Arterial blood gas interpretation worksheet with answers

Free printable Arterial blood gas interpretation worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

Practice values: Na⁺ 137, K⁺ 3.8, Cl⁻ 101 and HCO₃⁻ 21 mmol/L. Calculate the anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), without potassium.

Na⁺ 137 mmol/LK⁺ 3.8 mmol/LCl⁻ 101 mmol/LHCO₃⁻ 21 mmol/L
AG = mmol/L
2.Easy

A practice blood gas shows PaO₂ 99 mmHg (13.2 kPa) while the inspired oxygen is 28%. Calculate the ratio P/F = PaO₂/FiO₂ in mmHg.

PaO₂ 99 mmHg (13.2 kPa)FiO₂ 28%
P/F = mmHg
3.Medium

A practice gas shows PaCO₂ 27 mmHg (3.6 kPa). Use the rule that in chronic respiratory alkalosis HCO₃⁻ falls by 5 mmol/L for every 10 mmHg that PaCO₂ is below 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.

PaCO₂ 27 mmHg (3.6 kPa)baseline: 40 mmHg, 24 mmol/L
HCO₃⁻ = mmol/L
4.Medium

A practice gas shows a metabolic acidosis with HCO₃⁻ 8 mmol/L. Use Winter’s formula to find the expected PaCO₂ (the centre of the range) in mmHg.

HCO₃⁻ 8 mmol/L
PaCO₂ = mmHg
5.Hard

Practice values: Na⁺ 136, Cl⁻ 115, HCO₃⁻ 10 mmol/L and albumin 24 g/L. Find the albumin-corrected anion gap AGc = AG + 0.25·(40 − albumin).

Na⁺ 136 mmol/LCl⁻ 115 mmol/LHCO₃⁻ 10 mmol/Lalbumin 24 g/L
AGc = mmol/L
6.Hard

Practice values: Na⁺ 146, Cl⁻ 111, HCO₃⁻ 22 mmol/L and albumin 36 g/L. Find the albumin-corrected anion gap AGc = AG + 0.25·(40 − albumin).

Na⁺ 146 mmol/LCl⁻ 111 mmol/LHCO₃⁻ 22 mmol/Lalbumin 36 g/L
AGc = mmol/L

Answer key

  1. 1. AG = 15 mmol/L
  2. 2. P/F = 353.6 mmHg
  3. 3. HCO₃⁻ = 17.5 mmol/L
  4. 4. PaCO₂ = 20 mmHg
  5. 5. AGc = 15 mmol/L
  6. 6. AGc = 14 mmol/L

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