Exam 3 - Lecture 2 Flashcards
Flow volume loops are most focused on
maximal peak expiratory force during expiration
How is maximal peak expiratory force measured?
During FVC maneuver (from TLC to RV with max effort)
Flow rate is on the _ axis and lung volume is the _ axis
Y;X
What do these flow volume loops often lack?
Don’t give a “zero” or standard axis, just a rough liter scale.
Depending on the machine, you may not get exact _____
values for RV or TLC
On flow volume loops, what are the results of restrictive disease?
low lung volume with less air to exhale = lower peak expiratory flow rate
What is restrictive disease more prone to and why?
Low lung volume raises airway resistance, which also results in more narrow airways, so its EASIER TO COLLAPSE
In restrictive lung disease, expiratory flow rate is limited NOT by _____, but by _______
People often think OBSTRUCTION, but its due to lung emptiness.
What is the specific reason for decreased lung volumes in restrictive disease?
more elastic tissue
During expiration in obstructive disease, the airway _____ which leads to increased RV
collapses, retaining air
On the flow volume loop with obstructive disease, the loop shape is _____ due to small airway collapse.
Scooped/concave
In obstructive disease such as emphysema/COPD, elastic tissue is reduced, which increases ______
compliance
Elastic tissue/recoil and compliance have a _______ relationship.
Inverse
When ER is decreased, compliance is increased
Passive expiration relies on 2 things:
Elastic recoil and pleural pressure change
During passive expiration, what happens to intrapleural pressure and recoil pressure?
Recoil pressure is elevated (+10 for random example), and intraplerual pressure becomes less negative (from -10 to say now -8)
Why is there no airway collapse during passive expiration?
Inner (airway) pressure > outer pleural pressure
During forced expiration, pleural pressure will be _____ and elastic recoil pressure is +10, which makes the alveolar pressure ___
Very positive (+25), and recoil at first is still +10, so the alveolar pressure is very positive at +35
during forceful expiration
Choke point on respiratory tree occurs due to
airway pressure decreases to +20 as it goes up tree, but intrapleural pressure is +25, causing airway collapse before cartilage.
The ability for the airway to stay open is SOLELY based on
airway pressure vs intrapleural pressure
(where cartilage isn’t present)
In emphysema, recoil pressure may drop to ___
+5 instead of +10
Loss of elastic tissue results in loss of recoil pressure AND ___
airway traction
The two combined make small airways much more collapsible
More springs means more recoil AND more ____, protecting us from what?
airway traction; airway collapse
Example of a fixed obstruction and how it affects flow loops?
ET tube; reduces both inspiratory and expiratory flows, loop is chopped FLAT on top and bottom
Why are both flows reduced in fixed obstruction?
Impossible for a ET tube to be as wide as the trachea
3 variable intrathoracic examples and what does it affect? Why?
COPD, emphysema, asthma
only affects forced expiration
Need to use forced expiration causing airway collapse
Why does variable intrathoracic obstruction not affect inspiratory pressure?
negative pressure “pulls open” the obstruction, so therefore its not affected.
2 variable extrathoracic examples and what does it affect? Why?
Paralyzed vocal works and weak trachea
Only affects inspiration
Negative pressure during inspiration causes collapse of upper airway because the cartilage is weak and can’t keep it open.
What can temporarily fix variable extrathoracic pressure?
Mechanical ventilation d/t positive pressure
FEV1
Volume of air exhaled in one second of a max forced breath
FVC
total volume exhaled with max force (vital capacity)
What is a normal ratio of FEV1/FVC?
80%
FEV1 is 80% of FVC, you should be able to exhale 80% of your breath in ONE SECOND
What does a lower FEV1/FVC ratio indicate?
obstructive disease
Restrictive disease can be indicated with FEV1/FVC ratios how?
Normal OR high ratio with a LOW FVC
On the FEV1/FVC ratio graph, what does obstructive look like
slow rise, long time to empty lungs, loop is scooped
On the FEV1/FVC ratio graph, what does restrictive look like
steep rise but short total volume, loop is narrow and peaked
What is a key sign of obstructive disease on flow loops?
Expiratory loop flattens early and drags out
Bronchodilator response test results indicate?
IF bronchodilator improves FEV1, its reversible and likely asthma
If no improvement, problem is structural and likely emphysema
What is the test setup for closing volume and closing capacity test (nitrogen washout test)?
Patient exhales room air to RV, then inhales a full breath from 100% O2 to TLC
-all nitrogen in lungs at TLC is from the oxygen remaining at RV, and when patient exhales, nitrogen meter tracks how much you exhale.
What do the results of closing volume and closing capacity test (nitrogen washout test) tell us?
Exhaled nitrogen concentration tells you which lung region air is coming from (?if anyone reads this does this sound right? lmk please)
At RV, the apex is ____% full, and the base is _____% full
30;20
When filling to TLC from RV, the apex adds ___% new air, and the base adds ____% new air
70;80%
When inhaling 100% O2, since the base adds more % new air when inhaling from RV to TLC, what does this indicate during exhale?
More dilution of N2 with more air added, and there will be lower concentrations of N2 in air expired from base.
Phase I
How much nitrogen, how much volume? what respiratory zone did this air come from?
no nitrogen
~100mL
100% O2 came from conducting zones
Phase II
What happens to nitrogen? what can it estimate and how?
Nitrogen rises
Can estimate anatomical deadspace by measuring the midpoint of slope (~150mL in healthy pt)
What phase is the transition phase?
Phase II
same as fowlers test
What phase has the alveolar plateau?
Phase III
Phase III
Where is the air coming from?
What’s the slope on graph?
Air from alveoli only
Starts with mostly base air (diluted N2), ends with apex air (less diluted N2)
Slight upward slope because source shifts from base to apex
Phase IV
What happens to nitrogen?
What happens at lung base, and where is the most air coming from?
Sudden steep rise in nitrogen
Most air comes from apex with high N2, that’s why it rises steeply
lung base airways collapse from high intrapleural pressure
What could cause phase IV to occur sooner than normal?
Loss of traction, thin or narrow airways
Closing volume (Phase IV) is considered to be part of which capacity?
FRC/ERV
Start of phase IV =
Closing volume
Closing capacity = ___ + ____
Closing volume + RV
Why does phase IV matter?
If phase IV starts early, it indicates premature small airway collapse. this is very sensitive to early disease and can detect it before symptoms start.
What should be a part of routine physicals?
closing volume
What decreases with age in the lungs?
Elastic tissue is lost
less recoil -> small airways collapse earlier
In a healthy 20 year old, phase IV starts when?
after FRC
hardly any airway collapse during normal breathing, tiny phase IV
In 70 year olds, phase IV starts when?
Before FRC
Airway collapse happens on every breath, which means they have to work to get them back open. increased work of breathing even if healthy.
When is the cross-over point for when phase IV occurs?
around age 55
What lung function has the greatest change as we age?
Closing capacity
