ABG interpretation practice that shows every step of the reasoning.
Practise arterial blood gas interpretation step by step: primary disorder, compensation, anion gap and delta gap, A–a gradient and P/F ratio, with timed exam-style ABG cases in RescueEM's ABG Master.
Step-by-step acid–base approach
Work any gas the same way every time: pH, primary disorder, compensation, gap, delta-delta — with the reasoning shown at each step.
- Primary vs compensatory
- Mixed disorders
- Winter's formula built in
Anion gap and delta gap
Automatic anion gap, albumin correction and delta-delta so you catch the second disorder hiding behind a normal pH.
- Albumin-corrected gap
- Delta ratio
- HAGMA vs NAGMA causes
Oxygenation tools
A–a gradient, P/F ratio and expected values by age and FiO2, tied to the causes of hypoxaemia you have to name in the exam.
- A–a gradient by age
- P/F ratio and ARDS bands
- Shunt vs V/Q mismatch
Cause-specific plans
Each result maps to the likely causes and the exam-expected next steps, so the number turns into a decision.
- Differential by pattern
- Expected next investigations
- Common exam traps
Timed case drills
Exam mode fires real gases with a clock and scores you, then shows exactly where your reasoning broke.
- Scored rounds
- Weak-pattern tracking
- Full worked answers
Linked to the question bank
Every acid–base concept connects to chapters, MCQs, case simulations and summaries across the RescueEM library.
- 4,000+ exam-style MCQs
- Case simulations
- Spaced-repetition review
Gas patterns you will practise
- Metabolic acidosis with a high anion gap
- Normal anion gap (hyperchloraemic) acidosis
- Metabolic alkalosis, chloride-responsive and resistant
- Acute and chronic respiratory acidosis
- Respiratory alkalosis and its causes
- Mixed and triple acid–base disorders
- Salicylate, toxic alcohol and DKA gases
- Lactate, sepsis and shock states
- A–a gradient and causes of hypoxaemia
- P/F ratio and oxygenation targets
- Venous vs arterial sampling pitfalls
- Compensation formulas and expected ranges
Frequently asked
- Do I need a subscription to practise ABGs?
- Every new account gets a free first month with full access. After that, Pro is $10/month and the Student & Resident plan is $6/month.
- Can I use it as a bedside calculator?
- No. RescueEM is exam-preparation and revision material only — it is not a clinical decision-support or dosing tool.
- Which exams does this suit?
- Acid–base questions appear on ABEM, MRCEM, Saudi Board, Arab Board and Egyptian Board EM exams; the drills are written to that level.
Exam revision only. Not medical advice, not a dosing or diagnostic tool, and not for use in patient care. All cases are fictional teaching scenarios. Educational Use Disclaimer.