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ABG + CXR Interpretation Drills: Fixed Scripts, Faster Marks

Two high-yield interpretation scripts (ABG + chest X-ray) plus a drill system and error labels to compound speed and accuracy.

Review date
Feb 2026
Reading time
11 min read
Author
Dr. Kola Tytler MBBS CertHE MBA MSt MRCGP
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Key points

  • Speed comes from scripts: the same order, every time, under time pressure.
  • Build a small pattern library and drill it weekly (not ‘random exposure’).
  • Label errors so you fix the cluster (not the individual question).
Interpretation questions feel hard because candidates ‘scan’ and improvise. The solution is to run a fixed script that catches the common patterns and prevents misses. Once your brain trusts the script, you get faster and calmer — which produces better answers.
1

ABG: the 60-second script

1) Oxygenation: PaO2/SaO2 (context: FiO2). 2) pH: acidemia/alkalemia. 3) Primary driver: PaCO2 vs HCO3/BE. 4) Compensation: appropriate or mixed disorder? 5) Anion gap / delta thinking if metabolic issue suspected. 6) One-line clinical meaning + next step (e.g., ventilatory failure → escalate).
2

CXR: the 90-second script

1) Quality: rotation, inspiration, exposure. 2) A/B/C: Airway, Breathing (lungs/pleura), Circulation (heart/mediastinum). 3) Diaphragm (free air, effusions). 4) Everything else: bones, soft tissues, devices/lines. 5) One-line summary + ‘so what’ action.
3

The drill (10 per week, sustainable)

Every week: 5 ABGs + 5 CXRs. For each: run the script out loud, commit to a one-line diagnosis and next step, then check the explanation. Capture the error label. Re-test your common error label set 48 hours later.

Error labels (use these so you can fix the cluster)

  • Script break (skipped step: quality/oxygenation/compensation).
  • Pattern miss (classic COPD retention, DKA, pulmonary oedema, pneumothorax, lobar collapse).
  • Overcall (saw pathology that isn’t there).
  • No ‘so what’ (failed to state implication/next step).
  • Device/line blind spot (ETT/NG/central line/pacemaker).

Why scripts win

Under time pressure, your working memory is the bottleneck. A fixed script reduces cognitive load and makes your thinking predictable — which is exactly what exams reward.
SourceABGs made easy: stepwise method (open access, PMC)
Open Link
SourceBlood gas interpretation: structured five-step approach (open access, PMC)
Open Link
SourceAmerican Thoracic Society: ABG interpretation (six-step process)
Open Link
SourceNCBI Bookshelf: a systematic approach to chest radiographic analysis
Open Link
SourcePatient.info (Doctor): systematic chest X-ray approach
Open Link
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  • 1) Oxygenation: PaO2/SaO2 (context: FiO2). 2) pH: acidemia/alkalemia. 3) Primary driver: PaCO2 vs HCO3/BE. 4) Compensation: appropriate or mixed disorder? 5) Anion gap / delta thinking if metabolic issue suspected. 6) One-line clinical meaning + next step (e.g., ventilatory failure → escalate).

    Return to this section

  • 1) Quality: rotation, inspiration, exposure. 2) A/B/C: Airway, Breathing (lungs/pleura), Circulation (heart/mediastinum). 3) Diaphragm (free air, effusions). 4) Everything else: bones, soft tissues, devices/lines. 5) One-line summary + ‘so what’ action.

    Return to this section

  • Every week: 5 ABGs + 5 CXRs. For each: run the script out loud, commit to a one-line diagnosis and next step, then check the explanation. Capture the error label. Re-test your common error label set 48 hours later.

    Return to this section
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