Final answer:
Respiratory rate is used to calculate minute ventilation, which is the total volume of air that enters and leaves the lungs in one minute.
Step-by-step explanation:
The respiratory rate is used to calculate Minute ventilation. Minute ventilation is the total volume of air that enters and leaves the lungs in one minute. It is calculated by multiplying the respiratory rate (number of breaths per minute) by the tidal volume (amount of air inhaled or exhaled in one breath).