Usefulness of Doppler Ultrasound Carried Out by the Vascular Surgeon After Loco-regional Anesthesia for Preferred Access

Overview

Preoperative vascular mapping with echo-Doppler is acknowledged as indispensable to create an arteriovenous fistula for haemodialysis (AVF). The conditions for performing this examination are not always ideal (venous vasospasm in cool temperatures, variability of the volume status in the dialysis patient). On the other hand, the use of a loco-regional anaesthesia (LRA) results in the vasodilation of the limb thus rendering it possible to use the veins which were initially considered too small. The aim of this study is to assess the functionality of our AVF when ultrasound identification was used by the surgeon after the LRA. These results have been compared with those of the preceding year during which this identification was not implemented.

The investigators conducted a prospective study in the year 2020 during which all the patients (n=90) had an AVF creation with preoperative venous identification by the surgeon at university hospital of TOULOUSE (France)(echo group). All the patients gave their consent, and the database was anonymised upon completion. All patients were seen in a preoperative consultation with venous mapping carried out by a physician specialised in the use of Doppler ultrasonography. Following this consultation, a type of fistula was programmed in accordance with the Silva criteria (notably a vein with a diameter of over 2.5mm and an artery of 2mm). On the day of the operation, loco-regional anaesthesia was performed under sonographic guidance according to the previous description . The decision of the block approach and the choice of local aesthetic agent was left to the discretion of the anaesthesiologist. The surgeon carried out an ultrasound and modification of the type of AVF was then made if the Silva criteria differed from those described during initial consultation. The modification could be a more distal creation, a more proximal creation, a change of vein or a change of artery. The investigators succeeded to create more distal AVF when the vein had a diameter of over 2.5mm after LRA. Furthermore, the investigators reassembled the AVF when the vein appeared too small or residual (for example, following the attachment of an infusion having occurred between mapping and the surgery). The same team of 4 surgeons participated in the creation of the AVF for both the echo group and the control group. All patients were given a preoperative assessment of their heart function and cardiovascular risk factors (HTA, diabetes, smoking, dyslipidaemia). Prior strokes and coronary diseases were also registered as well as the patients' BMI and American society of anesthesiology score. The definition of the good development of the haemodialysis access is based on the National Kidney Foundation's criteria: Blood flow\>600ml, diameter over 6mm and lower depth of 6mm. On the other hand, permeability was based on the criteria of the Society for Vascular Surgery : primary permeability lasts from the creation to the first dilation episode or transposition of anastomosis required to maintain the access. Assisted primary permeability ends at the time of the first occlusion episode. Secondary permeability ends with the abandonment or the definitive withdrawal of the AVF due to failure. The first postoperative consultation took place at around the 6th week after the creation which is the normal time necessary for the smooth development of an AVF . The investigators compared all these results with our control group which consists of all the patients who had a native AVF placed during the year 2019 without having received immediate preoperative ultrasound and therefore there was no alteration in the surgical project in relation to that planned at the time of the consultation. Demographic data was similarly compiled and all the evaluation criteria compared