8.2 Performing Standard & Position-Variant Spirometry

From selected protocol to performed maneuver (II.B.2)

Domain II.B Perform task II.B.2 (standard and position-variant spirometry, outline a/b) is where RPFT candidates earn—or lose—points on coaching quality. Instrumentation may be perfect and the protocol correctly chosen, yet poor blast, early stop, or leaky seal will destroy FEV1, FVC, and PEF. This section is the hands-on performance layer aligned with ATS/ERS 2019 spirometry technical standards concepts used throughout modern PFT practice and NBRC-style stems.

Goals of a well-performed forced maneuver

Each acceptable FVC effort should demonstrate:

1. Maximal inspiration to total lung capacity (TLC) before the blast.
2. Explosive start of forced expiration without hesitation (supports valid PEF and timed volumes).
3. Maximal effort throughout expiration without glottis closure, leak, or obstructed mouthpiece.
4. Complete exhalation to residual volume (RV) meeting end-of-test criteria concepts.
5. For full flow–volume loops, a maximal forced inspiration after emptying when the protocol includes the inspiratory limb.

Primary reported indices from these efforts include PEF (peak expiratory flow), FEV1 (forced expiratory volume in 1 second), and FVC (forced vital capacity), plus derived ratios and mid-flows used later in Domain III.

Coaching the FVC maneuver step by step

Setup in the chair (or supine surface)

• Confirm upright seated posture: feet flat, no forward lean onto the knees, nose clip on, tight lip seal.
• Explain the maneuver in plain language before the mouthpiece is busy: “Big breath in, blast out hard and fast, keep blowing until I say stop.”
• Demonstrate with your own hands or a demo mouthpiece; show the on-screen target if available.

Tidal breathing to FVC transitions

A common, standards-aligned sequence:

1. Tidal breathing on the mouthpiece for several breaths so the patient settles and the seal is checked.
2. Maximal inspiration — coach “deeper… deeper… full lungs” to TLC. Incomplete inspiration is a major cause of low FVC and low PEF.
3. Blast — without pause at TLC if possible (or only a brief pause if needed for coordination; prolonged breath-hold at TLC can reduce PEF). Cue: “Blast! Hard and fast!”
4. Complete exhalation — immediately switch coaching tone from explosive to endurance: “Keep going… squeeze… more… more…” until end-of-test criteria or safety stop.
5. Maximal inspiration (when capturing FIVC/inspiratory loop): “Now big breath all the way in!”
6. Come off the mouthpiece, rest, and review the curve before the next effort.

Why tidal-to-forced transitions matter on the exam: stems may describe a patient who “starts blasting from mid-breath” or “does not take a full inspiration first.” Those are performance errors, not disease patterns, until proven otherwise.

PEF, FEV1, and FVC acquisition—what coaching targets

Coach both the start and the finish. Technologists who only shout “blow hard” often get high PEF with truncated FVC; those who only say “empty all the way” may get long but non-explosive efforts with low PEF and distorted FEV1 timing.

End-of-test criteria concepts (ATS/ERS 2019)

ATS/ERS 2019 updated how we decide a forced expiration is sufficiently complete. For exam purposes, remember the concepts (software may flag them automatically):

Plateau concept

A satisfactory end of forced expiration includes an expiratory plateau on the volume–time display: volume change of about ≤0.025 L (25 mL) for at least 1 second. That plateau means the patient has essentially reached residual volume for that effort.

Duration when plateau is hard to achieve

Patients with severe obstruction may empty very slowly. Standards allow ending when forced expiratory time is long (commonly discussed around ≥15 seconds in adult practice under the 2019 framework) and the patient is still trying, or when continuing is not safe/possible—even if a perfect plateau never appears. Do not force endless blowing that causes syncope.

Patient cannot or should not continue

Stop the effort for dizziness, extreme distress, chest pain, or other safety concerns (Chapter 7). Document why the effort ended. Multiple incomplete efforts may still yield usable FEV1 even when FVC is limited—grading is section 8.3.

Practical coaching language tied to EOT

• “Keep a tight seal—don’t stop when it feels empty; keep squeezing.”
• Watch the volume–time curve: if volume is still rising steeply at 3–4 seconds in an adult, coach longer.
• If the patient repeatedly stops at 2 seconds with no plateau, reteach rather than accepting three identical early terminations as “best possible” without trying to improve.

Exam trap: “FEV1 is all that matters, so stop at one second.” False—FVC and the full curve are required for pattern recognition, VC comparisons, and many quality rules.

Special coaching: children

Pediatric spirometry is a performance skill, not a smaller adult script.

• Use age-appropriate vocabulary: “Blow out the candles,” “make the rocket fly,” rather than “maximize peak flow.”
• Demonstrate exaggerated blast and long blow; children copy better than they parse abstract instructions.
• Allow practice blows that are not scored emotionally as failures.
• Use incentive animations when available, but do not let the child stop the moment the animation “wins” if emptying is incomplete—coach through the end.
• Expect more trials and shorter attention; rest between efforts; involve a caregiver for calm, not for shouting over you.
• Watch for leaks, laughing mid-blow, and incomplete inspiration—the same physiologic requirements apply within pediatric acceptability rules (repeatability numbers differ by age in standards; validity detail in 8.3).

Special coaching: elderly and frail adults

• Speak clearly; reduce multi-step instructions into chunks.
• Allow longer recovery between efforts to avoid fatigue-related declining FVC.
• Address dentures: loose dentures break seals—remove if they interfere and the patient can seal without them, or use a flanged mouthpiece per lab practice.
• Cognitive impairment: model the maneuver, use hand signals for “blast” vs “keep going,” and limit total attempts to avoid exhaustion while still seeking three acceptable efforts when possible.
• Fear of “running out of air”: explain that the next breath will be a big inspiration after the blow; stay visible and calm.

Performing position-variant (supine) spirometry

Once II.A selected an upright/supine protocol, II.B requires competent performance in both positions.

Upright phase

Perform standard maximal efforts first when possible so the patient learns the maneuver while stronger and less orthopneic. Obtain acceptable upright FVC/FEV1 before moving.

Transition to supine

• Assist safely to full supine or near-supine per protocol; support the head; avoid extreme neck flexion.
• Re-apply nose clip; re-establish seal; allow several quiet tidal breaths for adaptation.
• Watch for orthopnea, desaturation if monitored, or panic—safety overrides data.

Supine forced maneuver differences

Report upright and supine values clearly labeled. Do not average positions together.

Session workflow that exam items assume

1. Confirm protocol and pre-test status (8.1).
2. Demonstrate and practice.
3. Collect forced efforts aiming for at least three acceptable maneuvers when possible (acceptability formalized in 8.3), usually with a practical upper limit around eight attempts to avoid fatigue.
4. Rest 30–60 seconds or more between maximal efforts as needed.
5. Review PEF, FEV1, FVC, and curve shape after each blow; give specific feedback (“blast harder at the very start” vs vague “do better”).
6. For position-variant: complete upright set → reposition → supine set with re-instruction.
7. For bronchodilator protocols: complete valid pre set before drug (8.4).

Common performance errors and real-time fixes

What “good performance” looks like on the display

• Flow–volume loop: rapid rise to PEF, smooth descending limb without large notches from leak or glottis closure, and (if recorded) a full inspiratory loop.
• Volume–time: steep early rise, then approach to plateau without abrupt flatline at 1–2 seconds in patients who can empty further.
• Efforts that improve with coaching show rising PEF/FEV1/FVC toward a plateau across trials—your job is to drive that improvement until criteria or safety limits are reached.

RPFT performance vignettes

Vignette 1: Adult with COPD blows hard for 2 seconds then stops, FVC far below prior SVC. Action: reteach complete emptying, coach through plateau/long FET, do not accept early stop as “obstruction only” without attempting full FVC.

Vignette 2: Child laughs and leaks every blast. Action: pause, demonstrate, shorter sessions, incentive device, caregiver quiet support—performance skill, not automatic “unable to test” after one try.

Vignette 3: Supine ALS patient desaturates and panics after one effort. Action: stop, sit up, stabilize—safety first; document limited data rather than forcing three heroic supine FVCs.

Link forward

Performance produces raw efforts; Domain II.C.2 decides which efforts are acceptable, whether FEV1/FVC are repeatable, and how to grade sessions that never fully meet ideal criteria (section 8.3). Bronchodilator sessions reuse these same performance skills after drug delivery (section 8.4).