Vascular Access Surgery

Pre-op Workup
Duplex USS of arm veins and arteries.
- if not enough info, consider angio
Cardiac, pulmonary and clotting function analysis
Consider anticoagulants.
Best to receive patients before they are on chronic dialysis; more likely to have unmutilated veins that can be used for fistula instead of prosthetic graft.

AV Fistula: Technical Aspects
1. Place the fistula as distally as possible.
- allows chance for revisions further up the arm
- radial-cephalic preferred; then brachial cephalic, then brachial basilic
2. Ideally pick a vein branch point;
- can ligate two ends and use large aperture for the fistula.
3. Fashion with running monofilament e.g 4-0 prolene
Ideally performed by high-volume experienced surgeons for best results.
Take 4-12 weeks to mature ready for use
- but can usually be used within 10-14d

Complications
Thrombosis
- may need endovascular therapy, or revision
Infection
- can lead to secondary abscesses, endocarditis etc.  S. aureus particularly prominent agent.
- usually from chronic cannulation and not the surgical aspect; suspect hygienic practice when using fistula
- suspect fistula infection in bacteremias of unknown origin
Also seromas, aneurysms, pseudoaneurysms, prox. vein occlusion, bleeding.
If failure, grafting better than going back to haemodialysis through central cuffed catheters (infective risk).



 

What are the options for dialysis access

            Catheter base: Peritoneal dialysis and Haemodialysis via venous catheters

            Tissue Base: AV fistula formation

What are the other indications for vascular access

        High flow angioaccess for dialysis

        Sclerotic solutions are administered IV – chemotherapy, TPN

        Frequent administration of blood or blood products or drawing of blood is required

How do you insert a central venous catheter

In an appropriately consented, investigated and prepared patient

Preparation should include a FBC and coag screen.

Pre-op venous duplex should be arranged in patients with previous lines or history to suggest venous obstruction

        My preference is always for IJ canulation because of the lower rate of stenosis and fewer implications for subsequent fistula formation

        Supine. Rolled fluid bag between shoulders. Head ring. 5 degrees Trendelenberg to distend veins and reduce the risk of air embolus. Turn head to contre-lateral side. Sterile prep and drape. ECG monitoring, SaO2 and oxygen via nasal prongs.

        Mark the landmarks with pen – SCM, Clavicular head and level of cricoid. I use fluoroscopic control.

        I approach the vein about 2 fingers above the clavicle. I check the contents of the kit, flush all lumens of the catheter with saline and check for any leaks in catheter.

        I place the thumb of my non-dominant hand on the Carotid pulsation and my index finger on the sternal notch for orientation.

        I use my thumb to protect the carotid artery medially.

        Infiltrate 1% lignocaine  10ml aspirating before injection.

        I use a 23 needle with a 10ml syringe to locate the vein by inserting it into the skin and pointing at the clavicular head until drark blood is draw. If bright red blood comes out, I withdraw the needle and press for 10 minutes.

        Once the IV is located with the small needle, I use a larger 16g long needle with a 10ml syringe filled with 3-4ml of saline to canulate the vein. Some kits have syringe which allows passage of the guidewire down the hub of the syringe. If the kit does not include this, I remove the syringe and advance the guidewire through the needle. I use fluoroscopy to ensure that the catheter passes to SVC and watch the ECG monitor for ectopic beats.

        Once I am satisfied with the guidewire position, I insert remove the needle and exchange it for the dilator over the guide wire and dilate the tract into the vein.

        I remove the dilator and make a small incision over the wire exit site.

        I thread the catheter over the wire to the desired length to the estimated junction of SVC and RA (Level of angle of Louis).

        I secure the flange to the catheter and suture the flange with two 0 nylon sutures and cover with tegaderm.

Why do you use the IJ

        The risk of venous stenosis is greater in the subclavian vein (50% in 2 weeks). This  substantially increases the risk of fistula failure or swollen arm when an AV fistula is constructed and so the IJ is preferential access site for renal patients (IJ stenosis rate <10%).

        It is easier to use US-guided technique in the IJ.

        Arterial puncture is easier to control.

Where do you place the puncture site for the subclavian vein

        One cm below the junction of inner 1/3 and outer 2/3 of calvicle.

        I place the non-dominant hand on the chest with index finger pointing to the sternal notch.

        I infiltrate local.

        I walk the needle down to the undersurface of the clavicle and direct the needle to the sternal notch with the needle shaft almost parallel to the floor.

How do you use US

        I use a 5MhZ linear US transducer

        I use the device before sterile prep to provide general orientation and adjust the settings on the machine. I mark the IJ and CA: the IJ is the larger, more superficial and more compressible vessel

        I then cover the probe with sterile sheath and use sterile jelly during catheterization.

        I use the US probe transverse to the long axis of the vein.

        I stand at the head of the bed with the transducer in the non-dominant hand transverse to the long axis of the vein.

        I  insert the needle cephalad to the probe, with the needle seen as a bright spot in the vein.

        The needle is seen as a hyper-echoic spot.

How do you insert a tunnelled line (Hickman type)

        Canulation of the vessel (IJ or subclavian) is the same using a Seldinger tecnhque.

        The vessel is canulated using a canula with a peel away outer sheath.

        An incision is made on the anterior chest wall, usually over the 4th IC space.

        A tunnelling device is inserted from the chest wall incision to the subcutaneous tissue underlying the vessel puncture site. A heavy suture is pulled back into the remote exit site and tied to the tip of the silastic catheter which is then pulled back through exit site where the vessel was punctured.

        The Dacron cuff is secured 4cm from the skin exit site.

        The length of silastic catheter required is estimated so that it will lie at the junction of SVC and RA. The silastic catheter is flushed with saline

        The catheter is trimmed.

        The introducer is removed leaving the peel-away catheter in place.

        The silastic catheter is threaded down the peel-away catheter which is then peeled away as the silastic catheter is advanced.

        The skin is closed over the vessel puncture site with 3/0 Nylon. An occlusive, opsite dressing is placed over the puncture site.

        The tunnel exit site is closed around the catheter with interrupted 3/0 nylon either side of catheter.

How do you insert the infuse-a-port type device

        It is the same as a hickman line except a pocket is created on the chest wall, exposing the pectoral fascia. The infusion port is fixed to chest wall by placing sutures that pass through the flanges of the port onto the fascia of the chest wall in 4 places to ensure that the port will not flip.

        It is vital that a non-coring Huber needle of no more than 22g is used to avoid damage to the silicon rubber septum

What are your post-procedure instructions

        Monitoring ECG, SaO2 and BP for 1 hour post procedure whilst an erect CXR is performed to check position and exclude pneumothorax.

        If a penumothorax is small (<30%) and the patient is asymptomatic, it can be observed with observation in hospital and repeat CXR in 6 hours. A chest drain is required if it is enlarging or large or the patient is symptomatic.

What are the modes of access for dialysis

External angioaccess

Internal angioaccess

Prosthetic jump graft

What are the types of external angioaccess

        Non-tunnelled central venous catheter inserted into subclavian, IJ, femoral – usually used for emergency access or short term <2 weeks

        Tunnelled central venous catheter inserted into subclavian, IJ

        Peripherally inserted central catheter.

        Catheters may be totally implantable (Port-a-cath or infuse-a-port) or external (Hickman).

        Catheters may have a Dacron cuff which prevents infection

What are the devices used for dialysis

        Dual lumen silicone rubber or polyurethane catheters (Vascath or Permcath)

        Soft and placed using the Seldinger technique in the IJ or EJ vein using a peel-away sheath.

What are the problems peculiar to dialysis central venous lines

        Recirculation of blood via the catheter. When placed in IJ there is only about 5% recirculation. This is a more common problem in femoral vein catheterization than IJ or SV

        Venous stenosis caused by temporary access may complicate subsequent fistula formation. More common with subclavian than IJ placemnt of catheters

What are the complications of central venous catheter insertion

        Immediate

§  Pneumothorax (1-4%), haemothorax, arterial injury, air embolus, injury to nerves (Vagus, sympathetic trunk, phrenic, femoral), bleeding, great vessel injury, inability to advance the catheter, pericardial tamponade.

        Early/late

§  Thrombotic: Presents as inability to draw blood. Clot may be in catheter or in vessel surrounding catheter (fibrin sheath) or both. May be due to irritation of wall by catheter, hypercoagulable state or irritatnt nature of infusion. Contrast radiograph to check position and integrity of catheter is necessary. If the catheter is surrounded by fresh thrombus, use a small amount of tPA to lyse the clot. Treat for DVT with heparin and warfarin.

·       Prevention of thrmbosis includes low dose warfarin (1mg) or heparin flushing of catheter

§  Catheter infection: Rate is about 2 infections per 1000 catheter days. More common with thrombosis, multi-lumen catheters, immuncompromise. May be early or late. May be exit site or catheter-related sepsis. Diagnosis can be obscure. Most definitive is catheter tip culture, this requires catheter removal. Alternatives include CFU counts (>15 CFU/ml confirms diagnosis) and ratio of catheter to blood culture CFU (10:1 confirms diagnosis). Prophylatic measures include strict asepsis at insertion, coating the catheter with Abx or anti-septic solution (internal and external coating with Rifampicin appears superior).

·       Treatment options –

            Systemic Abx via the line directed against the offending organism. If deterioration or failure to improve after 48 hours then remove catheter.

            Removal of catheter is appropriate for severe infection with systemic sepsis.

Trying to conserve the catheter may be appropriate for patients needing long-term access where other sites are not available or need to be conserved with mild, superficial infection and no sepsis.

For exit site infection, the catheter can be exchanged over a guide-wire and a new exit site chosen.

§  Mechanical complications – The catheter is malpositioned, there is shearing between the clavicle and first rib. If malpositioned (eg passed down subclavian/axillary branch) must be re-positioned. If shearing between the clavicle and first rib is suspected then remove to prevent breaking and embolization.

What are the types of AV fistula

        Natural and prosthetic

        The complications and costs of natural fistulas are lower and these are preferable.

What are the types of natural fistula

        Site:

o   Radiocephalic at wrist – Brescia-Comino

o   Posterior radial branch-cephalic (snuff box fistula).

o   Ulnar cephalic forearm

o   Radial basilica (Fienberg)

o   Brachial cephalic (antecubital vein to brachial artery)

o   Brachial basilica

        Type of anastomosis

o   Side artery to side vein – higher rate of venous hypertension in hand (swelling and ulceration)

o   End-vein to side artery

o   End artery to side vein

o   End to end – higher rate of thrombosis

How do you evaluate a patient for a fistula

        First preference is for non-dominant radio-cephalic (Brescia-Comino graft)

        Allen’s test to confirm adequate collaterals via ulnar artery

        Duplex mapping – an artery >2mm and vein >2.5mm

        If suspicion of vein stenosis then venogram to allow visualization of stenosis behind the clavicle

How do you make an AV fistiula

Bresia-Cimino (radiocephalic)

        In an appropriately consented, investigated and prepared patient

        Preparation should include a FBC and coag screen.

        Side should be marked. Preferably non-dominant hand

        Pre-op venous duplex should be arranged in patients with previous lines or history to suggest venous obstruction

        GA. Supine. IV cefazolin. Arm table. Sterile prep and drape including preparing the hand so that perfusion can be assessed.

        Incision is 4cm long 1cm lateral to the radial artery starting just distal to the proximal skin crease of the wrist.

        Use diathermy to stop dermal bleeding. Using skin hooks deepen incision down to deep fascia and divide the fascia over the medial aspect of brachioradialis tendon

        I elevate skin flaps laterally and locate the cephalic vein.

        I isolate a sufficient length of cephalic vein to easily reach the radial artery. I mark the anterior surface of the vein using indelible pen to ensure that the vein is not twisted during transposition.

        5000u of heparin is given IV.

        I ligate the vein distally and any side branches of it.

        I control any back bleeding from the vein with a vessel loop and spatulate the divided end flush with hep-saline

        Place self-retaining retractor.

        I expose the radial artery over 10mm.

        I sling the artery proximally an distally using silastic vessel loops.

        I use sharp dissection with scissors to separate the venae commitantes from the artery over about 10mm.

        I place silk ties twice around the branches of the radial artery  to occlude and control them, but do not tie.

        Bulldog clips are placed proximally and distally on the artery.

        A longitudinal arteriotomy is created about 6mm in length.

        I complete my anastomosis using 7/0 double-ended prolene performing the back wall first from inside the lumen and the front wall from outside the lumen.

        Before the final suture is tied, I release the proximal clamp and flush the air from the vessels and then replace it

        I finally flush with Hep-Saline and then tie the suture with 6 throws.

        I release proximal and distal arterial clamps and the vein vessel loop.

        I remove all the side branch ties, check haemostasis, washout and ensure that the hand is adequately perfused.

        I close the wound in layers using 3/0 vicryl for fascia then fat. 4/0 Nylon to skin.

        Post-op orders: Limb in kept warm in a foil blanket with moderate elevation to prevent swelling and regular hand observations.

What are the complications

Immediate (<24 hours)

        Bleeding, arterial thrombosis or embolism leading to hand ischaemia, air embolus

        Damage to superficial branch of radial nerve

Early (30 days)

        Failure to mature

        Thrombosis

        Cardiac failure in patients with marginal cardiac reserve where flow exceeds 500ml/min. Can be reduced by placing Teflon band around outflow

        Arterial steal syndrome – more common is proximal fistula (30%). Treated by ligation of fistula or narrowing the venous limb. Avoided by end venous to side arterial

Late

        Stenosis of venous limb

        Aneurysm formation – repeated needle punctures

        Thrombosis

        Venous hypertension - causing swelling, pigmentation, induration, ulceration. More common in side to side anastomosis

        Infection

How are prosthetic grafts classified

By position

        Radial artery in wrist to cephalic vein just below elbow – low patency rate due to low flow rate

        Brachial artery to antecubital vein forearm loop

        Brachial artery to axillary vein arm loop

        Superficial femoral to Saphenous vein

        Popliteal artery to femoral vein

        Axillary artery to axillary vein across the chest

        Brachial artery to IJV

        The arm fistulas are constructed preferentially

        Forearm fistulas have a higher rate of thrombosis but a lower risk of distal ischaemia than arm fistulas

        Lower limb fistulas are used when there are no useable vessels in the upper limbs. Lower limb fistulas are very poor choice in older patients, patients with diabetes or arterial disease

What are the technical aspects of prosthetic fistulas

        Use a 6mm non-ringed straight PTFE graft.

        Rotation or pinching of the graft must be avoided

        Although the fistula can be used straight away, allowing 1-2 weeks for maturation may minimize complications from bleeding by allowing tissue ingrowth.

How do you construct a Brachial artery to antecubital vein forearm loop

        In an appropriately consented, investigated and prepared patient

        Preparation should include a FBC and coag screen.

        Side should be marked. Preferably non-dominant hand

        Pre-op venous duplex should be arranged in patients with previous lines or history to suggest venous obstruction

        GA. Supine. IV cefazolin. Arm table. Sterile prep and drape including preparing the hand so that perfusion can be assessed.

        Incision is 5cm long 1cm distal to elbow crease

        Use diathermy to stop dermal bleeding. Using skin hooks and cat’s paws to lift skin deepening incision down to deep fascia to expose the bicipital aponeurosis and brachial artery.

        I elevate skin flaps taking great care not to damage the cephalic, median cephalic, median basilic and median antecubital veins.

        I insert a self-retaining retractor

        I retract some fibers of the bicipital aponeurosis laterally to expose the brachial artery, just lateral to the biceps tendon. I take great care not to damage the median nerve which lies just lateral to the artery

        I isolate about 10mm of artery passing silastic vessel loops around the proximal and distal limits

        5000u of heparin is given IV.

        I separate the venae commitantes from the artery without dividing them.

        Any side brnaches of the artery are controlled with double slinging with 2/0 silk ties without ligation

        I control the vein vessel loops around the proximal and distal limits

        I make a counter-incision in the forearm about 12 distal.

        I tunnel the PTFE graft in a U-shaped loop about 6cm wide to the distal incision ensuring that it is not twisted

        Bulldog clips are placed proximally and distally on the artery.

        I spatulate the PFTE graft

        A longitudinal arteriotomy about 8mm on the ventral surface of the artery is performed using scalpel and potts scissors and flushed with hep-saline

        I complete the arterial anastomosis using 6/0 double armed prolene continuous suture.

        I open the proximal bulldog to flush the air from the graft Controlling the venous limb of the graft first with fingers then a bull dog.

        I perform a longitudinal venotomy about 8mm and complete my anastomosis using 7/0 double-ended prolene performing the back wall first from inside the lumen and the front wall from outside the lumen.

        Before the final suture is tied, I release the proximal clamp and flush the air from the vessels and then replace it

        I finally flush with Hep-Saline and then tie the suture with 6 throws.

        I release proximal and distal arterial clamps and the vein vessel loop.

        I remove all the side branch ties, check haemostasis, washout and ensure that the hand is adequately perfused.

        There is often bleeding from suture holes. I cover the holes with Surgicel and apply gentle pressure for 5 minutes.

        I close the wound in layers using 3/0 vicryl for fascia then fat. 4/0 Nylon to skin.

        Post-op orders: Limb in kept warm in a foil blanket with moderate elevation to prevent swelling and regular hand observations.

What are the complications

Immediate (<24 hours)

        Bleeding is more commonly from suture holes

        Arterial thrombosis is from narrowing the inflow or outflow or kinking of the graft

        Embolism leading to hand ischaemia, air embolus

        Damage to superficial branch of radial nerve

Early (30 days)

        Failure to mature

        Thrombosis – often due to low blood pressure or excessive external pressure

        Cardiac failure in patients with marginal cardiac reserve where flow exceeds 500ml/min. Can be reduced by placing Teflon band around outflow

        Venous hypertension - causing swelling, pigmentation, induration, ulceration. More common in side to side anastomosis

        Arterial steal syndrome – more common is proximal fistula (30%). Treated by ligation of fistula or narrowing the venous limb. Avoided by end venous to side arterial

o   Complications can be treated using rapid taper 4 to 7mm grafts.

Late

        Stenosis of venous limb – can be repaired by a patch graft, angioplasty or bypass

        Aneurysm formation – repeated needle punctures. Can be treated with covered stents

        Thrombosis – late thrombosis is due to venous intimal hyperplasia at or distal to the anastomosis.

        Infection is a major problem in prosthetic grafts. Commonly S aureus or S epidermidis. Infection rates in IV drug users or HIV patients are up to 30-40%

o   If it involves the suture line, the risk of false aneurysm is too high and the graft removed and the artery re-constrcted.

o   Infection not involving the suture line can be treated with abx and drainage of infection

        The patency rates of prosthetic jump grafts are less than autogenous AV fistulas. The patency is greater for more proximal fistulas, but the ischaemic complications are more common.

How can the long term patency of fistulas be improved

        Early intervention for graft stenosis with PTCA extends the life of the graft.

        Graft and fistulas should be monitored by feeling for a thrill, measuring pressures  (3 pressures >150mmHg with flow rates of >250ml/min indicates a venous stenosis), Doppler examination.

        When there is a thrill in the entire length of the graft or fistula then the flow rate is >450ml/min.

        When there is a stenosis >50% with haemodynamic compromise (reduced thrill, increased pressure) the intervention is recommended.

o   The options for intervention are surgical or endovascular.

o   Endovascular interventions include Baloon angioplasty (30atm; 15min). Cutting balloon and covered stents have also been used

o   Surgical therapy seems to be superior for venous stenosis than endovascular therapy, but is more invasive and requires temporary access.

o   Percutaneous techniques are also used for central venous stenoses

How do you insert a peritoneal dialysis catheter

I use a laparoscopic approach to ensure the correct position of catheter tip

In an appropriately consented, investigated and prepared patient

GA. Supine. IV Abx. Sterile prep and drape. In the patient who is not anuric I insert an IDC

        Open Hasson canulation. P12 F12. Inspect the peritoneal cavity for adhesions, omentum obscuring entry into pelvis ect.

        I make a 4cm vertical paramedian incision below the umbilicus.

        I divide the anterior rectus sheath and split the muscle to expose the peritoneum.

        I insert an Vicryl purse string suture in the peritoneum.

        I insert the tenckoff catheter through the purse string and guide the tip into position in the pouch of Douglas.

        If I cannot easily position the tip in the pelvis, I insert a single 5mm port on the opposite side to that chosen for the catheter at the same level.

        I position the first Dacron cuff in the rectus muscle and tie the purse string suture to ensure a water-tight seal.

        I tunnel the exit site of the catheter a short distance from the surgical incision leaving the second cuff in the subcutaneous fat just superficial to the fascia.

        I remove the laparoscopic ports and deflate the pneumoperitoneum. I close the Umbilical port under vision with 0 Vicryl.

        I instil fluid into the peritoneal cavity and confirm there is no leakage around the purse string. If there is leakage I place additional sutures to ensure water-tight closure.

        I close the anterior rectus sheath around the catheter using 0 Vicryl interrupted suture.

        I close the skin incision using 3/0 Nylon and drain the fluid from the peritoneal cavity.

What are the complications of peritoneal dialysis catheter placement

Immediate

        Leakage of dialysis fluid

        Bleeding into peritoneum

        Bowel or bladder perforation

        Subcutaneous haematoma from tunnelling

Early

        Hernia formation

        Ileus post-operatively

Late

        Exit site infection – Most commonly S aureus. 0.8 per patient years

        Mechanical – Poor inflow can be caused by obstruction of some catheter holes, omental wrapping or catheter displacement. Complete blockage is caused by kinking, blockage of all catheter holes, omental wrapping of entire catheter.

        Peritonitis – Average 1.3 episodes per patient year.

            There are four routes of infection –

            around dialysis tubing

            through dialysis tubing

            contamination of peritoneal cavity (eg diverticulitis or PID)

            blood-borne infection

Usually caused by a single pathogen. Gram-positive cocci (Coagulase negative Staph -60%), Gram negative bacilli (30%), Pseudomonas 10%. It is treated with a combination of IV and peritoneal Abx guided by gram stain and culture. A Y connector with a closed system reduces the incidence of peritonitis.  

The survival of CAPD catheters is 85% for 1 year and 80% after 3 years.

Survival is less in diabetics