A peripherally inserted central catheter (PICC line) is a long, thin tube inserted through a vein in the upper arm, with its tip guided into a large central vein near the heart, often the superior vena cava. This specialized access device is intended for long-term intravenous therapy, typically lasting weeks to months, and is frequently used to administer chemotherapy, extended courses of antibiotics, or total parenteral nutrition (TPN). A PICC line provides a durable route for fluid and medication delivery, avoiding repeated needle sticks. However, the catheter is susceptible to occlusion, a common complication that can delay treatment. Restoring patency to a blocked PICC line is a complex, sterile medical process that must always be performed by trained healthcare professionals.
Identifying the Type of Occlusion
The first step in addressing a non-functioning PICC line is determining the precise nature of the blockage, as treatment protocols vary significantly based on the cause. Occlusions are broadly categorized into two types: thrombotic and non-thrombotic. Thrombotic occlusions are the most common, involving a blockage caused by blood products, such as a fibrin sheath forming around the catheter tip or a blood clot (thrombus) lodged inside the lumen.
A clinician assesses the line’s function by observing resistance during aspiration and infusion attempts. A total occlusion means the inability to both draw blood back and push fluid into the line. A partial occlusion, often called persistent withdrawal occlusion, allows flushing saline into the line but prevents drawing blood back, commonly indicating a fibrin flap over the catheter tip.
Non-thrombotic occlusions result from mechanical issues or chemical precipitation. Mechanical causes include external factors such as a kink in the tubing, a closed clamp, or a catheter tip that has migrated and is resting against a vein wall. Chemical causes occur when incompatible medications form precipitates, or when lipid residue from TPN builds up inside the lumen. Identifying the specific type of non-thrombotic clog guides the choice of specialized clearance solution, such as ethanol for lipid precipitate or hydrochloric acid for mineral precipitate.
Initial Non-Pharmacological Interventions
Once an occlusion is suspected, healthcare providers begin with immediate, non-drug interventions to rule out mechanical issues before introducing pharmacological agents. The clinician first inspects the entire external line, checking for obvious kinks in the tubing, ensuring all clamps are open, and verifying that the needleless connector cap is functioning.
If the external examination does not reveal the cause, the patient may be asked to change position. Simple maneuvers include asking the patient to raise their arm, cough forcefully, or change their body position in bed, as these actions can shift the catheter tip location and resolve an occlusion caused by the tip pressing against a vessel wall.
A gentle attempt to restore patency is then made using a pulsatile flushing technique with sterile normal saline. This involves injecting a small volume of saline in a quick, start-stop motion to create turbulence inside the catheter, which may help dislodge a small clot. A syringe smaller than 10 milliliters must never be used to flush any central access device, as the smaller bore creates excessive pressure that can rupture the catheter. If significant resistance is met during gentle flushing, the procedure must be immediately stopped to avoid damaging the line.
Pharmacological Treatment for Thrombotic Occlusions
When mechanical causes are ruled out, the definitive intervention for a suspected thrombotic occlusion involves instilling a thrombolytic agent. The primary medication used is Alteplase, a recombinant tissue plasminogen activator (rTPA), which is a powerful clot-dissolving drug. Alteplase works by binding to fibrin, the main protein component of the clot, and converting plasminogen into plasmin, which breaks down the fibrin matrix.
The standard adult dose for clearing a PICC line is 2 milligrams of Alteplase contained within a 2-milliliter volume. The clinician instills this volume directly into the occluded lumen, ensuring the dose fills the catheter and reaches the clot site. The line is then clamped, and the Alteplase is allowed to “dwell” inside the lumen for a defined period.
The initial dwell time is typically 30 minutes, followed by reassessment of catheter function. If patency is not restored, the dwell time is extended for an additional 90 minutes, totaling 120 minutes (two hours). If the catheter remains blocked after this period, a second identical 2-milligram dose of Alteplase may be instilled, and the 30- and 120-minute assessments are repeated.
Once function is restored, the clinician must carefully aspirate and discard at least 3 to 5 milliliters of blood and the residual Alteplase mixture to remove the drug and clot fragments. The lumen is then flushed vigorously with normal saline. This procedure requires a physician’s order and close patient monitoring, as the use of thrombolytics carries a risk, though the small, localized dose used for line clearance is generally safe.
Strategies for Maintaining PICC Line Patency
Routine maintenance is the foundation of long-term PICC line function, as preventing an occlusion is preferable to treating one. Ongoing care centers on meticulous flushing protocols performed after every use and on a scheduled basis when the line is idle. Flushing involves instilling sterile normal saline using the push-pause technique, which creates internal turbulence to clear residual blood or medication from the lumen.
When the line is not in continuous use, flushing is typically performed every 24 hours. The line is then locked with a solution, which can be saline, heparin, or citrate, depending on the institutional protocol.
Maintaining the external integrity of the line is also important for patency and infection prevention. The sterile dressing covering the insertion site must be changed at least every seven days, or immediately if it becomes wet, soiled, or loose.
Patient Precautions
Specific patient-care precautions are necessary to protect the catheter from damage. Patients must avoid placing a blood pressure cuff or applying a tourniquet to the arm containing the PICC line. The compression creates significant external pressure on the vein, which can damage the catheter or potentially dislodge a clot. Patients are also advised to avoid strenuous activity and to keep the PICC arm below a certain weight-bearing limit, which helps maintain the line’s position and integrity.