained and informed about this system. The entry of event data that have endangered or harmed patients is mandatory. Results 141 reports of blood loss were identified for a total of approximately 3 million hemodialysis treatments performed in 174 renal centers in between 2020 and 2022, including venous needle loss due to complications in the extracorporeal blood circuit, 15 of which required inpatient treatment. The breakdown of the causes and consequences of blood losses is shown in the Figure. Conclusion Venous disconnection must be reduced by earlier detection with appropriate technical and patient-adapted measures. Patients should be educated about their individual risk and about individual measures to manage risk. Identification of patient-specific and shunt-specific risk factors is necessary. Patient-related risk factors include cognitive impairment, frailty, and dialysis in special areas (ICU, isolation area, nocturnal dialysis). Monitoring systems (blood sensors) currently on the market have good technical blood detection sensitivity. Such systems should be investigated with regard to their clinical benefit according to the rules of evidence-based medicine before their broad introduction into routine care.

A modeling study of position and orientation of hemodialysis needles and the impact on vascular access

Patients with chronic kidney disease (CKD) need renal replacement therapy (RRT) and the favored method is hemodialysis (HD). An arteriovenous fistula is the preferred choice of vascular access, with two metal needles used to transfer the blood with waste to the dialysis machine and return the blood without waste from the dialysis machine to the patient’s body. However, wounds on the veins can cause blood clots which if left untreated could be life threatening. The hemodialysis needles can cause vascular wall abnormalities. The position and orientation of these needles might cause intimal hyperplasia (IH) and finally lead to blood clots. This study aims to analyze the hemodynamic effects on the vascular endothelium in AVF vascular access. A 15G needle was placed inside a vein at angles of 20°, 40°, and 90° with normal insertion and flipped needle in an idealized cephalic vein with the bore of the needle centrally located, conforming to standard cannulation practice. The 3D model created by SolidWorks consists of shaft, back eye, bevel, and vein only; the vein and 15G needle were assembled together. The mathematical model of blood rheology in this paper used Carreau’s law in the fluid domain. It was imported into Ansys CFX for calculation, a finite volume based software, which was implemented to solve the governing equations of the blood flow. The result showed that if the venous needle was not towards the venous return, a vortex appeared at the vein both upstream and downstream due to the venous needle, resulting in wall shear stress at the vein increasing significantly, and the flipped bevel seems to cause higher wall shear stress. For antegrade positioning of the vein vascular access return in the model when normally inserted, it was found that only 1% of the flow out of the back eye and vortex occurred downstream of the vein. Needles placed at a higher angle can increase wall shear stress and pressure on the vein. The flipped bevel is not significant in terms of either pressure or wall shear stress. However, when the needle is placed at a greater angle, wall shear stress and pressure on the vein were also increased. The flipped bevel caused higher wall shear stress and pressure when increasing the needle angle. Jetting from the venous needle causing intimal hyperplasia (IH) leads to blood clots, pain on the vein, and ultimately arm pain. Thus, the best cannulation procedure is for the venous needle to be toward the venous return, at a lower angle, and with the tip of the needle on the middle of the vein. Furthermore, the back eye should not be used for the venous needle but should be used for the arterial needle.

Detection of Hemodialysis Venous Needle Dislodgment Using Venous Access Pressure Measurements: A Simulation Study.

In rare instances, hemodialysis venous needles may become dislodged, and when left undetected can lead to severe injury or death. Although dialysis machines have alarms to detect venous needle dislodgment, their range of detection is limited. An understanding of the clinical conditions that may lead to missed needle dislodgments is needed for development of more robust detection systems. We created a sham dialysis circuit with a Fresenius 2008 K dialysis machine for in vitro simulation testing of machine alarm behavior under variable conditions. The circuit used a blood substitute and mimicked a patient's venous access site. We varied blood flow rate, venous pressure, and upward drift in venous pressure and analyzed the time to alarm for the machine and an improved alarm algorithm. We also performed a cross-sectional retrospective study to identify the clinical occurrence of venous pressure upward drift between September 1, 2016, and November 1, 2016 in patients on hemodialysis with an arteriovenous fistula. Of 43,390 venous pressure readings for 147 patients on hemodialysis, 16,594 (38%) showed an upward drift in venous pressure (range 20-79 mmHg), with a mean ± SD increase of 11±18 mmHg within 20±14 minutes. A total of 19 venous needle dislodgment simulations under different venous pressure and blood flow parameters resulted in 19 (100%) algorithm alarm activations. Only 8 simulations (42%) activated a machine alarm, and machine alarm activation time was longer than the algorithm activation time for all 8 machine alarms (range 1-13 seconds). Patients can experience changes in venous pressure during hemodialysis which may not trigger a machine alarm in the case of a venous needle dislodgment. Our simulations showed that current dialysis machine alarm systems may not compensate for upward drift in venous pressure, and improved algorithms for detecting needle dislodgment during hemodialysis are needed.

Study on the blood flow characteristics of venous needle retention with different super-hydrophobic surface structures

A venous retention needle, as an implanted device, is very likely to cause thrombosis. In view of the thrombosis phenomenon caused by retention needles, this paper compares the influence of different superhydrophobic surface retentions on blood flow. Compared with other superhydrophobic bulges, the fluid velocity of the four-prism bulge is the highest (0.08 m/s), and the vorticity and shear force of the hemispherical bulge are higher. A large number of vortices can inhibit thrombosis better. The tire vortices generated in the superhydrophobic convex grooves are important vortices to inhibit thrombosis. The enhancement and development of the tire vortex weakens the resistance near the wall of the needle and reduces the probability of platelet aggregation. The superhydrophobic surface structure studied in this paper can not only provide guidance for the design of venous retention needles with better performance but also provide corresponding technical support for the development of human implantation devices.Graphical

Needle Direction and Distance of Arteriovenous Fistula Cannulation in Hemodialysis Adequacy; a Systematic Review and Meta-Analysis.

This systematic review and meta-analysis aimed to summarize the evidence regarding the impact of needle direction and distance of arteriovenous fistula (AVF) cannulation on KT/V (where k is the dialyzer urea clearance, t, the duration of dialysis, and V, the volume of distribution of urea) and access recirculation (AR) as hemodialysis (HD) adequacy criteria. A comprehensive systematic search was performed on international and domestic electronic databases from the earliest to June 4, 2022 using keywords. Analysis was performed in STATA software v.14. Three randomized control trials (RCTs) and four non-RCT articles were included in the final review. Six studies reported the effects of direction, while four mentioned the effects of distances of AVF cannulation on outcomes of HD adequacy based on KT/V or AR. Results of three non-RCT studies showed that retrograde direction decreased KT/V more than antegrade direction (ES: 0.44, 95% CI: -0.38 to 1.27). Two non-RCT studies showed that antegrade decreased AR compared to the retrograde direction (ES: -0.64, 95%CI: -1.94 to 0.67). However, the results of two RCTs indicated uncertainty about this issue. Two of the four studies suggested that a distance of 5 cm or more in arterial and venous needles had greater adequacy than a distance of less than 5 cm. However, other studies did not confirm this finding. Overall comparison of the results qualitatively and quantitatively indicated uncertainty about the effects of direction and distance of AVF cannulation on HD adequacy outcomes. More studies with high-quality designs, such as RCTs, are required to better understand and adjudicate the effects of needle direction and distance of AVF cannulation on HD adequacy outcomes.

The development and testing of a prototype venous needle dislodgement detection device.

Inadvertent venous needle dislodgement (VND), from graft or arterio-venular fistula, can lead to haemorrhage resulting in a serious life-threatening complication and in some cases death by exsanguination. This paper eloquently articulates the development and testing of a novel Arduino based VND detection device. The VND detector is subjected to four testing protocols to critically analyse the efficiency of VND detection within a 12-second window. Implementation of statistical analytic methods to the obtained results successfully demonstrated the VND detector's ability to detect VND within 12 seconds.

Real-Time Internet of Medical Things System for Detecting Blood Leakage during Hemodialysis Using a Novel Multiple Concentric Ring Sensor.

Venous needle dislodgement (VND) is a major healthcare safety concern in patients undergoing hemodialysis. Although VND is uncommon, it can be life-threatening. The main objective of this study was to implement a real-time multi-bed monitoring system for VND by combining a novel leakage-detection device and IoMT (Internet of Medical Things) technology. The core of the system, the Acusense IoMT platform, consisted of a novel leakage-detection patch comprised of multiple concentric rings to detect blood leakage and quantify the leaked volume. The performance of the leakage-detection system was evaluated on a prosthetic arm and clinical study. Patients with a high risk of blood leakage were recruited as candidates. The system was set up in a hospital, and the subjects were monitored for 2 months. During the pre-clinical simulation experiment, the system could detect blood leakage volumes from 0.3 to 0.9 mL. During the test of the IoMT system, the overall success rate of tests was 100%, with no lost data packets. A total of 701 dialysis sessions were analyzed, and the accuracy and sensitivity were 99.7% and 90.9%, respectively. Evaluation questionnaires showed that the use of the system after training changed attitudes and reduced worry of the nursing staff. Our results show the feasibility of using a novel detector combined with an IoMT system to automatically monitor multi-bed blood leakage. The innovative concentric-circle design could more precisely control the warning blood-leakage threshold in any direction to achieve clinical cost-effectiveness. The system reduced the load on medical staff and improved patient safety. In the future, it could also be applied to home hemodialysis for telemedicine during the era of COVID-19.

Effect of needle bevel position in arteriovenous fistula cannulation and bleeding during hemodialysis

This study investigated the effect of needle bevel position during arteriovenous fistula cannulation on bleeding stop time in patients with chronic hemodialysis. An arteriovenous fistula puncture was performed on patients using the needle bevel up and down and the bleeding stop time was recorded in minutes. The outcomes of the two techniques were compared. The anticoagulant type used did not affect the bleeding stop time in the 55 patients with hemodialysis included in this study. On separately considering puncture outcomes and anticoagulant type used, the bleeding stop time in both arterial and venous needle bevel down punctures was found to be significantly lower compared with the bevel up puncture (p<0.05). The bleeding stop time was found to be shorter in bevel down arteriovenous fistula puncture.

Effect of Roller Pump Pulse in the Arterial Needle Area during Hemodialysis.

Vascular access is a lifeline for hemodialysis patients. Its lifetime is affected by many hemodynamic factors such as pressure, flow regime and wall shear stress. During hemodialysis, changes in hemodynamic parameters occur due to the flow from needles inserted into the vascular system. Primarily, there is a change in shear stress that affects the vascular wall. Pathological effects of high or low WSS are known. The effect of jet from a venous needle on hemodynamics parameters was studied, but the influence of the arterial needle on hemodynamics parameters is not sufficiently studied. To understand its possible effects, we performed in vivo and in vitro studies. Methods. In vivo experiment: The existence of flow reversal around the suction needle was visualized in a group of 12 randomly selected patients using ultrasound velocity profiling (Doppler ultrasonography) during hemodialysis. In vitro experiment: The flow field was measured using the stereo particle image velocimetry method (stereo PIV). Two regimes were studied. In the first regime, the fluid in the extracorporeal circuit was pumped by a peristaltic pump. In the second regime, the continuous pump was used in the extracorporeal circuit. The conditions were set to resemble those in vascular access during a hemodialysis session. Flow volume was set to 600 mL/min for vascular access and 200 mL/min for the extracorporeal circuit. Results. The main finding of this study was that the wall in the region of the arterial needle was stressed by backflow through the arterial needle. Since this was a variable, low-shear stress loading, it was one of the risk factors for the development of stenosis. Cyclic flow reversal was apparent in all of the included hemodialysis patients. The stereo PIV in vitro experiment revealed the oscillating character of wall shear stress (WSS) inside the model. High shear stress was documented upstream of the injection point of the arterial needle. An area of very low WSS was detected right behind the injection point during a pulse of the peristaltic pump. The minimal and maximal values of the WSS during a pulse of the peristaltic pump in the observed area were −0.7 Pa and 6 Pa, respectively. The distribution of wall shear stress with the continual pump used in the extracorporeal circuit was similar to the distribution during a pulse of the peristaltic one. However, the WSS values were continual; the WSS did not oscillate. WSS ranged between 4.8 Pa and 1.0 Pa.

Hemostasis of arteriovenous fistula: Comparison of direct two-finger pressure to an adjustable device

Background and objectivesTo evaluate the pressure generated by an adjustable hemostasis clamp on arteriovenous fistulas (AVF) during the hemostasis proccess, and compare it with the direct two-finger pressure applied by the patient. To evaluate the variations of the direct two-finger pressure along the hemostasis process. MethodsWe analyzed data obtained in 51 hemodialysis procedures from 15 patients. AVF intraaccess pressure was used as indirect indicator of the pressure generated by both methods. It was recorded before venous needle removal (PBasal), at clamp application (P1), after clamp adjustement by a nurse (P2), at the beginning of the direct two-finger pressure by the patient (M0), after 3 min of two-finger pressure (M3) and after 6 min of two-finger pressure (M6). ResultsIntra-access pressure was lower with the adjusted clamp (P2) than with the direct two-finger pressure by the patient (M0) (variation of −18.57%, 95%CI −14.09 to -4.77 mmHg, P < 0.001). Intraaccess pressure generated by the direct two-finger pressure method showed a decreasing trend along the hemostasis process (M3-M0: −8.82 mmHg, P < 0.001; M6-M0: −12.55 mmHg, P < 0.001). ConclusionAn adjustable fistula arm clamp generates a lower pressure in AVF than the direct two-finger pressure applied by the patient. The latter showed a decreasing trend along the hemostasis process. These data suggest that some of the recommendations from clinical guidelines could be based on inaccurate premises.

Using two-holed needles for both arterial and venous accesses to the arteriovenous fistula to improve flow during hemodialysis.

This prospective study compared methods using both arterial and venous needles with back eyes with those using only arterial needle with back eye for arteriovenous fistula cannulation. Sixty-one patients receiving hemodialysis (HD) via an arteriovenous fistula were evaluated. All patients underwent arteriovenous fistula puncture using only arterial needle with back eye in first 3 months and both arterial and venous needles with back eyes in following 3 months. Arterial and venous pressures, blood flow velocities, total blood volume cleared, and Kt/V values were compared. Mean blood flow velocity, arterial pressure, Kt/V, and cleared total blood volume values were higher and venous pressure was lower in patients who underwent cannulation using both needles with back eyes than in those with only the arterial needle with back eye. For arteriovenous fistula cannulation, using both arterial and venous needles with back eyes provides adequate HD more successfully.

MO665THE BRAND-NEW NEEDLE CAP ELIMINATES ALL VISIBLE AIR BUBBLES DURING THE AUTOMATIC PRIMING PROCESS OF HEMODIALYSIS MACHINES

Abstract Background and Aims The air contamination from the dialysis circuit into the patient's body is an unsolved serious problem. Recently, Automatic priming function of dialysis machines is widely used. There are rarely any air bubbles left in the extracorporeal circuit after automatic priming of the dialysis machines. To use this method, the arterial and venous sides of the extracorporeal circuit are connected to create a closed circuit so that dialysate can circulate and overflowed through a line from this closed circuit. However, air bubbles may enter when disconnecting the closed extracorporeal circuit and attaching the needles. We tried to solve this problem by simply connecting the arterial and venous needles to the extracorporeal closed circuit before the process of automatic priming process. To prime the whole extracorporeal circuit with needles, we had made a brand-new suitable cap of the needle, which is tightly connected with a needle and has an open end. (Fig) This special cap allows the needle to be incorporated into the closed circuit prior to the automatic priming process, allowing the dialysis machine to completely remove the air during priming process. The purpose of this study is to present the details of this new method and compare its effectiveness in preventing air bubble contamination between the traditional method and this new method. Method A prospective, non-randomized, comparative study was conducted to verify whether air remained grossly visible after the needle was connected to the extracorporeal circuit. The traditional method: DCS-100NX (Nikkiso Co Ltd, Tokyo Japan) was used for extracorporeal circuit priming. After the automatic priming was finished. Nurses disconnect the arterial and venous side of the extracorporeal circuit and connect both ends to the needles by hands. The nurse operates the dialysis machine to blow the small amount of dialysate out of the needle and tried to remove the air. It takes nearly 2minutes in each case. We examined the extracorporeal circuits consecutively. New cap-based method: The needles were connected to the closed circuit with the new cap and auto-primed by the dialysis machine N100. Automatic priming, including the needle were performed consecutively. In each method, we thoroughly checked for any remaining macro bubbles with the naked eye. Since bubbles in the extracorporeal circuit on the arterial side are likely to be supplemented by the air trap chamber, only bubbles on the venous side were compared. Results The study was conducted in October 15th to 24th 2020 at the Yokohama Minami Clinic. The traditional method: We checked 50 extracorporeal circuits consecutively. There were bubbles in the venous side of the extracorporeal circuits 29 times out of 50 times. New cap-based method: 10 consecutive automatic priming, including the needle was performed. DCS-100NX was used as the dialysis machine. There were no bubbles visible to the naked eye in the arterial and venous side of the circuit. Statistical Results There was a statistically significant difference of the bubble count between the traditional method and new cap-based method. (p=0.0001, Pearson's chi-square test) Conclusion All visible bubbles were removed automatically by simply connecting the needles using this brand-new cap before a process of automatic priming. This easy-to-use and highly effective cap could be considered an essential device for hemodialysis treatment like seat belts in automobiles.

Hemostasia en fístulas arteriovenosas: comparación de la presión manual con la ejercida por un dispositivo regulable

Background and objectivesTo evaluate the pressure generated by an adjustable hemostasis clamp on arteriovenous fistulas (AVF) during the hemostasis proccess, and compare it with the direct two-finger pressure applied by the patient. To evaluate the variations of the direct two-finger pressure along the hemostasis process. MethodsWe analyzed data obtained in 51 hemodialysis procedures from 15 patients. AVF intra-access pressure was used as indirect indicator of the pressure generated by both methods. It was recorded before venous needle removal (PBasal), at clamp application (P1), after clamp adjustement by a nurse (P2), at the beginning of the direct two-finger pressure by the patient (M0), after 3min of two-finger pressure (M3) and after 6min of two-finger pressure (M6). ResultsIntra-access pressure was lower with the adjusted clamp (P2) than with the direct two-finger pressure by the patient (M0) (variation of −18.57%, 95%CI: −14.09 to −4.77mmHg, P<.001). Intra-access pressure generated by the direct two-finger pressure method showed a decreasing trend along the hemostasis process (M3-M0: −8.82mmHg, P<.001; M6-M0: −12.55mmHg, P<.001). ConclusionAn adjustable fistula arm clamp generates a lower pressure in AVF than the direct two-finger pressure applied by the patient. The latter showed a decreasing trend along the hemostasis process. These data suggest that some of the recommendations from clinical guidelines could be based on inaccurate premises.

Access recirculation and adequacy of hemodialysis in different types of vascular access

Introduction: Haemodialysis requires recirculation, and it happens when dialysed blood returningthrough the venous needle re-enters the extracorporeal circuit through the arterial needle, ratherthan returning to the systemic circulation. Significant recirculation should be expected, when there isan inadequate reduction in the values of urea. During End-Stage Renal Disease (ESRD), adequatedialysis is of utmost importance because it influences the morbidity and mortality of the patients.Methods and materials: The study was carried out in 200 patients who underwent haemodialysisat the dialysis unit in Kalyani kidney care centre, Erode. Patients were actively evaluated fromFebruary 2018 till November 2018. Patients were randomized and accordingly 64 patients wereenrolled in category I Arteriovenous fistula (AVF), 63 Patients in category II Internal JugularCatheter (IJC) and category III Femoral Catheter (FC) each and 10 patients in category IV PermCatheter (PC). Success recirculation was estimated and adequacy of haemodialysis was donevirtually. Calculated Kt/V was done in almost all patients. Results: The mean access recirculationrate was 6.3+5.1% in those with AVF, while in IJC and FC groups were 6.7+4.5% and 24.4+11.7%respectively. When the two groups were compared, AVF vs FC groups, the difference was statisticallysignificant (p value&lt;0.001) and in IJC vs FC groups, the difference was statistically less significant(p-value &lt;0.001) in both AR% and online Kt/V. Conclusion: An arteriovenous2QQ2 fistula has lessaccess recirculation, when compared to temporary catheters. On the other hand, the femoralcatheter has more access recirculation, when compared to the internal jugular catheter. Thedifference in calculated Kt/V with the three types of vascular access has no statistical significance.

Relationship between arteriovenous fistula cannulation practices and dialysis adequacy: A prospective, multicenter study

Successful arteriovenous fistulacannulation ensures maximum patient benefit in the haemodialysisprocedure. The aim of this study was to determine the effect of various cannulation methods used for arteriovenous fistulas on dialysis adequacy. It is a descriptive, cross-sectionaland multicenterstudy. A total of 164 dialysis patients from four dialysis centers were included. Data were collected by determining patients' characteristics and the arteriovenous fistula cannulation method used, in addition to recording the Kt/V and urea reduction ratiovalues to evaluate dialysis adequacy. The mean Kt/V and urea reduction ratio values over 3 months after dialysis initiation were used. This trial is registered with ClinicalTrials.gov, NCT04270292. Cannulation with the puncture method was used in 53% of the patients; the fistula needles wereinserted in the antegrade direction in 43.9% of the patients; the arterial needle was rotated after fistula needle placement in 63.4% of the patients; and the arterial and venous needles were on the same vascular line in 15.2% of the patients. Placement of the fistula needle in the antegrade direction increased the Kt/V value 0.164 times (95% confidence interval:0.002-0.212, p = .047). Antegrade placement could be a factor influencing dialysis adequacy. We suggest antegrade interventions to the fistula to maximize the patient benefit from the haemodialysis treatment.

A case in which increasing the outer diameter of the venous needle was found to be effective at treating intimal hyperplasia and stenosis

A case in which increasing the outer diameter of the venous needle was found to be effective at treating intimal hyperplasia and stenosis

Venous Needle Dislodgement and Access-Bloodline Separation

Serious hemodialysis therapy complications are venous needle dislodgement and access-bloodline separation. In 2020, the American Nephrology Nurses Association (ANNA) brought together a task force to update the information and resources developed by the 2012 ANNA Venous Needle Dislodgement Task Force along with the development of additional resources, if needed. The 2020-2021 ANNA Venous Needle Dislodgement Task Force conducted a literature review, requested information from ANNA members, and tested taping techniques. This article discusses the results of the literature review, information requests, and taping technique testing, and provides resources on venous needle dislodgement and access-bloodline dislodgement, along with practice recommendations.

Recirculation and adequacy of dialysis in end stage renal disease patients on regular hemodialysis at Menoufia university hospitals

Background Early detection of vascular access complication prevents more severe conditions and reduces hospitalization periods of patients on regular hemodialysis (HD). Access recirculation (AR) is one of the tools for early evaluation of arteriovenous fistula (AVF) complication for early intervention. The aim of our study was to evaluate the AV AR as a risk factor for inadequate HD in patients with end-stage renal disease in Menoufia university hospitals. Patients and methods This is a cross-sectional study that included 300 patients on regular HD sessions at four centers at Menoufia university hospitals. All patients were subjected to detailed history taking, clinical examination, laboratory investigation, and measurement of recirculation by urea-based method. Results This study included 300 patients on regular HD. It showed that 51.7% presented with aneurysm, whereas the infected AV access was presented in 6% of patients. AR was found in 17.7% of patients, being more frequent in patients with the left brachiocephalic AVF (37.7%), and it showed highly significant relation with duration of dialysis and duration of AVF creation. The risk factors for recirculation were the distance between arterial and venous needle sites, puncture site aneurysm, and stenosis. There were negative correlations between AR and both urea reduction ratio and KT/V and positive with both serum potassium and parathyroid hormone level. Conclusion AR in our unit was associated mainly with stenosis, aneurysm, and improper needle puncture sites, so screening for recirculation may be used as a surveillance technique for the early detection of AVF in concomitant with regular training of dialysis staff in cannulation of the AVF.

Arterio-Venous Fistula Recirculation in Hemodialysis: Causes and Prevalence

Recirculation is an important issue in hemodialysis (HD) patients as increased percent recirculation causes decreased dialysis delivery of the patients. The purpose of the study was to determine the prevalence and possible causes of recirculation in those patients. The study was a cross sectional one carried in the department of Nephrology, Ain Shams University Hospitals. A total of 100 end stage renal disease patients with arterio-venous fistula who were on HD for more than 3 months were purposively selected. The degree of recirculation was measured with urea based two needle technique method. For each patient distances between arterial and venous and distances of needles from fistula and its directions were recorded. Echocardiography and A-V fistula Colour Doppler Ultrasound were also performed for patients with high degree recirculation percent (more than 10%). The prevalence of A-V fistula recirculation was 55% with a range 0-66%. The most common factors were close proximity and improper arterial and venous needles placement. No difference was observed between diabetic and non- diabetic also between hypertensive and normotensive. A-V fistula recirculation is common occurrence in HD patients and the most common factors of recirculation are misplacement and close proximity of needles therefore emphasis should be given on education and training of HD staffs