A peripherally inserted central catheter (PICC line) is inserted into a vein in the upper arm, with its tip positioned near the heart. This device provides safe, long-term access for administering medications, fluids, or nutrition that would otherwise irritate smaller veins. A common complication is occlusion, which is the partial or complete blockage of the line. An occluded line can delay necessary therapy and may require the catheter’s complete removal and replacement.
Identifying the Cause of the Blockage
Restoring flow to a PICC line requires identifying the source of the blockage. The most frequent cause is a thrombotic occlusion, resulting from blood components clotting inside the catheter lumen. This occurs when blood refluxes into the line, such as during blood sampling or due to insufficient flushing after an infusion, leading to a blood clot or fibrin sheath formation.
A second type is non-thrombotic or precipitate occlusion, which is a chemical blockage. This happens when incompatible medications or solutions are administered sequentially without adequate flushing, causing them to mix and form crystals or precipitates. For example, lipids from total parenteral nutrition (TPN) can build up if not adequately cleared from the catheter’s interior.
The final category is mechanical occlusion, where the line is physically obstructed. Causes include a kink in the tubing, a closed clamp, or the catheter tip being positioned against the vein wall. A partial mechanical occlusion allows fluids to infuse but prevents blood withdrawal, known as persistent withdrawal occlusion.
Immediate Action and Safety Protocols
Discovering a sluggish or completely blocked PICC line requires immediate cessation of all infusions. The most important safety rule is never to attempt to force a flush if resistance is felt. Applying excessive pressure can cause the catheter to rupture, or, if the blockage is a blood clot, it risks dislodging the clot and sending it into the bloodstream.
If the infusion pump alarms or a gentle flush meets resistance, immediately stop the procedure and check all external clamps. If the issue is not a simple closed clamp or an external kink, the patient or caregiver must contact the healthcare provider or medical team without delay. Professional evaluation is necessary to determine the cause and safely restore patency. The medical team should also be alerted to associated symptoms, such as pain, swelling, or fever.
Clinical Methods for Restoring Patency
Once a blockage is confirmed, trained medical staff will select a method to restore flow based on the suspected cause.
Thrombotic Occlusions
For thrombotic occlusions, the standard procedure is thrombolytic therapy, which involves instilling a specialized agent into the blocked lumen. Tissue plasminogen activator (tPA), often referred to as Cathflo, is commonly used. It works by converting plasminogen to plasmin, an enzyme that dissolves the fibrin within the clot. The agent is carefully instilled into the lumen, typically using a 10mL syringe, and allowed to dwell for a specific period, often between 30 minutes and two hours. This dwell time allows the medication to actively lyse the clot before the nurse attempts to aspirate the solution and the dissolved debris. If the initial attempt is unsuccessful, the procedure may be repeated one time, following manufacturer’s guidelines.
Non-Thrombotic Occlusions
For non-thrombotic blockages, specialized chemical instillation procedures are used to dissolve the precipitate. For example, a diluted solution of hydrochloric acid (0.1 N) may be used to break down precipitates formed by acidic medications. Conversely, an 8.4% sodium bicarbonate solution treats alkaline precipitates. For lipid occlusions, such as those from TPN, a concentrated solution of 70% ethanol may be instilled, as it is effective at dissolving the fatty deposits.
Mechanical Issues
When a mechanical issue is suspected, the initial step is often a simple physical intervention, like asking the patient to change arm position, cough, or perform the Valsalva maneuver to shift the catheter tip away from the vein wall. If these maneuvers fail, a chest X-ray or fluoroscopy may be ordered to confirm the catheter’s physical position and check for a pinch-off or internal kink. In rare instances, a specialized wire or catheter-clearing device may be inserted by a physician or radiologist to physically clear the obstruction.
Daily Care to Prevent Future Blocks
Preventing future occlusions relies on routine maintenance and proper flushing technique. The most recognized method for routine care is the SASH method, an acronym that stands for Saline, Administer (Medication), Saline, and Heparin or Lock Solution. This regimen ensures the catheter is flushed before and after medication to clear drug residue, which is a common cause of chemical blockage.
It is recommended to use a 10mL syringe for flushing, as smaller syringes generate higher pressures that can damage the catheter wall. The flush should be administered using a push-pause technique. This involves injecting a small volume of saline, pausing briefly, and then repeating the action. This turbulent flow helps dislodge any material adhering to the inner lumen wall more effectively than a continuous, steady push.
Proper sealing of the line is achieved by clamping the catheter while the last milliliter of the lock solution is being injected, a process known as clamping under positive pressure. This technique prevents blood from flowing back into the catheter upon syringe disconnection, minimizing the risk of clot formation at the catheter tip. Consistent adherence to this protocol is the best defense against future loss of PICC line patency.