5.3 Infection Control Materials & Methods

Infection control as instrumentation (not an afterthought)

Every forced expiration, DLCO breath-hold, body-box pant, nebulized challenge, and sputum induction moves respiratory secretions into shared air and hardware. The NBRC PFT DCO therefore scores infection control under instrumentation:

• I.A.18 — Infection control materials and methods (setup / maintain),
• I.B.18 — Infection control (troubleshoot when contamination pathways or process failures appear).

RPFT-level practice treats filters, disinfectants, PPE, and reprocessing equipment as seriously as calibration syringes. A dirty pneumotach is both an infection risk and a measurement error risk (moisture, mucus, and debris change sensor resistance).

Core materials you must have ready (I.A.18)

Personal protective equipment (PPE)

Stock and use PPE matched to task and transmission risk:

PPE that is out of stock, wrong size, or left outside the room fails Domain I readiness the same way a missing nose clip fails spirometry setup.

Surface and device disinfectants

• Use EPA-registered hospital disinfectants (or facility-approved equivalents) with listed contact (wet/kill) times.
• Keep manufacturer instructions for use (IFU) for spirometers, sensors, body boxes, and cables—solvents that clear a countertop may cloud plastics, damage pneumotach screens, or leave residue that alters flow.
• Separate clean vs dirty utility areas; never place “cleaned” mouthpieces back into a contaminated bin.

Sterilization vs disinfection (know the distinction)

Exam principle: match reprocessing level to how the item is used and what the manufacturer allows. Over-wiping a delicate flow sensor with the wrong chemical is an I.B.18 troubleshooting scenario (readings drift, odors, sticky valves) as well as a materials error.

Bacterial/viral filters on breathing circuits

In-line disposable filters between patient and spirometer/DLCO circuit are standard in modern labs:

• Reduce contamination of internal sensors and shared manifolds,
• Lower cross-infection risk between patients,
• Must be orientation-correct, fully seated, and free of tears or occlusive moisture,
• Changed between patients (or sooner if soiled/saturated)—a waterlogged filter increases resistance and can mimic obstruction.

Some systems also use instrument-side barriers or disposable flow-sensor elements. Know your device architecture: filter + cleanable sensor vs fully disposable pneumotach.

Other single-use and limited-use items

• Mouthpieces, nose clips, filter elements, spacer one-way valves (if single-patient),
• ABG needles/syringes (never reuse),
• Disposable nebulizer kits when policy specifies single patient use.

Between-patient cleaning workflow

A practical sequence that maps to exam expectations:

1. Remove and discard single-use items (filter, mouthpiece, nose clip) into appropriate waste (biohazard if saturated with bloody secretions per policy).
2. Disinfect contact surfaces: patient chair arms, table, exterior of device, pulse oximeter probe (or replace disposable wrap), BP cuff if contaminated—observe wet time.
3. Reusable breathing pieces: transport in a closed container to dirty utility; clean then high-level disinfect or sterilize per IFU; dry fully before reassembly (residual liquid breeds organisms and ruins gas analyzers).
4. Hand hygiene after glove removal and before the next patient setup.
5. Document equipment cleaning when policy requires (especially after isolation patients).

Turnover pressure is not an excuse on the RPFT exam. A scenario that skips filter changes or reuses a wet nebulizer cup without reprocessing is testing I.A.18 / I.B.18 judgment.

Reusable vs disposable: decision framework

High-cut items may ask which option best prevents cross-contamination given a device type—or what went wrong when multiple patients grew the same organism after sharing an unfiltered circuit.

Cross-contamination pathways in PFT

Think like an infection-control walk-through:

• Direct contact: shared mouthpieces, ungloved hands, contaminated nose clips.
• Indirect contact: keyboard, pen, stadiometer headpiece, oximeter cable handled with soiled gloves.
• Droplet / aerosol: open coughing during FVC, nebulized drugs, sputum induction, ultrasonic mists.
• Instrument interior: absent or bypassed bacterial filter; cracked valve housings; condensate drained incorrectly onto clean surfaces.

Troubleshooting (I.B.18): if a filter will not seat, resistance is suddenly high, a chemical odor persists after disinfection, or visible soil remains in a valve, stop testing that pathway until corrected—do not “work around” with tape or a missing filter.

TB and airborne considerations for aerosol-generating tests

Procedures that provoke cough or generate aerosols include:

• Forced spirometry maneuvers (especially continuous open coughing),
• Nebulized bronchodilators and bronchial provocation,
• Sputum induction,
• Exercise testing with heavy ventilation in some settings.

When tuberculosis or other airborne diseases are known or suspected:

• Follow facility airborne precautions: appropriate respirator (e.g., fit-tested N95 or higher—not a loose surgical mask alone for airborne risk), eye protection, gown/gloves as indicated,
• Prefer AIIR (negative-pressure) rooms when required by policy for induction or high-risk aerosol procedures,
• Schedule strategically; minimize staff exposure; use closed circuits and exhalation filters when available,
• Delay non-urgent elective PFTs until infectious workup/clearance per infection prevention guidance,
• Handle specimens as potential biohazards; bag and label correctly.

Even without known TB, treat heavy aerosol generation as higher risk: ventilation, distancing when feasible, PPE, and surface disinfection after sessions.

Link to patient safety procedures

Infection control materials enable—but do not replace—patient safety procedures (Domain II / Chapter 7 themes):

• Screen for contagious symptoms when policy requires,
• Stop testing if equipment barriers fail,
• Protect immunocompromised patients by not placing them immediately after an untreated coughing infectious case without full room/device turnover,
• Integrate monitoring and emergency gear (section 5.2) so bronchospasm during induction is managed without abandoning PPE discipline.

Safety + infection control + valid data are one system: a contaminated pneumotach can transmit pathogens and falsify FEV1.

Daily/shift infection-control setup checklist (I.A.18)

1. Stock filters, mouthpieces, nose clips, gloves, masks/respirators, gowns, eye protection.
2. Verify disinfectant bottles in date; know required wet times.
3. Confirm dirty and clean utility pathways; empty sharps containers before overfill.
4. Inspect reusable valves for cracks and residual moisture before first patient.
5. Check that spirometer/DLCO/body-box circuits accept the lab’s filter brand (adapters if needed).
6. For challenge/induction days: disposable nebulizers or sterilized cups, exhalation filters, and PPE staged before agent is drawn up.

Exam traps

• Believing a bacterial filter lasts all day for every patient if it “still looks clean.”
• Using alcohol wipes alone when IFU requires a specific high-level process for a semi-critical part.
• Reassembling tubing while wet.
• Wearing the same gloves from a bloody ABG to the clean filter drawer.
• Performing sputum induction for possible TB in an unventilated room without airborne PPE.

Mastering infection-control materials and methods closes Domain I’s ancillary block: habitus and sampling tools, monitors and emergency gear, and the barriers that keep both patients and instruments safe for the next test.