Expert Guide: How to remove blood clot from cannula? Safely and Effectively

According to the National Institutes of Health, catheter occlusion is a common and costly complication in patients with intravenous (IV) therapy. When this occurs, knowing the proper and safe method for how to remove blood clot from cannula is crucial, as incorrect procedures can lead to severe and life-threatening consequences.

Quick Summary

Healthcare professionals use specific techniques and pharmacology to manage a clotted cannula. Assessment, gentle flushing with saline, and sometimes specialized clot-dissolving medications for central lines are key, while forceful flushing must be avoided to prevent dangerous embolism.

Key Points

• Do Not Force a Flush: Never use excessive force or a small syringe (<10mL) to push fluid through a blocked cannula, as this can dislodge the clot and cause a dangerous pulmonary embolism.

• Initial Action is Assessment: A medical professional should first assess the cannula for mechanical issues like kinks and attempt gentle aspiration before any flushing.

• Use the Push-Pause Technique: For minor blockages, a healthcare provider can use a 10mL+ syringe with a push-pause or turbulent flush technique to help clear the line safely.

• Alteplase for Central Lines: If gentle flushing fails for a central venous catheter, a physician may order a fibrinolytic agent like alteplase to dissolve the clot.

• Peripheral IV Removal: If a peripheral IV remains blocked after a gentle flush attempt, the cannula should be removed and a new one inserted at a different site.

• Preventative Care is Key: Routine saline flushing using proper techniques is the best way to prevent blood clots and occlusions from occurring in the first place.

Understanding the Risks of a Blocked Cannula

A blood clot, or thrombus, can form inside an intravenous (IV) cannula due to blood reflux into the catheter lumen. This can happen for various reasons, such as improper flushing, mechanical issues with the line, or simply blood backing up when an IV bag runs empty. When a cannula is blocked, it is considered an occlusion, which can be partial or complete. The most significant danger associated with a clotted cannula is the risk of dislodging the thrombus. If a medical professional or patient uses excessive force to push a saline flush through the blockage, the clot could break free and travel through the bloodstream. In the case of a central venous catheter, this could cause a pulmonary embolism, a potentially fatal condition where the clot blocks an artery in the lungs.

For this reason, it is absolutely essential that only trained medical professionals attempt to clear a blocked cannula. Patients and caregivers should never try to force fluid through a blocked line on their own. Ignoring the blockage or not addressing it correctly can lead to delayed or missed medication doses, device malfunction, and increased risk of infection.

Initial Assessment and First-Line Management

When a healthcare provider suspects a clotted cannula, they must first perform a thorough assessment to determine the cause of the blockage and the correct course of action. The procedure typically includes:

• Stop all infusions: Immediately halt any fluids or medications currently infusing through the line.
• Assess the site: Inspect the area around the cannula for signs of infiltration or extravasation, such as swelling, redness, or pain.
• Check for mechanical issues: Ensure that the tubing isn't kinked, pinched, or clamped shut. Sometimes, a simple repositioning of the patient's arm can resolve the issue if the catheter tip is pressed against a vein wall.
• Attempt gentle aspiration: Using a 10 mL or larger syringe, a clinician may attempt to gently aspirate blood from the line to see if the clot can be pulled out. It is critical not to pull back too forcefully.

Pharmacological and Mechanical Interventions

If the initial assessment and gentle aspiration do not restore patency, the medical professional may proceed with a gentle saline flush. When performing a flush, the following guidelines are crucial:

1. Use a large syringe: For most catheters, a 10 mL syringe or larger is standard because it generates less pressure than smaller syringes. High pressure from a small syringe can rupture the catheter.
2. Employ the push-pause method: This technique involves injecting small, rapid pulses of saline (e.g., 1-2 mL) followed by short pauses. This creates turbulence inside the catheter lumen, which can help dislodge debris or a small clot more effectively than a steady, continuous flush.
3. Do not use excessive force: If significant resistance is met during the flush, the clinician must stop immediately. Forcing the flush can break the catheter or, more dangerously, force the clot into the patient's bloodstream.

For stubborn clots, especially in central venous catheters, healthcare providers may use pharmacological interventions. This involves instilling a specialized clot-dissolving medication, known as a fibrinolytic or thrombolytic agent, directly into the catheter lumen. Alteplase (Cathflo® Activase®) is the only fibrinolytic agent approved by the FDA for treating thrombotic occlusions in central venous catheters. The medication is left to dwell inside the catheter for a specific period (typically 30 to 120 minutes) before the clinician attempts to aspirate the dissolved clot.

Comparative Procedures for Different Cannula Types

Characteristic	Peripheral IV Cannula	Central Venous Catheter (CVC/PICC)
Initial Attempt	Stop infusion, assess site, reposition limb, attempt gentle saline flush with a large syringe (>10 mL).	Stop infusion, assess site, reposition patient, attempt gentle saline flush with a large syringe (>10 mL) using push-pause technique.
Pharmacological Intervention	No pharmacological intervention is used for clots. If a flush fails, the device is typically removed.	If flushing fails, a fibrinolytic agent (e.g., alteplase) may be instilled to dissolve the clot under physician's order.
What to Avoid	Forcing a flush with excessive pressure, using a small syringe.	Forcing a flush, using small syringes, or attempting home remedies.
Final Action if Unsuccessful	Remove the old cannula and insert a new IV at a different site.	Remove the old catheter, or proceed with catheter-directed thrombolysis or thrombectomy in severe cases.

When Professional Intervention is Required

If a gentle, push-pause flush with saline fails to clear the occlusion, or if the healthcare provider observes any signs of device-related complications, professional intervention beyond basic nursing care is needed. Signs that the issue may require more advanced medical attention include:

• Inability to flush the line without resistance.
• Failure to draw blood back from the catheter.
• Persistent swelling, pain, or redness at the insertion site.
• Signs of systemic infection, such as fever or chills.

In these instances, a physician or specialized vascular access team may need to be consulted. For serious blockages in central lines, they may perform a catheter-directed thrombolysis or, in rare cases, a thrombectomy, which involves surgically removing the clot. These are highly specialized procedures performed in a controlled clinical environment and are not applicable to standard peripheral IVs.

Prevention is Better Than Cure

The most effective strategy against clotted cannulas is prevention. Proper maintenance significantly reduces the likelihood of occlusion and the need for complex interventions. Key preventative measures include:

• Regular, routine flushing: Adhere to a strict schedule for flushing with saline (and sometimes heparin, depending on the catheter type and facility policy) to ensure patency, especially when the line is not in continuous use.
• Using a large volume: A 10-20 mL flush is often recommended after administering viscous fluids or drawing blood to ensure the line is thoroughly cleared.
• Maintaining positive pressure: Finish the flush with a positive pressure technique to prevent blood reflux back into the catheter lumen upon disconnecting the syringe.
• Proper catheter selection: Ensure the appropriate catheter size and type are used for the patient's therapy to reduce the risk of mechanical issues.

Conclusion

Dealing with a blocked cannula requires a methodical, cautious approach led by trained medical professionals. The primary risk of forcing a clot loose necessitates a firm adherence to safe protocols, starting with a careful assessment and gentle flushing. While pharmacological agents like alteplase can resolve central line clots, peripheral IVs usually require removal if a gentle flush fails. The most important takeaway for both patients and clinicians is that safety is paramount. Never force a flush through a blocked line. Prevention through meticulous care is the best way to avoid the risks and complications of a thrombotic occlusion. Always consult the appropriate clinical guidelines and professional medical staff for managing a blocked cannula.

For more detailed information on catheter care and maintenance, consult trusted resources like the Infusion Nurses Society (INS) standards.

Frequently Asked Questions

Can I remove a blood clot from my cannula myself?

No, you must never attempt to remove a blood clot from your cannula yourself. Only trained healthcare professionals should perform this procedure, as they have the knowledge and tools to do so safely. Forcing a flush can cause serious and life-threatening complications, such as a pulmonary embolism.

What is the first step a nurse takes to deal with a blocked cannula?

The first step for a nurse is to stop any infusions, assess the insertion site for swelling or other complications, and check for mechanical problems like a kinked line. They will then attempt to gently aspirate for a blood return using a large syringe.

Why is using a small syringe to flush a blocked cannula dangerous?

Using a small syringe (less than 10 mL) on a blocked cannula is dangerous because it generates very high pressure. This can cause the catheter to rupture or, more critically, dislodge the blood clot and push it into the bloodstream, potentially causing a pulmonary embolism.

What is the 'push-pause' technique for flushing?

The 'push-pause' technique is a method of flushing an IV line that involves injecting small pulses of saline with brief pauses in between. This creates turbulence inside the catheter, which helps to dislodge deposits or small clots more effectively than a steady, continuous flush.

When are clot-dissolving medications used for a cannula clot?

Specialized clot-dissolving medications, or fibrinolytics (like alteplase), are typically only used by medical professionals for stubborn thrombotic occlusions in central venous catheters, not for peripheral IVs. The medication is instilled directly into the catheter lumen and left to dwell.

What happens if a gentle saline flush fails to clear a peripheral IV?

If a gentle saline flush attempt fails to clear a blocked peripheral IV, the standard procedure is for a healthcare provider to remove the existing cannula and start a new IV line at a different site.

How can a cannula clot be prevented?

Clots can be prevented by adhering to a regular flushing schedule with saline (and sometimes heparin), using proper flushing techniques like the push-pause method, and ensuring positive pressure when disconnecting syringes to prevent blood reflux into the catheter.