1. Hemodialysis Vascular Access
Amir Hossein Miladipour M.D.
Nephrology &Transplantation Section
Shohada Tajrish Hospital

2. Hemodialysis Vascular Access
Acute hemodialysis vascular access:
Acute dialysis catheters
Cuffed,tunneled dialysis catheters
Chronic hemodialysis vascular access:
native arteriovenous (AV) fistulas
synthetic grafts

3. Acute Hemodialysis Catheters
 Double-lumen, non-cuffed, non-tunneled hemodialysis catheters have become the preferred method for obtaining acute hemodialysis vascular access
An acute triple-lumen dialysis catheter has been developed. The third lumen is available for blood drawing and the intravenous administration of drugs and fluid.
The maximum blood flow is usually blood pump speeds of 300 mL/min, with an actual blood flow of 250 mL/min or less.

4. Acute Hemodialysis Catheters
Site of catheter Insertion
can be inserted into the jugular, subclavian, and femoral veins
Routine use-life of catheters
The limits on use-life are caused by infection internal jugular catheters are suitable for 2 to 3 weeks of use
femoral catheters are usually used for a single treatment (ambulatory patients) or for 3 to 7 days in bed bound patients

6. Double lumen cuffed tunneled catheters
Are principally constructed of silastic/silicone and other soft flexible polymers, which are less thrombogenic than polymers used in acute catheters.
Require fluoroscopy for insertion due to their larger size and to the confirmation of tip location.
Many allow right atrial tip location based on their soft polymer construction

7. Double lumen cuffed tunneled catheters
Allow faster blood flows than acute catheters, Usually blood pump speeds of 400 mL/min
Actual blood flow rates are almost always lower than those reported by the blood pump(20%-30%)
Compare to fistulas or arteriovenous grafts, most patients require an increase in treatment time of approximately 20 percent to achieve equivalent urea removal.
Cuffed tunneled catheter survival
 is highly variable, 74 percent 1-year and a 43 percent 2-year catheter survival

8. Acute Double Lumen Catheter Complications
Complications associated with insertion:
Transient atrial or even ventricular arrhythmias due to overinsertion of guidewires
Hemothorax
Pneumothorax
Catheter-induced subclavian stenosis and subsequent loss of the ipsilateral arm for future hemodialysis access
The location of the catheter in subclavian and internal jugular insertion should always be confirmed by x-ray prior to the initiation of hemodialysis or the administration of anticoagulants

9. Catheter Malfunction
Definition:
Failure to achieve blood flow rate at least 300ml/min on 2 consecutive occasions or less than 200ml/min on a single occasion
Early:Inproper positioning of catheter tip
subcutaneous kinking of catheter
Late: intraluminal thrombi and less commonly extrluminal thrombi( fibrin tails)

10. Double Lumen Catheter Complications
Catheter thrombosis
Prevention
Heparin of either 1 mL = 1000 Units, 1 mL= 5,000 Units, or 1 mL = 10,000 Units can be used
alteplase (recombinant tissue-type plasminogen activator, rtPA)
administration of alteplase (2 mg injected into each lumen) was associated with significantly higher blood flow rates and better arterial and venous pressures compared with heparin
Treatment — Lytic agents such as urokinase and alteplase are effective
Non-cuffed catheters should be exchanged if flow is inadequate

11. Double Lumen Catheter Complications
Central vein thrombosis and stenosis
occur more often with subclavian (40 to 50 percent of cases in some studies) than with internal jugular insertions (up to 10 percent)
The K/DOQI guidelines therefore recommend avoiding placement in the subclavian vein, unless no other options are available

12. Double Lumen Catheter Complications
Infection  
local exit site infection
systemic bacteremia
Bacteremia generally results from either contamination of the catheter lumen or migration of bacteria from the skin through the entry site, down the hemodialysis catheter into the blood stream

13. Double Lumen Catheter Complications
 Prevention of infection:
strict adherence to proper placement technique
optimal exit site care
management of the catheter within the hemodialysis facility
antiseptic or antibiotic-bonded hemodialysis catheters, minocycline-rifampin coated catheter,citrate4%

14. Double Lumen Catheter Complications
MICROBIOLOGY  
Staphylococcal infection, both coagulase-negative and S. aureus, accounts for 40 to 81 percent of cases,and enterococci and Gram negative rods
DIAGNOSIS: 
Blood cultures
colony count four-fold higher in blood drawn from the catheter compared to the peripheral specimen had a sensitivity of 94 percent, a specificity of 100 percent,
A single bacterial count of >100 cfu/mL from catheter cultures with an identical organism growing from the peripheral blood specimen
it is common to occur in the absence of evidence of an exit-site infection

15. Double Lumen Catheter Complications
Treatment of infection:
initially treating with broad spectrum agents ( vancomycin and an aminoglycoside).
Obtaining of blood cultures two to four days after initiation of antibiotic therapy.

16. Double Lumen Catheter Complications
Catheter removal
All non-cuffed catheters should be removed in the presence of bacteremia
if follow-up blood cultures remain positive for more than five days despite appropriate antimicrobial therapy
signs of accompanying exit-site or tunnel infection (erythema or pus at exit-site)
infection with Candida or an infected clot.
An infected clot should be suspected if infusing or drawing blood through the line is difficult or associated with rigors.
the patient becomes hemodynamically unstable or if the fever persists or cultures remain positive after two to four days.
Patients who remain febrile or have positive cultures after the catheter is removed should undergo a thorough examination for metastatic complications (such as endocarditis and vertebral osteomyelitis)

17. Double Lumen Catheter Complications
Recommendations:
All personnel should be adequately trained in aseptic techniques and about the importance of routine hand hygiene before and after patient contact.
topical use of povodone-iodine on the catheter hubs
nurses or technicians routinely wear nonsterile gloves and a mask when dialysis catheters are accessed
monitor rates of dialysis-associated infections to detect and understand local trends in types of pathogens, incidence and antimicrobial resistance

18. Chronic hemodialysis vascular access
Native arteriovenous (AV) fistulas
Synthetic grafts
Double-lumen tunneled cuffed catheters

19. Native arteriovenous (AV) fistulas
constructed with an end-to-side vein-to-artery anastomosis between an artery and vein Radial artery and cephalic vein (radiocephalic or wrist fistula) Brachial artery and cephalic vein (brachiocephalic or upper arm fistula).

20. Native arteriovenous (AV) fistulas

22. Synthetic grafts
are constructed by anastomosing a synthetic conduit, usually polytetrafluoroethylene (PTFE, also known as Gortex), between an artery and vein. The 2006 K/DOQI work group recommends a graft either of synthetic or biologic material

24. Comparison of Fistulas and Grafts
Primary failure defined as an access that never provided reliable hemodialysis. In radiocephalic fistulas 24 to 35 percent brachiocephalic fistula 9 to 12 and brachiobasilic fistulas 29 to 36 percent forearm grafts 0 to 13 percent upper arm grafts 0 to 3

25. Comparison of Fistulas and Grafts
Time to use
Grafts 
Grafts can be cannulated for hemodialysis earlier than fistulas.
Grafts can usually be cannulated within weeks.
Some times within days of surgery
Fistulas 
Cannulation before two weeks of age should be avoided.
Cannulation between two to four weeks may be attempted but only if the fistula is considered mature.
Cannulation after four weeks of maturation may be safe, if the fistula is mature.
Independent of the age of the fistula, clinical examination prior to cannulation is very important, given that some fistulas require up to six months to mature.

26. Comparison of Fistulas and Grafts
Patency/secondary failure 
In native fistulas the risk of secondary failure is low.
The 5-year and 10–year cumulative patencies for radiocephalic fistulas are reported to be 53 and 45 percent, respectively
cumulative patency for PTFE grafts at one, two, and four years is approximately 67, 50 and 43 percent, respectively

27. Comparison of Fistulas and Grafts
Complications: grafts vs. AVF 
Thrombosis: 3.8 times
Infection: 10%,2%
Steal syndrome: 5% in both
Aneurysms: 5%, 3%
venous hypertension: 3% in both
seromas
heart failure: less than 1% in AVF
local bleeding
Thrombosis, infection, and seromas occur more frequently with grafts than with fistulas

28. Steal syndrome Symptoms and signs: Mild:
Coldness, numbness, paresthesias,pain during dialysis, with retained pulses
Severe(Indication for ischemia correction):
Constant pain, severe numbness,a nonhealing ischemic fissure,digital cyanosis or gangrene,finger contracture
Mild symptoms and signs usually improve over a period of weeks with the development of collateral blood flow.
Careful, frequent observations and an alert nursing staff are required in this setting

29. Aneurysm and Pseudoaneurysm
Usually result from repeated cannulation in the same area of the fistula
Can be avoided by rotation of needle insertion sites

30. Aneurysm and Pseudoaneurysm
Indications for revision/repair of AV fistula aneurysm:
The skin overlying the fistula is (ischemic)compromised
There is a risk of fistula rupture
Available puncture sites are limited
indications for revision/repair of pseudoaneurysm formation :
 symptomatic or threatens the viability of the overlying skin
Evidence of infection
Pseudoaneurysm that is enlarging in size or that exceeds twice the diameter of the graft
Limited number of cannulation sites
Cannulation through a pseudoaneurysm must be avoided

31. Venous Hypertension Sign and symptoms: severe upper limb edema
skin discoloration
access dysfunction
peripheral ischaemia with resultant fingertip ulceration.
In most cases, the underlying venous pathology follows ipsilateral central venous catheter placement with consequent venous stenosis.

32. Infection
The second most commonn cause of AV access failure(0-3% in AVF and 6%-25%in AV grafts)
Treatment:
AVFs:Local drainage and antibiotic therapy for 6 weeks
AV grafts:antibiotic therapy and surgical treatment( in most cases complete excision of prosthetic graft)

33. Buttonhole Technique for Cannulating AV Fistulae

34. Buttonhole Structure

35. Needles – sharp and blunt

36. Buttonhole Technique Reuse same sites each treatment with
blunt needles
Must follow the
track/tunnel of the
original cannulator

37. Doppler Ultrasound Tunnel

38. Benefits for the patient
Less painful – elimination of anesthetic
Fewer infections
Fewer missed needle sticks
Fewer infiltrations/hematomas
Cannulation of access takes less time

39. Why offer the Buttonhole Technique?
􀂾 Prolong AV fistula life 􀂾 Decrease hospitalizations related to access infections and complications 􀂾 Promote patient self-cannulation 􀂾 Decrease pain associated with needle Cannulation