Which combination of respiratory rate and tidal volume yields the lowest minute volume?

To determine which combination of respiratory rate and tidal volume yields the lowest minute volume, we must understand how minute volume is calculated. Minute volume is the product of the respiratory rate (breaths per minute) and tidal volume (the volume of air per breath). The formula is:

[ \text{Minute Volume} = \text{Respiratory Rate} \times \text{Tidal Volume} ]

When analyzing the given options:

• The first choice yields a minute volume of 12 breaths/min × 400 mL = 4800 mL/min.

• The second choice results in a minute volume of 14 breaths/min × 300 mL = 4200 mL/min.

• The third choice produces a minute volume of 10 breaths/min × 250 mL = 2500 mL/min.

• The fourth choice results in a minute volume of 20 breaths/min × 200 mL = 4000 mL/min.

Among these calculations, the combination from the third choice, with a respiratory rate of 10 breaths/min and a tidal volume of 250 mL, produces the lowest minute volume of 2500 mL/min.

The second choice would yield the second-lowest minute volume,