PFT EGANS
Terms
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- Ability of the lungs to perform depends on four general physiological functions
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1)Diaphragm and thoracic muscles must be capable of expanding the thorax and lungs to produce a subatmospheric pressure
2)the airways must be unobstructed to allow gas to flow into the lungs and reach the alveoli
3)the cardiovascular system must circulate blood through the lungs
4)oxygen and carbon dioxide must be able to diffuse through the alveolar capillary membrane - Three categories of pulmonary functions testing
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1)lung volumes and capcities
2)flow rates
3)the ability of the lungs to diffuse gases - Devices that measure gas volume
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1)water sealed spirometers
2)below spirometers
3)dry rolling seal spirometers - Devices that measure gas flow
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1)Pneumotachomters
2)turbinometers
3)sonic devices
4)Peak flow meters - Lung volumes
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1)Tidal volume
2)IRV
3)ERV
4)RV - Four lung capacities
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1)TLC
2)IC
3)FRC
4)VC - Those lung volumes that can be measured directly
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1)IC
2)IRV
3)ERV
4)VC - Those lung volumes that need to be measured indirectly
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1)RV
2)FRC
3)TLC - VT
- Measure the volume exhaled during one minute, and divide by the frequency
- Three methods to measure indirectly TLC and RV
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1)Helium dilution
2)nitrogen washout
3)body pleysmography - Helium dilution technique
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1)uses a closed, nonrebeathing circuit
2)Patient breathes until an equilibrium of gas is established between the spirometer and the lungs