Vascular access in hemodialysis patients

Arvind Kohli
Hemodialysis is the most commonly used method to treat advanced and permanent renal failure, hemodialysis is always a complicated and inconvenient therapy that requires a coordinated effort from the entire health care team, including a nephrologist, a vascular dialysis nurse, a dialysis technician, a dietitian and a social worker
vascular
. is the site on the patient's body where the blood is removed and returned during dialysis.
Vascular access must be prepared before the start of dialysis. Early preparation of vascular access will make blood removal and replacement easier and more effective with fewer complications. Ideal access should provide adequate blood flow for an indefinite period of time, so that the distribution of dialysis is maximized at each cannulation. Complications such as thrombosis, infection and hemorrhage should be absent. It is difficult to have such ideal access.
The three basic types of vascular access for hemodialysis are: an arteriovenous fistula
arteriovenous (AV)
Native AV Fistula. is an opening or a connection between one. the artery and vein, fistula .AV is useful because it allows the vein to grow and strengthen to facilitate access to the blood system. AV fistula is considered the best long-term vascular access for hemodialysis because it ensures adequate blood flow, lasts a long time and has a lower complication rate than other types of access. If an AV fistula can not be created, an AV graft or venous catheter may be necessary.
Arteriovenous Graft
In small veins that do not develop properly in a fistula, the patient can obtain vascular access that connects an artery to a vein using a synthetic tube, or graft, implanted under the skin in the arms. The transplant becomes an artificial vein that can be used repeatedly for needle placement and access to blood during hemodialysis. A transplant does not need to develop as a fistula, so it can be used sooner after placement, often in 2 or 3 weeks.
Compared with properly formed fistulas, grafts tend to have more problems with coagulation and infection. replacement sooner. However, a well managed transplant can last several years.
Venous catheter
For a very urgent vascular need. we need to use a venous catheter as a temporary access.
A catheter is a tube inserted into a central vein in the neck, chest, or leg near the groin. It has two rooms to allow a flow of blood in both directions. Catheters are not ideal for permanent access. They can become clogged, infect and cause narrowing of the veins in which they are placed
Permacath
In some people, fistula surgery or graft surgery fails and they must use a long-term catheter. Catheters that will be needed for more than 3 weeks or so are designed to be dug under the skin to increase comfort and reduce complications.And are called as Permacaths
Vascular Access Problems
Both AV fistulas and AVgrafts are most often lost because of thrombotic events, which are primarily related to mechanical vascular wall injury and abnormal flow, with lesions related to endothelial shear stress. The most common direct cause of late thrombosis is severe venous stenosis. a patient with vascular disease, such as diabetes mellitus, increasing age, increased thrombogenicity, inflammation, dyslipidemia and hyperhomocysteinemia, also predispose to the loss of the access system vascular
Central venous stenosis Manifestations such as high venous pressures dialysis ineffective prolonged bleeding Failure of AV graft and Caput Medusae
Early detection of impaired vascular access requires regular badessments of venous and arterial pressures, as well as visual inspection of the fistula and surrounding structures. To measure blood flow, a specific device (Transonic system) is required based on the technique of ultrasonic dilution and inversion of the blood lines of the inlet and outlet dialyser. Blood flow rates of thrombosis access systems overlap with non-thrombotic systems Blood flow can also be measured by Doppler ultrasonography next to the Transonic system
Clinical Criteria for the Venogram The venogram is a test to delineate the AX fistula and proximal blood vessels. Saline Dilution Technique or Augmentation of Venous Pressures or Maturation of Access and Edema of the Arms or Face A vesogram should be performed to exclude proximal venous stenosis
That is dialysis and fistula / transplant? obstructed or narrowed, which can prevent a patient from undergoing dialysis, interventionists use image-guided interventions to fix the oblem pr:
Catheter-directed thrombolysis, which dissolves blood clots that s'. accumulate in fistulas and grafts by injecting a drug.
Catheter-guided mechanical thrombectomy, where the clot is physically removed or crushed.
* Angioplasty and vascular stenting, which uses mechanical devices, such as balloons, to open fistulas and grafts and help them stay open. After balloon removal, a small tube of lattice called stent can be implanted to keep the fistula or graft open if angioplasty alone fails.
Therauptic Usage
Patients undergoing hemodialysis have narrowing fistula or dialysis grafts. In case of decreased flow in a graft or fistula, angioplasty or vascular stent angioplasty can be performed.
Thrombosis of fistulas or dialysis grafts. When blood does not flow easily, it can begin to coagulate, pbading from a free-flowing liquid to a semi-solid gel, called a blood clot or thrombus. When blood clots in a fistula or graft prevent dialysis, catheter-directed thrombectomy (clot removal) or thrombolysis with clot dissolving drugs may be performed
(The author is a surgeon vascular SSH Jammu)

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