Minute volume is determined by which factors?

• A. Only tidal volume
• B. Only respiratory rate
• C. Tidal volume and respiratory rate
• D. Oxygen saturation

Answer: (C)

Minute volume is the total amount of air moving in and out of the lungs each minute, and it depends on two factors: how much air is moved with each breath (tidal volume) and how many breaths occur each minute (respiratory rate). If you multiply the volume per breath by the number of breaths per minute, you get the total air moved per minute. Oxygen saturation, while important for gauging oxygenation, does not determine how much air is ventilated per minute. In practical terms, typical tidal volume is about 500 mL and a normal respiratory rate is around 12–20 breaths per minute, giving a minute ventilation in the 6–10 L/min range. Clinically, adjusting minute ventilation centers on changing tidal volume and respiratory rate to control CO2 removal, with oxygen saturation monitored separately to ensure adequate oxygenation.