CHAPTER 4

I. Planning for Vascular Access Recommendations Each center should establish a dedicated team for vascular access. (Grade D, opinion) Preserve arm veins suitable for placement of vascular access. Preservation should begin in patients with progressive kidney disease and an estimated GFR of less than 30 ml/min. (Grade D, opinion) The preferred type of vascular access is a radio-cephalic native vessel arteriovenous fistula. (Grade C) Background Arteriovenous (AV) access–related complications result in considerable morbidity. With a dedicated access team, including a nephrologist, an access surgeon, an interventional radiologist, and a dialysis nurse, a center can develop and maintain skills that should lead to better patient care. Arm veins, particularly the cephalic veins of the nondominant arm, should not be used for venipuncture or intravenous catheters. In patients with advanced chronic kidney disease, the dorsum of the hand should be used for intravenous line. When venipuncture of the arm veins is necessary, sites should be rotated. Patients should wear a Medic Alert bracelet to inform hospital staff to avoid intravenous cannulation of essential veins. The preferred type of access is a native AV fistula, followed by grafts and then central venous catheters (1–5). It has been shown that the relative risk of bacteremia is greater with central venous catheters than with AV fistulae (6). Compared with AV grafts, AV fistulae have been shown to be associated with better long-term survival, require less intervention to maintain patency, have lower infection rates, and lead to less health care expenditure (1–5,7). Data from the Canadian Organ Replacement Registry show equivalent patient survival on hemodialysis and peritoneal dialysis (8). This information should be considered before using central venous catheters for long-term hemodialysis as opposed to peritoneal dialysis, when both are technically feasible. The preferred sites for placing the AV fistula are (in order of preference) the wrist (radiocephalic) and the elbow (brachiocephalic) (3,9,10). If it is not possible to establish either of these types of fistula, access may be established using either a transposed brachial-basilic vein fistula (3) or an AV graft of synthetic material (e.g., polytetrafluoroethylene [PTFE]). The preferred site and type of graft is a forearm curved looped radiocephalic graft. This is followed by an upper arm straight graft (11). The least preferred sites and type of grafts are forearm straight radial cephalic and looped thigh grafts. However, the location for the graft placement is determined by each patient’s unique anatomical restrictions, previous access history, and the surgeon’s skill. During the planning phase for a new vascular access, venography may be beneficial and may be considered in patients with the following: edema in the extremity in which an access site is planned, collateral vein development or accessory vein enlargement in any planned access site, differential extremity size, if that extremity is contemplated as an access site, current or previous subclavian catheter placement of any type in venous drainage of planned access, current or previous transvenous pacemaker in venous drainage of planned access, previous arm, neck, or chest trauma or surgery in venous drainage of planned access, or multiple previous accesses in an extremity planned as an access site. For patients not yet on dialysis, the benefit of the information gained with venography must be weighed against the risk associated with exposure to radio-contrast media. II. Access Timing, Placement, and Maturation Recommendations Establish AV fistulae when the patient has an estimated GFR of 15 to 20 ml/min and progressive kidney disease. (Grade D, opinion) Background It is important to create an AV fistula at least 3 to 4 mo before its anticipated use. More time may be necessary depending upon the site’s referral and surgical wait times. Grafts can be used in patients who are not candidates for a primary AV fistula. Place dialysis PTFE AV grafts at least 3 to 6 wk before an anticipated need for hemodialysis. According to the available evidence, PTFE tubes are preferred over bovine grafts (12). There is no evidence available yet on the efficacy of newer synthetic materials. When using these materials, follow manufacturers’ recommendations. Cuffed and noncuffed hemodialysis catheters can be inserted immediately before their use because they do not require maturation time. Cuffed, tunneled, central venous catheters can be a valuable alternative to grafts, although there are concerns about infection, thrombosis, and dialysis adequacy. Adjust the catheter tip to the level of caval atrial junction or beyond. Subclavian access should be used only when jugular options are not available. Catheter position should be confirmed using radiography, and the catheter tip should be readjusted as necessary to ensure proper position. The use of real-time, ultrasound-guided insertion may be an advantage in reducing insertion-related complications, particularly in patients who have had previous catheter insertions (13,14). Do not place jugular or subclavian hemodialysis catheters on the same side as a maturing AV access. For patients with chronic kidney disease who need acute hemodialysis vascular access, use a noncuffed or a cuffed percutaneously inserted catheter. These catheters are suitable for immediate use and should not be inserted before needed (15). Femoral catheters should be at least 19 cm long to minimize recirculation. Noncuffed femoral catheters should be sutured in place and can be left in as long as there are no complications. AV fistulae need time to mature before cannulation (at least one month, preferably 3 mo). Recent data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) demonstrates a large intercountry variability in the timing of AV fistula cannulation. The majority of fistulae in Europe are cannulated early—within 8 wk of creation. Early cannulation does not appear to be associated with subsequent fistula failure and may decrease exposure time to central venous catheters (16). As AV fistula maturation depends on artery and vein size and integrity as well as cardiac output, clinical judgment should be used in determining time to first use. The following procedures have been used in an attempt to enhance maturation of AV fistulae: fistula hand-arm exercise (e.g., squeezing a rubber ball with or without a lightly applied tourniquet), selective obliteration of major venous side branches, rest, until swelling is resolved (for a new native AV fistula with induration and edema). A new PTFE dialysis AV graft should not be cannulated until swelling has gone down enough to allow palpation of the course of the graft—ideally 3 to 6 wk after placement. Ideally, no attempt should be made to cannulate the graft for at least 14 d after placement. Use a venogram or other noncontrast study to evaluate central veins in patients with swelling that does not respond to arm elevation, or that persists >2 wk after dialysis AV access placement. III. Monitoring and Maintenance of Vascular Access Recommendations Measure access flow bimonthly in AV fistulae (Grade D) and venous pressure or access flow monthly in AV grafts. (Grade D) Perform angiography if fistula flow decreases to <500 ml/min or drops >20% from baseline (Grade D); if AV graft flow decreases to <650 ml/min or drops >20% from baseline. (Grade D) Background Monitoring AV fistulae and grafts for hemodynamically significant stenosis, combined with corrective treatment, improves patency and decreases the incidence of thrombosis (17–24). A quality assurance program should collect and maintain data on each patient from the monitoring tests, clinical assessment, and dialysis adequacy measurements, and make this information available to all staff. The data should also be tabulated and tracked within each dialysis center and benchmarked against regional or national standards. Although recirculation studies have been shown to be useful for detecting AV fistulae stenosis, the recirculation only occurs when the total access flow is lower than the blood flow in the dialysate circuit. Therefore, the preferred method for monitoring AV fistulae is direct on-dialysis flow measures (18). When clinicians do not have access to on-dialysis flow measures, they can monitor AV fistulae using regular recirculation studies (25). When using flow measures, clinicians should be aware that AV fistulae are capable of sustaining a lower blood flow than an AV graft without clotting, so a flow measurement <650 ml/min in an AV fistulae is less likely to indicate a reversible stenosis or subsequent clotting. However, relative changes in flow measurement are still a cause for concern. After a successful angioplasty, AV fistulae should be monitored monthly and investigated if a flow <500 ml/min or a drop of access flow >20% of baseline occurs (18–20). When using access recirculation measures, clinicians should be aware that any access recirculation is abnormal and should be investigated. Recirculation >5% using non–urea-based methods and recirculation >15% measured using urea-based method is significant and should lead to angiography. Methods for monitoring AV grafts include: intra-access flow including monitoring for changes in flow (26–33), static venous pressures (25), dynamic venous pressures (34), slow-flow venous pressure (35). Blood access flows through AV grafts can be measured by indicator dilution or conductivity tracer techniques, using the Krivitski reversed line technique (28). In a prospective study of 170 chronic hemodialysis patients, May et al. demonstrated that access blood flow measurements were superior in the prediction of access thrombosis compared with static pressure monitoring or urea recirculation measurement (30). However, in a blinded, randomized, controlled trial of AV graft monitoring and angioplasty, monthly blood flow measurement did not improve graft thrombosis rate over and above the standard surveillance (dynamic venous pressure and physical examination) (36). When using pressure measurements to monitor access, clinicians should be aware that static pressure measurements are more accurate than dynamic pressure measurements (25). Methods to measure dynamic, static, and slow-flow venous pressures are provided in the Table 2 Other studies or information that may be useful in detecting AV graft stenosis include: measurement of access recirculation using urea concentrations; measurement of recirculation using dilution techniques (non–urea-based); unexplained decreases in the measured amount of hemodialysis delivered (urea reduction ratio, Kt/V); physical findings of persistent swelling of the arm with the graft, prolonged bleeding after needle withdrawal, or altered characteristics of pulse or thrill in a graft; elevated negative arterial prepump pressures that prevent increasing to acceptable blood flow; venography/Doppler ultrasound. Any finding of access dysfunction, whether based on the presence of access recirculation, low or deteriorating access blood flow rates, positive pressure tests, or any other test should be investigated using angiography to determine the appropriate intervention (e.g., angioplasty, surgery). In the process of investigating the dysfunction and taking corrective measures, it is vital that the clinician take interim measures to protect the patient. When the dialysis circuit blood flow exceeds the access flow, access recirculation will occur, which leads to inadequate dialysis. To optimize dialysis treatment, the dialyzer blood flow should be reduced to a level at or just below the patient’s measured access blood flow rate. The clinician should make the appropriate corrections by time and dialyzer surface area to ensure that the patient receives the desired and prescribed Kt/V (urea). IV. Infection Prevention in the Vascular Access Recommendations Instruct all staff and patients on infection control measures. (Grade D, opinion) Change catheter exit site dressings at each hemodialysis treatment (Grade D, opinion). Use dry gauze dressings and povidone iodine (Grade C), mupirocin (Grade C), or polysporin triple ointment (Grade A) at the catheter exit site. Background Proper infection control procedures can significantly reduce the risk of infection. Catheter care and accessing the patient’s circulation should be sterile procedures. During catheter connect and disconnect procedures, nurses and patients should wear a surgical mask or face shield. Nurses should also wear gloves during all connect and disconnect procedures, although the evidence for sterile versus nonsterile gloves is inconclusive. Use a clean technique for needle cannulation for all cannulation procedures. Ensure that only trained dialysis staff or caregivers change hemodialysis catheter dressings and manipulate catheters that access the patient’s bloodstream and minimize contamination. A randomized control trial of dry gauze dressing with povidone iodine ointment at the catheter exit site, along with sterile dressing technique, resulted in a significant reduction in Staphylococcal aureus exit site infections, bacteremia, and catheter tip colonization (37). The beneficial effect was most evident in S. aureus carriers. Similar results have recently been reported using mupirocin and polysporin triple ointment (38). In the recent study by Lok et al., polysporin triple ointment was associated with a survival benefit (39). Routine monitoring for staphylococcal nasal carrier status and its management remains controversial. Although some studies have shown reduction in S. aureus bacteremia in hemodialysis patients with nasal mupirocin ointment, development of antimicrobial resistance remains an important concern. V. Managing Vascular Access Complications Recommendations Use percutaneous angioplasty to treat all hemodynamically significant stenoses in patients with AV fistulae and AV grafts (Grade D); if percutaneous angioplasty is not possible, use surgical revision. In the case of AV fistulae aneurysm formation, surgically intervene if the skin overlying the fistula is compromised, the aneurysm is expanding, or available puncture sites are limited. (Grade D) In the case of AV grafts, surgically intervene in the presence of graft degeneration and pseudoaneurysm formation. (Grade D) Correct thrombosis of an AV graft with pharmacomechanical or mechanical thrombolysis or surgical thrombectomy. (Grade D) Background Angioplasty is the preferred treatment for both fistulae and graft stenosis (21,22,34,40,41). In native vessel AV fistulae, the most common site of stenosis/thrombosis is near AV anastomosis, distal to the insertion of an arterial needle (40,42). Stenosis, as well as the clinical parameters used to detect it, should return to within acceptable limits after the intervention. Centers should monitor stenosis treatment outcomes on the basis of patency. It is this committee’s opinion that reasonable patency goals (for the center as a whole) for angioplasty and surgical revision in the absence of thrombosis are: Angioplasty: 50% unassisted patency at 6 mo; for all patients, no more than 30% residual stenosis postprocedure and resolution of physical indicator(s) of stenosis. Surgical revision: 50% unassisted patency at 1 yr. If angioplasty is required >2 times within 3 mo and the patient is a good surgical candidate, referral for surgical revision may be consdiered. Stents are useful in selected instances (e.g., central venous stenosis, limited residual access sites, surgically inaccessible lesions, contraindication to surgery) when angioplasty fails. The choice of technique to correct thrombosis should be based on the center’s expertise. Treatment should be performed as rapidly as possible (within 24 h) after detection of thrombosis to minimize the need for temporary access. The access should be evaluated by fistulogram for residual stenosis postprocedure. Residual stenosis should be corrected by angioplasty or surgical correction. Outflow venous stenoses are present in >85% of instances of thrombosis of AV grafts. The need for percutaneous transluminal angioplasty or surgical revision is expected in most instances. Monitoring tests used to screen for venous obstruction should return to normal after the intervention. Centers should monitor outcome results on the basis of patency. It is this committee’s opinion that minimum reasonable goals (for the center as a whole) for percutaneous thrombolysis and surgical revision thrombectomy should be: Percutaneous thrombolysis with angioplasty: 40% unassisted patency and functionality at 3 mo. Surgical thrombectomy and revision: 50% unassisted patency and functionality at 6 mo and 40% unassisted patency and functionality at 1 yr. Immediate patency (patency to next hemodialysis session): 85% for both techniques. Prophylaxis of access thrombosis has not been extensively studied. A randomized, trial of versus to a in in AV grafts. bleeding was also more common in patients to There is also some whether the use of may be Although a randomized trial has provided some for the use of in the of AV graft thrombosis are required before use of this be hand from arterial with a distal If this or is not of the AV fistula or graft. (Grade D) central vein stenosis with percutaneous transluminal Place a only after (Grade D) hemodialysis catheters with of using a (Grade D, opinion) Background hand occurs in 2 to of patients with AV access. and use of artery as a A of this in of patients with AV access this The which an arterial just distal to the AV graft or and from a 4 to cm to the of the access to a just distal to the was performed in of these Immediate of in all and patency was vein stenosis can result in significant arm swelling when an AV access is on the When a patient has central vein stenosis and significant arm percutaneous angioplasty should be Angioplasty can be in case of A should be after more than one or a angioplasty A is for management of a hemodialysis catheter. Catheter dysfunction is as based on or mechanical to and maintain an blood flow to the prescribed hemodialysis without significantly or the hemodialysis A common cause for this dysfunction is the development of a the which can develop after The as a for and formation. With the of has been used to catheter patency reduced by of 2 in each for a of 24 resulted in patency in of the available treatment of a catheter using a for is If flow is not can be to the use of Although there is no this is based on use The should in that evidence to the of versus versus and the of the is If flow is still not studies followed by intervention. In patients with to of and catheter over a are alternative infection of a dialysis AV graft with and total graft (Grade D) of primary AV fistulae as with 6 wk of (Grade D) central venous bacteremia with and catheter over a (Grade D) catheter without bacteremia with and appropriate measures. Catheter is if the infection to respond to 2 wk of (Grade D) Background Use of central venous catheters is associated with a significantly risk of bacteremia compared with AV With AV grafts, the infection risk is It may be possible to a graft infection with a of and of the of the graft and However, infection of a graft total of the graft along with cuffed catheter infection is a treatment depends on the of the infection In patients with cuffed or noncuffed central venous catheters and AV fistulae, or AV graft infections, treatment with 1 to 2 depending on patient and after blood are In patients with or in with a of negative staphylococcal catheter infections, use 15 of blood results are available in patients without exit site or catheter the catheter should be over a and treatment for 2 to 4 wk as In all should be based on the For patients with central venous the catheter should be than in all instances if the patient is or if the patient remains for In patients with access, clinicians can attempt treatment without the catheter. However, the of catheter is low A access should not be until blood performed after of treatment, have been negative for at least Catheter exit site are by and at the exit site in the absence of and negative blood Treatment proper exit site care and or based on and The catheter does not need to be If there is treat with or in to following appropriate measures. should be based on Do not the catheter the infection to respond to or the patient is If the infection to respond after 2 wk of the catheter and it using a and exit site. For all infections, should be evaluated in with in or so that the and that are unique to the of Background AV fistulae should be in all suitable new patients who to hemodialysis as their of After failure of dialysis AV access, all patients should be for possible of a primary AV fistula. of patients should have a native AV fistula Each center should establish a to the types of accesses and the Centers should to the following The rate of graft thrombosis should not patient at risk After for (e.g., within the first 2 mo of fistula the rate of thrombosis of native AV fistulae should be patient at Dialysis should their thrombosis and the as of an The rate of infection should not patient at risk for primary AV fistula and patient at risk for AV grafts (6). For cuffed the rate of infection is patient at risk (6). The primary access failure of dialysis AV grafts in the following and should not be >15% in forearm straight grafts, in forearm grafts, and in upper arm grafts The patency rate of all dialysis AV grafts should be at least at 1 at 2 and 50% at 3 Recommendations for To improve the to monitor and intervene should a randomized prospective trial on intervention based on access flow measurements in both AV fistulae and PTFE grafts. should be performed to the of clinical and vascular studies before AV access to improve AV access for of venous thrombosis in AV grafts should be studies to determine characteristics that the successful and maturation of are Table Methods to measure dynamic, static, and slow-flow venous for central venous catheter

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.