Functional vascular access evaluation after elective intervention for stenosis
Authors: Roca-Tey R. , Samon R. , Ibrik O. , Martínez-Cercós R. , Viladoms J. 
Published: January 2018

Purpose To evaluate the functional effects of preventive vascular access (VA) intervention through periodic blood flow (QA) measurements during hemodialysis (HD) by the delta-H method. Methods We prospectively monitored the blood flow rate (QA) of 100 VA (arteriovenous fistula (AVF) 81% or AV graft (AVG) 19%; mean VA duration 24.6 ± 42.3 months) during HD in 89 end-stage renal disease patients (mean age 62.7 ± 13.6 yrs; mean time on HD 30.9 ± 43.9 months; 18% with diabetes) over a 3-yr period. QA was measured at least every 4 months by the delta-H method (Yarar (6)) using the Crit Line III Monitor (overall mean QA 1247.6 ± 519.7 ml/min). The mean arterial pressure (MAP) and Kt/V index were measured simultaneously with QA. Thirty-eight VA (38%) met the positive evaluation criteria (absolute QA <700 ml/min 50%, QA decreased >20% from baseline 50%). Most cases with positive evaluation underwent angiography (36/38, 95%) and had stenosis ≥50% (34/36, 94%). Of VA with significant stenosis, 17 (17/34, 50%) VA (AVF 76.5%, AVG 23.5%; mean VA duration 12.5 ± 22.4 months, mean percentage of VA stenosis 75.8%) in 15 patients (mean age 68.4 ± 9.8 yrs; mean time on HD 14.2 ± 18.2 months; 33.3% with diabetes) underwent corrective intervention by angioplasty, 35.3% (6/17), and revision surgery, 64.7% (11/17). Results Short-term results: Elective intervention was successful in 88% of treated VA (15/17). Mean QA increased from 563.8 ± 115.4 ml/min just before intervention (QA pre) to 975.7 ± 351.8 ml/min just after intervention (QA post) (mean ΔQA = 411.8 ± 290.1 ml/min) (p < 0.001). We found a significant difference between the overall mean QA before (689.6 ± 227.0 ml/min) vs after intervention (965.9 ± 396.8 ml/min) (p = 0.011). No difference was found when the highest recorded mean QA before intervention (877.7 ± 415.4 ml/min) and mean QA post were compared (p = 0.25). Mean MAP did not change after intervention (91.5 ± 12.5 vs 92.7 ± 14.2 mmHg, p = 0.46). Mean Kt/V index improved from 1.44 ± 0.24 just before intervention to 1.49 ± 0.23 just after intervention without any change in dialyzer type or HD duration (p = 0.025). Mean ΔQA was similar for diabetic patients vs non-diabetic patients (p = 0.34), for younger patients (age < 65 yrs) vs older patients (age ≥65 yrs) (p = 0.64) and for AVF vs AVG (p = 0.39). We found a positive correlation between mean ΔQA and mean QA post (r = 0.95, p < 0.001) or between mean ΔQA and overall mean QA after intervention (r = 0.77, p < 0.001). Long-term results Prevalence of VA thrombosis during the follow-up period (354.4 ± 293.1 days): 17.6% (3/17). Five (29.4%) treated VA showed restenosis and two of them (40%) underwent reintervention by surgery. Mean restenosis period and mean decrease in QA were 232.6 ± 74.1 days and 2.8 ± 0.6 ml/min/day, respectively. No significant correlation was found between mean ΔQA or QA pre and mean restenosis period or decrease in QA (p = ns). Conclusions 1) Monitoring QA by the delta-H method is useful in assessing the hemodynamic response to elective VA intervention. 2) Mean QA post was similar to the highest recorded mean QA before intervention. 3) Mean ΔQA was related to mean QA post and overall mean QA after intervention. 4) The HD effectiveness (Kt/V index) improved after intervention.