Instrumental diagnostics of limb ischemic disorders in arterio-venous fistulas for haemodialysis

Abstract

Despite the advances in vascular access surgery and the availability of seemingly adequate algorithms for preoperative examination of patients, the incidence of ischaemic syndrome has remained unchanged since the 80s of the last century. According to various data, the need for haemodialysis treatment in developed countries ranges from 70 to 120 cases per 100 people per year. More than 30% of hospitalised patients undergoing haemodialysis are associated with complications in the genesis of arterio-venous fistulas formed for this method of efferent therapy. The most formidable complication is the ischaemic steal syndrome, which develops in 2-18% of patients with a formed arterio-venous fistula. The purpose of the study. To analyse the instrumental methods of studying the ischaemic steal syndrome in order to determine the optimal methods of urgent correction during hemodialysis. Research materials and methods. Instrumental diagnostics of ischemic steal syndrome is aimed at confirming the diagnosis and is also used to monitor the effectiveness of surgical treatment. The most commonly used in clinical practice are: ultrasound duplex scanning with colour Doppler mapping, angiography, photoplethysmography, pulse oximetry, transcutaneous measurement of partial oxygen tension. Less widely used are electromyography and peripheral nerve conduction studies, magnetic resonance angiography or spiral computed tomography. Research results and discussion. The most widely used diagnostic method today is ultrasound duplex scanning with colour Doppler mapping. The purpose of this type of research is to determine the condition of the feeding artery, diameter and location of the anastomosis, stenotic lesions of the main arteries, proximal arterio-venous communication in the areas under visualisation, the volume flow rate of the arterio-venous fistula, the nature of blood flow in the distal artery, the condition of the peripheral vascular bed. If a haemodynamically significant stenosis of the main artery is detected or suspected, angiography with immediate angioplasty is indicated. The importance of angiography in the diagnosis of ISS is emphasised by many authors, especially in the presence of a pressure difference between the limbs with AVF and the opposite limb > 20 mm Hg. In most foreign publications, the most commonly used method of "objectifying" ischemic steal syndrome is the use of photoplethysmography and pneumoplethysmography with the determination of the finger-brachial index. Nerve conduction assesment is used to determine the degree of nerve damage in ischaemic steal syndrome. Other methods of 'objectifying' ischaemia include transcutaneous oxygen tension measurement and pulse oximetry, which are relatively simple and non-invasive to use. In addition, these methods are also used for intraoperative monitoring of the success of reconstruction. Conclusions. Ultrasound Doppler has only certain advantages over angiography in suspected ISS due to its non-invasive nature, speed, ability to be monitored, and low cost. Nevertheless, angiography is of crucial importance, as it is the only tool to determine the indication for urgent angioplasty. The use of intraoperative digital photoplethysmography and pulse oximetry as a guide is a useful method to alleviate the steal syndrome and preserve the shunt. Ultrasound and digital brachial indices measured by photoplethysmography or Doppler are used to predict fistulas that are more likely to cause ischaemia, but they are not reliable.