Buzz in the axilla: a new physical sign in hemodialysis forearm graft evaluation

A review of the current recommendations and practices for hemodialysis access monitoring and maintenance procedures

The growing number of prevalent arteriovenous (AV) accesses has been associated with an increase in the incidence of procedures being performed to maintain patency. To reduce the rate of unnecessary procedures, the 2019 Kidney Disease Outcome Quality Initiative guidelines addended the AV access surveillance recommendations, which includes clinical monitoring and assessment of dialysis adequacy alone. Abnormal clinical findings would necessitate follow-up angiography with or without confirmatory duplex ultrasound. Due to poor patency, increased surveillance schedules have been proposed to identify stenosis early and potentially prevent acute thrombotic events and AV access failure. In this review, we outlined current AV access monitoring and maintenance procedure recommendations, as described by the Centers for Medicare and Medicaid Services and 2019 Kidney Disease Outcome Quality Initiative guidelines. In addition, we highlight the findings of recently published randomized controlled trials that have examined increased surveillance schedules.

Clinical Aspects of Dialysis Interventions: Physical and Sonographic Findings

Physical examination (PE) of arteriovenous access remains of high clinical value and continues to be recommended by leading societies and guidelines. PE is easy to learn and perform. Once learned, examiners can provide a comprehensive arteriovenous (AV) access examination in 20 to 30 seconds. Therefore, we continue to advocate that AV access PE should be part of the training for all dialysis care providers. Similarly, ultrasound can provide important AV access evaluation and provide key information. It is relatively cheap and can be readily available at the bed side. Additionally, it is well accepted by patients, as it is not expected to be associated with pain or discomfort during the examination. We present in this review the key components of PE, signs and symptoms of AV access dysfunction, and the role of ultrasound in AV access evaluation as a complementary tool to PE.

Monitoring Dialysis Arteriovenous Fistulae: It's in our Hands

Vascular access problems are a daily occurrence in hemodialysis units. Loss of patency of the vascular access limits hemodialysis delivery and may result in underdialysis that leads to increased morbidity and mortality. Despite the known superiority of autogenous fistulae over grafts, autogenous fistulae also suffer from frequent development of stenosis and subsequent thrombosis. International guidelines recommend programmes for detection of stenosis and consequent correction in an attempt to reduce the rate of thrombosis. Physical examination of autogenous fistulae has recently been revisited as an important element in the assessment of stenotic lesions. Prospective observational studies have consistently demonstrated that physical examination performed by trained physicians is an accurate method for the diagnosis of fistula stenosis and, therefore, should be part of all surveillance protocols of the vascular access. However, to optimize hemodialysis access surveillance, hemodialysis practitioners may need to improve their skills in performing physical examination. The purpose of this article is to review the basics and drawbacks of physical examination for dialysis arteriovenous fistulae and to provide the reader with its diagnostic accuracy in the detection of arteriovenous fistula dysfunction, based on current published literature.

Physical Examination versus Normalized Pressure Ratio for Predicting Outcomes of Hemodialysis Access Interventions

PURPOSE

The ratio of intragraft venous limb pressure (VLP) to systemic pressure (S) has been proposed to help determine the endpoint of hemodialysis access interventions. It was hypothesized that physical examination of the access could be used in the same way and these techniques were compared as predictors of outcome.

PATIENTS AND METHODS

With use of a quality-assurance database, records from 117 hemodialysis access interventions were retrospectively reviewed. Only interventions in grafts were included. The database included physical examination (to establish thrill, thrill with slight pulsatility [TSP], pulse with slight thrill [PST], and pulse) at three locations along the graft (proximal, midportion, and distal), normalized pressure ratio calculated with S from a blood pressure cuff (S(cuff)) and S within the graft with outflow occluded (S(direct)), graft configuration and location, indication, operator, and time to next intervention (outcome of primary patency). Only procedures with complete follow-up data were included in the analysis (n = 97; declotting, n = 51; prophylactic percutaneous transluminal angioplasty [PTA], n = 46). Statistical analysis was performed with use of Cox proportional-hazards regression.

RESULTS

Graft configuration, location, side, VLP, S(direct), and S(cuff) did not affect outcomes. An operator effect was noted for two physicians and was adjusted for in all analyses. Pressure ratios were weak predictors of outcome (VLP/S(direct), P =.07; VLP/S(cuff), P =.08) and suggested that patency increased with increasing pressure ratio, contrary to earlier studies. Procedure type predicted outcome (declotting, median patency of 50 days; PTA, median patency of 105 days; P =.01). Thrill at distal physical examination was predictive of outcome (P =.04) and even more so when thrill and TSP combined were compared with PST and pulse combined (P =.03). Similar but less-pronounced effects were seen at midportion and proximal physical examinations.

CONCLUSIONS

The presence of a thrill or slightly pulsatile thrill at the distal (venous) end of a dialysis graft is the best predictor of outcome after percutaneous intervention. Based on the present study, the authors believe that physical examination of dialysis access should supplant pressure measurements as an endpoint of intervention and should serve as an essential component of quality assurance of access interventions.

Vascular access: anatomy, examination, management

A systematic approach to managing vascular access problems is the key to reducing current high rates of access thrombosis and failure. This approach begins with a thorough knowledge of vascular access anatomy that, when combined with the physical examination, can help optimize access planning and maintenance. Because of the high complication rate of synthetic grafts, there has been increased emphasis on creating autogenous arteriovenous (AV) fistulae, which, once established, are more trouble-free. The benefit of increased fistula creation will not be realized, however, until the high rate of early fistula failure is reduced. It is widely recommended that graft surveillance programs be implemented and that stenosis be corrected when accompanied by graft dysfunction. Graft blood flow (Q(a)) is the preferred surveillance method, but has a poor accuracy in predicting thrombosis. Most studies that have evaluated the benefit of Q(a) surveillance have used historical control groups, or have been retrospective or nonrandomized. Consequently, we believe it is not currently possible to make definitive, evidence-based recommendations concerning Q(a) surveillance. The most important factor in access survival may be a team approach with an organized commitment to access planning followed by recognition and treatment of access problems.