GORE -TEX@Vascular Grafts

for Hemodialysis:

Techniques for the Careand Cannulation

of A-V Grafts

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GORE- TEX@VASCULAR GRAFTS FOR HEMODIALYSISTechniques for the Care and Cannulation of A-V Grafts

Sustained care of the hemodialysis patient demands the safe,efficient cannulation of the GORE- TEX Vascular Graft implanted asan arteriovenous (A- V)fistula. Much of the responsibility for themaintenance of adequate vascular access sites falls on the dialysisnurse/technician. Despite differences in individual patients andequipment, certain techniques of graft cannulation taken from thecombined experiences of major dialysis centers have proven to be ofbenefit through the years. Consistent use of these techniques mayaid in increasing the life expectancy of the A-V graft and improvingthe quality of life for the patient. In addition, cannulation mayproceed faster, and with fewer problems, thereby contributing to theoverall efficiency of the dialysis unit.

I. EVALUATINGTHEA-VGRAFT

HEALING PERIOD BEFORECANNULATION

After surgical implantation of theGORE-TEX Vascular Graft as anA-V fistula, the physician may waitseveral weeks before allowing it tobe punctured. Healing characteristicsvary widely among patients but,within this time period, sufficientgrowth of tissue into the outer wallwill have stabilized the graft. This isimportant in the prevention of bothinfection and hematoma.

In some cases, the physicianmay advise that the patient undergohemodialysis before adequate heal-ing can take place. An extremelycautious approach to these patientsmust be taken [see SECTION V].Immediate or early cannulationshould be considered only whenthere is no other alternative.

Once the patient's graft hashealed, inspection of the access siteshould be part of every hemodialysissession. Infections, hematomas, andpseudoaneurysms can present prob-lems, making cannulation difficult,even dangerous. Early detection ofsuch problems and prompt referral tothe patient's physician may save thegraft and perhaps the patient's life.The most serious complications are:INFECTION

PSEUDOANEURYSMHEMATOMA

INFECTION

Local swelling, redness, pain, andpus drainage are all signs of anaccess site infection. Should these orother suspicious symptoms be pre-sent, a physician should be notifiedimmediately. Never insert a needleinto the graft through an infectedarea. To do so is to introduce bacteriadirectly into the bloodstream. Thechance of infection can be markedlyreduced by rigorous adherence toaseptic technique [see SECTION II].

FibrousPseudoaneurysm

Capsule

Graft

EVALUATING THEA-V GRAFT

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PSEUDO ANEURYSM resultsfrom the repeated puncture of thegraft at a single site. This results ina large hole in the wall of the graftand leads to loss of an area for punc-ture and perhaps a hematoma. Thechance of infection and clotting ofthe graft is also greater.

Photo A

Photo B

The result of repeated needlepuncture [Photo B] at one site, "one-site-itis," is pseudo aneurysm [PhotoA] and possible early failure of thegraft. The importance of rotatingpuncture sites cannot be overstated.

HEMATOMA is the result of theunchecked bleeding from a graftpuncture site. Blood spreads betweenthe tissue and the graft wall, resultingin swelling and discoloration. Do notattempt to insert a needle through ahematoma. The needle will often clot,making it necessary to puncture thegraft at a new site. This reduces the-;r

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available sites and complicates can-nulation since pressure on the non-usable puncture must be maintainedto prevent enlargement of thehematoma.

Prompt referral to a physicianfor removal and correctionof the causeof the hematoma may be indicated,depending on the severity of thehematoma. Careful technique duringand after cannulation will greatlyreduce the number of hematomas[see SECTION III].

CHECKINGTHE FLOWIN THE GRAFT

Any time blood flow through thegraft is reduced not only will bloodremoval be more difficult, but thereis a chance that graft occlusion willoccur. To check for adequate flow,palpate the entire length of the graftfor a strong "thrill." A thrill feels likea consistent vibration under the skinand should be distinguished from thepulse. While a pulse may be presentin a clotted graft, a thrill indicatessufficient blood flow.

If unable to palpate a thrill, lis-ten with a stethoscope for the sound,or "bruit," made by the blood rush-ing through the graft. Changes ineither the strength or nature of thesetwo diagnostic procedures should benoted on the patient's chart. Do notcannulate in the absence of either athrill or a bruit.

Knowing the direction of theblood flow in the dialysis graft isalso important. The venous needleshould be placed in the direction ofblood flow. This prevents recircula-tion and assists in the normal patternof venous return. Ideally, the surgeonprovides a diagram indicating thelocation of the graft and direction ofblood flow. If a diagram is not avail-able, you can determine flow direc-tion with this simple technique.

Apply momentary pressure tothe mid-point of the graft with yourfinger. Note the pulse in the graft.The side with the strongest pulsationis the direction from which bloodenters the graft, the arterial side.

NEEDLE SELECTION

The needle with the smallest gaugethat will achieve the required flowrate for the dialysis machine shouldbe used. A needle with an ultrathinwall and a back eye can be useful inthis regard. The length of the needlechosen may vary with the depth ofthe graft in the tissue. In most cases,a one-inch needle is adequate andhelps reduce the chance of damagingthe back wall of the graft. As a gen-eral guideline, always select thesmallest, shortest needle adequate forthe patient.

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EVALUATING THEA-V GRAFT

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A chart to map the position and dateof puncture helps keep track of graftsites used and avoids "one-site-itis."Puncture sites should be approx-imately one centimeter apart alongthe straight portion of the graft. Lettwo to three weeks elapse before punc-turing closer than one centimeterfrom a previous site. Avoid puncturescloser than three centimeters fromwhere the graft is sewn to the arteryor the vein.

The tightly curved portion of aloop graft should not be cannulated,because it is difficult to properly posi-tion the needle. External reinforcingrings, provided along this portion tohelp prevent kinking, may cause addi-tional difficulties in cannulation.

II. ASEPTICPREPARATION

Thorough aseptic preparation of theskin must be performed to reducethe chance of infecting the graft.Cannulation should be considered asurgical procedure with risks ofcontamination and infection. Dialysisstaff may choose to wear sterile gloves,depending on procedures followedin their own dialysis centers. However,touching a disinfected needle punc-ture site with unprotected hands,non-sterile instruments, or dialysisequipment should be avoided.

Prepare the graft puncture siteby using a topical antiseptic.Applying isopropyl alcohol prior tothe antiseptic may aid in removingdirt and oils from the skin, but it isnot effective as a disinfectant.

Apply the antiseptic in acircular motion away from the punc-ture site until a circle of two inchesin diameter has been covered.Follow the antiseptic manufacturer'sinstructions for effective disinfection.Local anesthesia may be injectedprior to the final skin preparation,if necessary.

III. CANNULATIONTECHNIQUE

II-

For dialysis using two needles, thearterial needle may be positionedeither with, or against, the flow.However, less turbulence will resultif the needle points in the directionof the flow. The venous (or return)needle must always be positionedwith the flow. In single-needle dialy-sis, the needle must always point inthe direction of flow.

Inspect the needle and makesure the clamp is in place on the can-nula line. The skin at the puncturesite may be pulled up and off thegraft, or "tented," so the needle willfirst pierce the skin [Figure 1].

Figure 1

Usually the bevel of the needlefaces upward and is introduced intothe skin at an angle determined bygraft configuration, location, anddepth [Figure 2J.

Figure 2

Gently insert the needle throughthe graft wall while maintaining thisangle [Figure 3J.

Figure 3

Holding the graft in place withthe other hand may aid in accuratelypiercing the graft wall. Watch forblood flashback into the cannula. If

the blood flashback does not appearor seems sluggish, verify the needleposition by attempting to irrigate theneedle and tubing with a syringe. Adecrease or lack of blood flashbackmay occur because:

1. Bevel of the needle is pressedagainst the graft wall.

2. Needle is only partly in thegraft lumen.

3. Needle has passed throughthe back wall of the graft.

4. Patient has low bloodpressure.

5. Graft has low blood flowdue to obstruction.

After confirming an adequateblood flashback, continue to insertthe needle for no more than one-

eighth of an inch to ensure the needletip is positioned well inside the graft.Typically, the needle is rotated 1800so that the face of the bevel is direct-ed downward [Figure 4].

Figure 4

CANNULATIONTECHNIQUE

Some clinicians do not rotate theneedle or rotate only if they have dif-ficulty achieving adequate bloodflow. Others prefer to cannulate withthe bevel down. Insufficient dataexist to support any of these meth-ods. The choice of technique remainswith the dialysis unit staff.

Next, move the needle shaftdown so that it is close to the skin

[Figure 5].

Figure 5

Continue to introduce the needleuntil it has been inserted up to thehub [Figure 6].

Figure 6

Rotating the needle and movingthe shaft close to, and nearly parallelwith, the skin surface may minimizethe chance of puncturing the backwall of the graft during full insertion.

An angle of approximately 4Ywill create a flap in the graft wall atthe puncture site. This may helpminimize bleeding from the puncturesite by forming a type of "valve"when the needle is withdrawn[Figure 7].

Figure 7

A needle entering the graft at agreater angle [Figure 8] would not createthe desired flap [Figure 9].

Figure 8

Figure 9

Near parallel entry may damagethe graft [Figure 10].

Figure 10

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With experience, the dialysisnurse/technician will gain a precise"feel" for graft puncture.

Please note that during all phas-es of needle insertion, care must betaken not to contaminate the disin-fected area around the puncture site.

Investigate unusual resistanceor pain occurring during cannulation.Once the needle is fully inserted andthe wings taped, the patient shouldnot experience discomfort. Persistentpain may indicate needle punctureof the back wall of the graft. In thiscondition, flow will often be sluggishand erratic upon aspiration. Low flowmay also be the result of a clottedneedle or an occluded graft. Correctsuch problems before continuingdialysis.

IV. AFTER DIALYSISIS COMPLETED

Upon completion of dialysis, theneedle should be carefully with-drawn and digital pressure applied tothe wound to halt bleeding. Mildcompression is more effective whenapplied to the area where the needleentered the graft, rather than where itentered the skin. Maintain light pres-sure with a cotton ball or folded

gauze dressing over the site of graftpuncture [Figure 11J, until thebleeding stops.

Figure 11

Inspect the puncture site frequentlyfor any external sign of abnormalbleeding.

There is a fine balance betweenenough pressure to prevent needlehole bleeding and excessive com-pression which may result in graftthrombosis. The decision to useadjustable arm clamps to controlbleeding should be made on apatient-by-patient basis.

Indicate and date the needlepuncture site on the patient's chart.

Graft Outer Surface

Graft Wall

Fibrous Tissue inNeedle Puncture Site

Graft Lumen

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This photo represents a properly punctured andwell-healed needle entry site in the GORE-TEXVascular Graft. Given sufficient time, fibroustissue will grow into the puncture site to helpmaintain the integrity of the graft.

V. SPECIALCONSIDERATIONSFOREARLYCANNULATION

In selected cases, a physician maydecide that a patient must undergodialysis shortly after the vascularaccess graft has been implanted.Extra precautions must be taken withthese patients because the danger ofgraft damage, hematoma formation,and infection is great.

Postoperative swelling maymake it difficult to locate the graftand place the needles. A misplacedneedle can damage the graft or punc-ture the back wall. Gentle digitalpressure can be used to temporarilydisplace the swelling. This makesit easier to locate the graft by touchor by listening for the bruit with astethoscope. A sketch by the surgeoncan be extremely helpful in thesecases.

Absolute adherence to aseptictechnique is critical in early cannu-lation. It is advisable to wear sterile

gloves since surgical incisions havenot had sufficient time to healadequately.

After dialysis is complete, pres-sure should be applied to the graftpuncture site until the bleeding stops.The patient may not be able to pro-vide sufficient pressure directly onthe puncture site due to the swelling.

Certain dialysis units success-fully employ the following practicesfor cannulation prior to tissueattachment.. local infiltrationof lidocaine. graft movement prevented

during cannulation. swift, clean puncture. 17-gauge needles. 200 ml/min blood flow for

the entire dialysis session. low dose heparin

A LIST OF REMINDERS

1.) Inspect the access sitefor any complications

2.) Assess flow in thegraft and determine itsdirection

3.) Select the smallest,shortest needle possible

4.) Rotate puncture sitesevery session

5.) Disinfect the chosenpuncture site and donot touch again

6.) Insert the needle throughthe graft at an appropriateangle

7.) Minimize the chanceof puncturing the backwall of the graft duringinsertion

8.) Evaluate the adequacyof the flow into and outof the needles

9.) Upon needle removal,mild non-occlusivepressure on the graftpuncture site is neededuntil bleeding stops

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DIALYSIS BIBLIOGRAPHY

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