Haemodialysis access surgery

Need 200-300mL/min for effective haemodialysis

Preparation:

Medication management
- Withhold clopidogrel 5-7 days
- Warfarin can probably continue, INR <2.5

Autogenous access principles:

Access and identify vein
- With transposition accesses, the vein is completely dissected and mobilised, ligating all side branches
- Transect distal end of vein and flush with heparinised saline to evaluate the calibre and extent of the vein and to identify any side branches
Control artery and make a 4-6mm arteriotomy (minimise length to decrease arterial steal)
Flush artery proximally and distally with heparinised saline to avoid thrombosis during the anastomosis
AV anastomosis performed between side of artery and end of vein (this configuration decreases the risk of venous hypertension)
AV anastomosis performed using 6/0 or 7/0 monofilament nonabsorbable suture (to avoid subsequent anastomotic dilatation)
With non-transposed access, large venous branches can be ligated through stab incisions to encourage flow in the main venous segment and thus promote early maturation

Pitfalls:

Failure of vein to mature
Anastomotic tension
Vein kinking
Vein twisting
Inadequate arterial inflow
Nerve or vessel injury

Prosthetic access principles:

Arteriotomy can be any size - steal will be limited by diameter of graft
Artery flushed proximally and distally with hep saline
6mm PTFE prosthetic graft used for conduit
Anastamosis using 6/0 or 7/0 continuous nonabsorbable
Careful attention to sterile technique

Transposition procedures:

Can be done as one-stage or two-stage procedures
First stage is direct anastomosis, followed by 4-6 weeks of waiting to evaluate for maturity, and then transposition can be performed
Should be done in two stages only when there is small-calibre (<4mm) vein

Set-up

Arm out on arm board
Mark artery, vein and incision with USS
Prep arm with tech holding up by hand, then hand goes into footbag (or for distal operations, a huck towel secured with a towel clip)
U drape, then bottom drape, then arm down, then top drape, then side drapes

Radiocephalic

3cm longitudinal incision in distal forearm, midway between radial artery and cephalic vein
Dissect cephalic vein free - ensure >3cm free for transposition
Dissect 2cm section of radial artery free - ligate small branches
5000 units IV heparin
Mark and transect vein, transfixing the distal end, and check length
Dilate and distend the vein
Occlude the artery with two small microvascular clamps, and make a 6mm arteriotomy
End-to-side anastomosis with 6/0 Prolene
Check thrill, distal pulse, hand perfusion
Deep dermal and skin sutures

Brachiocephalic

Three possible incisions - transverse across ACF, sigmoid coursing medially in upper arm across ACF and into lateral forearm, and separate incisions over the brachial artery and cephalic vein in upper arm
Palpate and mark brachial artery and cephalic vein
Dissect free cephalic vein 4cm
- Potentially you can just take the median antecubital vein and plug it into the brachial artery without interrupting the cephalic vein, as above picture
- Suture-ligate the median antecubital vein with silk if not using it
- Mark the top side of it to ensure no twisting
Expose 2-3cm of brachial artery - need to incise bicipital aponeurosis and maybe the flexor retinaculum of the brachioradialis muscle. If it's easy to expose the bifurcation, you can loop both radial and ulnar branches.
Distend vein with saline (check to ensure low resistance), spatulate, repair defects. May need to use Bakes dilators to rupture valves in the distal cephalic vein, which increases the length of vein available for dialysis (start with 3, then 3.5, then 4).
Give 5000 units heparin IV
Occlude brachial artery proximally and distally. 6mm arteriotomy. Anastomosis with 6-0 Prolene.
Check thrill, distal pulse, hand perfusion

Post-op

Generally stay in overnight. Must confirm that the hand is not ischaemic prior to departure (if no subjective complaints, and normal motor/sensory exam, taking into account regional anaesthesia, probably ok). Should also check serum electrolytes to ensure no need to dialyse.
Seen 2/52 post-op and monthly thereafter until access is used for dialysis.
- Takes a mean of 3 months. Waiting for sufficiently dilated artery.
  - 6mm in diameter, 6mm depth below the skin, 600mL/min.
Get an USS if not maturing right. Should not be cannulated early.
Prosthetic accesses can be used straight away

Complications

Steal syndrome
- Seen in almost all arm accesses, but significant steal (>15%) is uncommon
- You can test for this by seeing how the distal arterial pulse (and the pain) responds to compression of the graft
- Risk factors:
  - Diabetes
  - PAD
  - CAD
  - Brachial-based access
  - Female gender
  - Multiple previous access procedures
- Grading:
  - 0: no symptoms
  - 1: mild - cool extremity, few symptoms, flow augmentation with access occlusion
  - 2: moderate - intermittent ischaemia only during dialysis, claudication
  - 3: severe - ischaemic pain at rest, tissue loss
- Investigation
  - USS is helpful and determines flow rates
  - Angiography can tell you whether inflow stenosis is a factor
- Indications for intervention:
  - Grade 3 - mandatory
  - Grade 2 - consider
- Options for improving distal perfusion
  - Ligation
  - Plication
  - Banding
  - Proximalisation of arterial inflow
  - Distal revascularisation with internal ligation
  - Rudi
Hand ischaemia - 2%
- Related to 'steal' - blood just flowing down the path of least resistance
- Exacerbated by inflow disease proximal to AVF, and between AVF and hand
- Can be present despite still having a weak pulse at wrist
- Non-invasive (arterial pressures and waveforms) and invasive (arteriography) can be used to confirm diagnosis in equivocal cases
- Presentation:
  - Can present early (immediately post-op) or late (often during first dialysis session)
  - Range from coolness and paraesthesiae to rest pain and weakness
  - Improvement with access compression confirms the diagnosis and predicts a good response to revision
- DDx
  - Carpal tunnel
  - Venous hypertension
  - Ischaemic monomelic neuropathy
- Goals:
  - Relieve symptoms
  - Preserve access
- There are multiple approaches to resolve the problem, most simple is just to ligate the vein, however this obviously sacrifices the access.
- Other options
  - DRIL (Distal revascularisation/interval ligation is fairly good results apparently
  - Banding - limiting flow through access, but trying to leave enough to maintain the AVF
- Act promptly - chance to preserve function
Failure to mature/dilate of veins
- Normally, increased blood flow through the outflow vein of an autogenous access causes the vein to dilate and its wall to thicken and become 'arterialised'
- Usually matures sufficiently for canulation within 3-4 months
- Can be caused by:
  - Inflow stenosis
  - Persistent venous branches diverting blood away from main channel
  - Can be difficult to canulate for other reasons - too deep, inexperienced nurse
- Possibility of balloon-assisted maturation
Infection - common
- Classification:
  - Early (<30 days) vs late
  - Culture-positive or culture-negative
  - Site (para-anastomotic, mid-AV access, outflow veins, etc)
  - Grade (1 - resolved with antibiotics; 2 - loss of AV access; 3 - loss of limb)
- Mostly GPC organisms
- Can lead to endocarditis, osteomyelitis, septic emboli, septic arthritis
- Catheter-related: Abx, removal/exchange of infected catheter
- PTFE infections: balance between preserving functioning access and severity of infection
  - Sometimes, IV antis is enough for a local infection
  - Abscess/purulent drainage/infected pseudoaneurysms all mandate removal of infected portion or all of the graft
  - Infected mid-portion of graft can often be salvaged
  - Infected anastomosis requires complete excision
- Autogenous access - mostly resolves with antibiotics
Access failure - thrombosis/stenosis
- See separate topic under 'haemodialysis access'
Oedema from venous hypertension
- Usually a central venous cause of this oedema
Seromas
- Early - resolve spontaneously, common with PTFE grafts
- Chronic - rare. Sometimes require aspiration or surgical drainage. Can result in graft loss.
  - Indications for intervention: interferes with cannulation, continues to grow, or compromises overlying skin.
Wound problems - access infection 7%
Carpal tunnel syndrome
Access site bleeding
- Inadequate haemostasis
- Coagulopathy
  - CKD
  - Medications
- Anticoagulation
- Venous outflow stenosis
- Pseudoaneurysm
- Infection
Pseudoaneurysm
- Aetiology
  - Trauma from repeated punctures or poor technique leads to perigraft haematoma
  - More common in PTFE grafts, not as common in autogenous AVF
- Presentation:
  - Bulging enlargement of the access
- Indications for repair:
  - Skin over aneurysm cannot be pinched - elective
  - Ulceration or spontaneous bleeding - emergency
- Treatment:
  - Open:
    - Interposition graft - good for prosthetic grafts
    - Autogenous - convert to graft, or fistula reduction surgery
  - Endovascular:
    - Stent
True aneurysm
- Types:
  - Adjacent to the anastomosis, associated with haemodynamically significant stenosis
  - Within cannulation areas
  - Adjacent to stenoses mid-access
  - Next to vein junctions, valves, or rigid areas caused by prior catheters
Venous hypertension
- Mostly secondary to central venous stenosis or occlusion
- Primarily caused by catheters