The mechanical status of the ventilatory system are the absolute volume and changes of volume of gas space in the lungs during breathing. That a subject’s airway opening and body surface are exposed to atmospheric pressure

1. SSN COLLEGE OF ENGINEERING
TITLE
pulmonary volume measurements
Submitted
by
U.Mutheeswaran
1st year
Medical Electronics

2. Lung volume
• The mechanical status of the ventilatory
system are the absolute volume and changes of
volume of gas space in the lungs during
breathing.
• That a subject’s airway opening and body
surface are exposed to atmospheric pressure
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3. • TLC
The largest volume to which the subject’s lungs can be
voluntarily expanded is defined as the total lung capacity.
• RV
The smallest volume to which the subject can slowly deflate his lungs is
the residual volume.
• FRC
the volume of the lungs at the end of a quiet expiration when the
respiratory muscles are relaxed is the functional residual capacity.
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4. • The difference between TLC and RC is the vital capacity.
The maximal change in volume the lungs can undergo during
voluntary maneuvers.
Inspiratory capacity
IC=TLC-FRC
Expiratory capacity
ERV=FRC-RV
note : The peak -to- peak volume change during a quiet breath is the tidal
volume.
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5. Volume ranges of the intact ventilatory system
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6. volume ranges of the intact ventilatory system .
• total lung capacity
FRC and RV measured as absolute volumes
• vital capacity
IC, ERV, and Vt are volume changes ,closing volume and closing
capacity are obtained from a single- breath washout experiment.
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7. hh
The measurements of changes in lung volume has been in two ways
• one is to measure the changes in the volume of the gas space within the
body during breathing by using plethysmographic techniques.
• Referred to as spirometer , involves measurements of the gas passing
through the airway opening
• the latter measurements can provide accurate continuous estimates of
changes in lung volume only when compression of the gas in the lungs is
sufficiently small.

8. testing pulmonary function
• Directly by electronically intgrating output of a flowmeter placed at a
subject’s mouth .
• To continuously collect the gas passing through the airway opening and
to compute the volume it occupied within the lungs
• This representing a physical integration of the flow at the mouth it is
performed by a device called a spirometer.
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10. ABSOLUTE VOLUME OF THE LUNG
• The y and complex geometry and inaccessibility of the lungs we cannot
compute their volume accurately either from direct spatial measurements
or two- three dimensional pictures provided by various imaging
techniques.
• Three procedure have been developed the accurate estimates of the volume
of gas in normal lungs
• Two are based on static mass balances and involve the washout or
dilution of a test gas in the lungs .
• The third procedure is a total body plethysmography technique
employing dynamic mass balanced and gas compression in the lungs.
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11. NITROGEN –WASHOUT ESTIMATE OF
LUNG VOLUME
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14. REFERENCE
• John G. Webster - Medical Instrumentation
Application and Design, 4th Edition (2009)
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