Measuring Lung Volume

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Measuring Lung Volume

• Oni Pambagyo Triantoro, S.Pd, M.P

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• Ventilation brings about changes in lung volume,
  and these changes can be measured by a
  spirometer. In the spirometer shown in figure
  below

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• A person breathes from a tube connected to an
  oxygen-containing chamber that floats on a tank
  of water.
• The chamber falls during inhalation and rises
  during exhalation. A canister of soda lime
  absorbs all the carbon dioxide in the exhaled
  air.
• The chamber does not rise to the same height with
  each breath because oxygen is absorbed in the
  lungs.
• The movement of the chamber are recorded on
  kymograph trace (in the next slide).

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• A kymograph trace of a 17-year-old male with a
  mass of 70 kg who breathed normally, took a deep
  breath and breathed out as much as possible. The
  kymograph drum revolves at a speed of 2.5 mm s-1

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• Two measurement can be obtained from the trace
• Tidal volume is the volume of air breathed in
  and then breathed out during a single breath. The
  tidal volume at rest is about 0.5 dm3 (500 cm3).
• Vital capacity is the maximum volume of air that
  can be breathed in and then breathed out of the
  lungs by movement of the diaphragm and ribs. In
  young men the average is about 4.6 dm3 in
  young women it is about 3.1 dm3. In trained
  athletes the figure may be as much as 6.0 dm3
  for men and 4.5 dm3 for women.

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DISCUSS

• Looking at the trace in the kymograph trace,
  measure the tidal volume and vital capacity.
• And, looking at the part labelled A, calculate
• The rate of breathing in breathes per minute
• The ventilation rate (tidal volume x breathing
  rate)
• The volume of oxygen absorbed per minute.

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Lets Do It