Alveolar ventilation = (Tidal volume - Dead space) x Breaths/min
- Sample problem: A person with a tidal volume (Vt) of 0.5 L is breathing at a rate of 15 breaths/min. The Pco2 of his arterial blood is 40 mm Hg, and the Pco2 of his expired air is 36 mm Hg. What is his rate of alveolar ventilation?
Dead space = Vt x
PaCo2 - Peco2 PaCo2
40 mm Hg
Alveolar ventilation = (Tidal volume - Dead space) x Breaths/min = (0.5 L - 0.05 L) x 15 Breaths/min = 6.75 L/min
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