Spirometer

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Spirometer
24/10/2009

• Learning Objectives
• To have a clear understanding of what a
  spirometer is
• To have a clear understanding of how it is used
  to measure breathing rate and volumes

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What are they for?
24/10/2009

• Spirometers measure the volume of air moved into
  and out of the lungs
• A spirometer trace is created which allows you to
  calculate the volumes of air entering and leaving
  the lungs, either when breathing normally or when
  breathing in or out as hard as possible
• There are two types, digital (v. expensive!) or
  mechanical (v. simple!)

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Various spirometers
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The (Mechanical) Spirometer Explained
24/10/2009

• A floating drum contains an oxygen chamber
• As you breathe out into this, the drum rises up
  on the expired air
• This raises a pen which creates a trace of the
  movement on a chart recorder
• When you inhale from the oxygen chamber the
  floating drum moves down and this movement is
  recorded on the trace also
• A container of soda lime is usually connected
  along the breathing tube to absorb carbon
  dioxide
• For safety reasons spirometers should be filled
  with medical oxygen rather than air if they are
  to be used for more than a few minutes

6
What measurements are normally taken?
24/10/2009

• Tidal volume (TV)
• The volume inhaled and exhaled when breathing
  normally
• Vital Capacity
• The maximum volume breathed in when breathing in
  as hard as possible (called the inspiratory
  reserve volume - IRV) the maximum volume
  breathed out when breathing out as hard as
  possible (called the expiratory reserve volume
  ERV) TV
• Breathing Rate
• The total number of breaths in and out in one
  minute (normally 15 18 breaths/min)

7
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x 2
Vital Capacity 5 dm3
Tidal volume 0.5 dm3
Breathing Rate 12 breaths per minute
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