Download ② Pulmonary Funciton Test

? Pulmonary Funciton Test
Pulmonary function tests (PFT's); are a group of tests that measure how well the lungs take in and
release air and how well they move gases such as oxygen from the atmosphere into the body's circulation.
-The most common PFT’s are spirometry (spy-RAH-me-tree), diffusion studies and body plethysmography
(ple-thiz-MA-gra-fee)
Definition of Spirometry Test
Spirometry is one of the most commonly used lung function test. The spirometry can measure that how
much air can be inhaled into the lungs and how much air can be exhaled from the lungs. Patients have to
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? Pulmonary Funciton Test
take a deep breath before they exhale and then blow out all of the air as fast as possible. Patients will
exhale into a tube connected to the spirometer. The spirometer records the amount and the rate of air that
patients exhale and inhale over a period of time.
http://www.youtube.com/watch?v=o1F_jL0vkpo
Lung volume measurement can be done in two ways:
* The most accurate way is to have the patient sit in a sealed, clear box that looks like a telephone booth
(body plethysmograph) while they exhale and inhale into a mouthpiece. Changes in pressure inside the
box help determine the lung volume.
* Lung volume can also be measured when patients breathe nitrogen or helium gas through a tube for a
certain period of time. The concentration of the gas in a space attached to the tube is measured the
amount of air in the lung volume.
Why PFT is performed?
* Find out certain types of lung disease (such as asthma, bronchitis, and emphysema)
* Find out the cause of shortness of breath
* Measure whether exposure to chemicals at work affects lung function
* Check lung function before someone has surgery
* Assess the effect of medication
* Measure progress in disease treatment
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? Pulmonary Funciton Test
Definition of Terms
* Tidal Volume (TV): normal volume of air displacement between inhalation and exhalation.
* Vital capacity (VC): maximal amount of gas that can be exhaled after a maximum inspiration.
* Expiratory reserve volume (ERV): excess air of tidal volume that can be exhaled with maximum effort.
*Inspiratory reserve volume (IRV): amount of air in excess of tidal volume that can be inhaled with
maximum effort.
* Forced vital capacity (FVC): the amount of air which can be exhaled forcibly from the lung after deep
breathing.
* Forced expiratory volume (FEV):the amount of air which can be forcibly exhaled from the lung in the
first second of first forced exhalation.
* Forced expiratory flow 25% to 75%: 25-75% of expiratory flow during measurement of forced vital
capacity.
* Functional residual capacity (FRC): amount of air left in the lung after normal exhalation.
* Maximum voluntary ventilation (MVV): the maximum amount of air which can be inhaled and exhaled
within one minute.
* Residual volume (RV) : amount of air left in the lung after maximum exhalation.
* Peak expiratory flow (PEF): maximum speed of expiration.
* Slow vital capacity (SVC): amount of air that patient can breathe in.
* Total lung capacity (TLC): maximum amount of air in the lungs at the end of a maximum inspiration.
Spirometry total lung capacity
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? Pulmonary Funciton Test
Lung capacity can be measured via spirometry and it helps to measure inspired and expired gas volumes.
The normal resting tidal volume affects the inspiratory reserve volume (IRV) or the expiratory reserve
volume (ERV). When tidal volume is maximal, it is called vital capacity (VC). Vital capacity is defined as the
maximaum amount of gas that can be exhaled after maximum inspiration (VC= ERV+TV+IRV) and it is a
commonly measured pulmonary parameter. In some types of pulmonary problems, distensibility of the
lungs is reduced, but the total volume is slightly affected. Therefore, VC is normal, but the timed VC, or the
percentage of VC can be greatly reduced.
Inspiratory capacity (IC) is the maximum amount of air that can be inhaled after a normal expiration (IC=
TV+ IRV). Functional residual capacity (FRC) is amount of air left in the lungs following a normal
expiration (FRC= RV+ERV).
Even after a maximal expiration, some part of the air in lung cannot be going out. This volume is called
the residual volume (RV). Together, the VC and the RV make up the total lung capacity (TLC= RV+VC).
http://www.youtube.com/watch?v=9sUk8981pxM
REFERENCE
AMERICAN THORACIC SOCIETY, Patient Information Series, Pulmonary Function Tests
Exercise Physiology_ Human Bioenergetics and Its Applications, 4th edition; George A.B, Thomas B.F, Kenneth M.B
Exercise Physiology_ Theory and Application to Fintness and Performance, 7th edition ; Scott K.P, Edward T.H
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