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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Name: ____________________   Date: ____________

1.Easy

Practice values: Na⁺ 132, K⁺ 4.7, Cl⁻ 95 and HCO₃⁻ 17 mmol/L. Calculate the anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), without potassium.

Na⁺ 132 mmol/LK⁺ 4.7 mmol/LCl⁻ 95 mmol/LHCO₃⁻ 17 mmol/L
AG = mmol/L
2.Easy

Practice values: Na⁺ 138, K⁺ 3.8, Cl⁻ 101 and HCO₃⁻ 21 mmol/L. Calculate the anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), without potassium.

Na⁺ 138 mmol/LK⁺ 3.8 mmol/LCl⁻ 101 mmol/LHCO₃⁻ 21 mmol/L
AG = mmol/L
3.Medium

A practice gas shows PaCO₂ 28 mmHg (3.7 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 28 mmHg (3.7 kPa)baseline: 40 mmHg, 24 mmol/L
HCO₃⁻ = mmol/L
4.Medium

A practice gas shows PaCO₂ 80 mmHg (10.7 kPa). Use the rule that in chronic respiratory acidosis HCO₃⁻ rises by 3.5 mmol/L for every 10 mmHg that PaCO₂ is above 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.

PaCO₂ 80 mmHg (10.7 kPa)baseline: 40 mmHg, 24 mmol/L
HCO₃⁻ = mmol/L
5.Hard
pH7.357.457.16PaCO₂mmHg354549HCO₃⁻mmol/L222617appropriate compensationadded respiratory acidosisadded respiratory alkalosis

A practice gas shows a metabolic acidosis: pH 7.16, PaCO₂ 49 mmHg (6.5 kPa), HCO₃⁻ 17 mmol/L. Compare the measured PaCO₂ with Winter’s formula. Click your interpretation.

pH 7.16PaCO₂ 49 mmHg (6.5 kPa)HCO₃⁻ 17 mmol/L
  1. 1appropriate compensation
  2. 2added respiratory acidosis
  3. 3added respiratory alkalosis
6.Hard
pH7.357.457.21PaCO₂mmHg354570HCO₃⁻mmol/L222627acutechronicacute on chronic

A practice gas shows a respiratory acidosis: pH 7.21, PaCO₂ 70 mmHg (9.3 kPa), HCO₃⁻ 27 mmol/L. Use the rules ‘HCO₃⁻ rises 1 mmol/L per 10 mmHg (acute) or 3.5 mmol/L per 10 mmHg (chronic)’ to classify it. Click your answer.

pH 7.21PaCO₂ 70 mmHg (9.3 kPa)HCO₃⁻ 27 mmol/L
  1. 1acute
  2. 2chronic
  3. 3acute on chronic

Answer key

  1. 1. AG = 20 mmol/L
  2. 2. AG = 16 mmol/L
  3. 3. HCO₃⁻ = 18 mmol/L
  4. 4. HCO₃⁻ = 38 mmol/L
  5. 5. added respiratory acidosis
  6. 6. acute

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