Oxygen therapy & respiratory calculations worksheet with answers

Practice exercise (made-up values, not clinical guidance). The team wants an inspired oxygen of about 45% by nasal cannula. Using the rule of thumb FiO₂ ≈ 21% + 4% per L/min, what flow Q does it suggest? (Real FiO₂ varies with the patient's breathing.)

Practice exercise (made-up values, not clinical guidance). The gauge on a size D oxygen cylinder reads 1300 psi. Its cylinder factor is 0.16 L/psi. How many litres V can be used before the safe residual of 200 psi is reached?

Practice exercise (made-up values, not clinical guidance). A patient breathes 18 times a minute with a tidal volume of 640 mL. The anatomical dead space is 140 mL. Find the alveolar ventilation V̇A in L/min.

Practice exercise (made-up values, not clinical guidance). A patient has Hb 76 g/L, SaO₂ 97% and PaO₂ 96 mmHg (12.8 kPa). Find the arterial oxygen content CaO₂ = 1.34 × Hb (g/dL) × SaO₂ + 0.003 × PaO₂ (mmHg) in mL O₂/dL.

Practice exercise (made-up values, not clinical guidance). A ventilated woman is 181 cm tall and weighs 122 kg. Lung-protective ventilation is set at 6 mL per kg of predicted body weight. Using PBW = 45.5 + 0.91 × (height cm − 152.4) kg, find the tidal volume V_T to the nearest mL.

Practice exercise (made-up values, not clinical guidance). A patient has Hb 130 g/L, SaO₂ 96%, PaO₂ 79 mmHg (10.5 kPa) and a cardiac output of 4.3 L/min. With CaO₂ = 1.34 × Hb (g/dL) × SaO₂ + 0.003 × PaO₂ (mmHg), find the oxygen delivery DO₂ = CaO₂ × CO × 10 in mL/min.