PFT Flashcards
what is the purpose of PFT
- Identify and quantify changes in pulmonary function die to disease
- evaluate effectiveness of therapy
- perform epidemiological surveillance for pulmonary disease
- assess patients for risk of postoperative complications
primary abnormality for Obstructive disease
increased airway resistance
primary abnormality for restrictive disease
decreased lung volumes or lung compliance or both
PFT equipment
spirometer- used to measure lung volumes
pneumotachometer- used to measure flow
Every measuring device has capacity, accuracy, error, resolution, precision, linearity, & output
what are the 3 principles of measurements ?
- ) performing spirometry to measure airway mechanics 2.) measuring lung volumes and capacities
- )measuring diffusion capacity of lungs
what is the FVC maneuver
-most common test of pulmonary mechanics
- deep inhalation with force exhalation
- is dependent on pt cooperation
pt must performed 3 times in order to be acceptable
FEV1
FEV1/FVC
reduced with obstructive disease
normal with restrictive disease
should at least 70%
reversibility
If obstruction is present, reversibility must be evaluated
Done by performing spirometry before & after therapy
Bronchodilator is administered by small-volume nebulizer or MDI
Reversibility indicates effective therapy
Reversibility is defined as 12% or greater improvement in FEV1 & at least 200-ml increase in FEV1
techniques for measuring RV
Helium dilution - known amount of helium will be diluted by size of pt's residual volume. nitrogen washout 79% of RV is nitrogen volume of N exhaled divided 0.79= RV body box - follows Boyle's law
TLC normal values
about 6 L
normal VC
4.8 L, depends on age, gender, height and ethnicity
definition upper airway obstruction
defined as any obstruction from the carina up to the external orifices
extra thoracic- vocal chords to mouth.
intra thoracic- vocal chords to carina
Extrathoracic obstruction
(vocal chords to mouth)
- flow is reduced during inspiration, flow is normal during expiration.
Intrathoracic obstruction
vocal chords to the carina
inhalation is normal, expiration flow is decreased