Ventilation (physiology)

For other uses, see Ventilation.

In respiratory physiology, ventilation (or ventilation rate) is the rate at which gas enters or leaves the lung. It is categorized under the following definitions:

Measurement	Symbol	Equation	Description
Minute ventilation	$\dot{V}$	= tidal volume * respiratory rate	the total volume of gas entering the lungs per minute.
Alveolar ventilation	$\dot{V}_A$	= (tidal volume - dead space) * respiratory rate	the volume of gas per unit time that reaches the alveoli, the respiratory portions of the lungs where gas exchange occurs.
Dead space ventilation	$\dot{V}_D$	= dead space * respiratory rate	is the volume of gas per unit time that does not reach these respiratory portions, but instead remains in the airways (trachea, bronchi, etc.).

Sample values

Measure	Sample value at rest	Sample value moderate exercise
Tidal volume	0.5 L	3.0 L
Respiratory rate	12 breaths/minute	30 breaths/minute
Minute ventilation	6.0 L/min	90 L/min
Dead space	0.15 L	0.15 L
Dead space ventilation	1.8 L/min	4.5 L/min
Alveolar ventilation	4.2 L/min	85.5 L/min

Pulmonary ventilation may be evaluated using a breathing tube or spirometer, measuring the movement of the chest and abdominal walls using respiratory inductance plethysmography or by isolating the subject in an enclosed metabolic chamber.

See also

• Gas exchange
• Fowler method

External links

• MeSH Pulmonary+ventilation
• RT Corner (Educational Site for RT's and Nurses) at rtcorner.net