PFTs -Goya Flashcards
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%
Moderate: 60-69%
Moderately Severe: 50-59 %
Severe: 35-49%
Very Severe: < 35%
What test should be done for a new obstructive defect?
Bronchodilator Response
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?
concave
–> 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
- hemoglobin concentration
- CO
–> 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
Anemia
Can you diagnose restrictive lung diseases based on spirometry?
NO!
need lung volumes
If the TLC is >80% but the FVC is <80%, does the pt have a restrictive defect?
NO!
When is DLCO beneficial?
differentiating asthma (should have normal DLCO) from emphysema
evaluate restrictive lung disease
evaluate CV disease
