In this section
Many neonates and cardiac patients have residual shunts, either at atrial or ventricular level. Air or particles that enter the systemic circulation from venous access lines are often the cause of fatal emboli in these patients. In-line filters on venous access lines can prevent air and particles from entering the venous circulation and thereby minimise the risk of systemic embolisation in such patients.In particular, children with single ventricle defects or common atria are at risk of fatal systemic embolisation from unprotected venous access devices.
In-line filters should be placed on all intravenous lines, central and peripheral, in the following situations:
Please note: In the event the patient requires a CT with contrast, filters will need to be removed from the venous line that the pressure injector uses to deliver the contrast is attached as use of the filter will delay the delivery of the contrast.
A 0.2micron filter is routinely used, this filter reportedly removes air, microorganisms and particulate matter, there are two sizes available:
Figure 1. Pall Posidyne NEO filter
Figure 2. Pall Posidyne ELD filter
For PICU patients who are receiving Epoprostenol (Prostacyclin) as a part of ECMO, a Pall Supor AEF filter must be used (Figure 3). This filter is 0.2 micron with a priming volume of 1mL and a maximum flow rate of 9mL/min. It is extremely expensive, has low protein binding and is specifically reserved for the administration of particular drugs such as Epoprostenol (Prostacyclin). It is available from the PICU AUM on duty or the ECMO coordinator. This filter needs to be changed every 24 hours.
Figure 3. Pall Supor AEF filter
Identify in advance patients likely to require an in-line filter before admission to the unit or from theatre. The filters should be attached to the intravenous line prior to connecting to the patient, if safe to do so. Otherwise they should be placed in PICU or Koala as identified.
For postoperative cardiac patients, with continued venous-arterial communication, requiring inotrope infusions, filters should be placed onto the intravenous line by the anesthetist at commencement of infusion in theatre if safe to do so. Where this has not occurred, the infusion should be changed to one with a filter as soon as the patient's condition allows.Lines dedicated to infusions that don’t require bolus (i.e. inotrope line) attach filter as close as possible to the patient cannula. The filter is primed with the fluids or drugs being administered into the line. Multiple infusions that are compatible via one lumen, and don’t require bolus can be infused through one filter (see Figure 4 as an example).
4. In this example one in line filter is required near the patient cannula
while multiple inotropes can be infused distally via three way taps.
In the situation of a deteriorating patient, fluid boluses must be able to be administered quickly and easily. Thus despite the risk, a filter cannot be used on the filling line. Volume can be administered directly via a three-way tap or traffic light without a filter. The drug port and the maintenance line should have their own individual filters connected to the traffic light (Figure 5 & Figure 6).
Figure 5. Set up of ‘filling’ and maintenance CVAD lumen in PICU
Figure 6. Set up of ‘filling’ and maintenance CVAD lumen in PICU
Place the filter between the syringe and transducer, so that it does not interfere with the pressure reading (Figure 7).It should be noted that filters may result in a slightly dampened waveform trace. If detailed waveform analysis is required, the 3-way tap will need to be turned to isolate the transducer from the infusion temporarily.
Figure 7: Set up of pressure monitoring lines in PICU
Most of the common medications and fluids administered to cardiac patients can go through the 0.22 micron filter. For example sedatives, inotropes and dilators can all be filtered.There is limited evidence regarding the medications that cannot be filtered, those that are currently known are outlined in table 1.
1: Substances that are unable to pass through a 0.22 micron filter
Ideally the substances that cannot be filtered should be infused by themselves. If this is unavoidable, the placement of the filter and the short viggo can be swapped, leaving the unfiltered infusion attached as close to the patient as possible. All other compatible infusions should be infused through the filter.
If you notice increasing pressure on your infusion pump, or occlusion alarms then this may be due to a blocked filter. If a filter blocks and interrupts an infusion, this does not mean the filter has failed. It most likely indicates the filter has done what it is designed to do, filtering debris that might otherwise have entered the patient's circulation. In this instance a VHIMS should be completed detailing all the fluids/drugs running through the filter and at what rate. This will then add to the body of knowledge about our infusion compatibilities.
Evidence table for Filters for venous access lines in select group of cardiac patients nursing guideline.
Please remember to read the disclaimer.The development of this nursing guideline was coordinated by Grace Larson, CNC, Rosella, approved by the Nursing Clinical Effectiveness Committee. Published December 2018.