1. Does Cannulation Technique Impact Arteriovenous Fistula Survival?
Maria Teresa Parisotto
Director, Nursing Care Management
Fresenius Medical Care - NephroCare Coordination
Bad Homburg - Germany
Malmö, August 31st, 2013

2. Outline 1 2 3 4 5 6 7 Introduction Aim of the Study
Patients and Methods 4
Results 5
Summary 6
Discussion 7
Conclusions
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3. Introduction
The vascular access has a major impact on patient survival and the related problems are the main reasons for hospitalisation admission affecting patient outcome. AV fistula is most reliable access for HD.
Pisoni R, et al. Kidney Int 2002; 61: 305
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4. Cannulation Approach: Research Cinderella
Prevention of access complications has high priority in dialysis therapy and various recommendations exist aiming at maintaining access patency for long term use.
However, in practice, techniques for AV access cannulation are known to vary from clinic to clinic, mainly because of historical training approaches in the individual settings.
Examples:
Needle Gauge
Lenght of the needle
Puncture technique
Bevel up or down
Retrograde or antegrade arterial needle puncture
Rotation/back eye needle
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5. Puncture Techniques
Area cannulation refers to puncturing of the same general area session after session, but the repeated needle puncture in the same area weakens vessel walls and predisposes the access to the development of aneurysms and access stenosis.
Rope ladder technique, the cannulator rotates the needle placement sites for each dialysis, choosing sites at a defined distance along a line from the previous puncture sites.
Bottonhole technique: this is a method in which an individual cannulates the AV fistula in the exact same spot, at the same angle and depth of penetration every time. A scar tissue tunnel track develops, allowing the use of a buttonhole (blunt) fistula needle.
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6. Puncture Techniques Rope Ladder Area (regional) Buttonhole
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7. History of the Buttonhole Technique
Twardowski developed the technique in Poland more than 25 years ago
Dialysis supplies, including AV fistula needles, were very limited
AV fistula needles were reused for multiple cannulations
The needles became dull after repeated use and would not cut the skin
The “dull” needles would enter smoothly if the exact same cannulation site was used (same skin entry, same angle of entry, and same vessel entry depth)
Buttonhole technique was used to successfully solve the dull needle challenge
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8. Bevel Upwards or Downwards
During cannulation, the bevel of the needle can be directed upwards or downwards. The bevel is the slanted part of a needle, which creates a sharp pointed, or rounded, tip. The bevel of the needle allows for easy penetration of the skin. The orientation of the bevel (up or down) has an influence on the level of endothelial trauma.
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9. Arterial Needle Direction
Antegrade: direction of blood flow
Retrograde: against the blood flow
Both needles antegrade:
Easier for nurse to puncture
Easier for self-puncturing
May be fistula protective
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10. Aim of the Study
The advantages of native fistulas in comparison to grafts, specifically in term of better survival is today accepted.
There is a paucity of data in regards of how to use an AV fistula or a graft in extra-corporeal dialysis, justifying the aim of this study to investigate the impact of needle gauge, cannulation technique, bevel up or down, retrograde or antegrade needling, rotation of the needle, blood flow and venous pressure on the survival of the vascular access.
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11. Patients and Methods
In April 2009, a cross sectional survey was conducted in 171 dialysis units located in Europe, Middle East and Africa to collect details on vascular access cannulation practices. The results have already been published1.
On the basis of this survey, a cohort of patients was selected for follow-up to investigate vascular access survival. All patients on double needle HD or online HDF during the week of the survey were selected for our analysis, as long as they used a fistula or graft as vascular access, survey data was complete and follow-up data was available in our clinical database.
1Gauly A et Al. J Vasc Access 2011; 12(4): ).
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12. Statistical Analysis #1
Primary outcome in our analysis was the time until the first surgical access intervention resulting in the creation of a new access, where survey date serves as baseline.
Patients were censored for transplantation, death, loss of follow-up, or end of the follow-up period (March 31, 2012).
Information on cannulation taken from the survey consisted of fistula type and location, cannulation technique, needle size, needle and bevel direction, needle rotation, blood flow, arterial and venous pressure, use of disinfectants, local anesthesia and compression.
To adjust for individual patient differences, the following information was extracted from the clinical database: Patient age and gender, BMI, prevalence of diabetes and the use of ACE inhibitors, platelet anti-aggregants, salicylic acid and anticoagulants. Additionally the median blood flow prescriptions was documented on centre level at time of the survey.
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13. Statistical Analysis #2
For univariate analysis, Kaplan-Meier curves were calculated and comparisons were performed employing the log-rank test.
Combining univariate results, medical and statistical expertise, a set of variables for multivariate analysis was determined. In particular, specific interaction terms (e.g. bevel vs. needle direction) were defined for statistical examination.
A complete Cox model based on these variables was calculated, employing the sandwich estimator to adjust for within-country effects. Step by step the complete model was reduced, setting a p-level of 0.1 for variable inclusion.
All analyses were performed with SAS V9.2.
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14. Results #1
Out of the 10,807 patients enrolled for the original survey, access survival data was available for 7,058 (65%) from Portugal, UK, Italy, Turkey, Romania, Slovenia, Poland and Spain.
Mean age was years; 38.5% were female; 27.1% were diabetics; 90.6% had a native fistula and 9.4% had a graft. Access location was distal for 51.2% of patients. During the follow-up, 51.1% were treated with antiaggregants and 2.8% with anti-coagulant.
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15. Results #2
Prevalent  needle sizes were 15 G and 16 G for 63.7% and 32.2% of the patients, respectively (14 G: 2.7%, 17 G: 1.4%).
Cannulation technique was area for 65.8%, rope-ladder for 28.2% and buttonhole for 6%  of  patients, and the direction of arterial puncture was antegrade for 57.3%. The bevel direction was downward for 29.8% of the patients. The prevalent combination between arterial needle puncturing and bevel direction was antegrade with bevel upward (43.1%) followed by retrograde with bevel downward (27.1%). The proportion of the two other combination, antegrade and retrograde with bevel downward were 14.2% and 15.6% respectively.
Median blood flow was mL/min.
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16. Needle size, blood flows and venous pressure levels
14G Needle
16G Needle
15G Needle
17G Needle
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17. KM vascular access survival according to venous pressure
cumulative survival probability
Vascular Access
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18. Cox model with primary outcome vascular survival
Parameter
Category
Reference HR
95% CI
p-value
Age
18-50 yrs
65-76 yrs
>75 yrs
50-60 yrs
1.00
1.03
1.47
0.85
0.90
1.28
1.17
1.19
1.69
<0.0001
Gender
Male
Female
0.94
0.84
1.04
0.23
Diabetes
Yes No
1.14
1.02
0.03
Platelet Anti-Agggregation
1.11
1.23
0.06
Fistula Type
Graft
Fistula
1.74
1.49
2.03
AV-Fistula Location
Right
Left
1.12
1.01
1.26
0.045
Proximal
Distal
1.50
1.34
1.68
Needle Size
14 G
16 G
17 G
15 G
1.22
1.48
0.83
1.08
1.81
1.38
2.16
0.006
Blood Flow
<300 ml/min
ml/min
>400 ml/min
ml/min
1.18
0.92
0.79
0.75
1.37
1.13
0.02
Cannulation Technique
Buttonhole
Rope-Ladder
Area
0.78
0.88
0.61
0.99
Bevel and Needle Direction
Antegrade + Bevel Down
Retrograde + Bevel Up
Retrograde + Bevel Down
Antergrade +
Bevel up
0.98
0.82
1.16
1.39
Venous Pressure
<100 mmHg
mmHg
mmHg
>300 mmHg
mmHg
1.42
1.89
2.07
1.09
1.57
1.24
1.66
2.27
3.47
Arm Compression at Time of Cannulation
Patient Assistance
Tourniquet
None
0.80
1.05
0.67
0.96
1.20

19. Summary
In summary, this evaluation showed an increased risk for end of the vascular access function associated with the use of 16 and 17 G needles, the combination of retrograde and bevel down, the prescription of blood flows below 300 mL/min and the presence of a venous pressure greater than 150 mL/min. On the other hand, the practice of the buttonhole cannulation technique is associated with a significant lower risk.
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20. Discussion: Needle Gauge & Blood Flow – the Chicken or Egg dilemma
In our study, 17-gauge needle is associated with increased risk of early fistula termination. The same applies for blood flows below 300 mml/min.
The question: Is it the smaller needle influencing the fistula survival or the use of smaller needles indicates an already existing fistula malfunction? Is it the low blood flow affecting the fistula survival or an already problematic fistula allows only the use of low blood flow?
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21. Discussion: Antegrade puncturing may be fistula protective
Increased risk of haematoma formation from retrograde filling
Tract closure through flow force by antegrade puncture
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22. Conclusions
This study revealed that the practice of “area” cannulation is associated with a higher risk of vascular access failure, as is the retrograde placing of the arterial needle with bevel down. The higher HR associated with a negative venous pressure of mmHg should open a discussion on the current accepted limits. Given the relevant impact of the investigated variables on the survival of the vascular access, itself a key driver of haemodialysis patient survival, we believe it is time to organize a large scale randomized clinical trial to facilitate the formulation of practical and comprehensive cannulation practice guidelines.
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FME © Copyright - Does cannulation technique impact arteriovenous fistula survival?