Restoring patency using POP Technique

Submitted by Carolyn Johnston, IVNNZ Inc. Educator. Orginally printed in September 2007 IVNNZ Inc. Newsletter

Patients who require Central Venous Catheters (CVC) are reliant on venous access for administration of various fluids and medications. Although there are many advantages to having a CVC, it is recognised that catheter occlusion is the most common non-infectious complication in long term use of CVC’s (McKnight, 2004). An occluded catheter can lead to delayed treatment, increased risk of infection and cost of care. Occlusion also causes patient discomfort and decreases the availability of veins for future access. (Andris & Krzywda, 1999)

A catheter occlusion is the loss of catheter patency, ranging from partial to complete obstruction. A complete obstruction is when you can not infuse or aspirate fluid. A partial (or withdrawal) occlusion occurs when you can administer fluid, however are unable to aspirate. Successful management of an occluded catheter is paramount. Andris and Krzywda (1999, p 233) have outlined three principles that should be utilised when an occlusion is present in a CVC:

  1. Identifying the cause
  2. Understanding the physiology of the obstruction and
  3. Choosing the appropriate treatment.

It is estimated that intraluminal thrombus is the cause of 5% to 25% of all CVC occlusions (Andris, 1999). The percussion (POP) technique has been used to return patency to a CVC with an intraluminal thrombus.

Percussion technique (POP)

  1. 1ml saline is drawn up in to a 5 or 10ml syringe.
  2. This is attached directly to the hub of the occluded lumen of the catheter, with the syringe pointing down.
  3. The plunger is pulled back to the end of the barrel and release allowing the plunger to snap back.
  4. This process is repeated at 2 second intervals until blood is withdrawn
  5. Once blood begins to draw back, the blood is discarded, and fresh heparinise saline is flushed

(The above information was retrieved from an article written by David Stewart in the Care of the critically ill, 17(3) June 2001.)

A literature search identified two written studies had been conducted using this percussion technique.

Dr David Stewart from the Manchester Children’s Hospital evaluated the percussion technique, for restoring patency to CVC’s in the Paediatric Intensive Care Unit, over a four year period. The technique described uses the generation of shock waves down the catheter. “A shock wave (or simply “shock”) is a type of propagating disturbance. Like an ordinary wave a shock wave carries energy and can propagate through a medium i.e. solid, liquid or gas” (wikipedia).

“It occurs when the energy is deposited and instantly released in very confined regions of gasses, liquids, or solids. The action of the syringe plunger hitting a small amount of liquid at high speed within a confined area, creates a shock wave, which loosen the obstruction for the catheter wall, without appreciably expelling it” (Fetzer & Griffin, 2004, p 298).

Dr Stewarts study indicated a 94% success rate of restoring patency out of fifty occluded catheters with no reported complications and concluded the technique was safe and effective.

The second study reviewed, was an exploratory descriptive study, conducted using a certified laboratory by Fetzer & Griffin in 2004. The same percussion technique used by Dr Stewart on varying catheter types and sizes was used in this evaluation. The results demonstrated that patency was restored to 26 (86%) of the 30 occluded catheters, with no damage observed to the PICC, and allowed aspiration of the clot into the syringe. Fetzer & Griffin (2004) concluded this to be a safe and effective method for restoring patency to a PICC occluded in vitro by an intraluminial thrombus using a ten ml syringe with one ml of saline. Additional research was encouraged to confirm the positive finding identified above.

When a catheter becomes occluded the ultimate goal is to restore patency in a timely and cost effective manner, with minimal risk to the patient.

Prevention of complications should be the goal of each nurse who is responsible for the management of the CVC. Learning to identify and acting upon early warning signs can potentially save the catheter.

  • difficulty or resistance with infusing fluids or withdrawing blood,
  • and or a sluggish flow rate (McKnight, 2004).
  • Infusion pump alarms may sound frequently.

Preventative steps should be incorporated into nursing management of a CVC. Routine flushing with saline (using a turbulent flush) before and after medication administration, and blood sampling is recommended best practice. (For flushing regimes, refer to your organisational policy / procedure manual).

References Andris, D & Drzywda, E. (1999). Central Venous Catheter Occlusion: Successful Management Strategies. Medsurg Nursing, August, 8, (4), 229-236.

Fetzer, S & Manning, G. (2004). Safety and Efficacy of the POP technique for restoring Patency to occluded PIC catheters. Applied Nursing Research, 17,(4), 297-300.

McKnight, S. (2004). Nurse’s guide to understanding and treating thrombotic occlusion of central venous access devices. Medsurg Nursing, December 13, (6), 377-382.

Stewart, D. (2001).The percussion technique for restoring patency to central venous catheters. Care of the critically ill, June, 17,(3).

What is a shock wave definition: Retrieved 22 August 2007.