Lung Function Tests Flashcards
What kind of diseases are lung function tests helpful in?
Obstructive
Restrictive
What is spirometry used for?
Establish objective measures of lung function.
What does spirometry involve?
It involves different breathing exercises into a machine that measures volumes of air and flow rates and produces a report.
What is reversibility testing?
Involves giving a bronchodilator (i.e. salbutamol) prior to repeating the spirometry to see the impact this has on the results.
What is FEV1?
Forced expiratory volume in 1 second.
Amount of air a person can exhale as fast as they can in 1 second.
Measure of the ability of air to freely flow out of the lungs.
When will FEV1 be reduced?
Reduced if there is any obstruction to the air flow out of the lungs.
What is FVC?
Forced vital capacity
Amount of air a person can exhale after a full inhalation
When will FVC be reduced?
If there is any restriction on the capacity of their lungs.
When can obstructive lung disease be diagnosed?
FEV1 is less than 70% of FVC
(FEV1:FVC ratio < 70%)
When can restrictive lung disease be diagnosed?
FEV1 and FVC are equally reduced and FEV1:FVC ratio > 70%
What are the common causes of restrictive lung disease?
Respiratory: Pulmonary fibrosis; acute respiratory distress syndrome; pneumoconiosis
Neuromuscular: Myasthenia gravis, motor neuron disease
Thoracic: Obesity, kyphosis
What does peak flow measure? aka PERF
“Peak”, or fastest point, of a person’s expiratory flow of air.
Restrictive vs Obstructive patterns
Obstructive lung disease is diagnosed when the FEV1 is less than 70% of the FVC, meaning a FEV1:FVC ratio of less than 70%.
In restrictive lung disease:
FEV1 and FVC are equally reduced
FEV1:FVC ratio greater than 70%
A low FVC and a low FEV1:FVC ratio indicate a combination of obstructive and restrictive lung disease.
