A central venous catheter (CVC) is a flexible tube placed into a large vein, typically in the neck, chest, or arm, with the tip resting near the heart in the superior vena cava. This placement allows for the safe delivery of medications, fluids, and nutrition, and permits frequent blood draws over an extended period. When a CVC suddenly stops working, meaning it cannot be flushed easily or blood cannot be drawn, it signals a potentially serious complication that requires immediate attention from a healthcare provider. A non-functioning catheter is a frequent issue.
External and Kink-Related Issues
The simplest reasons for a CVC malfunction often involve mechanical issues outside the body or within the catheter’s tunnel. A common issue is a clamp that has accidentally been left in the closed position, which completely stops the flow of fluids or blood.
A kink in the catheter line, particularly where it is secured by the dressing or near the insertion site, can also restrict or halt function. These kinks are often visible and may be corrected with careful repositioning of the external tubing. A more complex mechanical issue, sometimes seen with lines placed through the subclavian vein, is “pinch-off syndrome,” where the catheter is compressed between the collarbone (clavicle) and the first rib. This intermittent compression can make the line difficult to use, especially when the patient moves their arm or changes position, and it can eventually lead to catheter damage.
Understanding Internal Blockages
Internal blockages are the most frequent biological cause of CVC failure, often related to blood clotting or drug residue. Most catheter occlusions are thrombotic, meaning a blood clot is responsible for the obstruction. This clot can form inside the catheter’s lumen, known as an intraluminal thrombus, or it can form on the outside around the tip.
A common occurrence is the formation of a fibrin sheath, a structure composed of blood proteins that encases the outside of the catheter like a sock. This sheath can form within days of insertion and may create a one-way valve effect at the catheter tip. The valve allows fluids to be infused through the line but collapses inward when negative pressure is applied to draw blood, resulting in a partial occlusion where the line infuses but does not withdraw blood.
Drug-related precipitate occlusions are non-thrombotic blockages caused by incompatible medications mixing within the catheter. Certain antibiotics, lipids from nutritional solutions, or other concentrated solutions can crystallize and harden inside the lumen, leading to a complete blockage where neither infusion nor aspiration is possible.
Catheter Migration and Positional Changes
Catheter function is highly dependent on the precise location of the tip, which is ideally situated in the superior vena cava, just above the heart’s right atrium. If the catheter tip moves out of this optimal position, it is referred to as catheter migration. Vigorous activities, forceful coughing, vomiting, or even changes in body position can cause the catheter to shift.
When the tip migrates, it may end up resting against the wall of the vein, which can block the opening and prevent blood withdrawal or fluid infusion. This is a common reason for a “postural occlusion,” where simply changing the position of the head, neck, or arm can temporarily restore flow. Monitoring the external length of the catheter is important, as any noticeable change can be a sign that the tip has migrated internally.
Immediate Steps to Take When the CVC Stops Working
If you discover your central venous catheter is not working, remain calm and avoid attempting to force a flush. Applying excessive pressure to a blocked line is dangerous and could cause a clot or precipitate to dislodge and travel into the bloodstream, or it could damage the catheter itself.
Instead, check all external clamps to ensure they are open and look for any visible kinks in the tubing that may be easily corrected. If the issue persists, try gently changing your body position, such as raising your arm, taking a deep breath, or sitting upright, as this may relieve a positional occlusion.
If these simple steps do not restore the line’s function, immediately stop using the catheter and notify your healthcare provider or home care nurse. Only trained medical professionals can safely assess the cause of the malfunction, diagnose blockages, or perform advanced troubleshooting procedures such as the administration of a thrombolytic agent to dissolve a clot.