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⁺ 136, K⁺ 4.6, Cl⁻ 106 and HCO₃⁻ 11 mmol/L. Calculate the anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), without potassium.

Na⁺ 136 mmol/LK⁺ 4.6 mmol/LCl⁻ 106 mmol/LHCO₃⁻ 11 mmol/L
AG = mmol/L
2.Easy

A practice blood gas shows PaO₂ 82 mmHg (10.9 kPa) while the inspired oxygen is 21%. Calculate the ratio P/F = PaO₂/FiO₂ in mmHg.

PaO₂ 82 mmHg (10.9 kPa)FiO₂ 21%
P/F = mmHg
3.Medium

Practice values: Na⁺ 148 mmol/L, glucose 10.3 mmol/L and urea 8.4 mmol/L. Calculate the serum osmolality Osm = 2·Na⁺ + glucose + urea to the nearest whole number.

Na⁺ 148 mmol/Lglucose 10.3 mmol/Lurea 8.4 mmol/L
Osm = mOsm/kg
4.Medium

A practice gas shows PaCO₂ 23 mmHg (3.1 kPa). Use the rule that in acute respiratory alkalosis HCO₃⁻ falls by 2 mmol/L for every 10 mmHg that PaCO₂ is below 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.

PaCO₂ 23 mmHg (3.1 kPa)baseline: 40 mmHg, 24 mmol/L
HCO₃⁻ = mmol/L
5.Hard

Practice values: Na⁺ 141, Cl⁻ 113, HCO₃⁻ 19 mmol/L and albumin 19 g/L. Find the albumin-corrected anion gap AGc = AG + 0.25·(40 − albumin).

Na⁺ 141 mmol/LCl⁻ 113 mmol/LHCO₃⁻ 19 mmol/Lalbumin 19 g/L
AGc = mmol/L
6.Hard
pH7.357.457.27PaCO₂mmHg354527HCO₃⁻mmol/L222612appropriate compensationadded respiratory acidosisadded respiratory alkalosis

A practice gas shows a metabolic acidosis: pH 7.27, PaCO₂ 27 mmHg (3.6 kPa), HCO₃⁻ 12 mmol/L. Compare the measured PaCO₂ with Winter’s formula. Click your interpretation.

pH 7.27PaCO₂ 27 mmHg (3.6 kPa)HCO₃⁻ 12 mmol/L
  1. 1appropriate compensation
  2. 2added respiratory acidosis
  3. 3added respiratory alkalosis

Answer key

  1. 1. AG = 19 mmol/L
  2. 2. P/F = 390.5 mmHg
  3. 3. Osm = 315 mOsm/kg
  4. 4. HCO₃⁻ = 20.6 mmol/L
  5. 5. AGc = 14.25 mmol/L
  6. 6. appropriate compensation

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