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Background: Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines suggest that high intra access pressure may be regarded as a surrogate for arteriovenous fistula (AVF) outflow stenosis. It can be measured using static venous pressure (sVP) or standardized dynamic venous pressure (dVP). Access blood flow (Qa) measurement is also recommended by (K/DOQI) as the preferred method for access surveillance, but it is not readily available at all dialysis facilities. We hypothesized that in absence of clinical signs of stenosis, venous pressure(both dynamic &static) can be used as predictor of AVF Qa: a simple and useful screening technique that can be used to detect fistulae with inappropriately high Qa (>1500ml/min). High Qa fistulae may compromise cardiac function, and may require an endovascular or surgical intervention to guard against heart failure. Methods: A prospective cohort study conducted on 59 chronic hemodialysis patients at Ain Shams University hospital. Inclusion criteria: patients with autogenous AVF. Exclusion criteria: clinical signs of AVF outflow stenosis (physical evaluation was done for localized edema/collaterals, jerky pulsations and hand elevation tests); and/or ultrasonic evidence of AVF stenosis or thrombosis. Measurements: standardized dVP (fistula needle gauge 16”, and dialysis machine pump speed set at 200ml/min for 5 minutes) ,while static measurement (P) will be from arterial needle exactly 30 seconds after stopping blood flow. All measures of AVF Qa were obtained by means of Color Doppler Ultrasound using Mindray-M5 ultrasound system. All the investigations were performed for all patients at baseline and were repeated after six months for follow up.
Results: This study included 59 chronic hemodialysis patients with 35 males (59.3 %) and 24 females (40.7%) with mean age 54.41±13.057 years. Twenty six subjects (44.1 %) had distal AV fistula while thirty three subjects (55.9%) had proximal AVFs. Mean value of baseline AVF Flow (Qa,) was 1.327 ± 0.847, while baseline DVP, SVP & adjusted SVP were 95.10 ± 35.807, 13.10 ± 21.7 & 0.015 ± 0.0496 respectively.
Patients with high access flow (>1.5 L/m) were 16 patients. Baseline results show that, their mean blood flow was 2.179 ± 0.681, with mean duration 53.75 months, and mean DVP, adjusted SVP to blood pressure& SVP were 103.13, 0.022 &17.19 respectively. Their mean URR was 0.701. Although there was a significant correlation between AVF flow & SVP with P value 0.027, but the evaluation of the test (the svp) using roc curve demonstrated Weak sensitivity and specificity making the test not suitable for screening.
Conclusion: our study demonstrated that surveillance of venous pressure readings obtained from hemodialysis machine detectors do not help to diagnose patients with high flow AVF (Qa ≥1500ml/min).
Key words: Venous Pressure, High Flow Access Prevalent Hemodialysis.