Diagnostic Accuracy of the Available Screening Tools in Detecting Stenosis and Predicting Incipient Thrombosis in Arteriovenous Graft for Hemodialysis: a Comparative Analysis
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 48
- 试验地点
- 1
- 主要终点
- Abnormal clinical monitoring (yes/not)
研究概览
简要总结
A well-functioning vascular access is essential for providing adequate life-sustaining treatment in patients with end stage renal disease on maintenance hemodialysis. The preferred long-term vascular access is the arteriovenous fistula (AVF), which is created using the vessels of the patient by surgically connecting an artery with a superficial vein to increase the blood flow (Qa) in the venous system, which will dilate allowing the insertion of two needles, one to carry the blood to the dialyzer, and the other to return the cleansed blood to the body with the aid of a dialysis machine. Unfortunately, the high prevalence of vascular disease of the hemodialysis patients make difficult to create an adequate AVF in as many as 20 to 60% of the patients.In these persons, a valid alternative is the arteriovenous graft: in graft method an artery is surgically connected to a vein with a short piece of synthetic soft tube which is implanted under the skin. Needles are inserted in the graft during the dialysis treatment. Compared to an AV, however, graft is at higher risk of complications. The most frequent complication is thrombosis (i.e. the formation of blood clot inside the graft). Usually, thrombosis is the consequence of an underlying significant stenosis (i.e. a greater than 50% narrowing of the vessel or graft lumen by comparison with the lumen of a normal adjacent vessel or graft) and its hemodynamic consequences of decreasing the access blood flow (Qa) and/or increasing pressure within the graft. Therefore, all vascular access guidelines recommend regular noninvasive screening programs of grafts for timely identification of a stenosis associated with some type of functional or hemodynamic impairment, because its repair may prevent thrombosis and lengthen the useful life of the access. Screening methods include clinical monitoring and surveillance, which uses special equipment either to assess the hemodynamic consequences of stenosis by measuring Qa and static venous intra-access pressure ratio (VAPR) or to visualize the stenosis by means of duplex ultrasound (DU). Guidelines also state that there is insufficient evidence to prefer one method to another due to the lack of adequate comparative studies. The purpose of our study is to identify an optimal screening program for stenosis detection and elective repair by comparing the diagnostic performance for stenosis and incipient thrombosis of all the available screening tools in the same graft population
详细描述
A well-functioning vascular access (a system that allows the blood of the patient to leave the body, be brought to the artificial kidney or dialyzer to be cleaned and return the cleansed blood to the body) is essential for providing adequate life-sustaining treatment in patients with end stage renal disease on maintenance haemodialysis.
The preferred long-term vascular access is the arteriovenous fistula (AVF), which is created using the vessels of the patient by surgically connecting an artery with a superficial vein to increase the blood flow (Qa) in the venous system, which after few weeks will dilate (maturation) allowing the insertion of two needles, one to carry the blood to the dialyzer (arterial needle), and the other to return the cleansed blood to the body (venous needle) with the aid of a dialysis machine, equipped with a blood pump and pressure sensors at the level of the "arterial" and "venous" needle to monitor for needles dislodgment.
Unfortunately, the high prevalence of vascular disease of the haemodialysis patients makes difficult to create an adequate AVF in as many as 20 to 60% of the patients.
In these persons, a valid alternative is the arteriovenous graft: in graft method an artery is surgically connected to a vein with a short piece of synthetic soft tube which is implanted under the skin. Needles are inserted in the graft during the dialysis treatment.
Compared to an AV, however, graft is at higher risk of complications. The most frequent and feared complication is thrombosis (i.e. the formation of blood clot inside the graft).
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Other
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •All the patients with a polytetrafluroethylene (PTFE) graft as haemodialysis vascular access who were treated at the haemodialysis Unit of the Polyclinic of B.go Roma Hospital in Verona during the recruitment period and who agreed to take part at the study
排除标准
- 未提供
结局指标
主要结局
Abnormal clinical monitoring (yes/not)
时间窗: 15 minutes
signs of graft dysfunction noted during dialysis: difficult cannulation, aspiration of clots, inability to achieve the prescribed dialysis pump blood flow (Qb), excessive post-dialysis bleeding or a \>0.3 drop in single pool dialysis dose
Qa measured by ultrasound dilution: QaU (ml/min)
时间窗: 15 minutes
Qa was measured by the Ultrasound dilution method during dialysis using the Transonic HD03 device, in the same dialysis session in which pressures were measured: each value is the mean of triplicate measurement
Qa measured by DU: QaD (ml/min)
时间窗: 10 minutes
Measurement of Qa is made in a straight portion of the brachial artery in the mid-third of the upper arm. The diameter of the blood flow was measured directly on the vessel thanks to b-flow color technology. Sampling volume was placed in the centre of the lumen and in the longitudinal plane. Typically, measurements were obtained over a sequence of 3 to 5 cardiac cycles (to allow for time-averaged mean velocities, TAV). TAV was calculated directly by the device from a doppler spectral waveform by the duplex scanner system. The Qa (in ml/min) is calculated by the device as the product of the artery diameter and the TAV. The mean value of at least 3 separate measurements was reported.
Presence of a significant stenosis at DSA (yes/not)
时间窗: 1 hour
presence of a greater than 50% reduction in the vessel or graft lumen diameter by comparison with the lumen diameter of a normal adjacent vessel or graft in mm/mm.
dynamic venous pressure: dVP (mmHg)
时间窗: 5 minutes
Dynamic venous pressure (dVP) was measured in the initial 5 minutes of dialysis and detected by the dialysis machine using the pressure sensor connected with the "venous" needle
Derived static venous pressure ratio: VAPR (mmHg/mmHg)
时间窗: 10 minutes
obtained in the initial 5 minutes of dialysis by the dVP, Qb, haematocrit and systemic systolic and diastolic blood pressure values, according to literature in mmHg/mmHg
Presence of significant stenosis at DU (yes/not)
时间窗: 30 minutes
presence of a greater than 50% reduction in the vessel or graft lumen diameter by comparison with the lumen diameter of a normal adjacent vessel or graft in mm/mm and/or a peak systolic velocity \> 400 cm/sec at the stenotic site
Dynamic arterial pressure / dialysis pump blood flow: dAP/Qb (mmHg/ml/min)
时间窗: 5 minutes
Dynamic arterial pressure (dAP) was measured in the initial 5 minutes of dialysis and detected by the dialysis machine using the pressure sensor connected with the "arterial" needle and expressed as the ratio with dialysis blood pump flow Qb.
occurrence of symptomatic acute hypotension during the follow up (yes/not)
时间窗: 4 months
during the follow up an episode of acute symptomatic hypotension in the intra- and inter-dialytic interval was recorded. Hypotension was defined as a sudden fall of systemic blood pressure associated with one or more of fainting palpitation, nausea, blurred vision, feeling weak or cold
次要结局
- inter-assay coefficient of variation of QaU, dAP/Qb,dVP and VAPR (%)(1 month)
- Concordance for the presence of significant stenosis between two radiologists (yes/not)(1 hour)
- intra-assay coefficient of variation of QaU and QaD (%)(15 minutes)
- correlation coefficient (r) between QaU and QaD measurements (ml/min / ml/mn)(30 minutes)