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
pH7.357.457.20PaCO₂mmHg354564HCO₃⁻mmol/L222624respiratorymetabolicacidosisalkalosis

A practice arterial blood gas shows pH 7.20, PaCO₂ 64 mmHg (8.5 kPa) and HCO₃⁻ 24 mmol/L. Which primary disorder is it? Click the cell in the grid.

pH 7.20PaCO₂ 64 mmHg (8.5 kPa)HCO₃⁻ 24 mmol/L
  1. 1respiratory acidosis
  2. 2metabolic acidosis
  3. 3respiratory alkalosis
  4. 4metabolic alkalosis
2.Easy

A practice blood gas shows PaO₂ 63 mmHg (8.4 kPa) while the inspired oxygen is 21%. Calculate the ratio P/F = PaO₂/FiO₂ in mmHg.

PaO₂ 63 mmHg (8.4 kPa)FiO₂ 21%
P/F = mmHg
3.Medium

A practice gas shows a metabolic acidosis with HCO₃⁻ 6 mmol/L. Use Winter’s formula to find the expected PaCO₂ (the centre of the range) in mmHg.

HCO₃⁻ 6 mmol/L
PaCO₂ = mmHg
4.Medium

A practice gas shows PaCO₂ 66 mmHg (8.8 kPa). Use the rule that in acute respiratory acidosis HCO₃⁻ rises by 1 mmol/L for every 10 mmHg that PaCO₂ is above 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.

PaCO₂ 66 mmHg (8.8 kPa)baseline: 40 mmHg, 24 mmol/L
HCO₃⁻ = mmol/L
5.Hard

At sea level, a practice gas taken on 40% oxygen shows PaO₂ 77 mmHg (10.3 kPa) and PaCO₂ 59 mmHg (7.9 kPa). Use PAO₂ = FiO₂·(760 − 47) − PaCO₂/0.8 to find the A–a gradient.

FiO₂ 40%PaO₂ 77 mmHg (10.3 kPa)PaCO₂ 59 mmHg (7.9 kPa)
A–a gradient = mmHg
6.Hard
pH7.357.457.33PaCO₂mmHg354533HCO₃⁻mmol/L222617added normal-gap acidosispure high-gap acidosisadded metabolic alkalosis

A practice gas shows pH 7.33, PaCO₂ 33 mmHg (4.4 kPa) and HCO₃⁻ 17 mmol/L, with Na⁺ 146 and Cl⁻ 95 mmol/L. Use the anion gap and the delta ratio to click the best interpretation.

pH 7.33PaCO₂ 33 mmHg (4.4 kPa)HCO₃⁻ 17 mmol/LNa⁺ 146 mmol/LCl⁻ 95 mmol/L
  1. 1added normal-gap acidosis
  2. 2pure high-gap acidosis
  3. 3added metabolic alkalosis

Answer key

  1. 1. respiratory acidosis
  2. 2. P/F = 300 mmHg
  3. 3. PaCO₂ = 17 mmHg
  4. 4. HCO₃⁻ = 26.6 mmol/L
  5. 5. A–a gradient = 134.4 mmHg
  6. 6. added metabolic alkalosis

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