Our department has 3 Multislice CT scanners.
We scan approximately 100 patients per day (26,000 to 30,000 patients per annum).
Extravasation injury results from a combination of factors,
which include infusion pressure,
duration of an indwelling venula and patient factors.
By analysing the processes using a flow chart,
we were able to identify the most likely causes for extravasation.
Fig 3 (Flow Chart) and 4 (Cause and Effect Diagram).
One cause of extravasation is the administration of a large volume of contrast medium at a high flow rate using by an electric power injector.
In our department,
the average dose is approximately 100 ml injected at 1 to 5 mls per second.
A venula that is in place for more than 24 hours is known to increase the chance of extravasation,
as the vascular integrity diminishes over time,
with the venula possibly inducing phlebitis.
Thrombus formation at the venula tip may cause obstruction leading to retrograde or perivascular efflux of contrast medium.
Patients who have small,
fragile veins (e.g.
in elderly patients and in those receiving chemotherapy) have a higher risk of extravasation.
If that vein ruptures,
contrast medium will leak into the surrounding tissues.
We summarised the main causes to be addressed using the Pareto Chart.
Fig 5 (Pareto Chart).
A strategy for change was devised by changing processes,
equipment and incorporating the latest technology.
The following steps were implemented:
1.
Radiographer to stay with patient throughout the injection phase for routine scans
A radiographer was required to be present in the room during the entire injection phase of a routine CT scan to closely observe the injection site.
This enabled early detection and timely intervention if extravasation was suspected.
2.
Extravasation Detection Sensor
An extravasation detection sensor system was installed to monitor for extravasation in studies requiring high flow rate and early acquisition of images (i.e.
CT angiogram or multiphase CT studies).
In these studies,
the radiographer has to vacate the room prior to completion of the intravenous injection.
The detection sensor is Nemoto Extravasation Sensor System.
Fig 6.
3.
Replacement of venula exceeding 72 hours duration
To prevent extravasation due to an old or thrombosed venula,
a CT nurse was appointed to ensure that all venulas inserted more than 72 hours prior were replaced.
4.
Standardising larger-sized venula (18G or 20G),
to be inserted in the antecubital fossa for CT Angiographic studies
The venula size for contrast medium injection was standardised at 18G or 20G,
to be positioned preferably at the antecubital fossa,
rather than at the wrist or dorsum of the hand.
The above strategies were progressively implemented by multiple Plan Do Study Act (PDSA) cycles.
Fig 7 (Intervention Chart).