7.3 - Measuring the Process

Question 1

What is the function of a peak flow meter?

Answer 1

Measures rate at which air can be expelled from lungs.

Question 2

What is a vitalograph?

Answer 2

Sophisticated peak flow meter, patient breathes out as fast as they can through a mouthpiece

• Graph is produced showing volume of air produced and its speed.

Question 3

How does a spirometer work and what is its function?

Answer 3

Measures volume of air inspired and expired by lungs

1. Subject should wear a nose clip to ensure air only comes from the mouth and system
2. As the subject inhales, oxygen is drawn from the chamber which in turn lowers
3. When the subject exhales, the chamber rises
   
   1. Air returning to the chamber passes a soda lime cannister to absorb the CO₂
4. Air movements recorded by a trace on a revolving drum
   
   1. Draws a kymograph

Question 4

Define

Tidal Volume

Vital Capacity

Answer 4

Tidal Volume: Volume of air breathed in and out in one breath. At rest this is 0.5dm³

Vital Capacity: Maximum volume of air that can be expired after the deepest inspiration

Question 5

Define

Inspiratory reserve volume

Expiratory reserve volume

Answer 5

Inspiratory reserve volume: Maximum volume of air one can inspire over normal inhalation

Expiratory reserve volume: Extra amount of air you can force out of lungs over the normal amount of air you exhale

Question 6

Define residual volume.

Answer 6

Volume of air that remains in lungs after hardest expiration (cannot be directly measured)

Question 7

Define total lung capacity.

Answer 7

Vital capacity + residual volume

Question 8

Define breathing rate and ventilation rate.

Answer 8

Breathing rate: number of breaths taken per minute

Ventilation rate: total volume of air inhaled per min

= tidal volume x breathing rate

Question 9

Label the different elements of a spirometer trace

Answer 9