Quantification of the severity of outflow stenosis of hemodialysis fistulas with a pulse- and thrill-based scoring system

Abstract

Background Hyper-pulsatility of hemodialysis arteriovenous fistula (AVF) is the basic physical examination finding when there is outflow stenosis. The arm elevation test can also be utilized to detect outflow stenosis. If there is no significant outflow stenosis, the AVF should collapse, at least partially, because of the effect of gravity when the AVF-bearing arm is elevated to a level above that of the heart. However, if there is significant outflow stenosis, the portion of the AVF downstream of the stenosis will collapse, while the portion upstream of the stenosis will remain distended (Clin J Am Soc Nephro 8:1220-7, 2013). In our daily practice, when performing the arm elevation test, we not only observe the collapsibility of the access outflow but also palpate the outflow to identify a background thrill that sometimes disappears with the arm at rest, only to reappear when the arm is elevated. If there is no thrill upon arm elevation, we assume that the outflow stenosis is severe and refer to this condition as “physical examination significant outflow stenosis” (PESOS). The aim of this study is to characterize PESOS using percentage stenosis and Doppler flow parameters. Methods We performed a case-control study using data collected prospectively between June 2019 and December 2019. A pulse- and thrill-based score system was developed to assess the severity of AVF outflow stenosis. We recorded the outflow scores and Doppler measurements performed in 84 patients with mature fistulas over a 6-month period. Angiograms were reviewed to determine the severity of outflow stenosis, which was assessed by calculation of percentage stenosis. Results Receiver operating characteristic analysis showed that a cutoff value of ≥74.44% stenosis discriminated PESOS from other AVF outflow scores, with an area under the curve of 0.9011. PESOS diagnosed cases with ≥75% outflow stenosis in an AVF, with a sensitivity of 80.39%, a specificity of 78.79%, a positive predictive value of 85.42%, and a negative predictive value of 72.22%. Conclusions PESOS can be used to diagnose ≥75% outflow stenosis in an AVF, with or without a significant collateral vein, and its diagnostic accuracy is high. The use of PESOS as an indicator for treatment implies that physical examination may represent a useful surveillance tool.

An eighth note

“…The eighth note is a deformity uniquely seen on autologous radiocephalic AVF. [3][4][5] Its incidence is low and has been reported as 1.7% (14 out of 808 patients). 3 The eighth note may not be seen if there was no collateral branch located at the proximal downstream of the anastomosis or it was ligated at the time of AVF creation surgery.…”

Quantitative physical examination indicators to detect patients with stenosis at a high risk of thrombosis at hemodialysis vascular access sites: A retrospective case–control study

“…In this study, the modified outflow scoring system was used to assess the severity of VA outflow stenosis. When a hyper-pulsatile site upstream to the outflow index stenosis was detected, a score was given based on a pulse-and-thrill scoring system (Figure 1), which was modified from that reported by Chen et al 9 Different scores might be detected along the VA outflow circuit; of them, the worst score was chosen as the delegate score and was recorded. When a hyper-pulsatile site was palpated downstream of the VA inflow, the site was slightly compressed with the palm, and a score was given according to the characteristics of the thrill.…”

“…Stenosis-related hemodynamic derangements can be detected by PE, and PE indicators have been reported to quantify stenosis severity. 8,9 The severity of inflow stenosis can be estimated using palpable pulsatility length (PPL), and a PPL of <11 cm, or an access pump index of ⩽1.3, indicates critical inflow stenosis. 8 The severity of outflow stenosis can be categorized by a thrill-and-pulse-based outflow scoring system.…”

“…The worst score is "PE significant outflow stenosis" (PESOS), which indicates stenosis of ⩾75% in the vascular access (VA) outflow circuit. 9 It is known that the risk of high-shear-related thrombosis is increased when the luminal diameter of stenosis decreases [10][11][12] ; however, the degree of stenosis in millimeters that would trigger thrombosis remains unclear. Spanish guidelines 13 consider stenosis with a minimal luminal diameter (MLD) of <2 mm as high-risk for VA thrombosis.…”

Characterization of hemodialysis fistulas experienced abrupt thrombosis and determination of a proper follow-up protocol: A retrospective cohort study and an interventionist’s perspective

“…The Spanish guidelines [3] proposed the concept of the thrombosis-high-risk stenosis (THRS), which was defined as a stenosis of >50% or with a residual luminal diameter of <2mm combined with additional criterion suggesting severe hemodynamic derangements. Asymptomatic or subclinical THRS was presumed as a probable cause of abrupt thrombosis of AVFs [4,5]. For AVFs where stenosis did not cause AVF dysfunction, detection of THRS, and performance of preemptive treatment were required to prevent abrupt thrombosis.…”