Unit 1 Lecture 5: Lung Volumes, Flow & Ventilation Flashcards
Restrictive diseases are characterized as what?
Healthier/normal airways due to less resistance & Reduced lung capacity
Remember: Minimal airway narrowing
What are causes for restrictive diseased lungs?
- Structural - pulmonary fibrosis which thickens the elastic fibre
- Neuromuscular disorders - i.e. phrenic nerve that contracts the diaphragm is damaged or the muscle itself is damaged
Note: Restrictive means its harder for the lungs to fill
What is this machine called and how does it work?
Spirometer
- As you ventilate, the air moves in and out and moves the drum inside which is surrounded by water
- The drum is being displaced
In this diagram explain what each one represents
- Residual Volume: The amount of air left in the lungs after maximal expiration - dashed line at the bottom
- Normal ventilation is tidal volume
- End of expired breath all the way to maximum inspiration is Inspiratory capacity
- Amount you can breathe in after normal inspiration - Inspiratory reserve volume
- How much you can fully expire after end of normal breath out - Expiratory Reserve Volume
- Staring from breath in to maximal inspiration and then maximal expiration - Vital Capacity
- Total Lung Capacity - how much you can fully expire (Vital capacity) + the remaining amount of air that can’t be released (residual volume)
- How much air remains after expiration in passive expiration - Functional Residual Capacity
- The top of the graph represents a filled lung while the bottom represents an empty
What is Functional Residual Capacity a balance of?
Balance of the inward recoil of the lung and the outward force of the chest wall
If there was a situation in which the tidal volume was higher than it should be, what happens to Inspiratory reserve volume and Inspiratory capacity?
Since tidal volume is higher up, the amount of air we breathe in and out may be normal but the amount that we can fully inspire is less (IRV ↓) and the amount of air we fully inspire after the end of a normal exhalation - IV - Decreases (↓)
What does Lung volume derived by force maneuvers mean?
Volume as a fraction of time; the maximum amount of force required to change the lung volume
What is Forced Expiratory Volume in One Second (FEV1)?
Volume of air expired during the first second of maximal expiratory effort starting from TLC
How much air you can forcefully exhale out in a second
What is Forced Vital Capacity?
Similar to vital capacity, but measured during a maximal expiratory effort starting from TLC
As fast as you can; maximal effort starting from TLC
What is the FEV1/FVC ratio?
Index of how well you can move air out
- Helps with figuring out flow and provides critical information on lung function
- Those with obstructive diseases have airflow limitation (increased airway resistance)
Low FEV1/FVC is a sign of what type of lung disease?
High FEV1/FVC is a sign of what type of lung disease?
Low TLC is a sign of what type of lung disease
- Obstructive - not much air going out, impaired FEV1 not as impaired FVC
- Restrictive - Severely impaired FVC and impaired FEV1
- Restrictive - Restricted from filling
Explain the Spirometry tracings and how lung volume forced maneuvers work?
- Normal lungs will push air out in one second very easily so the FEV1 is normal
- For obstructive, tidal volume is a bit higher but the FEV1 is much lower so after one second not much air is forcefully expired but FVC is normal
- For restrictive, the FEV1 is also low but not because of airway resistance but less volume
Higher flow is equivalent to what? Lower/-ve flow is equivalent to what?
Higher (+ve) flow means expiration & Lower (-ve) flow means inspiration
What is a healthy lung show for Peak expiratory flow, FEV1 and FVC?
Expiratory flow peaks (flow is high) and FEV1 is a linear slope so the forced expiration at one second is normal and finally the forced vital capacity (how quick you breathe all your air/how much air can you forcefully breathe out) is normal
What does the FEV1, FVC, and Peak E.F. look like for an obstructed lung?
- The Peak expiration flow is impaired because obstructed does not allow for proper expiration
- FEV1 drops very easily in this “scoop” like shape which means that FEV1 takes forever
- FVC (forced vital capacity stays) the same because although it is harder to breathe out, they will eventually breathe it out after a period of time
What does FEV1, FVC and Peak Expiratory Flow look like for a restricted lung?
- Peak expiratory flow is normal as the recoil is preserved allowing for expiration to occur
- FEV1 is impaired due to volume decrease & not airway resistance
- FVC is also impaired because there is not much volume to forcefully exhale
What does this diagram show?
The amount of air available for gas exchange (V̇a) is not the same as the total amount of air moved (V̇e)
- Alveolar ventilation is the key variable & we must adjust total ventilation to deadspace to get enough alveolar ventilation
- Less tidal volume & increased frequency of breathing gives almost half of normal alveolar ventilation.
- Need to double the total minute ventilation (V̇e)
- Too much dead space (in 3) it challenges the system to generate more alveolar ventilation
V̇a is only critical for homeostasis point of view but V̇d and V̇e are important to know how to achieve V̇a
