Diagnostic Value of Digital Pulse-Wave Amplitude in Dialysis Access-Associated Steal Syndrome
Bright Benfor1, Kihoon Bohle2, Eric K. Peden1
1Houston Methodist Debakey Heart and Vascular Center, Houston, TX;2School of Engineering Medicine, Texas A&M, Houston, TX
BACKGROUND- While current guidelines recommend digital pulse-volume recording in the workup of dialysis-associated steal syndrome (DASS), the diagnostic value of the pulse-wave amplitude (PWA) has not been well-established. The aim of this study was to quantify PWA change with access compression and investigate its influence on treatment strategy.
METHODS- This was a retrospective study involving DASS patients undergoing noninvasive vascular testing at our institution between 2015 and 2021. Digital PWA was measured using a photoplethysmography sensor placed on the second digit. Measurements were taken before and during manual access compression (Fig1) and a wave amplitude index (WAI) calculated as the ratio of the latter to baseline value. Clinical presentation, hemodynamic parameters, treatment strategy and outcomes were studied, and a logistic regression was performed to investigate the association between WAI and progression to a flow-targeted intervention at 90 days.
RESULTS- Our cohort comprised 322 subjects with a mean age of 60±13 and a median access age of 9 months. Upper arm accesses were reported in 67% and arteriovenous grafts in 16%. The most common presentation was paresthesia in 67.5%, followed by rest pain in 58%. Tissue loss was reported in 4% and the mean flow volume was 1271±878 ml/min. The pulse-wave amplitude (PWA) measured 2.3±0.9mm at baseline and increased to 5.0±3.2 mm with access compression (p < 0.001), accounting for a median wave amplitude index (WAI) of 2. Patients who had a WAI≥2 were more likely to present with coolness (32% vs. 21%, p=0.025), pallor (6% vs 1%, p=0.048) and had significantly lower baseline digital pressures (83 vs 110mmHg, p<0.001), lower digital-brachial index (0.6 vs 0.8, p<0.001) and higher flow volumes (1363 vs 1146 ml/min, p=0.027). Surgical interventions were performed in 29% and consisted of ligation in 12%, access-preservation procedures in 16% and arterial inflow revascularization in 3%. Subjects with WAI≥2 were more likely to have interventions (36% vs 16%, p<0.001). Eighty percent (80%) of patients receiving access-preservation procedures reported symptom improvement at 30 days. In multivariate analysis, WAI≥2 was found to be independently associated with the need for flow-targeted access preservation interventions (OR: 3.6 [1.6 - 7.7], p=0.001) (Fig 2.)
CONCLUSION- A doubling of the digital pulse-wave amplitude with access compression is associated with worse hemodynamic parameters and the need for intervention in patients presenting with dialysis-associated steal syndrome. Future studies are warranted to further investigate its effectiveness in predicting outcomes of flow-reduction procedures and potential role in selecting the appropriate treatment strategy.
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