Dialysis study guide

Chapter 7 of 12

Module 7 — Vascular Access

Sources: Condensed study notes based on Core Curriculum for the Dialysis Technician, 7th ed. (MEI), plus free CDC/CMS/NIDDK resources.

Vascular access — the patient’s lifeline

Study guide

  • A vascular access must deliver and return enough blood for prescribed HD while remaining usable over time. The main permanent options are an arteriovenous fistula (AVF), an arteriovenous graft (AVG), and selected newer endovascular fistulas. A central venous catheter (CVC) is generally temporary or used when another access is unavailable.
  • Access choice is individualized. The clinician weighs vessels, comorbidities, life expectancy, prior access history, treatment goals, and the patient’s values and preferences; there is no single “right” access for everyone.
  • Treat every access as a lifeline: protect it from unnecessary puncture, pressure, infection, infiltration, thrombosis, and trauma. Report changes promptly and document what was seen, done, and communicated.

Why answers are correct

  • HD needs high, dependable blood flow. A compromised access can cause inadequate dialysis, blood loss, hospitalization, loss of the access, or limb-threatening complications.

Limitations / traps

  • Do not use an access arm for routine blood pressure checks, IVs, or blood draws unless an authorized emergency policy specifically permits it.
  • Do not change needle size, blood flow, anticoagulation, or cannulation plan outside the prescription, access plan, and clinic procedure.

Clinical pearl / safety

  • Before cannulation: identify the access and its direction, inspect the skin, listen for a bruit, feel for a thrill/pulse, and compare with the patient’s usual findings.

Exam cue

  • Look, listen, feel, protect, report. A changed access finding is a clinical signal, not a minor inconvenience.

Central venous catheters (CVCs)

Study guide

  • A CVC places a catheter in a large central vein so blood can be withdrawn and returned for dialysis. Tunneled cuffed catheters are intended for longer use than nontunneled temporary catheters; catheter tips are typically positioned in a central vein/right atrial region according to the placement plan.
  • CVCs provide immediate access without waiting for AVF/AVG maturation, but they have higher infection and dysfunction risk than a well-functioning AVF and generally should not replace planning for a durable access.
  • The catheter, lumens, clamps, caps, dressing, and connection points form one closed system. Maintain aseptic technique for every connection, disconnection, dressing change, and cap manipulation.
  • Assess the exit site and tunnel for redness, drainage, tenderness, swelling, warmth, or separation. Check for fever, chills, malaise, or other systemic infection signs. Report promptly; bloodstream infection can progress rapidly.
  • Poor aspiration, poor flow, high pressures, or repeated alarms may indicate a clamp problem, kink, malposition, fibrin/thrombus, or stenosis. Do not force flushes or improvise a declotting treatment; follow the access protocol and notify the nurse/provider.
  • Keep the dressing clean, dry, and intact. The patient should not submerge the catheter or manipulate caps/dressings except as taught by the care team. Never leave a lumen uncapped or unsecured.

Why answers are correct

  • A catheter directly connects the outside environment to central circulation. Touch contamination, a loose cap, a wet/loose dressing, or an unrecognized break can become a bloodstream infection.

Limitations / traps

  • A CVC may be usable immediately, but “usable” does not mean low risk. It is not a reason to ignore AVF/AVG planning or infection prevention.
  • Do not use a CVC for non-dialysis purposes unless the authorized policy explicitly allows it.

Clinical pearl / safety

  • Fever or chills during treatment, purulent drainage, new exit-site redness, unexplained hypotension, or sudden catheter dysfunction requires immediate nurse notification and the clinic’s infection/access response.

Exam cue

  • CVC priority: asepsis and closed-system protection. Never trade speed for contamination risk.

Arteriovenous fistulas (AVFs)

Study guide

  • An AVF is a surgically created connection between the patient’s own artery and vein. Arterial pressure enlarges and strengthens the vein (maturation) so it can tolerate repeated dialysis cannulation and provide adequate flow.
  • Common configurations include radiocephalic (wrist), brachiocephalic (upper arm), and brachiobasilic/transposed fistulas. An endovascular AVF (endoAVF) uses percutaneous devices and energy to connect vessels without the usual open surgical incision.
  • Maturation is judged by examination and, when needed, ultrasound or other testing. Look for a usable cannulation segment, adequate diameter/depth, increasing flow, and a continuous thrill/bruit. Do not assume a fistula is ready solely because it is visible or has been present for a certain number of days.
  • A mature AVF can usually support prescribed flow with two needles, but it still needs correct site rotation and gentle technique. Use the entire usable segment rather than repeatedly puncturing one spot.
  • Buttonhole cannulation creates one needle track and angle over repeated treatments; rope-ladder cannulation rotates sites along the access. Follow the clinic’s plan. Buttonhole requires strict site/scab care and trained consistency; area cannulation is unsafe because it weakens one segment.

EndoAVF: key differences

  • EndoAVFs may be created at forearm or proximal/radial/ulnar sites and may have multiple outflow veins. The surgeon’s cannulation guide should identify the zone, blood-flow direction, and depth; ultrasound can help when the guide is absent or anatomy is difficult.
  • Readiness indicators described include arterial flow of at least 500 mL/min, outflow diameter over 4 mm, and depth no greater than 6 mm. Confirm the actual plan rather than relying on memory.
  • EndoAVFs often have a longer or multiple cannulation zone and may feel softer than a surgical fistula. The flashback may be less forceful; wet cannulation may help. Inflow is placed in the highest-flow vessel, often at about a 20–35° angle; use the specified retrograde/antegrade direction.
  • The outflow needle points toward venous return. It may use the same vessel more proximal to the inflow needle or a parallel vessel at least 4 mm in diameter. Use a shallow angle for superficial veins, adjusted to depth and patient anatomy.
  • EndoAVFs have no obvious scar. Protect them from routine BP checks and blood draws just as with surgical AVFs, and use the clinic’s specific cannulation map.

Why answers are correct

  • Arterialized venous walls need time to enlarge and strengthen. Correct site rotation spreads mechanical stress; repeated puncture at one location promotes aneurysm, pseudoaneurysm, and loss of usable tissue.

Limitations / traps

  • A thrill or bruit confirms flow, not maturity, safe needle placement, or absence of stenosis.
  • Never cannulate blindly, through a prior track, through an aneurysm/pseudoaneurysm, or across the elbow crease when the plan can avoid it.

Clinical pearl / safety

  • Position the arm comfortably on a padded support. Keep the patient seated and the needles secured until the procedure is complete; a loose needle can move and infiltrate.

Exam cue

  • AVF = patient’s own vessel, best long-term durability when it matures and is protected.

Cannulation essentials

Study guide

  • Wash hands, use required PPE, inspect the access, apply a tourniquet when indicated, prep the skin with the approved antiseptic, and allow it to dry completely. Use the prescribed needle length and gauge; do not assume every new access needs small needles or a reduced blood flow.
  • Confirm arterial/inflow and venous/outflow directions from the access plan. The arterial needle draws blood toward the machine; the venous needle returns blood toward the patient. Keep adequate distance between tips to limit recirculation.
  • Use gentle, controlled insertion. Stop advancing when resistance changes or the needle enters the vessel; never force, twist, or “fish” for the lumen. A flashback does not excuse poor assessment of depth or direction.
  • Dry cannulation inserts the needle without saline in the needle; wet cannulation uses saline according to policy and may be helpful in selected endoAVFs. Use the method ordered by the clinic.
  • Tape must stabilize the needle and tubing without compressing the access. Secure the tubing so movement cannot pull on the needle. Each safe taping method must wrap around the tubing; an overlap that does not capture the tubing is unsafe.
  • Remove tape and needles only after blood has been returned and the patient is stable. Remove the needle fully at its insertion angle before applying pressure; pressing too early can drive the bevel through the vessel wall or damage the intima.

Needle fear and pain

  • Acknowledge fear instead of dismissing it. Explain what will happen, use calm communication, and offer distraction, slow breathing, music/video, or guided imagery. Anxiety and repeated pain can reinforce one another.
  • If approved by the prescriber and clinic, options include topical lidocaine/EMLA, intradermal lidocaine, vapocoolant, or other approved measures. Check for allergy or skin reaction; do not apply cream to a rash.
  • EMLA is applied well before treatment, covered to improve absorption, and washed off immediately before cannulation. Intradermal lidocaine is placed just under the skin with a separate syringe/needle per policy; never inject lidocaine into the AVF/AVG or bloodstream. Vapo-coolant can cause frostbite and is flammable; follow label distance and exposure time and clean the site correctly afterward.
  • A three-point technique may reduce pain: tourniquet; stabilize the AVF above the planned site with the non-needle hand; use the needle hand to keep skin and vessel steady while placing the needle. Gentle pressure can briefly reduce pain signaling.
  • Self-cannulation can reduce pain for some patients by improving control, distraction, and placement accuracy. Support it only under clinic policy after teaching and competency demonstration. Imaging/handheld ultrasound can improve visualization and reduce infiltration in difficult accesses.

Taping and patient comfort

  • Secure needles with a chevron, butterfly, or other approved technique that keeps tape around the tubing and stabilizes the wings. Cover the site with sterile dressing/gauze or tape so it remains protected during treatment.
  • Ask how the patient wants to use the arm (reading, computer, knitting). Avoid crossing the elbow crease and help position belongings so the patient does not move the access arm.

Why answers are correct

  • Needle movement, excessive force, poor stabilization, and blind reuse of old tracks cause infiltration, hematoma, intimal injury, pain, and loss of access.

Exam cue

  • A safe needle is placed deliberately, stabilized securely, observed continuously, and removed before pressure is applied.

Arteriovenous grafts (AVGs)

Study guide

  • An AVG uses a biologic or synthetic bridge to connect a native artery and vein. PTFE is the common synthetic material; grafts may be tapered or uniform in diameter. Common placements include looped or straight forearm, straight upper arm, and looped thigh.
  • AVGs usually mature in weeks rather than the months often needed for AVFs. Some early-cannulation grafts may be usable within about 72 hours; use only the manufacturer’s and provider’s instructions.
  • Pros: high dialysis blood flow, usefulness when vessels are unsuitable for an AVF, shorter maturation, and potential reduction in CVC exposure. Cons: more infection, stenosis, thrombosis, pseudoaneurysm, and shorter long-term lifespan than a successful AVF.
  • Use the rope-ladder method for PTFE grafts unless a specific protocol supports another technique. Repeated area puncture produces “one-site-itis,” weakens the graft, and can cause pseudoaneurysm and rupture. Do not assume buttonhole is safe for every graft.
  • Assess direction by the access map, bruit, and thrill. The arterial end generally has stronger flow/bruit; the venous end may have a softer bruit and fading thrill. If unsure, stop and ask the nurse rather than guessing.
  • HeRO grafts combine a subcutaneous PTFE segment with a central outflow component. Do not cannulate the venous outflow component or any metal sleeve; follow the specific access record and procedure.

Why answers are correct

  • Graft material is foreign to the body and each puncture makes a hole that must seal. Repeated puncture in one area causes structural failure and gives bacteria a route into a difficult-to-treat infection.

Exam cue

  • AVG: follow the material-specific plan, use rope ladder, and never needle an unapproved outflow component or damaged bulge.

Patient education for AVFs and AVGs

Study guide

  • Keep the access skin clean and intact. Avoid tight watches, jewelry, elastic sleeves, heavy objects, sleeping on the access, or resting a purse/box on it. Remove post-treatment bandages after the clinic’s interval (the text describes 4–6 hours) so the skin can breathe.
  • Never pick scabs. Watch for thin/shiny skin, pigment loss, raised needle scabs, redness, warmth, swelling, drainage, pain, fever, or chills. Report changes immediately.
  • Check that the access is working by learning the normal thrill and bruit and noting changes. A missing or markedly changed thrill/bruit is urgent; do not attempt cannulation.
  • Teach bleeding response: apply direct pressure with one or two fingers, raise the access above heart level, call for help/911, and keep pressure in place. A clean screw-cap bottle can be used over a rupture only as an emergency bridge if taught by the clinic. Do not repeatedly peek.
  • Patients and families need written instructions and supplies for bleeding after discharge. Access bleeding can be deceptively rapid because flow is high and blood may be near body temperature.

Exam cue

  • Protect the arm every day, learn the normal thrill, and treat uncontrolled bleeding as a life-threatening emergency.

After-treatment needle removal and bleeding control

Study guide

  • After blood return and stability: remove tape carefully, cover each site with gauze, remove one needle at its original angle, pull it fully out, then apply firm pressure. Repeat for the other site.
  • Pressure must stop external bleeding without occluding access flow. Teach capable patients to hold one site at a time with two fingers. Avoid clamps unless necessary and permitted; a slipping clamp can cause uncontrolled bleeding.
  • A site still bleeding after about 20 minutes should be reported. Prolonged post-dialysis bleeding can indicate stenosis or excessive anticoagulation. Patients using blood thinners may need a pressure dressing; they should hold constant pressure for the instructed interval rather than checking repeatedly.
  • If a needle dislodges or a bloodline separates, stop the pump, clamp lines per policy, apply pressure, and call for help immediately. Keep every needle and line visible throughout treatment; pooling blood under clothing or blankets can be missed.

Stenosis

  • Stenosis is narrowing that restricts flow and raises pressure, commonly from neointimal hyperplasia after wall injury. Sites include inflow/juxta-anastomotic stenosis, outflow stenosis (often at an AVG’s venous anastomosis), and central venous stenosis.
  • Central venous stenosis is associated with prior central IV/PICC lines, dialysis or other CVCs, and pacemaker/defibrillator wires in the access drainage route.
  • Report a new high-pitched/loud/whistling bruit; an inconsistent, pounding, or water-hammer thrill; a weak or hard-to-compress pulse; persistently high arterial-negative or venous pressures; prolonged bleeding; difficult cannulation; recirculation/low adequacy; or persistent access-side/neck swelling not explained by infiltration.
  • Evaluation may include ultrasound, fistulogram, or venogram. Angioplasty expands a narrowed segment with a balloon; a stent may be used when appropriate. Never cannulate through a stent.

Thrombosis

  • Thrombosis is clot formation inside the access. Low blood pressure, dehydration, external compression, infiltration/hematoma, and stenosis can contribute. AVG thrombosis is more common than AVF thrombosis.
  • If there is no bruit or thrill, do not cannulate. Notify the nurse promptly so the nephrologist or vascular surgeon can be contacted; early thrombectomy or other repair may save the access.

Recirculation

  • Recirculation occurs when already-cleaned blood is drawn back into the circuit, reducing effective clearance. Causes include reversed lines, needles too close, stenosis, aneurysm/pseudoaneurysm, or a blood flow rate the access cannot support.
  • A recirculation sample may be ordered about 30 minutes into treatment. Follow the clinic’s collection method and investigate a drop in adequacy rather than simply increasing settings.

Steal syndrome and ischemia

  • An access can divert too much arterial blood from the hand, causing ischemia. Symptoms include numbness/tingling/pain, coldness, reduced hand or finger function, rest pain, symptoms that worsen during HD, pale/dusky/blue-purple nail beds, wounds, ulcers, necrotic spots, or gangrene.
  • Risk is higher with peripheral vascular disease, neuropathy, older age, hypertension, diabetes, and poor circulation. Report any suspicion immediately; treatment may revise inflow or, in severe cases, ligate the access and create another one.
  • During dialysis, comfort measures such as a glove/sock, comfortable positioning, a squeeze ball if allowed, and avoiding hypotension may help, but they do not replace evaluation.

High-output cardiac failure

  • A large/high-flow AVF can lower systemic vascular resistance and increase cardiac workload. Risk is higher with an upper-arm AVF, male sex, and volume overload. Symptoms include fatigue, poor exercise tolerance, swelling, tachycardia, and unusually warm hands; untreated disease can reduce organ perfusion and be fatal.
  • Diagnosis may use chest imaging and echocardiography. Creating a distal access can reduce risk; treatment may reduce access flow or revise the access under medical direction.

Infiltration and hematoma

  • Infiltration occurs when the needle passes through the access wall or backs out, allowing blood into tissue. Stop and respond quickly; continued pump flow increases bruising and swelling and may damage the access.
  • Minor injuries may need ice and rest for 1–2 days; major injuries cause substantial swelling and take over a week to recover; severe injuries may require transfusion, emergency care, hospitalization, or surgery. A hematoma can compress the access and promote thrombosis; a severe one may make the access unusable for months and require a CVC during healing.
  • Listen to the patient if they feel the needle puncture the back wall. Do not flip, twist, or fish a needle. Flush only as directed to confirm painless placement without swelling or resistance. Prevention: gentle technique, full visual assessment, tourniquet when appropriate, no blind/prior-track cannulation, stop at the first unusual resistance, and secure the needle.
  • Before heparin, remove an infiltrated needle and apply pressure; after heparin, alert the nurse because bleeding may last longer and the nurse must decide whether the needle can remain. Use an ice pack wrapped in cloth for the first 24 hours as directed; dry heat/warm compresses may be used after 24 hours. Place a new needle as far from the injury as possible, document cause/outcome, and do not shorten the prescribed treatment—replace lost time when ordered.

Aneurysm and pseudoaneurysm

  • An aneurysm is a dilated, thin, weak access wall; a pseudoaneurysm is blood leaking through a wall defect and being contained by surrounding tissue. Area cannulation, stenosis, high pressure, infection, and repeated trauma promote them.
  • Cannulate the thick sides or base only if the access plan permits; never puncture the thin top of an aneurysm, a pseudoaneurysm, or eroded skin. Inspect at every treatment and report growth, pain, swelling, bruising, scabs, ulceration, pigment loss, or drainage.
  • A practical progression described is: Grade 1—enlarged but intact, thinned skin; Grade 2—larger with skin breakdown/ulcers and prompt surgical evaluation; Grade 3—thin, shiny, stretched, rapidly changing, or ulcerated skin needing urgent surgical evaluation; Grade 4—bleeding/rupture needing emergent repair. A CVC may be required while repair is pending.

Infection in AVFs and AVGs

Study guide

  • Access infection can spread through the bloodstream and seed joints, bones, or the heart. AVG infection risk is higher because graft material can harbor bacteria and may require drainage or graft removal; antibiotics alone may not be enough.
  • Signs include redness, warmth, pain, swelling, abscess, drainage of clear fluid or pus, skin-texture change, chills, and fever. Even a seemingly minor local infection can progress to sepsis.
  • Use hand hygiene, PPE, skin antisepsis, adequate drying time, sterile supplies, and no-touch technique. Follow the clinic’s exact site-preparation and dressing policy. Report suspicious findings immediately; cultures and antibiotics may be needed.
  • Infection can erode skin over an AVF/AVG, leading to rupture and catastrophic bleeding. Do not cannulate an unsafe infected or eroded area; escalate to the nurse/provider.

Exam cue

  • The safest infection intervention is prevention; once infection is suspected, report rather than watch and wait.

Access rupture and emergency bleeding

Study guide

  • A ruptured access is a life-and-death emergency: high access flow can cause fatal blood loss within minutes. Causes include aneurysm, stenosis, infection, trauma, or intentional injury.
  • In clinic: apply direct pressure over the bleeding point, raise the limb above heart level, call for help and follow emergency policy, and reduce access flow only as authorized. Some policies allow pressure above the arterial anastomosis or a blood-pressure cuff over the rupture; never “peek” by releasing pressure.
  • A tourniquet over an anastomosis/directly over bleeding is a last resort only under policy because it can sacrifice the access or limb. Do not improvise a procedure while delaying emergency response.

Monitoring, surveillance, and quality improvement

Study guide

  • Clinical monitoring is the physical examination and observation of access function: arm swelling, pain, skin change, bruit, thrill, pulse, bleeding time, pressures, and cannulation difficulty. Surveillance uses periodic trend data and special tests to identify dysfunction before access loss.
  • Measures can include dynamic/static venous pressure, access-flow measurement with appropriately reversed lines/device, online clearance/conductivity data, and duplex Doppler ultrasound. Trends matter more than one unexplained number; escalate changes according to policy.
  • A reverse-flow surveillance device such as the described Twister system can measure access flow without the usual bloodline setup when compatible with the machine and clinic protocol. Avoid kinks and follow manufacturer instructions.
  • Continuous quality improvement (CQI) and QAPI use local data to reduce access problems. Track access type, placement date, surgeon/quality, problem type, action, One Minute Check findings, clinical observations, dose/adequacy, hospitalization, and patient participation. Graph patterns, trial a small change, measure results, adopt or revise the plan, and recheck later.
  • National and professional resources mentioned include KDOQI vascular-access guidance, the ESRD National Coordinating Center Lifeline resources, My Vascular Access, Save Your Vein, and CDC dialysis-safety tools. Use current facility-approved guidance rather than relying on an old handout.

Why answers are correct

  • Early recognition of altered pressure, flow, appearance, or function allows evaluation before thrombosis, infection, rupture, or inadequate dialysis becomes irreversible.

Exam cue

  • Trend the access, report the change, document the response, and participate in prevention.

Vocabulary

Uncommon words from this chapter. Plain definitions + a short dialysis-related example.

arteriovenous
Connecting an artery to a vein so the vein can carry high-flow dialysis blood.
Example. An arteriovenous fistula uses the patient's own vessels as the lifeline.
maturation
The time an access enlarges and strengthens enough for safe, repeated needles.
Example. Do not assume a fistula is ready just because it is visible; wait for maturation signs.
bruit
The whooshing sound of access flow heard with a stethoscope.
Example. A new high-pitched or whistling bruit can be a stenosis warning.
thrill
The buzzing feel of blood flowing through the access.
Example. A missing thrill is urgent; do not cannulate.
aseptic
Keeping germs out of connections, dressings, and needle sites.
Example. CVC care needs aseptic technique at every cap and dressing change.
cannulation
Placing dialysis needles into the access.
Example. Safe cannulation is gentle, mapped, and never forced.
buttonhole
Using the same needle track and angle over many treatments.
Example. Buttonhole cannulation needs strict scab care and is not assumed safe for every graft.
rope-ladder
Rotating needle sites along the usable access segment.
Example. Use rope-ladder on PTFE grafts to avoid weakening one spot.
stenosis
Narrowing that restricts flow and raises pressure.
Example. Stenosis can cause high pressures, prolonged bleeding, or swelling.
thrombosis
Clot forming inside the access.
Example. No bruit or thrill can mean thrombosis; notify the nurse at once.
recirculation
Already-cleaned blood being drawn back into the circuit.
Example. Needles that are too close can cause recirculation and lower adequacy.
ischemia
Not enough arterial blood reaching the hand or fingers.
Example. Cold, painful, or dusky fingers during HD can be access-related ischemia.
steal syndrome
The access taking so much arterial blood that the hand is starved.
Example. Steal syndrome can worsen during dialysis and needs prompt evaluation.
infiltration
The needle going through the wall so blood leaks into tissue.
Example. Stop the pump quickly if infiltration is suspected; extra flow worsens swelling.
hematoma
A collection of blood in tissue that can swell and compress the access.
Example. A large hematoma can make the access unusable and force a temporary catheter.
aneurysm
A dilated, thin, weak area of the access wall.
Example. Never puncture the thin top of an aneurysm.
pseudoaneurysm
Blood leaking through a wall defect and being held only by surrounding tissue.
Example. Repeated area puncture can cause a pseudoaneurysm and rupture risk.
hyperplasia
Thickening of the inner vessel lining after injury.
Example. Neointimal hyperplasia is a common cause of access stenosis.
angioplasty
Opening a narrowed vessel with a balloon.
Example. Angioplasty may treat stenosis; never cannulate through a stent.
surveillance
Scheduled tests and trends used to catch access trouble before the access is lost.
Example. Surveillance looks at flow and pressure trends, not one unexplained number.
endovascular
Done from inside the blood vessel rather than through a usual open cut.
Example. An endovascular fistula may have no obvious scar and needs its own cannulation map.

Module conclusion — must-know summary

  • AVF: patient’s own artery and vein; usually best durability after maturation; protect and rotate sites.
  • AVG: bridge material; faster usability but more stenosis, infection, thrombosis, pseudoaneurysm, and shorter lifespan; use the prescribed rope-ladder plan.
  • CVC: immediate access but highest infection/dysfunction concern; use strict asepsis and protect the closed system.
  • Every treatment: inspect, listen, feel, confirm direction, cannulate gently, secure needles, watch continuously, remove safely, and document.
  • Never cannulate a site that lacks expected flow, is infiltrated, infected, aneurysmal, eroded, or otherwise outside the access plan.
  • Recognize the emergencies: uncontrolled bleeding, dislodged needle/line separation, absent thrill/bruit, severe infiltration, infection/sepsis, ischemia/steal, and access rupture. Call the nurse/emergency response without delay.

Read aloud is ready.

0:00