Section 2: Atraumatic Technique and Surgical Instruments
Dialysis access in general and AV fistulae placement in particular require three cardinal concepts working in concert or the old surgical maxim “choose well, cut well, and get well” can be directly translated to dialysis access as “the right access for the right patient access at the right time.” (Reference 3, and Reference 4). A recent review concludes that there are no defined technical steps or suggestions for arterio-venous fistula creation. (9). This section is an attempt to do so.
First, knowledge and experience are required to properly select patients and dialysis access mode and type for optimal outcome. Second, much of this decision making entails an ability to see and listen to the individual patent’s need and desire to select the most appropriate therapeutic steps. Third, proper surgical skills will optimize fistula outcome and functionality. Nowhere is this more important than in the creation of a forearm radio-cephalic fistula used here as an example, as most of the technical aspects also apply to other native AVFs.
The choice of instrumentation is personal. Downsizing) from large, (10-15 mm) vessel surgery to (3-5 mm) is partly a mindset, which should translate into choosing micro-instrumentation, the use of magnifying loupes and in case of pediatric cases, an operating microscope.
The images (Figure 6), (Figure 7), (Figure 8) are examples of instruments and tools the reader may find helpful to perfect technique.
Figure 6
Instruments depicted here are helpful for making vascular anastomosis surgery atraumatic. The micro-forceps (top panel) enables atraumatic technique necessary for successful AVF creation. The non-locking needle driver (bottom panel) allows smooth suturing movements without re-resetting the needle between bites although a locking micro needle holder such as the Castroviejo is preferred by many
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The forceps in Figure 6 have an ‘eye’ or a “ring tip” with ridges made ideal for holding the vascular adventitia. At no time should the vascular intima (the inside) be grabbed with any type of forceps. This damages the endothelium and creates a pro-thrombotic surface which may result in thrombosis or scarring and an anastomotic stenosis. Likewise, traumatic mobilization of the vein (“stripping”) may contribute to fibrosis and juxta-anastomotic stenosis formation.
Vessel clamps need to be able to control the vessel, while gentle enough to not cause injury. Depending upon the size and nature of the vessel, a variety of clamps are available.
For small vessels, a silicon sling passed around the vessel two times may be sufficient. In small wrist vessels atraumatic clamps such as Heifetz or bulldog clamps can be used (figure 7).
Figure 7
The so-called Heifetz temporary vascular clips come in diverse sizes, shapes, and pressure forces. The right panel shows a so called Velcro disposable clamp that come in different pressure exhibiting
These come in various strengths and can be chosen for arteries and veins accordingly minimizing injury to the vessels. Second, the small Heifetz clips shown in Figure 7 can be placed behind the vessel to avoid being caught by the sutures and optimize surgical exposure. Disposable Velcro clamps or so called “bulldog” clamps come in many sizes, colors and pressures applied Figure 7 These are gentle to small vessels. The various vascular clamps allow for personal choice and creativity in achieving the best operative exposure and safety.
“Standard “vascular clamps that are required for carotid, aortic or iliac vascular surgery are usually unsuitable for smaller vessels but may be appropriate for larger upper arm arteries.
Figure 8
Disposable soft Velcro clamps are atraumatic, but the design and size make them hard to keep out of the operating field causing suture catching. Like Heifetz clip shown in figure 7 they are very useful tools.
In access surgery flushing the vessels with heparinized saline is required and a variety of tools are available. The so-called “Christmas trees” flushing devices that attach to a standard 10 or 20 ml syringe come in various forms. The angle type shown in Figure 9 is especially useful as it fits in vessels from 2.5 mm up to 5 mm. It has several important uses. It will dilate the anastomosis when inserted (gently); It can be used to “hydro- dilate” the vessels both veins and arteries, at the same time the vessels can be flushed in both directions with heparinized (10 units/ml) saline, while the small vascular clamps are sequentially opened. This is described in the video series below. Shown also is a so called “pink cannula” available in different color-coded sizes (Pink 20g; Green 18g; Grey 16g; Orange 14g) Other disposable types are available such as the one shown in Figure 11.
Figure 9
This angled smooth “Christmas tree’ is a very useful tool to flush vessels with heparinized saline. Also, it can be used to gently dilate vessels at the anastomosis site. Because of the angled design almost any vessel can be approached.
The type of “Christmas” tree shown in Figure 10 should be used with great caution as it may induce injury to the intima at the anastomosis from its ridges. Its lack of angulation makes it hard to access into vessels as is not the case in the device in Figure 9.
Figure 10
This type of “Christmas” tree should be used with great caution as it may induce injury to the intima at the anastomosis from its ridges. Its lack of angulation makes it hard to get into vessels. We advise against using these ridged cannulas.
Other flushing methods may use a standard cannula with the needle removed (e.g. Venflon) or Tibbs cannula Figure 11.
Figure 11
Cannula attached to a syringe with the needle removed is suitable for flushing small vessels (left panel). Another type of flushing small vessels are the Tibbs cannulas (right panel). These are designed similar to the cannula in figure 9 and can be manually bend to enter any vessel location.Regardless of devices used, care should be taken to avoid vessel intimal injury
Manual dilatation of vessels is not recommended particularly use of dilators, as these can injuries the endothelium and when used aggressively ruptures intima and causes fibrosis and possibly early thrombosis Figure 12.
Figure 12
Vascular dilators are used in dialysis access surgery come in a variety of sizes. The authors caution against this practice as “hydro-dilatation” is smoother and easier to control. Mechanical dilators can easily cay-use intima damage or rupture when used in an aggressive way.
Optimal exposure of the surgical field is a key component for success in all surgeries, access surgery being no exception. There are many retractors available. Surprisingly often, no retractor is required in access surgery. For wrist AV fistula surgery although the eyelid retractor also known as the Alm retractor (Figure 13) is an excellent choice as it stays flat at skin level and does not add ‘depth’ to the surgical field. Larger retractors may be counterproductive as they add to the surgical field depth and tend to snag sutures…
Figure 13
This small static eye-lid retractor (also known as the Alm retractor) is especially useful in most cases of wrist AVF creation. The eyelid retractors come in varied sizes and configurations.
Occasionally, larger retractors are needed for leg access and in the axilla and in cases of obesity. Figure 14 The Wheitlaner retractor is especially useul in he upper arm and the axilla and in the obese arms.
Figure 14
The Wheitlaner self-retaining retractors come in several forms and configurations and are useful in many types of dialysis access surgeries in the upper arm and leg. For the radio-cephalic AVF at the wrist the Eyelid retractor is a better choice (Figure 13).
Other retractors that are useful are “Catspaw” or Senn retractor or a small Langenbeck Figure 15
Figure 15
The Senn retractor has a “cat’s paw” on one side and small Langenbeck retractor on the opposite end. These are useful for vascular access exposure and require an assistant to hold.
Vessel loops (“sloops”) are useful to identify, manipulate and protect vessels and nerves. They come in various sizes and colors representing red for arteries, blue for veins and yellow for nerves.
Figure 16
Vessel loops (also known as “sloops”) are used to encircle vessels as shown here in a graft. Normally red is used for artery and blue for veins but here in a graft interposition the outflow is also red.
