Clinical Evaluation of Lung Function Flashcards
Purpose of Pulmonary Functional Tests
To distinguish between obstructive and restrictive respiratory disorders
Obstructive Respiratory Disorder
Restrictive Respiratory Disorders
The smaller the diameter of the airway the…
Greater the resistance
Air trapping
Cant get air out
Airway obstructive disorders cause
Difficulty getting air out (expiration)
What are 4 types of airway obstructive disorders
bronchoconstriction
Smooth muscle contracts narrowing the airway therefore decreasing the diameter
When does hyperinflation of the lungs occur?
in obstructive disorders which has a greater affect on expiration -> greater limit on expiration than inspiration because the airway gets narrower on expiration vs broader on inspiration
What happens when we have a deep breath in vs breathing out
rib cage expands which is attached to pleura and lungs, pulling lungs open causing airways to be bigger on inspiration; during expiration chest wall is falling and elastic contracts = smaller airways = most resistance
COPD, chronic bronchitis and emphysema all result in
Air not getting out but cannot get in = hyperinflation
Why is emphysema an obstructive disorder
because it occurs in the conducting zone event though there is a loss of elasticity in the parenchyma
What happens if there is an obstruction in the airway and give examples
It limits airflow (eg. mucous, infection, swelling, bronchospasm)
What does hyperinflation do to the lungs
causes pouches that burst out as shown in broken elastics
What happens in restrictive disorders
Expansion of the lungs is restricted (inspiratory dysfunction) so there is a decreased volume of air inspired since decreased expansion of the lungs
What are 2 methods of restrictive disorders
In restrictive disorders is the conducting zone preserved?
Yes
What are 2 ways to categorize the clinical evaluation of lung function
What is the gold standard test of lung function
Spirometry
What are 2 devices that can be used to measure lung function
Describe this image
Normal tidal breathing (regular breathing) = 500mL of breathing
Tidal Volume: regular breathing
Inspiratory Reserve Volume: how much more air they can take in to reach capacity
Expiratory Reserve Volume: Can only exhale to end of expiratory reserve volume and beginning of RESIDUAL VOLUME (will always have some air left in the lungs )
Residual Volume: As much air as you can get out of your lungs
Vital Capacity: Volume from most you can inhale to residual volume
Inspiratory capacity: How much air you can take in from lowest tidal volume
Functional Residual Capacity: From lowest tidal volume to residual volume (only get that if you get winded)
Total Lung Capacity: Max lung capacity for both inhalation and exhalation
**Note on graph = never hit residual volume unless winded
**Volumes of graph are normative values for each stage
What is the flow volume loop and how is it administered
Administered: Take breath in and out normally, then take large breath in and out which is what makes the flow volume loop
Describe the flow volume loop and its purpose
Purpose: Measures speed with which lung volumes may be changed
Forced inspiratory flow (FIF) = how fast is inspiration
Forced expiratory flow (FEF) = how fast is expiration
Forced Vital Capacity (FVC) = total amount of air that can be exhaled out of from total lung capcity
Forced Expiratory Volume (FEV1): How much air came out at one second(usually up to bottom of residual volume)
What is dynamic airway compression
The limitation against forced expiration (expiration part of dynamic lung volumes)
Solve this graph and what it means
Describe this image
As you blow air out, pressure in airway drops so the pressure inside becomes the same as the pressure outside
Dynamic Airway Compression: Greater pressure outside favours lung compression and collapse
(Second image is just another version of the same things)
Name 3 parameters that affect normal predicted lung function values
Describe the difference between normal, restrictive and obstructive dysfunction in terms of lung volumes
Normal = normal
Restrictive: Lungs cant expand so have lower lung volumes because cant get as much air in
Obstructive: Increased residual volume due to air trapping (hyperinflation) and their expiratory reserve volume is less
Describe this image
Describe this image
Restrictive on right = lower lung volumes
Obstructive on left = hyperinflated = higher lung volumes
Describe this image
Also the same for the forced expiratory flow rate over middle half by volume of forced vital capcacity (FVC) -> FEF (25-75%)
