CPFT Practice Questions (2026) — Free Sample Questions with Answers

Answer: C

2.94 L: 2.94 L is a 2% error, inside the ±3% tolerance (2.91–3.09 L).

3.05 L: 3.05 L is about a 1.7% error and passes.

3.12 L: Correct. 3.12 L is a 4% error, outside the ±3% limit; the spirometer must be recalibrated or serviced before testing.

3.08 L: 3.08 L is about a 2.7% error, still within ±3%.

2019 ATS/ERS: a 3-L syringe check must read within ±3% (2.91–3.09 L); outside that range, do not test patients until the device is corrected.

Answer: C

Prescribe oxygen only at night: The desaturation documented is exertional, so nocturnal-only oxygen would not address it.

Repeat the walk on room air to confirm: The desaturation is already clear; repeating on room air adds risk without new information.

Repeat the walk with titrated supplemental O2: Correct. Repeat the walk with supplemental oxygen, titrating flow until SpO2 stays at or above 88% during exertion, and document the flow required.

Stop testing; resting SpO2 is normal: A normal resting value does not exclude clinically important exercise desaturation.

Ambulatory oxygen assessment: document room-air desaturation (≤ 88%), then titrate oxygen during repeat exercise to keep SpO2 ≥ 88%.

Answer: C

3 ± 1 seconds: Too short; little CO would be taken up and results would be unreliable.

6 ± 1 seconds: Six seconds is the minimum adult forced exhalation goal in older spirometry standards, not the DLCO breath-hold.

10 ± 2 seconds: Correct. The standard breath-hold is 10 ± 2 seconds, with inspired volume at least 90% of the largest vital capacity.

20 ± 2 seconds: A 20-second hold is not standard and would distort the calculated uptake.

Single-breath DLCO: exhale to RV, rapid inspiration to ≥ 90% of VC, breath-hold 10 ± 2 s, smooth exhalation and sample collection.

Answer: D

Acceptable, since BEV is under 0.30 L: There is no fixed 0.30 L limit; the limit is the greater of 5% of FVC or 0.100 L.

Acceptable, if the plateau criterion is met: A good end of test does not compensate for an unacceptable start of test.

Unacceptable, because FVC is below 4.5 L: FVC size has no bearing on acceptability; only start, end and artifact criteria apply.

Unacceptable, because BEV exceeds 5% of FVC: Correct. The limit is the greater of 5% of FVC (0.20 L) or 0.100 L; 0.25 L exceeds 0.20 L, indicating a hesitant start, so FEV1 is invalid.

Start-of-test criterion: BEV must be < 5% of FVC or < 0.100 L, whichever is greater; a large BEV means a slow or hesitant start that falsely raises FEV1.

Answer: D

Interstitial lung disease: Interstitial disease is restrictive but typically lowers DLCO because the alveolar-capillary membrane is damaged.

Emphysema with hyperinflation: Emphysema shows obstruction and an elevated, not reduced, TLC.

Pulmonary vascular disease: Pulmonary vascular disease usually lowers DLCO with normal lung volumes.

Extraparenchymal restriction from obesity: Correct. Restriction with a normal DLCO and a low ERV points to a chest wall or extraparenchymal cause, here obesity.

Restriction (low TLC) + normal DLCO = extraparenchymal cause (obesity, neuromuscular, chest wall); restriction + low DLCO = parenchymal (interstitial) disease.

Answer: B

1.8 L: This multiplies system volume by the final concentration ratio (3.0 × 0.6) rather than using the dilution equation.

2.0 L: Correct. FRC = Vsys × (He initial − He final) / He final = 3.0 × (10 − 6) / 6 = 2.0 L.

1.2 L: This divides the difference by the initial concentration (3.0 × 4 / 10), which is not the dilution equation.

5.0 L: 5.0 L is the total diluted volume (system + lung), not the FRC alone.

Helium dilution: FRC = system volume × (He_i − He_f) ÷ He_f, then correct for dead space and to BTPS.