UKMLA Respiratory Masterclass: Breathlessness Deep Dive

Breathlessness is the single most frequently examined presentation on the UKMLA AKT. Across the GMC content map's 212 presentations, "shortness of breath" sits at the top of the respiratory cluster and recurs inside cardiology, oncology, anxiety, anaemia, and acid-base stems. A typical 200-question AKT paper contains 25–35 stems where dyspnoea is the lead complaint — more than chest pain, more than abdominal pain, more than any other symptom.

The reason breathlessness is heavily tested is that it forces you to triage fast across a dozen plausible causes with overlapping presentations. Pulmonary oedema, PE, asthma, COPD, pneumonia, pneumothorax, anaphylaxis, and acute coronary syndrome can all present similarly in the first minute of assessment. The AKT tests whether you can use the specific discriminators — the single fact in the stem that makes one diagnosis correct and the other four incorrect — to arrive at the right diagnosis and the right first action.

This masterclass walks through the breathlessness differential algorithm UK F1s are expected to run on autopilot, then drills the six core respiratory conditions the UKMLA tests aggressively — asthma (with the 2024 NG245 restructuring), COPD, community-acquired pneumonia, PE, pneumothorax, and pleural effusion — plus brief coverage of interstitial lung disease and the ABG interpretation framework that threads through every respiratory stem.

Table of contents

1. Why breathlessness dominates the AKT
2. The breathlessness differential algorithm
3. Acute pulmonary oedema
4. Pulmonary embolism
5. Asthma — the 2024 NG245 guideline
6. Acute asthma exacerbation
7. COPD — stable and acute
8. Community-acquired pneumonia
9. Hospital-acquired pneumonia
10. Pneumothorax
11. Pleural effusion
12. Interstitial lung disease basics
13. ABG interpretation
14. Common AKT question patterns
15. FAQ

1. Why breathlessness dominates the AKT

Respiratory content accounts for roughly 15–20% of AKT questions when you include pure respiratory stems. But dyspnoea as a presenting symptom threads through cardiology, emergency medicine, anxiety, anaemia, and oncology too — so the functional weighting is closer to 25%.

The AKT tests three distinct skills under the breathlessness umbrella:

1. Differential triage — from a stem of obs and symptoms, narrow to one of six or seven causes.
2. Protocol retrieval — once the diagnosis is clear, retrieve the NICE or BTS/GINA-aligned management step.
3. ABG interpretation — classify acid-base disturbance and link it to the clinical cause.

Candidates lose respiratory marks most often through two errors: confusing asthma and COPD management (particularly post-2024 with NG245's restructuring), and failing to recognise PE in atypical presentations. The sections below target both directly.

Your target: 75%+ subscore on respiratory Q-bank filters. The emergency presentations post covers the acute-care framing; this post expands into chronic management and the deeper respiratory content.

2. The breathlessness differential algorithm

Every breathlessness stem can be triaged with a three-question decision tree:

Question 1 — Acute (minutes–hours) or chronic (days–months)?

Acute onset shortens the differential dramatically:

• Seconds to minutes: pneumothorax, PE, anaphylaxis, upper airway obstruction
• Minutes to hours: acute pulmonary oedema, severe asthma, massive PE
• Hours to a few days: pneumonia, COPD exacerbation, ACS
• Days to weeks: anaemia, pleural effusion, heart failure decompensation
• Weeks to months: ILD, chronic HF, lung malignancy, COPD progression

Question 2 — What do the examination/obs discriminators point to?

• Crackles bilateral + raised JVP + orthopnoea → pulmonary oedema
• Wheeze + prolonged expiratory phase → asthma / COPD
• Unilateral absent breath sounds + hyperresonance → pneumothorax
• Unilateral crackles + fever + productive cough → pneumonia
• Pleuritic pain + normal CXR + risk factors → PE
• Stridor + urticaria + hypotension → anaphylaxis
• Tachycardia + crushing chest pain → ACS

Question 3 — What does the CXR show?

• Bilateral bat-wing shadowing → pulmonary oedema
• Unilateral consolidation → pneumonia
• Pleural line with no lung markings peripheral to it → pneumothorax
• Blunt costophrenic angle → pleural effusion
• Reticular/honeycomb pattern → ILD
• Normal → PE, asthma, ACS, anaemia

Drill this three-question algorithm until it runs in under ten seconds. The AKT typically gives you all three pieces of information in the stem — your job is the mapping.

3. Acute pulmonary oedema

Presentation: sudden dyspnoea, orthopnoea, PND, frothy pink sputum, bilateral fine inspiratory crackles, raised JVP, S3 gallop.

CXR features:

• Alveolar shadowing (bat-wing distribution)
• Kerley B lines (interlobular septal thickening)
• Upper lobe venous diversion
• Cardiomegaly
• Pleural effusions (often bilateral, right > left)

Management (sit-up, oxygen, diuretic, nitrate, CPAP):

1. Sit patient upright with legs dependent.
2. High-flow O₂ (15 L non-rebreather).
3. IV furosemide 40–80 mg (higher doses if already on oral loop diuretic).
4. GTN infusion 1–10 mg/hour if systolic BP >100.
5. CPAP if respiratory distress persists.
6. Consider IV opiate for symptom control (no longer routinely recommended; evidence is weak).
7. Treat underlying cause — MI, arrhythmia, valve lesion, non-compliance.

Do not give β-blockers acutely in decompensated HF — they are started once euvolaemic.

Chronic HFrEF management (ACEi + β-blocker + MRA + SGLT2) is covered in the cardiology masterclass.

AKT question pattern. Elderly patient, sudden dyspnoea, orthopnoea, crackles, raised JVP. First-line investigation? CXR. First-line drug after oxygen? IV furosemide.

4. Pulmonary embolism

PE is the most over- and under-diagnosed cause of breathlessness on the AKT. Recognising when to suspect it, the Wells pathway, and the management flow are essential.

When to suspect PE:

• Pleuritic chest pain + dyspnoea
• Unexplained tachycardia
• Unilateral leg swelling (DVT source)
• Risk factors: recent surgery/immobilisation, malignancy, pregnancy/postpartum, COCP/HRT, thrombophilia, long flights, prior VTE, Factor V Leiden

Wells score for PE:

• Clinical signs of DVT — 3
• PE as or more likely than alternative — 3
• HR >100 — 1.5
• Immobilisation/surgery in past 4 weeks — 1.5
• Previous PE/DVT — 1.5
• Haemoptysis — 1
• Malignancy (treated last 6 months or palliative) — 1

Interpretation:

• Wells >4 → PE likely → CTPA
• Wells ≤4 → PE unlikely → D-dimer → if positive, CTPA

Management:

• Haemodynamically stable → anticoagulation. Apixaban 10 mg BD for 7 days then 5 mg BD (first-line). Alternative: rivaroxaban 15 mg BD for 21 days then 20 mg OD.
• Massive PE with haemodynamic compromise → thrombolysis (alteplase 100 mg over 2 hours; in cardiac arrest, 50 mg IV bolus).
• Duration: 3 months for provoked PE; ≥6 months for unprovoked; lifelong for recurrent or high-risk ongoing factors.

Cancer-associated PE: DOAC now first-line (replaces historical LMWH) per 2023 NICE update. Caveats remain for GI malignancy, where edoxaban or apixaban is preferred over rivaroxaban due to bleeding.

Pregnancy: LMWH throughout pregnancy and 6 weeks postpartum (DOACs contraindicated).

AKT question pattern. Post-op patient, sudden dyspnoea + pleuritic chest pain + tachycardia. Wells score? Calculate → >4 → CTPA. First-line anticoagulant? Apixaban 10 mg BD for 7 days.

5. Asthma — the 2024 NG245 guideline

The 2024 joint BTS/NICE/SIGN asthma guideline (NG245) is a substantial restructuring from the previous stepwise ladder. If your study materials predate November 2024, update them — NG245 is being tested aggressively on 2026 papers.

Key NG245 changes:

• No more SABA monotherapy — SABA-only treatment is now considered unsafe in all adults and children ≥12. Every adult with asthma gets an inhaled corticosteroid (ICS) from diagnosis.
• MART (Maintenance and Reliever Therapy) approach — low-dose ICS/formoterol combination is used both as maintenance and as the reliever. One inhaler, twice-daily regular use plus PRN for symptoms.
• AIR (Anti-Inflammatory Reliever) approach — low-dose ICS/formoterol PRN only, for milder asthma.

NG245 adult ladder (≥12 years):

1. Step 1: low-dose ICS/formoterol PRN (AIR) OR twice-daily + PRN (MART).
2. Step 2: low-dose MART (regular ICS/formoterol + PRN same inhaler).
3. Step 3: moderate-dose MART.
4. Step 4: add LTRA (montelukast) or LAMA (tiotropium).
5. Step 5: specialist referral — biologics (omalizumab, mepolizumab, benralizumab, dupilumab) for severe eosinophilic/allergic asthma.

Paediatric ladder (5–11):

Slightly different — lower ICS doses, LTRA featured earlier, MART options introduced at later steps.

Diagnosis of asthma (NG245):

• Adults: FeNO ≥50 ppb + BDR FEV1 ≥12% → diagnostic
• Peak flow variability ≥20% over 2 weeks
• If FeNO and BDR negative but clinical suspicion remains → bronchial challenge test
• Skin prick/IgE testing for atopic asthma

AKT question pattern. 18-year-old with asthma on SABA-only. Next step? Start ICS/formoterol combination (MART or AIR). Distractor: continue SABA + add ICS separately (outdated).

6. Acute asthma exacerbation

Severity classification (BTS):

Moderate: PEF 50–75%, speaking in sentences, HR <110, RR <25.

Severe (any of):

• PEF 33–50% best/predicted
• Cannot complete sentences
• RR ≥25
• HR ≥110

Life-threatening (any of "33/92 CHEST"):

• PEF <33%
• SpO₂ <92%
• Cyanosis
• Hypotension
• Exhaustion, altered consciousness
• Silent chest
• Tachyarrhythmia (bradyarrhythmia more sinister)

Near-fatal: raised CO₂ on ABG ± need for mechanical ventilation.

Management (OSHITME):

• Oxygen — titrate to 94–98%
• Salbutamol — 5 mg nebulised, back-to-back
• Hydrocortisone 100 mg IV or prednisolone 40–50 mg PO
• Ipratropium — 500 mcg nebulised (added to salbutamol for severe/life-threatening)
• Theophylline — aminophylline IV for non-responders (senior-led)
• Magnesium sulphate — 2 g IV over 20 min for life-threatening or non-responding severe
• Escalate to ICU for intubation if no improvement

Do not delay steroids even in stems focused on acute management — PO and IV steroids are equivalent within 4 hours of attack onset.

Discharge criteria: PEF >75%, no nebs for 24 hours, inhaler technique checked, steroid course (7 days PO pred), asthma action plan, GP follow-up 2 working days, respiratory clinic within 4 weeks.

AKT question pattern. Asthma patient, PEF 28% predicted, silent chest. Severity? Life-threatening. First drugs? Nebulised salbutamol + ipratropium + IV hydrocortisone + IV magnesium sulphate + ICU referral.

7. COPD — stable and acute

Diagnosis. Post-bronchodilator FEV1/FVC <0.7 with symptoms + risk factors (>35 years old, smoking/biomass exposure).

GOLD classification by FEV1 % predicted:

• GOLD 1 (mild): ≥80%
• GOLD 2 (moderate): 50–79%
• GOLD 3 (severe): 30–49%
• GOLD 4 (very severe): <30%

Stable COPD management (NG115):

1. Smoking cessation — single most important intervention.
2. Pulmonary rehabilitation if MRC dyspnoea ≥3.
3. Influenza + pneumococcal vaccination.
4. Inhaler ladder:
   • SABA or SAMA PRN for all
   • Asthmatic/steroid-responsive features (e.g. previous asthma dx, eosinophilia, diurnal variation) → LABA + ICS
   • No asthmatic features → LABA + LAMA
   • Not controlled on dual therapy → triple therapy LABA + LAMA + ICS
5. Long-term oxygen therapy (LTOT) criteria: PaO₂ <7.3 on air (or <8.0 with polycythaemia/cor pulmonale/peripheral oedema). 15+ hours/day. No smoking.
6. Non-invasive ventilation for chronic hypercapnic failure meeting criteria.

Acute COPD exacerbation:

• Controlled O₂ (target sats 88–92%, start with Venturi 24–28%).
• Nebulised salbutamol + ipratropium.
• Steroids: prednisolone 30 mg PO OD for 5 days (or IV hydrocortisone if oral unsafe).
• Antibiotics only if signs of infection (increased sputum volume/purulence, fever, raised WCC/CRP): amoxicillin 500 mg TDS or doxycycline 200 mg then 100 mg OD, 5 days.
• NIV (BiPAP) if ABG: pH 7.25–7.35 with raised CO₂ despite controlled O₂.
• Intubation if pH <7.25 or exhausted.

AKT question pattern. COPD patient admitted with exacerbation, pH 7.28, pCO₂ 9.8. Next step? Start NIV (BiPAP).

8. Community-acquired pneumonia

Diagnosis. Clinical: cough + fever + focal signs (crackles, bronchial breathing, dullness) + raised WCC/CRP + CXR consolidation.

CURB-65:

• Confusion (new disorientation)
• Urea >7
• RR ≥30
• BP systolic <90 or diastolic ≤60
• 65 — age ≥65

Interpretation:

• 0–1: outpatient management, amoxicillin 500 mg TDS 5 days
• 2: admit for observation; amoxicillin + clarithromycin OR doxycycline
• 3–5: severe; co-amoxiclav + clarithromycin; consider ICU if ≥3

Atypical cover. Clarithromycin (or doxycycline) covers Mycoplasma, Chlamydia, Legionella. Legionella: check urinary antigen if severe CAP or travel history.

Duration. 5 days for mild-moderate (NG138 2019 cut from 7 days). 7–10 days for severe.

Complications: parapneumonic effusion (simple → antibiotics; empyema → chest drain), lung abscess, sepsis.

AKT question pattern. 78-year-old with cough + fever + confusion + BP 85/50 + urea 9 + RR 32. CURB-65? 5. Management? Admit ICU, co-amoxiclav + clarithromycin IV.

9. Hospital-acquired pneumonia

Definition. Pneumonia >48 hours after hospital admission.

Empirical antibiotics: local trust guidelines govern but typical choice is co-amoxiclav + metronidazole, or piperacillin-tazobactam for severe/ICU. Add vancomycin if MRSA risk. Adjust based on culture.

Ventilator-associated pneumonia (VAP). Subset of HAP arising >48h after mechanical ventilation. Organisms skew toward Pseudomonas, MRSA, multi-drug resistant Gram-negatives.

Aspiration pneumonia. Risk factors: stroke, reduced consciousness, oesophageal disease, alcohol excess. Typically right lower lobe or right middle lobe. Cover anaerobes — co-amoxiclav or clindamycin.

10. Pneumothorax

Primary spontaneous. Tall young male smoker. Sudden pleuritic pain + dyspnoea. Unilateral hyperresonance + reduced breath sounds.

Secondary. Underlying lung disease (COPD, asthma, TB, cystic fibrosis, Marfan's).

Tension pneumothorax. Haemodynamic instability + tracheal deviation away from affected side + raised JVP. Emergency needle decompression — large-bore cannula in 4th–5th ICS anterior axillary line (updated from 2nd ICS MCL per BTS 2023). Then chest drain.

BTS 2023 update — initial management of spontaneous pneumothorax:

• No high-risk features + size not large + minimal symptoms → conservative (observation + outpatient follow-up).
• High-risk features (haemodynamic compromise, ongoing air leak, bilateral, secondary) → chest drain.
• Symptomatic/large without high-risk → needle aspiration OR ambulatory device (drain with one-way valve) — both acceptable first-line.

Chest drain insertion. Safe triangle: anterior axillary line (lateral border of pec major), mid-axillary line (base of axilla), 5th intercostal space. Typical size 12–14 Fr for pneumothorax.

AKT question pattern. Young male sudden pleuritic chest pain, tracheal deviation, hypotension. First action? Needle decompression (large-bore cannula 4–5th ICS anterior axillary). Then chest drain.

11. Pleural effusion

Types. Transudate (protein <25 g/L) vs exudate (protein >35 g/L). Light's criteria used when protein 25–35 g/L.

Light's criteria — exudate if any of:

• Pleural protein / serum protein >0.5
• Pleural LDH / serum LDH >0.6
• Pleural LDH > two-thirds upper limit of normal serum LDH

Transudate causes: HF, cirrhosis, nephrotic syndrome, hypoalbuminaemia, constrictive pericarditis.

Exudate causes: infection (parapneumonic, empyema, TB), malignancy, PE, pancreatitis, connective tissue disease.

Investigations: pleural aspirate for biochemistry, cell count, Gram stain + culture, cytology, pH (empyema if <7.2). TB: adenosine deaminase, AFB, culture. Malignancy: cytology (low yield first time; repeat), pleural biopsy if needed.

Management: treat underlying cause. Empyema → chest drain. Malignant effusion → therapeutic aspiration, pleurodesis, indwelling pleural catheter.

AKT question pattern. Unilateral effusion post-pneumonia. Pleural fluid pH 6.9, turbid. Diagnosis? Empyema. Management? Chest drain + IV antibiotics.

12. Interstitial lung disease basics

Presentation. Progressive exertional dyspnoea + dry cough + fine end-inspiratory crackles + clubbing.

Common ILD subtypes:

• Idiopathic pulmonary fibrosis (IPF) — older patient, honeycomb/reticular pattern on HRCT, UIP pattern. Antifibrotics: pirfenidone, nintedanib.
• Hypersensitivity pneumonitis — occupational/environmental antigen (mouldy hay, bird fancier's, farmer's lung). Remove antigen; steroids.
• Sarcoidosis — multisystem granulomatous. Bilateral hilar lymphadenopathy + lung infiltrates + extrapulmonary features (erythema nodosum, uveitis, hypercalcaemia). ACE raised. Steroids if symptomatic.
• Drug-induced — amiodarone, methotrexate, nitrofurantoin, bleomycin.
• CTD-associated — RA, SLE, systemic sclerosis, dermatomyositis.
• Asbestosis — occupational exposure + pleural plaques + progressive fibrosis.

Investigations: HRCT (gold standard), spirometry (restrictive: reduced FEV1 + FVC + normal/raised ratio, reduced TLCO), autoimmune screen.

AKT question pattern. Older smoker + progressive dyspnoea + fine Velcro-like crackles + clubbing + HRCT showing honeycomb pattern. Diagnosis? IPF. Treatment? Antifibrotic (pirfenidone or nintedanib).

13. ABG interpretation

Every respiratory stem benefits from a fast ABG framework. Use the five-step approach:

Step 1 — Is there hypoxia? PaO₂ <10 kPa on air (or <FiO₂ × 10 − 10 on O₂).

Step 2 — Acidosis or alkalosis? pH <7.35 → acidosis; pH >7.45 → alkalosis.

Step 3 — Respiratory or metabolic?

• Respiratory acidosis: pH ↓, pCO₂ ↑
• Respiratory alkalosis: pH ↑, pCO₂ ↓
• Metabolic acidosis: pH ↓, HCO₃ ↓
• Metabolic alkalosis: pH ↑, HCO₃ ↑

Step 4 — Compensation? If primary respiratory, look for metabolic compensation (and vice versa). Partial compensation ≠ normalised pH.

Step 5 — Anion gap (for metabolic acidosis): Na − (Cl + HCO₃). Normal 8–16.

• Raised anion gap acidosis (MUDPILES): methanol, uraemia, DKA, paraldehyde/propylene glycol, iron/INH, lactic acidosis, ethylene glycol, salicylates.
• Normal anion gap acidosis: GI HCO₃ loss (diarrhoea), renal tubular acidosis, Addison's.

Common ABG patterns:

• Type 1 respiratory failure: PaO₂ <8, PaCO₂ normal/low. Cause: V/Q mismatch (PE, pneumonia, pulmonary oedema).
• Type 2 respiratory failure: PaO₂ <8, PaCO₂ >6. Cause: alveolar hypoventilation (COPD, severe asthma, neuromuscular).
• Respiratory alkalosis: anxiety, PE, high altitude, early sepsis.
• Metabolic acidosis with respiratory compensation: DKA (Kussmaul breathing), sepsis (lactic acidosis), renal failure.

AKT question pattern. Patient with pH 7.26, pCO₂ 9.5, HCO₃ 30, PaO₂ 7.2. Classification? Type 2 respiratory failure with partial metabolic compensation. Likely diagnosis (given COPD history)? Acute COPD exacerbation. Next step? Controlled O₂, NIV.

MLA Prep's respiratory module includes 100+ ABG interpretation drills — every one tagged to the respiratory condition it represents — plus NG245-aligned asthma stems. Start the free diagnostic to see your respiratory subscore and ABG accuracy.

14. Common AKT question patterns

Six respiratory stem templates recur on almost every AKT.

Template 1 — Differential triage from CXR. Stem gives CXR findings; task is the diagnosis. Reticular pattern + clubbing → IPF. Bat-wing → pulmonary oedema. Unilateral absence of lung markings → pneumothorax.

Template 2 — CURB-65 scoring and antibiotic choice. Stem gives obs + bloods; calculate CURB-65, pick outpatient vs admit + correct abx.

Template 3 — Asthma severity classification and escalation. Stem gives PEF + obs + exam findings; classify moderate/severe/life-threatening and pick the next drug.

Template 4 — COPD exacerbation + NIV. ABG shows pH 7.28 + raised CO₂; recognise NIV indication.

Template 5 — PE Wells pathway. Calculate Wells, pick CTPA vs D-dimer.

Template 6 — ABG pattern recognition. Classify failure type, link to probable diagnosis, pick first intervention.

Recognising the template tells you what the question is testing. Tag each respiratory stem in practice sessions accordingly.

15. FAQ

How many AKT marks come from respiratory? Approximately 30–40 of 200 touch respiratory content directly; more if you count dyspnoea-as-symptom stems.

Is BTS/GINA or NG245 the authority for asthma? NG245 (the joint BTS/NICE/SIGN 2024 guideline) is now the UK standard and is being tested on 2026 papers. GINA remains the global reference but the UKMLA follows NG245.

Do I need to know specific Legionella risk factors? Yes — travel (hotels, cruise ships), air-conditioning, male > female, middle-aged smokers. Hyponatraemia and deranged LFTs are classic stem clues. Urinary antigen is the rapid diagnostic.

When is NIV vs intubation in COPD exacerbation? NIV: pH 7.25–7.35 + raised CO₂ despite controlled O₂. Intubation: pH <7.25, exhaustion, GCS drop, inability to tolerate NIV.

Are inhaled steroids safe long-term? Yes at standard doses. Risks at high doses: oral candidiasis (rinse after use), dysphonia, skin thinning, cataracts, osteoporosis, adrenal suppression (rare unless very high dose long-term).

What about pulmonary function test interpretation?

• Obstructive (FEV1/FVC <0.7): asthma (reversible with bronchodilator), COPD (fixed).
• Restrictive (FEV1/FVC normal/raised, FVC reduced): ILD, chest wall disease, neuromuscular.
• Reduced TLCO: ILD, emphysema, pulmonary vascular disease.
• Raised TLCO: pulmonary haemorrhage, asthma (slightly), left-to-right shunts.

Is tiotropium used in asthma? Yes — as add-on LAMA in step 4 of NG245 for uncontrolled asthma. Was historically COPD-only.

How is PE during pregnancy managed? LMWH (tinzaparin or enoxaparin) throughout pregnancy + 6 weeks postpartum. DOACs contraindicated. CTPA acceptable in pregnancy (small radiation dose to fetus) — V/Q perfusion-only scan is alternative.

What's the role of biologics in severe asthma? Eosinophilic severe asthma → mepolizumab, benralizumab, reslizumab. Allergic (high IgE) → omalizumab. Type 2 inflammation → dupilumab. Initiated by specialists; AKT may test recognition that severe uncontrolled asthma warrants biologic referral.

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Breathlessness threads through more AKT stems than any other presentation, and respiratory pattern recognition is among the highest-leverage blocks of study. Six core conditions, one differential algorithm, one ABG framework, and six question templates — that's the whole surface area.

Pair this masterclass with the cardiology masterclass (which handles pulmonary oedema and PE from the cardiac angle), the emergency presentations post, and the NICE guidelines post (which covers asthma and COPD prescribing aligned to NG245 and NG115). The 12-week plan slots respiratory immediately after cardiology for most candidates.

MLA Prep's respiratory module covers all 10 conditions above with NG245-aligned asthma stems, 2023-updated pneumothorax management, and a dedicated ABG interpretation drill set. Start the free diagnostic to benchmark your respiratory subscore, or compare plans for full access.