Lecture 14: Pulmonary Function Tests (Exam III) Flashcards
Where on the PFT graph below does N2 start to show up on our nitrogen meter?
What is the partial pressure of nitrogen in room air?
560mmHg
What test is depicted in the graph below?
Nitrogen washout test
What should a normal nitrogen concentration in the atmosphere be?
75 - 80 %
What percentage nitrogen should a healthy 20 y/o have at 3 minutes into a nitrogen washout test?
2.5% in 3 min
What is a normal reading on a nitrogen washout test?
2.5% in less than 7 min
What is an abnormal reading on a nitrogen washout test?
2.5% in greater than 7 min
Which of the two nitrogen washout tests below displays an abnormal and uneven air distribution?
Right graph
How might VD be estimated from the graph below?
VD = phase I + ½(phase II)
What lung volume comprises the entirety of phase I in the figure below?
VD (Anatomical Dead Space)
What lung volume(s) comprise phase II in the figure below?
Phase II = Transitional Phase = VD + VA air
Where is air coming from in phase III in the figure below?
What is the nitrogen concentration of this air?
- All areas of the lungs
- [N₂] ≈ 20%
What phase in a closing capacity/volume test is the longest for healthy people?
Phase III
What causes the sharp upswing noted in Phase IV in the figure below?
Lung base small airways start to collapse so [N₂] starts to increase.
In what area of the graph below will we notice excessive compliance?
At what lung volume does inspiration start when conducting a closing volume/capacity test?
RV
What is indicated by 1 in the figure below?
Closing Volume
What is indicated by 2 in the figure below?
Residual Volume
What is indicated by 3 in the figure below?
Closing Capacity
What is indicated by 4 in the figure below?
Vital Capacity
What lung capacity changes the most with age?
Closing Capacity
At what age will closing capacity equate to functional residual capacity?
What does this mean?
- Age: 50
- CC = FRC means that the airways of the lung base collapse in normal respiration.
Which lung capacities decrease with age?
- IC
- VC
- ERV
Which lung capacities increase with age?
- FRC
- RV
- CC
Where would closing volume be located on the graph below?
Why are small airways more prone to collapse as we age?
Loss of traction
If a full inspiration of FiO₂ 100% were taken from this lung in the graph below, where would [N₂] be more diluted?
Base of the lung due to having a lower starting volume of 20%.
someone check this one, the O₂ should theoretically go to the apex first since we’re taking an inspiration from RV, right?
At what stage of the respiratory cycle would you expect a healthy person to have the best possible traction?
2 seconds into inspiration and right before expiration when the lungs are fullest.
Best traction at higher lung volumes.
Does traction increase or decrease as we get closer to RV?
Traction decreases
How can vital capacity be determined from the graph below?
TLC - RV
Would effort-dependent expiration occur at higher or lower lung volumes?
Effort-dependent expiration = TLC and higher lung volumes
Would effort-independent expiration occur at higher or lower lung volumes?
Effort-independent expiration = RV and lower lung volumes
In a healthy patient, what percentage of vital capacity expiration should occur in the first second of expiration?
80% of VC expired in 1st second of expiration.
What is the forced expiratory flow rate in someone young and healthy?
10 L/s
What sort of pathology would you expect from the peak expiratory curve below? Why?
- Emphysema
- Loss of PER causes leftward shift of effort independent expiratory flow.
What sort of pathology is indicated by figure 1 below?
Obstructive disease (Emphysema)
What sort of pathology is indicated by figure 2 below?
No Pathology, normal expiratory function curve.
What sort of pathology is indicated by figure 3 below?
Restrictive disease (Fibrosis)
What causes the pathology noted by 1 in the figure below?
Emphysema → Loss of PER
Which of the following curves would have the greatest degree of effort-independent expiratory flow?
- Emphysema
What are the peak expiratory flow rates of each of the curves below?
- 8 L/s
- 13 L/s
- 10 L/s
What are vital capacities of each of the curves below?
- VC ≈ 3.75L (8.5 - 4.75)
- VC ≈ 4.5L (6 - 1)
- VC ≈ 3L (4.1 - 1.1)
Does a forced expiration or a passive expiration present more of a risk for small airway collapse?
Forced Expiration
When would small airway collapse be more likely?
COPD/Emphysema
Loss of what capability would increase the risk of small airway collapse?
PER
How does pursed-lip breathing prevent airway collapse?
Pursed-lip breathing will restrict outflow and increase airway pressures
Airway pressures > PIP = no collapse
What causes the increased pressures seen in the rightmost figure below?
Contraction of intercostal muscles, accessory muscles, and abdominal muscles.
Loss of _____ will result in more collapsible airways.
PER (Traction)
The flow-volume curve below is indicative of what?
Fixed Obstruction (ex. ETT)
The flow-volume curve below is indicative of what?
Variable extra-thoracic obstruction (ex. scar tissue, paralyzed vocal cords)
The flow-volume curve below is indicative of what?
Variable intra-thoracic obstruction (ex. small airway collapse, traction loss on expiration)
What does the dotted line in the graph below indicate?
Increased volume from emphysema allows some air escape at the beginning of expiration when lungs are fullest.
