Minute ventilation

Physiological significance of minute volume

Blood carbon dioxide (PaCO₂) levels generally vary inversely with minute volume. For example, a person with increased minute volume (e.g. due to hyperventilation) should demonstrate a lower blood carbon dioxide level. The healthy human body will alter minute volume in an attempt to maintain physiologic homeostasis. A normal minute volume while resting is about 5–8 liters per minute in humans. Minute volume generally decreases when at rest, and increases with exercise. For example, during light activities minute volume may be around 12 litres. Riding a bicycle increases minute ventilation by a factor of 2 to 4 depending on the level of exercise involved. Minute ventilation during moderate exercise may be between 40 and 60 litres per minute.

Hyperventilation is the term for having a minute ventilation higher than physiologically appropriate. Hypoventilation describes a minute volume less than physiologically appropriate.

Relationship to other physiological rates

Minute volume comprises the sum of alveolar ventilation and dead space ventilation. That is:

${\displaystyle \dot{V}={\dot{V}}_A+{\dot{V}}_D}$

where ${\displaystyle {\dot{V}}_A}$ is alveolar ventilation, and ${\displaystyle {\dot{V}}_D}$ represents dead space ventilation.