Infusion Filtration: Clinical Guide to Filter Selection and Requirements

In-line filtration is an evidence-based safety intervention for intravenous infusions. Filters remove particulates (glass, plastic, rubber, precipitates), air, and microbial contaminants from the infusate before they reach the patient’s bloodstream or vascular access device. Selecting the appropriate filter type for each infusion, and knowing which medications cannot be filtered, are essential clinical skills for infusion therapy practice.

Parent guide: Infusion Therapy Safety: Complete Reference

Why Filter?

Particulate contamination in IV fluids: Even commercially prepared IV solutions contain particulate matter from the manufacturing process (glass fragments from vials, rubber from stoppers, plastic from IV bags and tubing). Studies consistently find thousands of particles per liter in standard IV fluids. While large particles are visible, most contaminating particles are in the 2–50 micron range — invisible to the naked eye but potentially harmful.

Consequences of unfiltered particles:

Granuloma formation in lungs, liver, and spleen with repeated exposure (pulmonary microemboli from large particulate load)
Phlebitis from particulate irritation of vessel endothelium
Catheter occlusion from precipitate formation
Risk of introducing microbial contamination (though modern IV preparation has low bioburden)

Air elimination: Filters with air-eliminating membranes remove microbubbles from IV infusions. While large air emboli require specific vascular access prevention (see Air Embolism Guide), microbubble accumulation in the vascular system is associated with cerebral microemboli and adverse outcomes in some patient populations (cardiac surgery, critically ill).

Filter Types

0.2 Micron Filters (Standard In-Line Filter)

Pore size: 0.2 microns (also written as 0.22 μm).

What it removes:

Particulates ≥0.2 microns
Microbial contamination (bacteria are typically 1–5 microns; most bacteria are retained)
Air (most 0.2 μm filters are air-eliminating)
Yeast (Candida: 3–6 microns)

What it does NOT remove:

Viruses (<0.02 microns) — viruses pass through 0.2 μm filters
Endotoxins (molecular size)

Standard indications: Most IV medications, IV solutions without lipids, standard antibiotic infusions.

Change interval per INS 2021: Change 0.2 μm filter every 96 hours (with administration set change).

1.2 Micron Filters (Lipid-Compatible Filter)

Pore size: 1.2 microns.

Why needed for lipids: Lipid emulsions (fat globules 0.4–1.0 micron) are larger than the 0.2 μm filter pore size — they would be trapped by and clog a 0.2 μm filter. The 1.2 μm filter allows lipid particles to pass while still retaining larger particulates.

What it removes:

Particulates ≥1.2 microns
Some (not all) microbial contamination
Limited air removal

Standard indications: Lipid emulsions (Intralipid, Clinolipid), 3-in-1 (TNA/TNA) parenteral nutrition admixtures containing lipids.

Change interval per INS 2021: Change 1.2 μm filter every 24 hours (with lipid administration set change interval).

Medications and Solutions Requiring Filtration

Per INS 2021 Standard 30 (Filtration):

Always filter:

All parenteral nutrition (TPN/PN): 0.22 μm for 2-in-1 (amino acids + dextrose), 1.2 μm for 3-in-1 (all-in-one with lipids)
All blood products and derivatives: specific blood filters (170–260 μm for standard blood, leukocyte-depleting filters as ordered) — NOT standard IV in-line filters
Medications with known particulate risk (etoposide, teniposide, fat-soluble vitamins in PN)

Filter routinely for CVADs:

INS 2021 recommends in-line filtration for all infusions administered via CVAD
0.22 μm air-eliminating filter for most infusions
1.2 μm for lipid-containing infusions

High-risk patients requiring filtration:

Neonates (NICU): 0.22 μm filter for all IV infusions (particulate load proportionally larger effect on small patient; air embolism risk)
Immunocompromised patients
CNS access (epidural, intrathecal, ventricular): 0.22 μm filter mandatory for all infusions

Medications That CANNOT Be Filtered Through 0.2 μm Filter

Critical: These medications will be adsorbed onto or blocked by the filter membrane, resulting in incomplete drug delivery. Do not administer through a standard 0.2 μm in-line filter.

Medication	Reason Cannot Be Filtered	Alternative
Amphotericin B (conventional, lipid formulations)	Lipid particles/colloidal suspension	1.2 μm filter acceptable for some formulations; check package insert
Blood products	Red cells and platelets larger than filter pores; cells would be destroyed	Blood-specific filters only
Fat emulsions (Intralipid, Clinolipid)	Lipid particles occlude 0.2 μm filter	1.2 μm filter required
Lymphocyte immune globulin (ATG, horse ATG)	Large molecules; may be adsorbed	Per package insert; high-flow filter specified
Mannitol (if crystals present)	Crystals can clog filters and may not pass 0.2 μm	Inspect for crystals; if present, warm to dissolve before filtering; consult pharmacy
Tacrolimus	Adsorption onto filter membrane reduces delivered dose	Administer without 0.2 μm filter or with DEHP-free and filter-free setup
Diazepam	Adsorption; also precipitates in aqueous solutions	Short infusion; glass bottle with non-PVC tubing; specific pharmacist guidance
Insulin (regular insulin infusions)	Moderate adsorption; clinically significant in low doses	Saturation technique or per institutional protocol; many institutions filter; check pharmacy guidance

When in doubt: Consult pharmacy before filtering any medication. For medications not on this exclusion list, filtering is appropriate.

TPN/PN Filtration Standards

Per INS 2021 and ASPEN guidelines:

2-in-1 PN (amino acids + dextrose, no lipids): 0.22 μm air-eliminating filter required. The 0.22 μm filter provides maximum particulate and microbial removal from the PN admixture.

3-in-1 (TNA) PN (amino acids + dextrose + lipids in one bag): 1.2 μm filter required. The 1.2 μm filter is acceptable for lipid-containing PN and still provides significant particulate retention.

Why this matters: TPN is a high-risk admixture — compounding errors, physical incompatibilities, and microbial contamination risks are all elevated. The filter is the last line of defense before the admixture enters the patient’s bloodstream. Never administer PN without the appropriate filter.

Lipid filter change: TPN administration sets and filters are changed every 24 hours (lipid-containing) or 96 hours (non-lipid PN); lipid-containing sets cannot be run longer without increasing microbial contamination risk from the lipid medium.

Neonatal and Pediatric Filtration

NICU standard: All IV infusions in neonates should be administered through a 0.22 μm air-eliminating filter. The neonatal patient cannot tolerate the particulate and air load that adults handle without clinical consequence. Microemboli to the CNS in neonates are associated with adverse neurodevelopmental outcomes.

Pediatric IV therapy: Standard 0.22 μm filtration for all CVADs; apply the same adult filtration standards.

Related guides:

Related policies:

References

Gorski LA, et al. (2021). INS Infusion Therapy Standards of Practice (Standard 30: Filtration). J Infus Nurs, 44(Suppl 1).
ASPEN. (2012). Safe practices for parenteral nutrition. JPEN, 36(Suppl 2):S1–S94.
Ball PA. (2003). Intravenous in-line filters: filtering the evidence. Curr Opin Clin Nutr Metab Care, 6(3):319–325.
Lehr HA, et al. (2015). In-line filtration reduces systemic inflammatory response syndrome after major cardiac surgery. J Surg Res, 198(1):165–172.