Ventilation and Ventilatory Tests

Respiratory Therapy

What is Tidal Volume (V_T)?

It's the volume of air inspired or expired during each respiratory cycle.
- Measured in L or mL.
- Corrected to BTPS.

What is respiratory rate (RR)?

It's the number of breaths per minute or how many breaths you breath in one minute.
- Normal range 12-20 breaths/min.
- Called "breathing frequency" or "respiratory frequency" (f_b).

How can Tidal Volume be directly measured?

By simple spirometry.

• Patient breaths into a volume-displacement or flow-sensing spirometer.

• It can also be measured from an integrated flow signal.

What are two stimuli measured in ventilatory response?

• High CO2

• Low O2

Difference between Alveolar Ventilation (V_A) and alveolar dead space.

Alveolar Ventilation is the gas that participates in gas exchange.

Alveolar dead space reaches the alveoli, but does NOT participate in gas exchange because there is no perfusion.