Prevention of complications in PICCs: how to prevent obstruction

by | Mar 16, 2022 | Care and Maintenance, PICCs, VAD Insertion | 0 comments




Maintenance of PICCs requires a set of washing and sealing procedures. However, what should be done if a PICC catheter is obstructed despite applying the protocols correctly?

In this article, we will review the prevention and unclogging techniques used to maintain catheter patency and ensure its correct operation.



Although the peripherally inserted central catheter (PICC) is an excellent resource in mid- to long-term intravenous therapy, occlusion continues to be one of its most common complications.

Occlusion can be defined as a partial or permanent inability to obtain blood reflux or to infuse substances through the lumen of the vascular access. Such obstruction can have serious consequences on the patient: the catheter can become unusable, thus delaying treatment and, in the worst case, making its removal and/or replacement necessary.

According to the study by Smith, Moureau and Chopra “Patterns and predictors of peripherally inserted central catheter occlusion: the 3P-O study”, which involved more than 13,000 patients, the occlusion rate of PICCs is 12%. In their work, the authors have noted three interesting facts:

– PICCs placed in the right arm have a lower incidence of obstruction
– Checking the position of the tip (compared to catheters whose position was not clearly established or documented) allowed the occlusion rate to be reduced
– Multi-lumen catheters present more episodes of obstruction


Multi-lumen catheterPicture 1: multi-lumen catheter present more episodes of obstruction


Two types of occlusions can be identified:

Partial occlusion: can be infused, although with difficulty, and there is little or no reflux
Total occlusion: impossible to either infuse or aspirate

According to the GAVeCeLT manual on PICC and Midline, the causes of PICC catheter obstructions include:

• Clots: may remain after blood or blood product extractions or infusions
• Thrombus: formed due to invasive placement and/or a tip not being placed in the lower 1/3 of the SVC
• Fibroblastic sheath: wraps around the tip of the catheter and allows infusion but not extraction (also known as PWO: Persistent Withdrawal Occlusion)
• Lipid aggregates: when parenteral nutrition with lipids is administered
• Drug precipitates: can occur after a simultaneous infusion or with a short time difference between incompatible drugs.
• Contrast medium: after CT or MRI tests with highly viscous contrast media

Pinch-off syndrome, which is the crushing of the catheter between the clavicle and the first rib caused by movements of the shoulder, can be added as a possible cause even if it is rare.



Proper washing is the key to preventing clogging. In this regard, the correct technique should be applied with a frequency that depends on the type of Vascular Access Device (VAD).

Following a proper protocol means:

1. PUSH/PAUSE flush with 10 ml of saline before and after each administration. Wash with 20 ml in the case of blood products, administration of lipids, blood extractions or administration of contrast media.

2. Seal only with saline. International recommendations are clear in this regard, Heparin must not be used since:

• The adverse effects it entails are a recurring problem
• It has been shown that, with proper use of saline, the patency of the catheter remains the same as with this anticoagulant

3. Avoid backflow of blood into the catheter during syringe disconnection by using a neutral displacement connector.

4. It is also important to use the fewest possible lumens, ensure correct positioning of the tip and an adequate exit point for the catheter, and use ultrasound and pumps whenever possible.

Washing must be performed before and after using the catheter, sealing after each use. When the VAD is unused, the frequency of washing + sealing is the same as for wound care: every 7 days.



In the event of an obstruction, it is important to be able to perform an ultrasound assessment and ask a radiologist for confirmation, if necessary, in order to determine its extent (possible thrombus).

In the case of occlusion of the PICC, the following unblocking techniques should be used:

• In case of partial obstruction:

A 10 ml syringe should always be used in non-high-flow catheters since it does not generate high pressures (syringes <10 ml could cause the catheter to break). In the case of high-flow catheters, and as noted by GAVeCeLT, it may be possible to use smaller syringes (2 or 5 ml) since exceeding 325psi (22.4 bar) with an injection through a syringe is impossible.

The manoeuvre consists of the repeated administration of a few millimetres of saline under pressure, combined with small and rapid aspiration/infusion movements, to mobilize the obstruction. Force must never be used as this could cause migration of the clot and result in serious consequences (pulmonary embolism).

If this manoeuvre is not effective, unblocking solutions must be used: administering the chosen solution in an amount corresponding to the dead space of the catheter and allowing it to act for at least 30 minutes. This manoeuvre should be repeated 3 or 4 times over the following 2 or 3 hours.

Depending on the type of occlusion, the solutions to be used are as follows:

– Clot: thrombolytic solution (Urokinase 10,000 units/ml)
– Lipids: 50-75% ethanol
– Contrast for CT or Magnetic Resonance: Molar bicarbonate (8.5%)
– Low pH pharmacological precipitates: acid solution
– High pH pharmacological precipitates: basic solution


How to resolve a PICC obstruction by unblocking a catheterPicture 2: how to resolve a PICC obstruction by unblocking the catheter


• In the case of complete obstruction:

The solution should be administered, without pressure, using the two-syringe method:

1. A three-way stopcock is connected to the PICC extension.
2. Two 10 ml syringes are connected to this same 3-way tap: one empty and the other containing the unblocking solution.
3. The key is turned so that only the empty syringe connects to the catheter. Aspiration is performed with this syringe to create a vacuum inside the catheter.
4. Then, maintaining aspiration with the syringe, the key is turned so that the catheter aspirates the solution present in the other syringe.

This manoeuvre is repeated every 15 or 30 minutes until aspiration with the empty syringe confirms blood reflux.


PICC catheter obstructions are easy to predict and therefore to avoid. This implies a cost-reduction and most importantly, an improvement in patient safety and quality-of-life.



-What is venous catheter obstruction? – GruMAV Blog 02/28/2019
– GAVeCeLT Manual on PICC and Midline 2016
-What is the recommended treatment for obstruction of a peripherally inserted central venous catheter? – Murcia Salud Virtual Library 04/26/2018
-PICC Peripherally Inserted Central Catheter NURSING CARE Written by the PICC Team of HOSPITAL DONOSTIA. Donostia Institute of Onco-Hematology – Donostia University Hospital March 2012[1íritu.pdf
-CARE OF THE PICC – María Luisa Martínez Sánchez, Resident of Pediatric Nursing Hospital Universitario Reina Sofíañados_del_picc.pdf
-Patterns and Predictors of Peripherally Inserted Central Catheter Occlusion: The 3P-O Study Shawna N Smith, Nancy Moureau, Valerie M Vaughn, Tanya Boldenow, Scott Kaatz, Paul J Grant, Steven J Bernstein, Scott A Flanders, Vineet Chopra – May 2017 -The C.L.O.T. Tool for Identifying Strategies to Prevent PICC Catheter Occlusion


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