Access Assessment and Signs of Access Failure

Look, Listen, Feel: The Standard Sequence

Access assessment is a required pre-cannulation clinical skill, and the exam tests it through the look, listen, feel sequence. The vascular access hierarchy matters here: the arteriovenous fistula (AVF) is preferred over the arteriovenous graft (AVG), which is preferred over the central venous catheter (CVC) because infection and failure risk rise down that list.

Look (inspect): examine the skin over and around the access for redness, warmth, drainage, swelling, shiny or taut skin, bruising, scabs, skin breakdown, and changes in any aneurysm or pseudoaneurysm. Note cannulation-site rotation and any area that looks thinned or about to erode.

Listen (auscultate): place the stethoscope over the access to hear the bruit — a continuous, low-pitched whooshing sound through both systole and diastole. Feel (palpate): lightly place fingertips over the access to feel the thrill — a soft, continuous buzzing vibration. Both are present along the length of a well-functioning access.

Normal vs Abnormal Bruit and Thrill

The distinction between a healthy and a failing access is one of the most reliably tested ideas in this domain. A patent access has a continuous bruit and thrill. Trouble changes their quality.

A high-pitched or systolic-only bruit and a pulsatile rather than continuous thrill are warning signs of stenosis. A completely absent thrill and bruit signals possible thrombosis and is an emergency for the access — report immediately and do not cannulate. Comparing today's finding to the patient's usual finding is essential, because what is "normal" varies between patients.

Infection, Infiltration, and Catheter Findings

Beyond patency, the technician screens for infection and infiltration.

• Infection signs: localized redness, warmth, tenderness, purulent drainage, or fever and chills. Any of these in a fistula, graft, or catheter is reported before treatment.
• Infiltration signs: swelling, firm bruising (hematoma), pain during or after needle placement, and difficulty achieving flow. Infiltration during prior cannulation may have damaged the wall and changed today's landmarks.

For a CVC, focus on the dressing and exit site: report a wet, loose, or soiled dressing, exposed cuff, exit-site redness or drainage, catheter damage or cracks, and any fever or chills. Catheter care often requires sterile technique and may be restricted to specific trained staff by state and facility rules, so stay within assigned scope.

Protect the access limb at all times: avoid blood pressure cuffs, venipuncture, IV lines, tight clothing or jewelry, prolonged pressure, and heavy lifting on the access side unless policy directs otherwise.

Cannulation Readiness and the Patient History Check

Looking, listening, and feeling are paired with a brief history check before the needle goes in. Ask the patient about the access since the last treatment: new pain, numbness, a cold or discolored hand, prolonged bleeding after the last session, or any difficulty during the previous cannulation. A patient's report of "it bled a long time last time" or "my hand feels cold and tingly" can be the first clue to stenosis or a steal syndrome, where the access diverts so much blood that the hand becomes ischemic.

Readiness also depends on access maturity for a new fistula. A fistula needs time to mature — the vein must enlarge and thicken before it can tolerate repeated needling — and cannulating an immature fistula risks infiltration and access loss. The technician confirms the access is cleared for cannulation per the plan of care and uses the assigned cannulation approach (such as rope-ladder or buttonhole) with proper site rotation to protect the access over time.

Finally, plan needle placement to respect blood-flow direction and adequate spacing between arterial and venous needles to limit recirculation, where already-cleaned blood re-enters the dialyzer and lowers treatment efficiency.

The Exam's Favorite Trap: Proceed vs Escalate

CCHT questions frequently pair an efficient-sounding shortcut with an access warning sign. The shortcut — cannulate anyway, try a different angle, start slow to see if it flows — is almost always the wrong answer when a true failure sign is present.

Decision rules to memorize:

1. No thrill or bruit? Do not cannulate. Report to the RN; the access may be clotted.
2. New high-pitched bruit or pulsatile thrill? Report before use; suspect stenosis.
3. Redness, warmth, drainage, or fever? Report; suspect infection.
4. Swelling, pain, or new bruising? Report; suspect infiltration or a developing aneurysm.
5. Recent prolonged post-treatment bleeding? Report; may indicate high venous pressure or stenosis.

The safe pattern is consistent: stop, keep the patient safe, notify qualified staff, and document the exact finding. Using the access to "test" it can convert a salvageable problem into a lost access or a serious bleed.

Document the access assessment factually each treatment: the presence and quality of the bruit and thrill, the skin appearance, any patient-reported changes, and the action taken if a concern was found. Consistent documentation builds a trend the care team uses to catch a slowly failing access before it clots completely.