How to Assess a Peripheral Intravenous (IV) Cannula


Published: 21 June 2020

Most patients need at least one peripheral intravenous cannula (also known as an intravenous catheter) (PIVC) during their hospital stay for IV fluids and medications, blood products or nutrition (ACSQHC 2019).

PIVC complications are common but they can be prevented or minimised by routine assessment. This article discusses the key points of PIVC assessment.

Is an IV Cannula Needed?

Does the patient need this PIVC?

Many PIVCs are left in without orders for IV fluids or medications. Others are never used at all (Limm et al. 2013; New et al. 2014).

Some patients end up with two, three or even more concurrent PIVCs, despite only needing one in most cases (New et al., 2014).

There are even reports of patients being discharged home with an IV in place because no one noticed it was there! (The Nurse Path 2016)

PIVCs are often left in ‘just in case’ the patient might need it. But any IV cannula leads directly to the bloodstream and can be a source of infection (Ray-Barruel et al. 2017).

Assess the need for the PIVC every shift. If it wasn’t used in the past 24 hours or is not likely to be used in the next 24 hours, it should come out.

Exceptions might be an upcoming planned procedure, cardiac monitoring, history of seizures, unstable medical condition or recent rapid response call. If you’re unsure, check with the treating team.

Is the Cannula Working?

When a PIVC is inserted, a flashback of blood in the chamber confirms it’s in the vein. Afterwards, the cannula location is estimated by the flow of IV fluids (either by infusion pump or gravity) and/or IV flushes (manual injection).

Flushing the PIVC with 0.9% saline before and after IV medications reduces admixture of medicines and decreases the risk of blockage (Goossens 2015).

PIVCs often become blocked, kinked or dislodged, so make sure the cannula is still working each shift.

You can assess PIVC function with two simple questions:

  1. Does the IV flush easily?
  2. Does the IV fluid flow easily?

Resistance or failure to flush or flow indicates the PIVC might be kinked or blocked, or could have migrated out of the vessel (Goossens 2015).

peripheral intravenous cannula in patient's arm
Many PIVCs are left in without orders for IV fluids or medications. Others are never used at all.

Is the Cannula Tolerated by the Patient?

Provide explanations and education about the treatment, and check the patient’s (and their family’s) understanding. Ensure the patient knows why the PIVC is in, and encourage them to speak up if there are any problems, such as pain, leaking or swelling.

The PIVC should not be painful. Pain is an early symptom of phlebitis (inflammation of the vein) and means that the PIVC is not working well and should be removed (Ray-Barruel et al., 2014).

If the patient still needs an IV, and their veins are fragile, consider the insertion of a different device, such as a peripherally inserted central catheter (Demarco 2018).

An Irish study found that patients were seven times more likely to have a PIVC left in, unused, when they did not know why it was there (McHugh et al., 2011).

Involving the patient and family empowers them to voice their concerns, and prompts nurses to address problems and remove unused PIVCs.

Is the Cannula Appropriately Dressed and Secured?

Transparent polyurethane or sterile gauze and tape dressings are both recommended (Marsh et al. 2015). Polyurethane dressings are convenient, as they allow visibility of the IV site and can remain in place up to 7 days. Gauze and tape dressings work well for diaphoretic patients, but they should be changed every 2 days.

Dressings must be clean, dry and intact to prevent microbial contamination of the site. Change the PIVC dressing if it becomes damp, loose, or visibly soiled, and secure the PIVC and infusion tubing with tape, net or bandage, leaving the site visible (INS 2016).

Hospital audits show 25% of PIVC dressings are not clean, dry and intact (New et al. 2014; Alexandrou et al. 2015). This increases the risk of infection and cannula dislodgement.

A poorly secured PIVC encourages infection, as cannula movement in the vein can allow migration of organisms along the cannula and into the bloodstream (Marsh et al. 2015).

Any Signs of Infection?

PIVCs are so common it’s easy to forget they pose an infection risk.

This can be reduced by strict hand hygiene before and after touching the device, the dressing or any lines and connectors.

Aseptic non-touch technique when connecting lines is essential (INS, 2016). Needleless connectors should be scrubbed for 15 seconds and allowed to dry before accessing (Moureau & Flynn, 2015).

Don’t forget about possible bloodstream infection. If a patient has signs of systemic inflammatory response syndrome (low or high temperature, elevated heart rate, elevated respiratory rate, low or high white blood cell count), any invasive device is a possible cause (Shah et al. 2013), and insertion sites should be examined for inflammation or purulence. If a patient shows signs of infection with no obvious source, consider removing the PIVC.

cannula infection diagram
How a bacterial infection can spread from the cannula to the blood.

Any Other Complications?

Unfortunately, up to 40% of PIVCs have complications, stop working, or fall out before treatment completion (Wallis et al. 2014).

Cannula failure often means painful and time-consuming replacement of the PIVC, which can be tricky, especially for paediatrics, the elderly, and those with a lack of viable veins.

Many hospitals have implemented phlebitis scales to improve PIVC assessment. Phlebitis scales are not well-validated and are not recommended (Ray-Barruel et al., 2014). While phlebitis is a concern, catheter failure is more often caused by occlusion, infiltration or accidental removal (Wallis et al., 2014).

Common IV Cannula Complications:

  • Phlebitis (inflammation of the vein) is characterised by one or more of the following: pain, redness, swelling, warmth, a red streak along the vein, hardness of the IV site, and/or purulence.
  • Infiltration is the leakage of a non-vesicant solution into the surrounding tissues, causing pain and swelling.
  • Extravasation is the migration into the tissues of a vesicant medicine or fluid, such as chemotherapy. This can be severely painful and cause major tissue trauma.
  • Thrombosis or thrombophlebitis is the formation of a clot in the vessel, often caused by the cannula moving around in the vein and aggravating the vessel wall.
  • Nerve damage can occur during PIVC insertion. If the patient complains of a sharp pain shooting up the arm, or ongoing numbness or tingling of the extremity, the cannula should be removed immediately.
  • Partial or complete dislodgement of the PIVC indicates it is no longer in the vessel and must be removed.

(ACSQHC 2019; Kaur et al. 2019)

Early detection and treatment of complications can prevent long-term consequences.

If infiltration or extravasation is suspected, stop the infusion, disconnect the tubing, and attempt to aspirate the residual drug from the device.

If the site is warm, swollen or painful, elevate the limb on a pillow, seek medical advice, and apply hot or cold packs as tolerated (SCHN 2016). Offer paracetamol, unless contraindicated. Continue to assess regularly, and document your assessment and actions, and the patient’s response.

Finally, remember that post-infusion phlebitis can occur up to 48 hours after a PIVC has been removed (Webster et al., 2015), so it’s important to assess old IV sites, as well as current sites.

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