Clinical Guidelines (Nursing)

Filters for venous access lines in select group of cardiac patients

  • Introduction

    Aim

    Management

    Troubleshooting

    Resources

    Evidence Table

    Introduction

    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.

    Aim

    • To identify the select group of cardiac patients at risk of systemic emboli.
    • To prevent air and particulate matter from entering the systemic circulation.
    • To ensure in-line filters are correctly positioned in PICU patient lines.
    • To ensure in-line filters are correctly positioned for patients on Koala ward and/or transfer to Koala or other wards

    Management

    Cardiac patients requiring filters

    In-line filters should be placed on all intravenous lines, central and peripheral, in the following situations:

    • Pre-op (or unrepaired) patients with a congenital heart defect
    • Patients with single ventricle lesions: pre or post-op 
    • All direct atrial lines

    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.

    Filters available

    A 0.2micron filter is routinely used, this filter reportedly removes air, microorganisms and particulate matter, there are two sizes available:

    • Pall Posidyne NEO filter (Figure 1)
      A small priming volume of 0.4mL and low maximum flow rate of 110mL/hr and should be used for neonates and infants.
    • Pall Posidyne ELD filter (Figure 2)
      A priming volume of 2.6 mL, maximum flow rate of 1380mL/hr and should be used on children greater than 12 months of age. Both these filters need to be changed at a minimum of every 96 hours (4 days)

    Fig 1 Pall Posidyne NEO filter

    Figure 1. Pall Posidyne NEO filter

    Fig 2 Pall Posidyne ELD 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.

    Fig 3 Pall Supor AEF filter

    Figure 3. Pall Supor AEF filter

    Methods of placing and using the filters 

    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.

    Infusion lines

    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). 
    Fig 4 three way taps

    Figure 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.

    Special considerations for the PICU patient

    Management of the ‘filling’ and maintenance CVAD lumen in PICU

    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). 

    Fig 5 set up
    Figure 5. Set up of ‘filling’ and maintenance CVAD lumen in PICU

    Fig 6 set up2

    Figure 6. Set up of ‘filling’ and maintenance CVAD lumen in PICU

    Monitoring lines or direct atrial lines 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.

    Fig 7 set up pressure monitoring

    Figure 7: Set up of pressure monitoring lines in PICU

    Medications that cannot be filtered

    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. 

    Table 1: Substances that are unable to pass through a 0.22 micron filter

    • Blood products (excluding albumin)
    • Lipid
    • Propofol


    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.

    Troubleshooting

    Blocked 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.

    Resources

    Evidence Table

    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.