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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy

Practice values: Na⁺ 141, K⁺ 4.1, Cl⁻ 103 and HCO₃⁻ 10 mmol/L. Calculate the anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), without potassium.

Na⁺ 141 mmol/LK⁺ 4.1 mmol/LCl⁻ 103 mmol/LHCO₃⁻ 10 mmol/L
AG = mmol/L
2.Easy
pH7.357.457.62PaCO₂mmHg354524HCO₃⁻mmol/L222624respiratorymetabolicacidosisalkalosis

A practice arterial blood gas shows pH 7.62, PaCO₂ 24 mmHg (3.2 kPa) and HCO₃⁻ 24 mmol/L. Which primary disorder is it? Click the cell in the grid.

pH 7.62PaCO₂ 24 mmHg (3.2 kPa)HCO₃⁻ 24 mmol/L
  1. 1respiratory acidosis
  2. 2metabolic acidosis
  3. 3respiratory alkalosis
  4. 4metabolic alkalosis
3.Medium

A practice gas shows a metabolic acidosis with HCO₃⁻ 12 mmol/L. Use Winter’s formula to find the expected PaCO₂ (the centre of the range) in mmHg.

HCO₃⁻ 12 mmol/L
PaCO₂ = mmHg
4.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
5.Hard
pH7.357.457.19PaCO₂mmHg354574HCO₃⁻mmol/L222627acutechronicacute on chronic

A practice gas shows a respiratory acidosis: pH 7.19, PaCO₂ 74 mmHg (9.9 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 7.19PaCO₂ 74 mmHg (9.9 kPa)HCO₃⁻ 27 mmol/L
  1. 1acute
  2. 2chronic
  3. 3acute on chronic
6.Hard

At sea level, a practice gas taken on 30% oxygen shows PaO₂ 60 mmHg (8.0 kPa) and PaCO₂ 31 mmHg (4.1 kPa). Use PAO₂ = FiO₂·(760 − 47) − PaCO₂/0.8 to find the A–a gradient.

FiO₂ 30%PaO₂ 60 mmHg (8.0 kPa)PaCO₂ 31 mmHg (4.1 kPa)
A–a gradient = mmHg

Answer key

  1. 1. AG = 28 mmol/L
  2. 2. respiratory alkalosis
  3. 3. PaCO₂ = 26 mmHg
  4. 4. HCO₃⁻ = 17.5 mmol/L
  5. 5. acute
  6. 6. A–a gradient = 115.2 mmHg

Full step-by-step solutions: practise this topic on examproblems.com.