Pulmonary Function Tests Flashcards
What is tidal volume?
volume of air inspired and expired w/ each normal breath
What is forced vital capacity?
amount of air that can be forcefully expelled beginning with the lungs completely full and blowing maximally until the lungs are as empty as possible
(FEV1 is the amount of air expelled during the first second of this exhalation)
What is residual volume?
volume of air remaining in lungs after most forceful expiration
What is total lung capacity?
maximum volume to which lungs can be expanded with inspiration
What FEV1/FVC ratio is indicative of an obstructive pattern?
< 0.7
What is displayed on a Flow-Volume Curve?
expiratory flow
-can indicate obstructive or restrictive patterns
What is displayed on a Flow-Volume Loop?
expiratory and inspiratory flow
-can indicate obstructive or restrictive patterns; or obstructive lesions of the central airway
What test is used to measure gas exchange through the alveolar wall?
Diffusing Capacity of Lung for Carbon Monoxide
DLCO
What is bronchodilator therapy used for?
-used in obstructive lung disease to determine if the airway obstruction is reversible
(typically albuterol is used)
What is considered a positive response to bronchodilator therapy?
> 12% increase in FEV1 or FVC
AND an absolute volume increase of > 200mL
What does a positive bronchodilator therapy test indicate?
asthma
If the bronchodilator therapy test is negative, but you still suspect asthma, what test can you do next and what is the most common technique?
bronchoprovocation
-methacholine challenge is the most common
What is methacholine and what does it do?
- synthetic analogue to acetylcholine
- stimulates muscarinic receptors on airway smooth muscle cells leading to bronchoconstriction
What defines a positive methacholine challenge?
> 20% reduction in FEV1 after administration of methacholine
What type of downward slop does a normal Flow-Volume Curve show?
linear
What type of downward slope does an obstruction show on a Flow-Volume Curve?
concave (scooping) pattern
What type of downward slope does a restriction show on a Flow-Volume Curve?
peaked, steeple, or “witch’s hat” pattern
For upper airway obstructions, how does an extrathoracic obstruction (ex: vocal cord paralysis, airway burn) appear on a Flow-Volume Loop?
exhalation will look normal
-inhalation will be flattened
For upper airway obstructions, how does an intrathoracic obstruction (ex: airway trauma, foreign body) appear on a Flow-Volume Loop?
inhalation will look normal
-exhalation will be flattened
For upper airway obstructions, how does a fixed obstruction (ex: tracheal stenosis, goiters, upper airway tumors) appear on a Flow-Volume Loop?
both exhalation and inhalation will be flattened
What are some common causes of obstructive lung disease?
- COPD (chronic bronchitis and emphysema)
- asthma
- bronciectasis
- bronchiolitis
What are some common causes of restrictive lung disease?
- chest wall abnormalities (kyphosis, scoliosis, obesity)
- pleural abnormalities (chronic pleural effusions)
- drugs
- interstitial lung disease
- neuromuscular disease (ALS, Myasthenia Gravis)
What are the characteristics of an obstructive lung disease on spirometry?
- -FEV1 < 80% predicted
- -FEV1/FVC ratio < 0.7
- -Flow-Volume Curve w/ concave scooped pattern
What happens to the Total Lung Capacity in an obstructive lung disease?
increases d/t air trapping
