Catheter Occlusion Management: Alteplase, Troubleshooting, and Prevention

Catheter occlusion — defined as any situation preventing adequate blood withdrawal or infusion through a vascular access device — affects 10–25% of CVADs during their dwell. It is the most common non-infectious catheter complication requiring intervention. Prompt recognition and systematic troubleshooting prevent unnecessary catheter replacement and maintain infusion therapy continuity.

Parent guide: Catheter Complications: Complete Clinical Reference

Classification of Catheter Occlusion

Complete vs. Partial Occlusion

Complete occlusion: Catheter will neither infuse nor withdraw blood. Both flush resistance and absent blood return.

Partial occlusion (withdrawal occlusion): Catheter flushes without resistance but blood cannot be aspirated. The most common presentation of early fibrin sheath or positional occlusion.

Thrombotic Occlusion

Caused by blood clot or fibrin sheath formation within or around the catheter.

Intraluminal thrombus: Blood that has entered the catheter lumen (from inadequate flushing technique, blood reflux) forms a clot inside the catheter.

Fibrin tail/sheath: The fibrin sheath encasing the catheter tip grows over the tip opening, creating a one-way valve effect — infusate can push the fibrin tail aside (flow is possible), but aspiration pulls the tail over the opening (no blood return). This explains withdrawal occlusion.

Mural thrombus: Thrombus on the vessel wall at the catheter tip, adherent to both catheter and vessel.

Responds to: Thrombolytic therapy (alteplase).

Non-Thrombotic Occlusion

Medication precipitate: Chemical interaction between medications co-infused through the same lumen, or between a medication and flush solution, producing a precipitate that crystallizes within the catheter.

• Calcium-phosphate precipitate: From PN admixtures or from separate calcium and phosphate infusions
• Phenytoin precipitate: Phenytoin (pH ~12) precipitates with many co-infused medications; should never be co-infused with any medication or saline containing dextrose
• Lipid obstruction: Lipid deposits from prolonged PN infusion

Responds to: Specific chemical dissolution agents (not alteplase).

Mechanical obstruction: Catheter kinking, catheter pinch-off (subclavian approach — costoclavicular compression), suture too tight at insertion site, tip against vessel wall.

Responds to: Positional adjustment, repair, or repositioning.

Systematic Troubleshooting Approach

When a catheter occlusion is identified, apply the following systematic assessment before initiating alteplase:

Step 1: Exclude Mechanical Causes

Check:

• Is there a clamp closed on the catheter? (Common cause)
• Is the catheter kinked externally? (Look along the entire external catheter length)
• Does occlusion resolve with arm repositioning? (Suggests positional mechanical cause)
• Is there excessive tension on the catheter creating kinking at the insertion site?
• Has the patient had any recent procedures involving the arm, shoulder, or chest?

Pinch-off syndrome (subclavian-inserted CVCs): If infusion works when arm is at the side but fails when arm is elevated, suspect pinch-off syndrome — catheter is compressed between clavicle and first rib with arm elevation. Confirm with CXR or fluoroscopy; catheter may need replacement.

Step 2: Assess for Malposition

If mechanical causes are excluded:

• Is catheter external length unchanged from insertion documentation? (Migration would indicate tip position change)
• Does the patient have shoulder or chest discomfort during infusion? (Possible malposition with infusate extravasation)
• If malposition is suspected, obtain imaging before instilling thrombolytic

Step 3: Determine Occlusion Type

Consider the clinical history:

• What was infused most recently? (Medication compatibility issue?)
• When did the catheter last work normally?
• Is the occlusion in all lumens or one lumen? (One-lumen occlusion suggests intraluminal precipitate; all-lumen occlusion suggests fibrin sheath at tip)
• Has the patient had blood drawn through this catheter recently without adequate flushing?

Alteplase Protocol for Thrombotic Occlusion

Alteplase: Drug Overview

Drug: Alteplase (Activase, Cathflo Activase), recombinant tissue plasminogen activator (rt-PA).

FDA-approved use: Restoration of function in CVADs occluded due to thrombosis.

Mechanism: Converts plasminogen to plasmin, which degrades fibrin. Direct enzymatic dissolution of fibrin clot within or around the catheter tip.

Dose: 2 mg/2 mL per lumen (Cathflo Activase).

Protocol

Step 1: Instill alteplase

• Using aseptic technique, draw 2 mg alteplase into a 3 mL syringe
• Instill 2 mL (2 mg) into the occluded lumen
• Note: If catheter dead-space volume is <2 mL, instill only enough to fill the catheter (use manufacturer’s priming volume; do not overfill to avoid systemic alteplase administration)

Step 2: Dwell

• Allow alteplase to dwell in the catheter for 30 minutes
• The patient may ambulate during dwell; no restriction required
• Document time of instillation

Step 3: Assess for patency

• After 30-minute dwell: attempt to aspirate blood return
• If blood return restored: aspirate and discard 5 mL (to remove alteplase and any dissolved clot debris)
• Flush catheter with 20 mL normal saline using pulsatile technique

Step 4: If unsuccessful after 30 minutes

• Allow to dwell for additional 60–90 minutes (total dwell up to 120 minutes)
• Reassess at 90 and 120 minutes
• If successful at any point: aspirate 5 mL, flush as above
• If unsuccessful after 120 minutes: consider second dose

Second dose:

• If first dose unsuccessful after 120 minutes, instill a second 2 mg/2 mL dose
• Allow 30–120-minute dwell
• If second dose fails: reconsider diagnosis (is this thrombotic or non-thrombotic?); imaging; consider catheter replacement

Efficacy

Published efficacy of alteplase for CVAD thrombotic occlusion: 85–90% restoration of patency after 1–2 doses. Non-response suggests non-thrombotic occlusion, malposition, or mechanical cause.

Contraindications

Absolute:

• Known thrombocytopenia (platelets <20,000) — increased bleeding risk
• Active internal bleeding
• Active intracranial lesion or hemorrhage
• Recent (within 48 hours) major surgery, serious trauma, or thromboembolic event requiring systemic thrombolytic therapy

Relative:

• Recent (within 10 days) invasive procedure or surgery
• Severe uncontrolled hypertension
• Pregnancy

Note: Alteplase instilled at 2 mg/2 mL into a catheter produces negligible systemic thrombolytic effect — the dose is below systemic therapeutic levels. The risk profile is vastly different from systemic alteplase therapy for stroke or PE.

Non-Thrombotic Occlusion Management

Medication Precipitate

Identify the precipitant: Review medication administration record; identify recently infused medications with known incompatibility.

Dissolution agents (pharmacy-specific protocols required):

These protocols require pharmacy consultation and are not universally standardized. Do not instill HCl or 70% ethanol without explicit pharmacy guidance and institutional protocol.

Prevention is the priority: Verify medication compatibility before co-infusing; flush with 10 mL NS between incompatible medications; never co-infuse calcium and phosphate through the same lumen in a PN setting.

Lipid Occlusion (PN-Related)

Lipid deposits from prolonged PN infusion: 70% ethanol lock is the evidence-supported treatment. Instill 3 mL of 70% ethanol into occluded lumen; allow to dwell 1–4 hours; aspirate and discard before resuming infusion.

Prevention: SASH Protocol and Positive Pressure Technique

The Root Cause of Most Thrombotic Occlusions

Most thrombotic catheter occlusions result from blood reflux into the catheter lumen when:

• Infusion is stopped without flushing (blood fills the tip)
• Positive pressure not maintained at the end of flushing (blood refluxes during connector disconnection)
• Catheter is clamped incorrectly

SASH Protocol

Saline-Administer-Saline-Heparin (or Saline lock):

• Flush with 10 mL NS before each use (pulsatile technique)
• Administer medication/infusion
• Flush with 10 mL NS after each use (pulsatile technique)
• Lock with heparin 10 units/mL (or saline — per institutional policy)

Pulsatile Flushing

Push-pause technique creates turbulence that clears catheter lumen of fibrin and blood debris. Continuous slow flushing does not create adequate turbulence.

Positive Pressure Technique

Maintain thumb pressure on syringe plunger as the catheter clamp is closed or the connector is disconnected. Prevents negative pressure (from loss of forward pressure) from drawing blood into the catheter tip.

Related Resources

Related guides:

• PICC Care and Maintenance
• Catheter-Associated Thrombosis Guide

Related policies:

• Vascular Access Device Occlusion
• Flushing and Locking Vascular Access Devices

References

1. Gorski LA, et al. (2021). INS Infusion Therapy Standards of Practice (Standard 55: Occlusion). J Infus Nurs, 44(Suppl 1).
2. Baskin JL, et al. (2009). Thrombolytic therapy for central venous catheter occlusion. Haematologica, 94(2):273–281.
3. Deitcher SR, et al. (2002). Safety and efficacy of alteplase for restoring function in occluded CVCs: 2-year follow-up. J Thromb Haemost, 1(7):1499–1504.
4. Stephens LC & Haire WD. (1995). Normal saline versus heparin flush. Crit Care Nurs, 15(5):77–80.