8.1 Selecting Spirometry Protocols & Equipment

Why protocol selection is a scored Domain II skill

On the NBRC Pulmonary Function Technologist Examination, Domain II — Procedures is the largest content area (about 44% of scored items). Under II.A Select, task II.A.2 focuses on spirometry—both standard and position-variant pathways (outline items a/b). High-cut (RPFT) items rarely ask only “what is FVC?” They present an order set or clinical vignette and expect you to choose the right protocol, the right interface equipment, and the right pre-test constraints so that later acceptability and interpretation decisions are meaningful.

Section 8.1 is the decision layer before coaching begins (8.2), before quality grading (8.3), and before bronchodilator-response logistics (8.4). Instrumentation setup and calibration from Chapter 2 are assumed complete; here the question is what test to run and how to prepare the patient and circuit for that test.

Standard upright spirometry: the default protocol

Unless the order or clinical question specifies otherwise, diagnostic spirometry means:

1. Upright seated position (or standing if lab policy and the patient can maintain stable posture—seated is standard in most PFT labs).
2. Feet flat, legs uncrossed, spine straight, chin slightly elevated.
3. Nose clip applied; lips sealed around the mouthpiece/filter.
4. Maximal forced vital capacity (FVC) maneuvers yielding PEF, FEV1, FVC, timed volumes, and flow–volume morphology, usually with tidal breathing transitions and full inspiration before the blast (detail in 8.2).
5. Optional companion measures when ordered: slow vital capacity (SVC), inspiratory loops, or serial efforts for bronchodilator comparison.

Clinical purpose of the standard protocol: detect and quantify obstructive and restrictive patterns, establish a baseline for disease monitoring, and support pre-employment, pre-operative, or therapy-response pathways when position change is not the question.

Exam trap: Selecting “supine spirometry for everyone with dyspnea” is wrong. Position-variant testing is targeted, not default.

Position-variant protocols: upright vs supine (and related)

When upright/supine comparison is indicated

Upright-to-supine (or upright-to-recumbent) spirometry is selected when the clinical question involves respiratory muscle weakness, diaphragm dysfunction, neuromuscular disease (e.g., ALS, myasthenia, muscular dystrophy), suspected orthopnea-related restriction, or unexplained upright–supine symptom changes. Gravity and abdominal contents alter diaphragm mechanics in the supine position; patients with weak diaphragms often show a disproportionate drop in FVC when recumbent compared with healthy subjects.

Typical selection cues in orders or stems:

How the position-variant protocol differs in planning (not yet coaching)

Selection tasks for the technologist include:

• Confirming a flat surface or reclining chair that allows true supine/recumbent posture without neck flexion that kinks the airway or breaks the mouthpiece seal.
• Planning extra recovery time between efforts—supine forced maneuvers are harder for weak patients.
• Ensuring the same filter/mouthpiece configuration and software protocol so upright and supine values are comparable.
• Knowing lab thresholds used later in data management (commonly, a large relative fall in FVC from upright to supine raises concern for diaphragm weakness—exact cut-points are interpreted with the medical director; your job on II.A is to select and set up the comparison when indicated).
• Screening for contraindications to supine positioning (severe orthopnea, recent abdominal surgery, uncontrolled reflux with aspiration risk, inability to transfer safely).

RPFT vignette mindset: “Patient with ALS is ordered for spirometry to monitor respiratory muscle strength.” Best selection is not “one seated FVC and done”—it is standard efforts plus position-variant FVC if the lab protocol and patient safety allow.

Equipment selection for the chosen protocol (II.A.2)

Protocol selection is inseparable from patient-interface and support equipment. Even a perfectly calibrated spirometer fails if the circuit or posture supports are wrong.

Filter

• Use a bacterial/viral filter (or manufacturer-validated disposable sensor) appropriate to the device.
• Filters add small dead space and resistance; choose sizes validated for adults vs pediatrics.
• Replace when wet, soiled, or per single-patient policy—do not reuse a disposable filter across patients.
• For position-variant work, keep the filter dry and secure; supine testing increases saliva/condensation risk at the interface.

Mouthpiece

• Rigid cardboard or firm plastic with a tight lip seal is standard.
• Soft flanged pieces help edentulous patients but must not collapse during blast expiration or deep inspiration.
• Pediatric mouthpieces or masks (when lab-validated) are selected by age and cooperation—not by adult defaults.

Chair and posture supports

• Stable chair without wheels (or locked wheels); armrests help frail patients but should not encourage forward lean onto the thighs during forced expiration.
• For supine protocols: stretcher, fully reclining chair, or procedure table with head support; ensure the spirometer arm or tubing length reaches without tension that pulls the mouthpiece out.
• Step stool or foot support so shorter patients keep feet flat in the upright phase.

Nose clip

• Firm enough to prevent nasal leak during forced maneuvers.
• Document intolerance; watch for nasal leak patterns if a clip cannot be used.
• Have spare clips; saliva makes foam pads slip mid-session.

Related equipment choices tied to the order

Exam trap: “Any chair is fine.” A soft recliner that encourages slumped posture systematically alters FVC/PEF and is a selection error, not merely a coaching problem.

Pre-test instructions: protecting the baseline (PFT practice standards)

Selecting the protocol includes deciding what the patient must do before arrival and what the technologist verifies at check-in. ATS/ERS technical standards and typical PFT lab practice emphasize controllable factors that change FEV1/FVC independently of true disease progression.

Smoking and vaping

• Advise no smoking for at least 1 hour before testing (many labs use longer windows in patient handouts). Acute smoke exposure can irritate airways and alter results.
• Ask about recent smoking at check-in; document if the patient smoked anyway—do not silently discard data without policy, but flag the condition for the interpreter.

Bronchodilators and other inhaled medicines

Withholding depends on the purpose of the visit:

Critical selection point: If the order is pre- and post-bronchodilator, you must select a protocol that includes a true pre-drug baseline. Testing a patient who just used albuterol in the parking lot without documenting it invalidates “response” math later.

Recent illness and clinical stability

• Acute viral illness, uncontrolled asthma exacerbation, hemoptysis, pneumothorax, recent MI/unstable angina, or recent eye/thoracic/abdominal surgery may be relative or absolute reasons to defer testing—coordinate with ordering provider and lab precautions (Domain II safety concepts from Chapter 7).
• Selecting “proceed anyway” for a patient with active hemoptysis is a safety/protocol failure, not a heroic data capture.

Other practical instructions

• Avoid heavy meals immediately before testing (discomfort limits deep inspiration).
• Avoid vigorous exercise shortly before testing when possible.
• Wear loose clothing; tight belts/corsets restrict thoracic expansion.
• Bring inhalers and medication lists so withholding vs “on therapy” status can be verified.
• Arrive with enough time for resting tidal breathing before forced efforts.

Check-in verification checklist (exam-ready)

1. Confirm identity, order, and which protocol (standard only vs +supine vs +BD response).
2. Review contraindications and infection-control needs.
3. Record height, weight, age, sex/gender as used for reference equations (body habitus details in Chapter 7).
4. Document last bronchodilator/smoking/illness.
5. Select filter size, mouthpiece, clip, chair or supine surface.
6. Confirm instrument is in-calibration (Chapter 2) before the first effort.

Mapping orders to protocol choices (II.A.2 a/b)

Integration with infection control and equipment QC

Protocol selection still respects Chapter 5–6 realities: disposable filters between patients, no testing on a device that failed morning syringe checks, and isolation considerations for infectious patients. A “correct” neuromuscular protocol on an out-of-calibration spirometer is still a failed selection chain for the lab.

RPFT decision scenarios

Scenario A: Order: spirometry. Patient used albuterol 30 minutes ago for wheeze, feels better, wants “just the breathing test.” Selection decision: clarify whether the clinician wants on-therapy values or a withheld baseline. If a bronchodilator response was intended, the pre-drug baseline is compromised—contact the ordering provider; do not invent a fake “pre” value.

Scenario B: Order: PFTs. History of myasthenia gravis with orthopnea. Selection decision: plan upright and supine FVC if safe, with appropriate support equipment and rest between positions—not upright-only “because that’s what we always do.”

Scenario C: Pediatric patient, first spirometry, cooperative but small mouth. Selection decision: pediatric mouthpiece/filter, incentive display if available, standard upright protocol, more time allotted—do not force adult flange hardware that leaks.

Link forward

Once protocol and equipment are selected and pre-test conditions are documented, Domain II.B.2 requires you to perform standard and position-variant maneuvers with correct coaching and end-of-test criteria (section 8.2). Domain II.C.2 then grades acceptability and repeatability (section 8.3). Bronchodilator studies combine selection, performance, and validity under II.A/B/C.15 and inhaled-delivery tasks (section 8.4).