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Lung Volumes and Capacities

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					Lung Volumes and Capacities
  Dr ibraheem Bashayreh
Lung Volumes and Capacities

 The total volume contained in
 the lung at the end of a
 maximal inspiration is
 subdivided into volumes and
 subdivided into capacities.
There are 4 volume subdivisions

 They do not overlap
 They can not be further divided

 When added together equal total
  lung capacity
Lung Capacities

 Aresubdivisions of the total
 volume that include two or
 more of the 4 basic lung
 volumes
Basic Lung Volumes

   Tidal Volume: TV
     The amount of gas inspired or
      expired with each normal breath.
     About 500 ml
Basic Lung Volumes

 Inspiratory Reserve Volume: IRV
  Maximum amount of additional
   air that can be inspired from the
   end of a normal inspiration.
Basic Lung Volumes

 Expiratory Reserve Volume: ERV
  The maximum volume of
   additional air that can be expired
   from the end of a normal
   expiration.
    Basic Lung Volumes
   Residual Volume: RV
     The volume of air remaining in the lung

      after a maximal expiration. This is the only
      lung volume which cannot be measured
      with a spirometer.
       Gas dilution tech

          nitrogen

          helium

        Body Plethysmograph
Lung Capacities
   Total Lung Capacity: TLC
     The volume of air contained in the

      lungs at the end of a maximal
      inspiration.
     Called a capacity because it is the
      sum of the 4 basic lung volumes
     TLC= RV+IRV+TV+ERV
Lung Capacities
   Vital Capacity: VC
     The maximum volume of air that can be

      forcefully expelled from the lungs
      following a maximal inspiration.
     Called a capacity because it is the sum
      of inspiratory reserve volume, tidal
      volume and expiratory reserve volume.
     VC= IRV+TV+ERV = TLC - RV
Lung Capacities
   Functional Residual Capacity: FRC
     The volume of air remaining in the

      lung at the end of a normal
      expiration.
     Called a capacity because it equal

      residual volume plus expiratory
      reserve volume.
     FRC= RV+ERV
Lung Capacities
   Inspiratory Capacity: IC
     Maximum volume of air that can be inspired

      from end expiratory position.
     Called a capacity because it is the sum of

      tidal volume and inspiratory reserve
      volume.
     This capacity is of less clinical significance

      than the other three.
     IC= TV+IRV
Respiratory Diseases
   Restrictive Disease:
     Makes it more difficult to get air in to the lungs.

     They “restrict” inspiration.

     Decreased VC; Decreased TLC, RV, FRC

     Includes:

       Fibrosis

       Sarcoidosis

       Muscular diseases

       Chest wall deformities
Respiratory Diseases
   Obstructive Disease
     Make it more difficult to get air out of the

      lungs.
     Decrease VC; Increased TLC, RV, and

      FRC
     Includes:

       Emphysema

       Chronic bronchitis

       Asthma

				
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posted:1/30/2013
language:English
pages:14