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FCPS Part 1 Respiratory MCQs
Respiratory physiology questions test lung volumes and compliance, airway resistance, ventilation and perfusion, oxygen and carbon dioxide transport, the control of breathing and responses to altitude.
Below are 5 free single-best-answer questions drawn from the most frequently examined respiratory concepts, each with the answer and a rationale for every option. The full bank has 80 respiratory concepts, each asked several different ways.
Free respiratory questions
Question 1
Net pressure that distends the lungs as the chest wall expands:
- A. Intrapulmonary pressure
- B. Transpulmonary pressure
- C. Atmospheric pressure
- D. Transthoracic pressure
- E. Intrapleural pressure
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Answer: B. Transpulmonary pressure
Transpulmonary pressure is alveolar pressure minus pleural pressure, the net pressure across the lung wall. As pleural pressure falls in inspiration it rises, expanding the lung against elastic recoil.
Why not the others: Intrapleural: only one term of the difference. Atmospheric: reference pressure. Transthoracic: acts across the chest wall. Intrapulmonary: alveolar pressure alone. Intrathoracic: general term for chest pressure.
High-yield: Lung distending pressure = alveolar − pleural; about +5 cmH2O at end-expiration.
Question 2
Soldier flown from sea level to 12,000 ft becomes breathless at rest 2 to 4 days later. Cause:
- A. Secondary polycythaemia
- B. Pulmonary oedema
- C. Decreased 2,3-DPG
- D. Hypoventilation
- E. Airway obstruction
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Answer: B. Pulmonary oedema
Hypoxia causes patchy pulmonary vasoconstriction and raised pulmonary arterial pressure. Capillaries in the unconstricted areas are over-perfused and leak, producing oedema within hours to days.
Why not the others: Secondary polycythaemia: takes weeks, does not cause acute dyspnoea. Hypoventilation: altitude drives hyperventilation instead. Decreased 2,3-DPG: it rises, not falls. Airway obstruction: no mechanism at altitude. Heart failure: not the primary mechanism.
High-yield: Breathlessness at rest 2 to 4 days after rapid ascent = high-altitude pulmonary oedema; treat with descent and oxygen.
Question 3
A woman taking the combined pill has abrupt pleuritic pain, tachycardia and hypoxia. Diagnosis?
- A. Aortic dissection
- B. Air embolism
- C. Pulmonary embolism
- D. Myocardial infarction
- E. Acute pericarditis
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Answer: C. Pulmonary embolism
Virchow's triad of stasis, hypercoagulability and endothelial injury produces deep vein thrombi that embolise to the pulmonary arteries. Peripheral infarction explains pleuritic pain and a pleural rub.
Why not the others: Myocardial infarction: central pain without pleuritic pattern. Acute pericarditis: positional pain with diffuse ST elevation. Air embolism: venous air entry, usually iatrogenic. Aortic dissection: tearing pain, unequal pulses.
High-yield: Risk factor + sudden pleuritic pain or dyspnoea = pulmonary embolism.
Question 4
Respiratory effect of the head-down tilt during pelvic surgery:
- A. Decreased airway resistance
- B. Decreased functional residual capacity
- C. Increased residual volume
- D. Increased chest wall compliance
- E. Increased lung compliance
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Answer: B. Decreased functional residual capacity
Head-down tilt pushes abdominal contents against the diaphragm, shrinking functional residual capacity and favouring atelectasis. Obesity and the supine position reduce FRC in the same way, shrinking the oxygen store.
Why not the others: Increased lung compliance: compliance falls. Decreased airway resistance: resistance rises as lung volume falls. Increased chest wall compliance: chest wall compliance falls. Increased residual volume: not the expected change.
High-yield: Head-down, supine, obese, pregnant = lower FRC = faster desaturation.
Question 5
Spirometric volume most reduced in COPD, falling more than FVC:
- A. Total lung capacity
- B. Closing capacity
- C. Functional residual capacity
- D. FEV1
- E. Residual volume
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Answer: D. FEV1
In obstruction, airflow in the first second of a forced expiration is limited, so FEV1 falls more than FVC and the ratio decreases. Residual volume, FRC and TLC rise from air trapping.
Why not the others: Residual volume: rises with air trapping. TLC: rises in COPD. FRC: rises in COPD. Closing capacity: rises with airway collapse.
High-yield: Obstruction: FEV1 down most, ratio down, RV and FRC up.
Keep going with respiratory
Anaesgen brings every concept back on a spaced-repetition schedule timed to your exam date, as a different question each time, with full mock papers for Paper 1 and 2.
Get full access Try the 5 sample questionsHigh-yield respiratory one-liners
The most-tested respiratory concepts, as a clue and the answer it points to:
- Distending pressure, alveolar minus pleural, opposes recoil → transpulmonary pressure.
- Rapid ascent, dyspnoea within hours to days, frothy sputum → pulmonary oedema.
- Combined pill, long flight, postoperative dyspnoea, pleuritic pain → pulmonary embolism.
- Tetralogy of Fallot → severity set by RVOT (infundibular) stenosis.
- Head-down, supine, obesity, quick desaturation → decreased functional residual capacity.
- COPD, asthma, airway obstruction, first-second volume → FEV1.
- Wheeze, variable obstruction, FEV1 reverses → pre/post-bronchodilator spirometry.
- Obstruction, hyperinflation, air trapping → raised FRC (ERV plus RV).
- Trauma, rib fracture, hyperlucent lung, absent markings → pneumothorax.
- Hyperventilation faint, early salicylate toxicity, tetany → respiratory alkalosis.
- Term pregnancy, progesterone, minute ventilation up 50% → decreased PaCO₂ (about 30 mmHg).
- Pulmonary vasoconstriction, one-lung ventilation, erythropoietin release → hypoxia.
- Low PaO2, altitude, hypoventilation, shunt → hypoxic hypoxia.
- Altitude, right shift, reduced affinity, more unloading → increased 2,3-BPG.
- Mixed venous sample, venous emboli, PO₂ about 40 mmHg → pulmonary artery.
- Trendelenburg, ↓tidal volume, minute ventilation defended → ↑respiratory rate.
- Stony dull + trachea away from the side → large pleural effusion.
- Third-space loss, balanced crystalloid, calcium (not with blood) → Ringer's lactate.
- Rapid breathing, normal gases, resolves at rest → strenuous exercise.
- Pregnancy, progesterone, raised minute ventilation, low PaCO2 → increased tidal volume.
Other FCPS Part 1 subjects
AnatomyPharmacologyPathologyBiochemistry & GeneticsCardiovascularNeurophysiologyMicrobiologyHaematologyGeneral PhysiologyImmunologyEndocrineEmbryologyObstetrics & GynaeRenal & Acid-BaseHistologyGI & LiverPhysicsBiostatistics
New to the exam? Read the FCPS Part 1 exam guide: dates, format and a 12-week study plan.