If ventilator rate is decreased from 10 to 6 breaths/min, with the same ventilator settings, what is the approximate tidal volume delivered per breath?

If ventilator rate is decreased from 10 to 6 breaths/min, with the same ventilator settings, what is the approximate tidal volume delivered per breath?

• A. 600 mL
• B. 700 mL
• C. 800 mL
• D. 900 mL

Answer: (C)

In volume-targeted ventilation, the tidal volume per breath is determined by the ventilator setting and remains essentially the same when you change the rate. Decreasing the rate from 10 to 6 breaths per minute lowers minute ventilation but does not change the amount of air delivered with each breath, provided the tidal volume setting and inspiratory parameters stay the same. A typical tidal volume is about 8 mL/kg of predicted body weight, so for many adults this is around 800 mL per breath. Therefore, the approximate tidal volume per breath remains 800 mL. Minute ventilation would drop from about 8 L/min to roughly 4.8 L/min, but the per-breath volume stays unchanged.

In volume-targeted ventilation, the tidal volume per breath is determined by the ventilator setting and remains essentially the same when you change the rate. Decreasing the rate from 10 to 6 breaths per minute lowers minute ventilation but does not change the amount of air delivered with each breath, provided the tidal volume setting and inspiratory parameters stay the same. A typical tidal volume is about 8 mL/kg of predicted body weight, so for many adults this is around 800 mL per breath. Therefore, the approximate tidal volume per breath remains 800 mL. Minute ventilation would drop from about 8 L/min to roughly 4.8 L/min, but the per-breath volume stays unchanged.