5 Hemodialysis
Authors: Young Lee and Matthew Smeds
5.1 Planning access creation
Management of Dialysis access is an important topic of discussion, not only because it is a significant part of board examinations, but also because healthcare costs continue to rise for ESRD patients, particularly during the transition from CKD to ESRD. This is attributed to use of dialysis catheters and frequent hospitalizations for arteriovenous access failures and related procedures.
The National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-KDOQI) and SVS has provided guidelines in the follow areas:(Foundation 2015; Sidawy et al. 2008)
Timing of referral to access surgeons
Operative strategies to maximize placement of autogenous AV accesses
First choice for autogenous access
Choice of AV access when a patient is not a suitable candidate for a forearm autogenous access
The role of monitoring and surveillance of AV access management
Conversion of a prosthetic AV access to a secondary autogenous AV access
Management of nonfunctional or failed AV access
This brings us to the question, who needs dialysis access?
Patients should be referred to a vascular surgeon for access when their creatinine clearance is <25mL/min which is CKD stage 4. You want to provide adequate time for your autogenous access to mature, so the ideal time for access creation would be > 6 months before anticipated need of dialysis. This allows for time for any subsequent interventions if your access is not maturing.
Should prosthetic access also be placed several months before anticipated dialysis?
Prosthetic access patency is limited by duration of access placement, thus, if a patient requires prosthetic access, placement should be delayed until about 3-6 weeks before initiation of dialysis.(Foundation 2015)
For dialysis access creation, which site should be considered and used first?
Due to the easier accessibility and lower infection rates, upper extremity access sites are used first. Furthermore, you want to place your access as far distally in the extremity as possible to preserve the proximal arm for future accesses.
What are some important considerations in a patient’s history when planning a dialysis access?
It is important to find out recent history of:
Previous access procedures
Peripheral IV lines
Sites of any existing or previous indwelling catheters including pacemakers and defibrillators
Trauma or surgery to the upper extremities
Moreover, you also want to consider the patient’s quality of life, thus, noting which extremity is dominant is important. If possible, you want to create your dialysis access in the non-dominant arm so that when the patient is receiving dialysis multiple times a week, they are able to use their dominant arm during their dialysis sessions.
However, placing a fistula with lowest rate of failure is preferred to using non-dominant hand. Therefore, placement of access on the patients dominant side would be preferred over placement of access with high risk of failure (i.e. on the side of an implantable cardiac device).(Sgroi et al. 2019)
As with any preoperative planning, physical examination is extremely important. Central venous stenosis can cause problems such as prolonged bleeding after dialysis sessions at the puncture site. What are some signs of central venous stenosis?
Unilateral arm swelling or edema and prominent venous collaterals are signs of central venous stenosis. Central venous stenosis can lead to venous hypertension which affects access patency and function, and also causes disabling edema. Placement of AV access in a patient with undiagnosed SVC stenosis or obstruction can cause SVC syndrome.(Kalra, Bjarnason, and Gloviczki 2019)
Beyond signs of central venous stenosis, when examining a patient, an Allen’s test should always be performed to evaluate palmar arch patency.
Preoperative planning should also include arterial and venous assessments. What are your size requirements for the artery and the vein to be used in your dialysis access creation?
First, you want equal pressure gradients in bilateral upper extremities. If there is a pressure differential >20mmHg or pulses are non-palpable then patients should undergo a duplex ultrasound to evaluate for arterial insufficiency and and the artery should be greater than or equal to 2mm. Segmental pressures have limited applicability. Patients with correctable lesions on duplex may consider undergoing angiography and intervention to optimize inflow.(Sidawy et al. 2008)
A venous duplex should also be done to evaluate for diameter, distensibility and continuity. A vein mapping is useful to determine the size of the patient’s superficial veins at various points in the forearm and upper arm. The vein should ideally be at least 3mm, but 2.5mm will likely dilate after regional anesthesia and be sufficient for access particularly in smaller patients.(Huber et al. 2002; Smith, Gohil, and Chetter 2012)
Autogenous access should always be considered first due to higher patency rates, lower infection rates, and longer duration of access survival. What are the different configurations of autogenous accesses?
The first and best option would be direct arteriovenous anastomosis. However, if that is not possible, then venous transposition should be considered next follow by venous translocation.
Venous transposition is for deeper veins such as the basilic vein, which is transposed so the vein lies just below the skin for easier access for puncture during dialysis sessions. This can be done in either a one-stage or two-stage procedure. In a 2-stage procedure, the direct arteriovenous anastomosis is created during the first stage and once the vein has arterialized 4-6 weeks later, the second stage of transposition is done when the vein is easier to mobilize. Translocation procedures include harvesting the femoral or saphenous vein and using it as a conduit for AV access creation in the upper extremity.
When can a venous transposition be done in a one stage procedure?
Many surgeons will do a brachiobasilic arteriovenous fistula creation with the transposition in one-stage. However, if the vein is <4mm, it is generally recommended to do a two-stage procedure so that if the fistula fails to mature, the patient does not have to undergo a second operation with extensive dissection of the vein. When a patient has not been initiated on dialysis and there is marginal vein that would require transposition, but carry a significant risk of graft failure then a first-stage BB fistula may be appropriate.
When comparing single- to two-stage brachiobasilic fistula, two-stage creation had high rates of primary patency at 2-years. However, there was no difference in infection rate, steal syndrome, hematoma, pseudoaneurysm, stenosis, failure rate, primary or secondary patency at 1-year or secondary patency at 2-years.(Jun Yan Wee et al. 2018)
It was mentioned earlier that the dialysis access should be created as distally as possible on the extremity. What are some of the most distal locations?
The snuffbox fistula, which is the posterior radial branch to cephalic direct access and Brescia-Cimino-Appell (often shortened to just Cimino) fistula which is the radial-cephalic wrist direct access are two of the most distal fistulas that can be created. Overall, these have comparable patency and ischemia risk. While snuff box fistulas carry a 10% failure rate at 1mo, the majority are able to be converted to RC fistulas.(Siracuse et al. 2019)
Take a Listen
Check out our episode on the history of AV Access where we interview Dr. Kenneth Appell, one of the surgeons who pioneered this surgical technique.
What are your arterial and venous options in the upper extremity?
In the forearm, you have your radial, ulnar, and brachial arteries and cephalic and basilic veins. In the upper arm, you have your brachial or proximal radial arteries and cephalic, basilic, brachial and axillary veins.
If adequate vein is available, most common access sites distal to proximal include:
Snuff box
Radiocephalic
Basilic transposition in forearm
Brachiocephalic fistula - these have a few advantages over more distal fistulas, including higher maturation rates, decreased time to maturity, higher patency and functional primary patency.(Nguyen et al. 2007)
Brachiobasilic fistula(Gilmore 2006)
Vein transposition from a remote site - Femoral vein transposition can be used for upper extremity dialysis access in patients with previous upper extremity access complicated by infection, thus not a candidate for prosthetic, but no central stenosis. There is a high rate of hand ischemia due to larger conduit (up to 43%).(Huber et al. 2004)
If you need to use a prosthetic graft, what would you use?
PTFE is the most commonly used prosthetic graft. Either a 6mm graft or a tapered 4-7mm graft can be used. The tapered grafts help to ensure that the size of your arterial anastomosis isn’t too large to minimize chances of steal. However, recent publications found that there is no difference between tapered and non-tapered grafts in terms of primary patency, steal syndrome, complication rates or need for reintervention.(Roberts et al. 2019; Han, Seo, and Ryu 2017) Both the 6mm PTFE graft and the tapered 4-7mm PTFE grafts are standard sizes used for dialysis access creation.
Overall AVG have benefit of earlier cannulation, however they have lower patency rates and higher infection rates. There is no difference between grafts and fistulas for perioperative morbidity and mortality.(Macsata and Sidawy 2019)
Most prosthetic access will fail because of the development of venous outflow stenosis as a result of smooth muscle proliferation at vein graft interface. Thus, a major cause of graft failure is due to thrombosis. Heparin-bonded PTFE (HB-PTFE) grafts are an option, however, studies have shown no improvement in graft patency with HB-PTFE compared to standard PTFE grafts.(Shemesh et al. 2015; Davies, Anaya-Ayala, and El-Sayed 2016)
There are also early cannulation prosthetic grafts, which is another option for patients who need more immediate dialysis access. These grafts are constructed in 3 layers with an elastomeric membrane in the middle between two layers of ePTFE material. This allows for cannulation as early as 24 hours from implantation because the graft configuration minimizes dialysis needle bleeding. This graft options allows for avoidance of a central venous catheter. Studies have shown similar patency rates compared to standard ePTFE, earlier cannulation and catheter removal, and decreased catheter related complications.(Julien Al Shakarchi and Inston 2019; Wagner et al. 2019)
For patients with central venous stenosis or occlusion, what is another alternative upper extremity access creation?
Two overall strategies for managing patients with severe central venous stenosis or occlusion are lower extremity AV access of hybrid catheter/grafts. Patency of femoral vein transposition is better than hybrid catheter/graft placement.(Brownie 2016; Glickman 2011) We will cover specifics of these techniques later.
For lower extremity AV access, femoral vein transposition has been shown to have the best outcomes, followed by saphenous vein transposition and graft placement. Lower extremity access should be avoided in patients with peripheral vascular disease or lower extremity ischemic symptoms–when in doubt perform duplex and segmental pressures to fully evaluate. Veins should also be evaluated to ensure patency more proximally.(Parekh, Niyyar, and Vachharajani 2016)
For patients where lower extremity access may not be appropriate, the hemodialysis reliable outflow (HeRO) device can come to the rescue. These devices may not have been encountered in your training, so we will go into detail here. This device is composed of 2 components: a graft which is made of 6mm PTFE with a titanium coupler at one end, and a venous outflow component of a 19 Fr silicone catheter reinforced with a nitinol braid to prevent kinking. The graft portion is anastomosed to an artery, usually brachial, and is tunneled subcutaneously and the venous component is percutaneously placed into the right atrium via the IJ or subclavian vein. The two components are connected with a titanium coupler at the deltopectoral groove. If you need more immediate dialysis, the super HeRO comes to the rescue in which the graft portion is the early cannulation graft.
For patients with thoracic central venous occlusion, there is also the SURFACER inside-out access catheter system. This is a device used to cross central occlusions from the right femoral vein. It allows placement of a tunneled central venous catheter, but it can also be utilized as an adjunct for HeRO placement. In a multicenter study, the results from the SAVE (Surfacer System to Facilitate Access in Venous Obstructions) registry showed that in 29 or 30 patients with thoracic central venous occlusion, a central venous catheter was successfully placed. Moreover, there were no device-related adverse events, catheter malposition, or intra- or postprocedural complications. (Gallieni et al. 2020)
Hybrid catheter/grafts are good alternatives in patients with previous line infections, central stenosis, peripheral vascular disease and no suitable vein in the upper extremities. They have shown fewer bacteremia episodes than catheter, low primary patency rate and acceptable secondary patency rates.(J. Al Shakarchi et al. 2015) Absolute contraindications include donor artery <3mm, inability to dilate outflow vein to 19f, allergy to device materials (ePTFE, silicone, titanium, nitinol), and current active infection.(Medical, n.d.)
5.2 Techniques for access creation
The techniques of arteriovenous fistula creation are common across access sites. Can you go through the techniques?
First the vein is identified and the distal end is transected and flushed with heparin. By flushing with the heparin, you are able to access the caliber and extent of the vein as well as identify any side branches
Then after distal and proximal control of your artery, a 4-6mm arteriotomy is made. The length is limited to decrease incidence of arterial steal. The artery is then flushed with heparin to avoid thrombosis during the anastomosis and an anastomosis is created between the side of the artery and the end of the vein. A 6-0 or 7-0 nonabsorbable continuous suture should be used to create the anastomosis to avoid future dilation of the anastomosis.
For prosthetic accesses, the length of the arteriotomy does not have to be limited to 4 to 6mm since the incidence of arterial steal is limited by the graft diameter. Both arterial inflow and venous outflow vessels need to be dissected prior to graft anastomoses. The graft should be tunneled close to the surface of the skin to allow for easier cannulation. Meticulous attention to sterile technique is important to avoid graft infections. And as with the fistula creations, a 6-0 or 7-0 nonabsorbable continuous suture should be used to create the anastomosis to avoid future dilation of the anastomosis.
Take a Listen
What are some other options if an access is not able to be created in the upper extremity?
Autogenous accesses can also be created in the lower extremity. Femoral artery to femoral vein or saphenous vein anastomosis can be created. Both veins have to be transposed. Synthetic grafts have high infection rates (as high as 22% in some series) and only a 50% patency at 6 months.(Antoniou et al. 2009; Lazarides et al. 2018; Pike et al. 2019) Risk of lower extremity ischemia increased with burden of PVD, AV fistula vs graft, distal arterial inflow, and large femoral vein mismatch, but can be tempered by banding/narrowing of femoral vein at the time of surgery.(Antoniou et al. 2009; Bourquelot et al. 2012; Gradman, Laub, and Cohen 2005)
Access creation in the chest wall or cervical region is also possible with axillary artery to ipsilateral axillary vein loop access, axillary artery to contralateral axillary or jugular vein straight access (ie necklace access) and brachial artery to jugular vein straight access. Keep in mind that for these fistulas, the central veins must be patent.
5.2.1 Anesthetic Considerations
Are there benefits to different anesthetic techniques used during access placement, such as regional anesthesia?
Regional anesthesia for AVF creation has been associated with higher perioerative flow and lower rates of vasospasm resulting in higher rates of short term patency. Regional anesthesia has not been associated with perioperative rates of major morbidity or mortality.(Aitken et al. 2016; Siracuse et al. 2014)
Due to underlying comorbidities, it is often best to avoid general anesthesia in these patients. Many access procedures can be performed under regional or straight local anesthetic. There, it is very important to understand the pharmacokinetics and maximum doses of common local anesthetics.(Neal et al. 2018) Historically, it has been taught that the inclusion of epinephrine allows for higher dosages, but more recent reports do not include this adjustment.(Sztajnkrycer 2019) Common local anesthetics include:
Bupivacaine - Long acting. Max SubQ Dose is 2mg/kg.
Lidocaine - Medium acting. Max SubQ Dose is 4.5 mg/kg.
Mepivacaine - Medium acting. Max SubQ Dose is 4.4 mg/kg.
Ropivacaine - Long acting. Max SubQ Dose is 3 mg/kg.
5.2.2 Endovascular AV Fistula
What is the role for endovascular creation of AV fistula?
Endovascular approach to fistula creation without open surgery is another option for dialysis access creation. The results of the NEAT study (Novel Endovacular Access Trial), prospective multicenter study which showed that 98% of the 80 patients enrolled had EndoAVFs created. Of these, 87% were physiologically suited for dialysis, and functional usability (2 needle cannulation) was 64%. Primary patency was 69% and and cumulative patency was 84%. Total complication rate was 8% and this is a promising alternative to surgical arteriovenous fistula creations. (Lok et al. 2017)
5.3 Maintenance and complications
When is the newly created dialysis access ready for use?
A good way to remember this is the rule of 6’s. Fistulas should be created about 6 months prior to start of hemodialysis. It is ready to use when the fistula is 6mm in diameter, has a flow of 600ml/min, is 6mm from the surface of the skin and usually takes 6 weeks to mature.
Prosthetic AV accesses can be used as early as 2 weeks postoperatively. If you use the 3-layer early cannulation grafts, the access can be used as early as 24 hours after access creation. This is great because it offers the potential for avoidance of dialysis catheters in patients who need dialysis immediately.(Glickman et al. 2015)
5.3.1 Failure to mature
What are some reasons why an access may fail to mature?
Sometimes your access may have arterial inflow stenosis. This is difficult to detect clinically because there will be a palpable thrill, however, due to the stenosis, the flow is not sufficient enough for dialysis. Dialysis access duplex is a useful way to assess flow volumes and identify areas of stenosis that could be further assessed with fistulogram. In the absence of arterial inflow issues, collateral or large venous branches can divert blood away from the main access channel resulting in insufficient flow. This can be resolved by coiling or ligating the large venous branches that limit maturation of the fistula.
If the newly created AV fistula is not maturing, what are some secondary procedures to help with maturation?
First a duplex ultrasound can help to identify whether this is an inflow, outflow, or conduit issue. Once the likely source of the issue is identified, then there are multiple open or endovascular techniques to assist maturation.
Endovascular procedures include arterial and venous angioplasties to improve inflow or outflow issues.(Sidawy et al. 2008) In particular, balloon assisted maturation (BAM) has been described to decrease maturation time. A prospective randomized controlled study by Elkassaby et al. showed that BAM significantly decreased maturation time and had higher successful functional maturation. However, BAM was also shown to have increased fistula complication rates.(Elkassaby et al. 2021) Open procedures include vein patches, interposition vein grafts, vein transposition to proximal arteries, branch ligations, and vein superficialization.
5.3.2 Access Failure
Once a dialysis access is created, maintenance of the access is extremely important. The flow disturbances and hemodynamic changes associated with AV access creation causes intimal hyperplasia leading to venous outflow stenosis. This can ultimately lead to access thrombosis and failure. What are some methods of detecting access failure?
One way of detecting a well functioning access is a strong thrill at the arterial anastomosis which continues a few centimeters into the outflow vein. If you feel a pulsation near the venous outflow, then a stenosis or thrombosis is likely. If you feel a thrill distal to the area of pulsation, then you have likely localized your area of stenosis. It is important to note that you may feel a pulsation at a pseudoaneurysm independent of venous outflow issues.
Other signs of outflow stenosis are collateral veins or upper extremity edema.(Padberg, Calligaro, and Sidawy 2008) This is indicative of venous hypertension likely secondary to stenosis. You will typically see this in the shoulder area or anterior chest as a results of subclavian vein stenosis/thrombosis. Moreover, these high venous pressures as a result of the stenosis can result in excessive and prolonged bleeding after removal of needles from the dialysis puncture sites. This is often the first sign of elevated venous pressures. These patients should undergo a fistulogram to evaluate for underlying outflow stenosis.(Caro Monroig et al. 2018) Sometimes, a hematoma from dialysis access cannulation can result in compression of the fistula. In these cases, the hematoma should be drained to relieve the compression.
The most common cause of graft failure in upper extremity fistulas is venous outflow stenosis and in grafts is venous anastomotic intimal hyperplasia.(Berman and Gentile 2001; Padberg, Calligaro, and Sidawy 2008) Diagnostic fistulogram is a very useful tool to diagnose and treat potential access complications. Diagnostic fistulogram is often performed with proximal access of the fistula a few centimeters distal to the anastomosis. Compression of venous outflow is necessary to evaluate for inflow and anastomotic issues.(Bountouris et al. 2018)
Finally, even patients with normal physical exam can have issues while on the hemodialysis circuit, such as recirculation. When in doubt, if there are recurrent issues with hemodialysis, the patient should undergo a fistulogram to evaluate for occult venous outflow stenosis that may be missed on other diagnostic modalities.(Sidawy et al. 2008)
What are some endovascular interventions for a failing access?
First line therapy for outflow stenosis is a simple balloon angioplasty of the stenosed area.(Berman and Gentile 2001) Insufflation times are generally up to 2-3 minutes. Treatment of stenosis 2/2 intimal hyperplasia often require high pressures of 20 ATM or more. However, this is a double edge sword because this can lead to trauma in the veins stimulating a further intimal hyperplasia process. Some advocate a cutting balloon before high pressure dilation. There are also studies showing improved primary patency with drug coated balloons with no difference in survival compared to plain angioplasty.(Han, Seo, and Ryu 2017; Chen et al. 2020; Moreno-Sánchez et al. 2020; Yin et al. 2021) Stenting is also an option to treat residual stenosis or dissections after balloon angioplasty. Covered stents have shown good patency results.
Some unique situations include, recurrent cephalic arch stenosis which may be best treated with bare metal stenting.(Shemesh et al. 2008) Proximal occlusions (i.e. subclavian) may be best treated primarily with a covered stent.(Agarwal 2015; Anaya-Ayala et al. 2011)
If endovascular interventions fail, what are some open options for managing a failing access?
Generally an interposition graft or patch angioplasty is performed and the results of the two techniques are largely equivalent.
If an AV access has ultimately failed and thrombosed, what are your endovascular options at this point?
Some endovascular options are catheter directed thrombolysis with about 2-4mg of tPA injected into the clot, followed by balloon angioplasty (typically an 8mm by 8cm high pressure balloon). A mechanical thrombectomy device, such as angiojet, can also be used in combination to thrombolysis.
Alternatively, an open thrombectomy with a thromboembolectomy balloon and patch angioplasty of venous stenosis areas can also be used. Moreover, a hybrid approach of open thrombectomy with percutaneous interventions of venous stenosis areas has been described. Thrombosed fistulas are difficult to salvage, but thrombosed AV grafts have a high likelihood of successful recannalization and should be managed aggressively.
Immediate postoperative thrombosis of an AV graft is likely technical - inadequate inflow (i.e. small brachial artery) or outflow stenosis/occlusion. Open revision and thrombectomy is often the best option.(Paulson, Ram, and Zibari 2002)
What are some ways to manage failing AV access in the setting of ipsilateral vTOS?
Performing a first rib resection in a hemodialysis patient is high risk and controversial. However, if there is a prominent external jugular vein, then there are reports of external to internal jugular vein transposition offering more in line drainage and access salvage.(DeGiovanni, Son, and Salehi 2020)
5.3.3 Steal Syndrome
Earlier, you mentioned steal syndrome, can you explain to us what this is?
Steal syndrome is also known as Access Related Hand Ischemia (ARHI). It is an uncommon but devastating complication of access creation. All patients with arteriovenous fistulas have some degree of physiologic steal or reversal of flow in part of the artery distal to the fistula. However, this is not sufficient enough to cause ischemia. Rather, ischemia results from inadequate collateral circulation and inability of peripheral arteries to meet the increased demand. Diseased vessels do not dilate and stenosis of arteries leads to decreased distal perfusion pressure. Furthermore, hypotension during dialysis further decreases perfusion causing symptoms. Steal can be limb threatening and is graded as follows:
Grade 0 - asymptomatic, no flow augmentation or steal
Grade 1 - asymptomatic, mild ischemia with signs of cool extremity and flow augmentation with access occlusion (May be seen in over half of AV access patients)(Leake et al. 2015)
Grade 2 - moderate/intermittent ischemia that is experienced only during dialysis and patients feel effort induced ischemic pain.
Grade 3 - severe, ischemic pain at rest with tissue loss.
What are some symptoms and signs of Steal syndrome?
Symptoms include coolness, parasthesias, rest pain, and weakness. Signs of steal include cool to touch, pallor, cyanosis, delayed capillary refill, absent pulses/signals, diminished sensation, weak grip, and in severe cases ulceration or gangrene. If the patient shows improvement with access compression, diagnosis is confirmed.
Patients with acute pain and loss of pulses immediately after AVF creation should first have arterial injury/thrombosis ruled out, but then after diagnosed with steal syndrome should undergo fistula ligation.(Schanzer and Eisenberg 2004; Yevzlin, Chan, and Asif 2016)
When is an intervention necessary to treat steal syndrome?
You do not need to intervene for grade 0 and 1.(Leake et al. 2015) For grade 3 an intervention is mandatory. The goal of treatment includes symptom resolution and access preservation, and this is achieved by reducing access flow and increasing distal arterial flow.
The most important finding on duplex ultrasound to evaluate for steal syndrome is fistula flow rate. High flow rates suggest a primary problem with the fistula, low or normal flow suggests underlying PVD and inflow insufficiency as etiology.(Julien Al Shakarchi et al. 2016; Leake et al. 2015) Approximately 5% of steal is secondary to inflow stenosis.
What are your intervention options for resolving steal syndrome?
There are multiple ways to manage steal syndrome, detailed as follows:(Leake et al. 2015; Gupta et al. 2011)
AV Fistula Banding is a simple option to reduce access flow. This is done by suture plication, placement of single narrowing tie or wrap by constrictive cuff to cause a stenosis in the AV access near the arterial anastomosis.
A minimally invasive approach is used by the MILLER banding which uses an endoluminal 4 or 5mm balloon as a sizer and a suture is placed around the access with the balloon inflated.
This procedure increases arterial inflow towards the hand. One technique describes using intra-operative finger pressures and plication to result in intraoperative increase in finger pressure by 20% or a minimum of 90mmHg. Flow should be maintained at 600ml/min.
Revision using distal inflow (RUDI) involves ligation of the fistula at the arterial anastomosis and reestablishment of flow via a more distal artery by bypass or vein translocation. This allows for decreased flow through the access by reducing the fistula diameter and by taking inflow form a smaller vessel. However, ultimately, the fistula is placed at risk.
Proximalizaiton of arterial inflow (PAI) involves ligation of AV anastomosis, and the inflow is moved to a more proximal level with a prosthetic interposition. Dialysis can be continue via the vein. The main advantage is the native artery’s continuity.(Zanow, Kruger, and Scholz 2006)
Distal revascularization-interval ligation (DRIL) is ultimately considered the best option by many vascular surgeons due to the excellent results shown. There is an arterial bypass created originating proximal to the access and ending distal to the access, with ligation of the artery distal to the anastomosis. This prevents retrograde flow from distal vessels and allows for a low resistance pathway for arterial supply to the hand. DRIL may be particularly useful in patients with distal brachial, proximal ulnar/radial disease, as this can bypass the underlying stenosis as well.(Leake et al. 2015)
Distal radial artery ligation (DRAL) can be performed for palmar arch steal syndrome from radio-cephalic av accesses, to prevent reversal of flow in the palmar arch. However, the ulnar artery patency needs to evaluated first.
5.3.4 Neuropathy and Neuropraxia
What complication often presents like steal syndrome, but with easily palpable distal pulses?
Access creation can result in neuropathy. It is important to note that over 2/3s of the patients have preexisting peripheral neuropathy. Neuropathy is also graded:
Grade 0 - asymptomatic
Grade 1 - mild intermittent changes (pain, paresthesia, numbness with sensory deficit)
Grade 2 - moderate persistent sensory changes
Grade 3 - severe sensory changes with progressive motor loss (motion, strength, muscle wasting).
Ischemic Monomelic Neuropathy (IMN) is rare but occurs acutely after AV access creation. Within hours of surgery, patients develop acute pain, weakness, or paralysis of hand and forearm muscles with prominent sensory loss. However, the hand is warm with palpable pulse or audible signal in distal radial and ulnar arteries. It is important to note that pain out of proportion is what differentiates IMN from ARHI. Treatment is access ligation or emergent augmentation of flow.
5.3.5 Perioperative neuropraxia
What are some common technical complications after placement of AV access?
Post operative numbness of the thumb, index and middle finger and weakness of abduction and grip strength may suggest median nerve neuropraxia and will likely resolve. However, you need to rule out steal syndrome.(Talebi et al. 2011; Vahdatpour et al. 2012)
Postoperative hematoma can often just be observed. However, signs of median nerve compression mandate immediate operative brachial sheath evacuation or the neurologic deficits may become permanent.(Padberg, Calligaro, and Sidawy 2008)
Prosthetic grafts can results in seroma from ultrafiltration of the graft and most resolve without intervention.
5.3.6 Bleeding and Aneurysm
What presentations require urgent revision?
Fistulas that present with bleeding from a visible ulcer, wet scabbing, frank infection or acute pseudoaneurysm often require urgent open revision. Some access may be salvaged, but in acute presentations with significant risk of life threatening hemorrhage the safest option may be to ligate the access and place a temporary dialysis access line.(Galbusera, Remuzzi, and Boccardo 2009)
Many fistulas develop aneurysms over time. When do fistula aneurysms require revision?
Pseudoaneurysms often result from trauma due to repeated punctures or poor technique
True aneurysms result from long standing hemodynamically significant outflow stenosis.(Hossny 2014; Patel et al. 2015)
Both can lead to cannulation difficulties, increased risk of thrombosis, pain, bleeding and cosmetic deformities. AV aneurysms should be revised if they develop skin thinning, ulceration or bleeding. Early skin changes can be observed. Intervention often requires revision with open plication/excision or ligation. When isolated to a short segment, attempts should be made to salvage the fistula.(Al-Jaishi et al. 2017; Al-Thani et al. 2017; Pasklinsky et al. 2011)
5.4 Dialysis Catheters
While ideally every patient would have surgically placed access, many patients still receive dialysis through catheters. What is the difference between an acute and chronic hemodialysis catheter?
Chronic catheters have a subcutaneous cuff at the exit site and tunneled to the vein. This decreases infection rates and makes them less likely to become dislodged. Tunneled hemodialysis catheters can be used up to 12 months.
If catheters cause so much problems such as infection and central venous stenosis, what would be an indication for them?
The most common indication would be for urgent hemodialysis. But other indications include patient who are not operative candidates due to advanced comorbidities, or patients who are unable to have an AVF or AVG due to anatomic feasibility. Temporary dialysis access may also be needed in patients who have just had a peritoneal dialysis catheter placement or in chronic peritoneal dialysis catheter patients requiring abdominal or inguinal surgery.
Which site is the most ideal site for a hemodialysis catheter?
The right internal jugular vein with a tip in at the cavo-atrial junction is preferred because it has the best patency. Subclavian veins are avoided due to high risk of stenosis and femoral veins are avoided due to infection risk.
If all traditional access sites are inaccessible, translumbar IVC catheters may be used as a last resort as salvage. Overall complications are similar to other permanent dialysis access sites, however obesity is a relative contraindication due to potential migration into the soft tissues.
Every procedure has potential complications. What are the immediate complications of catheter placement?
When placed in the internal jugular veins, there is always a chance of a pneumothorax or hemothorax. Wire embolism can occur is control of the wire is lost during the procedure. If the guidewire is placed too far, then there is always a chance of arrhythmia. Thus, the best place for the wire is through the IVC. With a left internal jugular vein approach, there is always a risk of thoracic duct laceration. If a leak is apparent, then the catheter needs to be removed immediately and a pressure dressing applied.
How do you manage infected hemodialysis lines?
Infected hemodialysis lines should be removed. Ideally you should avoid replacing any lines until blood cultures have been negative for 48hrs, particularly subsequent permanent lines(Group 2006)
5.5 Peritoneal Dialysis
Although not often managed by the vascular surgeon, we should still be aware of another method of dialysis in renal failure patients. What are the indications for peritoneal dialysis?
Peritoneal dialysis is better tolerated and less disruptive to daily life, so is often a better option for young, active patients with less comorbidities. PD can be considered first-line or in patients who are not candidates for HD, but require high patient engagement and education and so may not be appropriate for patients with other chronic diseases limiting independence, unstable housing, cognitive decline or poor management other medical issues.(Ansari 2011)
From a technical standpoint, PD may be difficult in patients who have had multiple previous open abdominal surgeries, but can be tolerated in patients who have had minimally invasive or minor abdominal procedures.(Sinnakirouchenan and Holley 2011) Long dwell times with glucose solution can sometimes lead to hyperglycemia. The major reason for conversion from PD to HD is PD catheter infection.(Li et al. 2017)