Assuming a dead space volume of 150 mL, which scenario would yield the lowest minute alveolar ventilation?

To determine which scenario yields the lowest minute alveolar ventilation, it's essential to first understand the components involved in calculating minute alveolar ventilation. This calculation factors in the respiratory rate and tidal volume while subtracting the dead space volume from the tidal volume to obtain the effective ventilation contributing to alveolar gas exchange.

In the specified scenario, a respiratory rate of 16 breaths per minute with a tidal volume of 300 mL results in a total minute ventilation of 4,800 mL (16 breaths/min × 300 mL/breath). However, since there is a dead space of 150 mL, the effective tidal volume contributing to alveolar ventilation is 150 mL (300 mL - 150 mL). Consequently, the minute alveolar ventilation in this case would be:

[

16 \text{ breaths/min} \times (300 \text{ mL} - 150 \text{ mL}) = 16 \times 150 = 2,400 \text{ mL/min}

]

This calculated value indicates how much volume effectively participates in gas exchange.

In contrast, when looking at the other scenarios, despite having different combinations of respiratory rates and tidal volumes, they all yield greater minute alveolar