Flashcards in PFTs -Goya Deck (11):
What is spirometry measuring? What is it used for?
-measures volume or flow as a pt inhales or exhales
--> FVC (forced vital capacity), FEV1 (forced expiratory volume in 1 second) and ratio FEV1/FVC
-good for detecting and quantifying pulmonary impairment (specific diagnoses cannot be made with spirometry alone) --> classify as normal, obstruction or restriction
-monitoring response to therapy
What does a FEV1/FVC ratio of less than 70% indicate?
obstructive ventilatory defect
How is severity determined in obstructive defects?
Mild: FEV1 > 70%
Moderately Severe: 50-59 %
Very Severe: < 35%
What test should be done for a new obstructive defect?
short acting beta agonist given in 4 separate doses --> improvement in FEV1 or FVC of 12% or more =+ response
What is the shape of the expiration on a flow-volume curve for an obstructive defect?
--> airway collapses as the pt exhales
What does an FVC < 80% suggest? What else should be done to confirm this diagnosis?
restrictive defect is suggested
need to obtain lung volumes of confirm diagnosis!
TLC 120% =obstructive
What does the DLCO depend on?
-intact alveolar-capillary membrane
--> measures the ability of the lungs to transport inhaled gas from alveoli to pulmonary capillaries
What could a decreased DLCO (<80%) indicate?
Obstructive Lung Disease
Parenchymal Lung Disease
Pulmonary Vascular Disease
Can you diagnose restrictive lung diseases based on spirometry?
need lung volumes
If the TLC is >80% but the FVC is <80%, does the pt have a restrictive defect?