\[\dot V_A=(V_T-V_D)\times RR\]
Variables
VA[V̇A]alveolar ventilation (L/min)
TVtidal volume (L)
VDdead space volume (L)
RRrespiratory rate (breaths/min)
Description
What is this formula?
Alveolar Ventilation represents the volume of fresh air reaching the alveoli each minute and participating in gas exchange. Unlike minute ventilation, it excludes air remaining in the anatomical dead space.
When to use it
Use this formula when evaluating gas exchange efficiency, analyzing respiratory physiology, adjusting mechanical ventilation settings, or assessing respiratory disorders.
Example
Data:
TV = 0.50 L
VD = 0.15 L
RR = 12 breaths/min
Formula:
VA = (TV − VD) × RR
Substitution:
VA = (0.50 − 0.15) × 12
VA = 0.35 × 12
VA = 4.2 L/min
Result:
Alveolar Ventilation = 4.2 L/min
Applications
- Respiratory physiology
- Mechanical ventilation management
- Critical care medicine
- Pulmonary disease assessment
- Gas exchange studies