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

A practice blood gas shows PaO₂ 86 mmHg (11.5 kPa) while the inspired oxygen is 35%. Calculate the ratio P/F = PaO₂/FiO₂ in mmHg.

PaO₂ 86 mmHg (11.5 kPa)FiO₂ 35%
P/F = mmHg
2.Easy
pH7.357.457.51PaCO₂mmHg354539HCO₃⁻mmol/L222630respiratorymetabolicacidosisalkalosis

A practice arterial blood gas shows pH 7.51, PaCO₂ 39 mmHg (5.2 kPa) and HCO₃⁻ 30 mmol/L. Which primary disorder is it? Click the cell in the grid.

pH 7.51PaCO₂ 39 mmHg (5.2 kPa)HCO₃⁻ 30 mmol/L
  1. 1respiratory acidosis
  2. 2metabolic acidosis
  3. 3respiratory alkalosis
  4. 4metabolic alkalosis
3.Medium

A practice gas shows PaCO₂ 21 mmHg (2.8 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 21 mmHg (2.8 kPa)baseline: 40 mmHg, 24 mmol/L
HCO₃⁻ = mmol/L
4.Medium

A practice gas shows a metabolic acidosis with HCO₃⁻ 14 mmol/L. Use Winter’s formula to find the expected PaCO₂ (the centre of the range) in mmHg.

HCO₃⁻ 14 mmol/L
PaCO₂ = mmHg
5.Hard
pH7.357.457.34PaCO₂mmHg354531HCO₃⁻mmol/L222616added normal-gap acidosispure high-gap acidosisadded metabolic alkalosis

A practice gas shows pH 7.34, PaCO₂ 31 mmHg (4.1 kPa) and HCO₃⁻ 16 mmol/L, with Na⁺ 145 and Cl⁻ 96 mmol/L. Use the anion gap and the delta ratio to click the best interpretation.

pH 7.34PaCO₂ 31 mmHg (4.1 kPa)HCO₃⁻ 16 mmol/LNa⁺ 145 mmol/LCl⁻ 96 mmol/L
  1. 1added normal-gap acidosis
  2. 2pure high-gap acidosis
  3. 3added metabolic alkalosis
6.Hard

A practice gas shows a metabolic alkalosis with HCO₃⁻ 45 mmol/L. Use expected PaCO₂ = 0.7·HCO₃⁻ + 21 to find the expected PaCO₂.

HCO₃⁻ 45 mmol/L
PaCO₂ = mmHg

Answer key

  1. 1. P/F = 245.7 mmHg
  2. 2. metabolic alkalosis
  3. 3. HCO₃⁻ = 20.2 mmol/L
  4. 4. PaCO₂ = 29 mmHg
  5. 5. added metabolic alkalosis
  6. 6. PaCO₂ = 52.5 mmHg

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