Preventing Phlebitis Through Correct Cannula Monitoring


In this Clinical Risk Alert, THEMIS’s Lead Clinical Partner, TMLEP, discusses correct cannula monitoring to prevent inflammation and infection.

A Case Example

The patient, in this case, was a young child who had a cannula placed at 10:40 am. This cannula was not reviewed until the next day at 6:00 pm when it was flushed, and a visual infusion phlebitis score was documented as zero. The child’s father noticed the arm was swollen several days later, at which point the cannula was removed. An ultrasound scan was then performed which showed acute thrombus of the left antecubital and basilica veins.

The main learning points from this review stem from the following events:

  • Not reviewing the cannula at regular intervals
  • Not flushing the cannula adequately, as per Trust protocol
  • No discussions took place between the nursing team and the lead consultant on the ward regarding the need for the cannula

Recommendations to Prevent Incident Recurrence and Improve Patient Safety

TMLEP’s recommendations to reduce recurrence and enhance patient safety are as follows:

  • Ensure cannulas are monitored three times per day, ideally morning, afternoon and night. There should be a visual check completed of the insertion site by removing any bandages that may be covering the cannula. This provides the opportunity to identify any concerns with the cannula such as swelling, redness and pain that may be indicative of phlebitis. Visual phlebitis scores should be documented at each check of the cannula. Phlebitis is the inflammation of a vein and signs to be aware of are localised redness, heat and swelling. It is important to document phlebitis scores, as if phlebitis is left untreated, it can develop into infection, either localised to the cannula site or a more serious bloodstream infection causing sepsis.

  • If the cannula is not being used for medications or infusions it should be flushed with 0.9% saline at each check to ensure patency. (6.2; RCN Guidance 2016). Failing to do so can lead to pain for the patient, as well as inflammation and infection, as it is a device that is ‘foreign’ to the body.

  • If the cannula is not flushed regularly, it can become blocked, therefore requiring removal and insertion of a new cannula, which is not a good patient experience and can cause trauma to the patient.

  • Assess the need for a cannula frequently. This should be discussed on a daily basis and the reason for it remaining documented in the medical notes, as any peripheral vascular device is an infection risk and should be removed if not required.


It is the role of the nurse looking after the patient to ensure that the patency of the cannula is maintained by following local policy and best practice guidance. To maintain patency of the cannula, flushing either ‘routinely’ (Parker 2002), daily (RCN 2005c) or eight hourly (Fuller and Winn 1998), has been recommended for peripheral devices. By maintaining the patency of the cannula and carrying out visual checks this will lead to there being a decreased chance of inflammation and infection occurring.