Dialysis Flashcards
Higher 1yr patency rates:
Brachiocephalic or radio-cephalic?
Brachiocephalic arteriovenous fistulas offer several advantages over radiocephalic arteriovenous fistulas, including a higher maturation rate, decreased time to maturity, and higher primary patency and functional primary patency. Despite these benefits, radiocephalic fistulas are generally preferred if there is adequate conduit available to prolong sites for future access placement, as many patients are on long-term dialysis and need all access options preserved.
Access is patients with AICDs?
Arteriovenous accesses created ipsilateral to an AICD have a higher primary failure rate compared with the contralateral arm and should be avoided as much as possible. If adequate vein is unavailable in the contralateral arm, it would be appropriate to consider a venogram to assess patency of the central veins, although that is controversial.
Regional anesthesia in upper extremity fistulas
Regional anesthesia has been associated with longer operative time. Perioperative flow in the access has been shown to be higher and association with vasospasm has been shown to be lower. This translates to an improved short-term patency. Regional anesthesia has not been shown to affect major morbidity, including perioperative myocardial infarction and mortality.
Prolonged bleeding after hemodialysis?
Patients often have prolonged bleeding after dialysis due to an underlying venous outflow stenosis with relative venous hypertension. This patient needs a fistulogram and possible intervention.
Lower extremity dialysis access
Of lower extremity access studies have demonstrated the best outcomes for femoral vein transpositions. Patients undergoing femoral vein transpositions should have minimal to no peripheral arterial disease or ischemic symptoms of the lower leg can develop after the fistula is created. Saphenous vein transpositions are another option and have superior patency to synthetic grafts. The major concern with synthetic grafts is infection, which has been reported to be as high as 22% in one series. Overall long-term patency rates for lower extremity grafts is poor with approximately half patent at 6 months.
Differences between 1 and 2 stage brachiobasilic fistulas?
A recent systematic review and meta-analysis included data from 2 randomized controlled trials and 9 case control studies to evaluate the difference between one- and two-stage brachial-basilic arteriovenous fistula creation. It showed no difference in failure rates, primary or secondary 1-year patency, or secondary 2-year patency. There was no difference in infection rates, steal syndrome, hematoma, pseudoaneurysms, or stenosis. There was a significant improvement in 2-year primary patency in the two-stage group (relative risk, 2.50; 95% confidence interval, 1.66-3.74; p < .00001) and a trend toward increased postoperative thrombosis in the one-stage procedure, although that did not reach statistical significance.
Absolute contraindications to hybrid catheter-graft access
Addition to pic:
Graft patency is significantly compromised in patients with a low systolic blood pressure (< 100 mm Hg) or severely depressed ejection fraction (<20%).
Optimal timeing of fistula creation? AVG?
Ideal timing for autogenous arteriovenous access is 6 months prior to dialysis initiation, while prosthetic access should be delayed until about 3 to 6 weeks prior to dialysis initiation. Early autogenous access is associated with reduced sepsis and death risk compared to late access.
Risk of gadolinium contrast in those with CKD?
MRI should not be used due to the risk of nephrogenic systemic fibrosis with gadolinium administration in patients with a glomerular filtration rate less than 30-45 mL/min.
What is recirculation?
Venous outflow stenosis is the most common reason for arteriovenous graft failure. A low flow rate that fails to exceed the dialysis pump rate results in recirculation during the dialysis session.
What is significant arterial stemosis?
Greater than 50% stenosis of the inflow artery associated with a non-functioning AVF is considered significant and should be treated
Tapered vs non-tapered grafts
Tapered grafts are often used with the intent of decreasing the incidence of ischemic steal. Recent studies have demonstrated that tapered grafts for upper extremity access do not affect primary patency, development of steal, or complication rates. There was also no difference in the number of endovascular interventions performed in comparison to non-tapered grafts. Graft choice should be based on operator comfort and familiarity.
Most common cause of AVG thrombosis
Intimal hyperplasia and stenosis can lead to arteriovenous graft thrombosis. In prosthetic access, this most commonly occurs at the venous anastomosis. Central venous stenosis can also lead to graft thrombosis, particularly in patients with arm swelling and a previous history of central venous access.
Signs of brachial shetah hematoma?
Clinical presentation
* The symptoms start with progressive pain, numbness and weakness. Then, the patient feels tingling of the thumb, index, middle, and half of the ring finger.
* Loss of sensation in the area where it is supplied by the median nerve in the hand (figure 1).
Source: Southern and Sloan, 2010
Figure 1. The area in the hand where its supplied by the median nerve sensory part.
* Loss or reduce the ability to move the thumb away from other fingers due to paralysis of the thumb muscles and inability to do a pinch grip (figure 2). Patient can not do things that required forearm, or wrist repetitive movements.
Source; Mathiowetz et al., 1985
Figure 2. The pinch grip become poor with the patient with median nerve palsy due to paralysis of the thumb muscles.
* In addition, median nerve compression at the elbow level, result in hand of benediction due to loss of the innervation of the median nerve at the second and third digits (figure 3).
Endovascular AVF creation
An endovascular AVF (endoAVF) can be reliably created using a radiofrequency magnetic catheter-based system, without open surgery. This approach may reduce vessel trauma, leading to better fistula maturation, and potentially decreasing morbidity and improving patient acceptance. In the Novel Endovascular Access Trial (NEAT), the technical success rate of creating an EndoAVFs was 98%; 8% had a serious procedure-related adverse event (2% device related); and 87% were physiologically suitable for dialysis (mean brachial artery flow, 918 mL/min; endoAVF vein diameter, 5.2 mm [cephalic vein]). EndoAVF functional usability was 64% in participants who received dialysis with 12-month primary and cumulative patencies of 69% and 84%, respectively.
NSF
Nephrogenic systemic fibrosis can begin days to months, and even years, after exposure to an older gadolinium-based contrast agent (group 1). Some signs and symptoms of nephrogenic systemic fibrosis may include:
Swelling and tightening of the skin
Reddened or darkened patches on the skin
Thickening and hardening of the skin, typically on the arms and legs and sometimes on the body, but almost never on the face or head
Skin that may feel “woody” and develop an orange-peel appearance
Burning, itching or severe sharp pains in areas of involvement
Skin thickening that inhibits movement, resulting in loss of joint flexibility
Rarely, blisters or ulcers
In some people, involvement of muscles and body organs may cause:
Muscle weakness
Limitation of joint motion caused by muscle tightening (contractures) in arms, hands, legs and feet
Bone pain, particularly in the hip bones or ribs
Reduced internal organ function, including heart, lung, diaphragm, gastrointestinal tract or liver
Yellow plaques on the white surface (sclera) of the eyes
The condition is generally long term (chronic), but some people may improve. In a few people, it can cause severe disability, even death.
What AVFs have the best patency
Upper arm (brachial-basilic or brachial-cephalic)
What medical treatment improve patency?
CCB - Primery patency of AVG
Aspirin - Secondary patency of AVG
ARBs - improves AVG patency.
Ace-i - Primery Patency of AVF
ARBs + Antiplatlets - patency of AVF.
What medical treatment reduce patency?
Warfarin reduces AVG Primery Patency.
What 3 arterial factors improve AV success rate and patency?
No pressure differance between hands
Diameter of 2mm or above
Patent palmar arch
What venous factors improve AV success rate, matoration and patency?
Diameter of 2.5-3 is good of success and early maturation.
3mm is optimal.
What are the advantage of upper extremities shunt over lower extremities?
Lower infection rate.
Better and more comfortable access.
What are the main principals in planning and selecting shunt type and location?
Non dominant hand first.
Start as distal as possible.
Prefer autologous shunt
Prefer type of fistula by this order: Direct anastemosis, Venous transposition, Venous translocation, Prosthetic.
What is the preferred vein for fistula in the Forarm?
Chephalic
What is the order of seletction of arteries for anastomosis in the Forarm?
Posterior branch of Radial (Snuffbox)
Radial
Ulnar
Proximal Radial
Brachial
What is the chalange of using basilic vein in the the Arm and Forarm?
The vein is medial and always requieres transposition.
In case of no autologous vein in the Forarm, what is the next choice?
Translocation of Saphenous or femoral vein.
Prosthetic graft is the last choice as a bridge to AVF in the Arm.
What are the risk of too meny endovascular salvage treatments to AVF?
Can damage the venous outflow.
What is the preferred vein for fistula in the Forarm?
Chephalic
What is the order of seletction of arteries for anastomosis in the Arm?
Proximal Radial
Brachial
When would you prefer a two stage transposition access surgery over one stage surgery?
When the vein in less than 4mm
After how long can you use AFG?
2 weeks.
What is the avarge time to maturation of AVF?
12 weeks.
What is the disadvantage of Balloon assisted maturation (BAM)?
Patency equals prosthetic graft but more expensive.
What Graft-arterial ratio is abnormal?
>0.75
What Graft-venous ratio is abnormal?
<0.5
What is the 1 year primery and secondary partency of AVF?
Primery 85%
Secondary 90%
What is the 2 year primery and secondary partency of AVF?
Primery 69%
Secondary 75%
What is the 1 year primery and secondary partency of AVG?
Primery 54%
Secondary 65%
What is the 2 year primery and secondary partency of AVG?
Primery 30%
Secondary 60%
AVF - P vs. S - 1 vs 2 years
AVG - P vs. S - 1 vs 2 years
85, 90, 70, 75
55, 65, 30, 60
