Exam III Flashcards
(442 cards)
1
Q
What is the Fowlers test, and what do you need to do it?
A
Pulmonary function test that looks at how much nitrogen is coming out of the patient via a nitrogen meter with each breath.
All you need is a nitrogen meter, a patient, & a source of 100% O2.
2
Q
If a normally breathing patient was hooked up to do the Fowlers test, what would you see?
A
Expect to see normal expired nitrogen content
(74.9% [569/760] for Guyton,
or
79.8% [569/713] for Levitzky who does not take into account water vapor)
3
Q
On ventilators, we have a capnograph. What are the two values that can be displayed depending on which button you push?
A
End tidal CO2
or
Partial pressure/concentration (i.e. 569 or 74.9-80% for nitrogen)
4
Q
How is the Fowlers test done?
A
Patient hooked up to a closed circuit with a nitrogen meter & a source of 100% O2.
Ask patient to inspire a little deeper than normal (i.e. instead of 500mL, do 1L so we have more air to work with)
As they exhale, the nitrogen meter will pick up the results.
5
Q
What happens inside the patients lungs during the Fowlers test, and what does the nitrogen meter pick up? (longer card sorry)
A
When breathing from 100% oxygen source, the patient will dilute this with water vapor which will lower then concentration slightly. However, no nitrogen is being inhaled.
Any nitrogen coming out of the patient is already in the lungs at the start of the test.
The last portion of inspired breath has no nitrogen since there is nothing at the source.
On expiration, the first portion of the breath will have no nitrogen.
As air from deeper areas of the lungs is exhaled, nitrogen sensed by the meter will increase (transitional zone)
^This was already in the lungs at the start of the test.
Eventually, the amount of nitrogen plateaus.
6
Q
Fowlers test: At the start of expiration, there is no nitrogen sensed by the nitrogen meter. Why?
A
This is the anatomical dead space. The last portion of inspired air was from a 100% O2 source, meaning no nitrogen should be there. All nitrogen in the lungs will be deep in the alveoli, thus won’t be picked up immediately on expiration.
7
Q
Why is the Fowlers test done?
A
Measure anatomical dead space of the lungs.
8
Q
Fowlers test: What is the transitional phase?
A
This is the air between the anatomical dead space and the alveoli. The air begins to look like normal lung air (though not as concentrated with nitrogen).
Note: This nitrogen was already in the lungs at the start of the test.
9
Q
Fowlers test: How do you figure out anatomical dead space?
A
Find the mid point of the transitional phase.
Find where the time, volume, and midpoint of the transitional phase line up. This gives you your anatomical dead space on the Y axis.
10
Q
Fowlers test: Why would we want to know what someones anatomical dead space is?
A
We can factor this into our tidal volumes. Someone with more dead space would require larger tidal volumes to make sure you are ventilating the lungs properly.
11
Q
What is the normal anatomical dead space of a healthy 20 y/o?
A
150mL anatomical dead space
11
Q
Fowlers test: How concentrated is the alveolar plateau?
A
Depends on how large the inspired breath was (dilution effect)
12
Q
What is a test that is similar to the fowlers test?
A
Nitrogen washout test
12
Q
What does the nitrogen washout test do, and what is required?
A
Analyzes evenness of ventilation in the lungs.
Requirements: Nitrogen meter + Source of 100% Oxygen.
13
Q
If you pulled some healthy person off the streets to do the nitrogen washout test, what would be the likely result?
A
74.9-80% nitrogen on expired air on the FIRST exhalation.
14
Q
During the nitrogen washout test, what happens as the patient continues to breathe in and out?
A
There will be less and less nitrogen picked up, as there is no new nitrogen being introduced through inspiration.
15
Q
During the nitrogen washout test, when is the greatest drop in nitrogen concentration?
A
Between the first and second breath. At this point, there is the greatest amount of nitrogen available to be diluted.
16
Q
What concentration of nitrogen is required for the nitrogen washout test to be completed/shut off? How long does this take?
A
2.5%
Takes way under 7 minutes in a healthy 20 y/o. Normal value for anyone is 7 minutes or less.
Note: Be prepared on the test to figure out how long/how many breaths it takes to get to 2.5%
17
Q
What is an abnormal result of the nitrogen washout test?
A
> 7 minutes to get to 2.5% nitrogen concentration.
This would be indicative of a sick set of lungs.
18
Q
Nitrogen washout test: If nitrogen levels were plotted on a graph, would it be a straight line? Why or why not?
A
Normally it would not be a straight line, but in Schmidts pptt it is a straight line. This is because they made the Y axis scale up toward the top.
Note: Blue dot = data point from a single breath. Left picture.
19
Q
Nitrogen washout test: What does it mean when it takes an abnormally long time to get nitrogen below 2.5% concentration?
A
Air is being directed to different places of the lungs on each breath. If inspired air is directed all over, the washout of existing nitrogen will not be orderly. You might have a little more or less dilution on each breath.
This is the hallmark of a sick lung. Note right picture, 60+ breaths to get down to 2.5% compared to the black line (normal) at around 20 breaths.
20
Q
What does an abnormal nitrogen washout test mean?
A
Indicates an unhealthy lung with uneven ventilation.
20
Q
How many phases of expiration are there on the closing volume/capacity test, and generally speaking, what happens?
A
4 phases
1 - Dead space is expired, no nitrogen is picked up.
2 - Nitrogen is picked up; transitional period. This is anatomical dead space mixed with alveolar air. More and more nitrogen as expiration continues.
3 - Nitrogen that is picked up levels off. Air from the beginning of phase 3 is from the base of the lung. (Air comes from all parts of lungs, but more and more from the apical region as expiration continues)
4 - abrupt increase in nitrogen levels coming from patient. The start of this phase tells us when the small airways in the base of the lung are starting to collapse.
21
Q
What does the closing volume/capacity test measure?
How is it done?
A
Nitrogen coming out of the patient.
Patient starts from TLC and exhales to RV.
They then breathe up to TLC from a 100% oxygen source.
Any nitrogen in the lung at this point was there before inhalation at RV.
Patient then expires down to RV, and nitrogen is measured at different time points.
21
What might the nitrogen washout test look like with someone that has large lungs, or COPD?
Normal tidal volume + large lungs = increases time needed to wash lungs of nitrogen. This is more of the large lung factor rather than uneven ventilation.
(Large amount of nitrogen to be removed)
22
What is a normal time for the nitrogen washout test?
What about an abnormal time?
Sub-7 minutes = normal
Above 7 minutes = abnormal
23
In the closing volume/capacity test, what is the general amount of nitrogen that comes out of the lungs from left to right on the graph?
None at first, then more toward the end of the expiration. This is due to the fact that air is coming from different regions of the lung. Depending on where these areas are, you can figure out different properties of the lung.
24
Why does the nitrogen level increase during expiration in phase 3 of the closing volume/capacity test?
As the base of the lung empties, a larger portion of air is coming from the apical portion of the lungs. The apical portion has a higher concentration of nitrogen.
24
When taking a breath to TLC, what fills first?
What about expiration as it relates to the closing volume/capacity test?
The apex fills first, and the lower portions fill last.
On expiration, the beginning will have no nitrogen, then transitional phase, followed by phase 3.
25
What is the difference between closing volume and closing capacity?
Same thing more or less.
Closing volume = Air coming out of the patient during phase 4.
Closing capacity = Closing volume + RV
26
Closing volume/capacity test: What is the point where phase 3 becomes phase 4 mark the start of? (Both in the patient and in the graph)
Patient - small airways at the base of the lung are starting to collapse.
Graph - "closing volume"
27
What are some causes of phase 4 coming early in the closing volume/capacity test?
Not as much traction
Airways are thinner/more narrow
27
Closing volume/capacity test: The earlier phase 4 occurs, the ____ off the lungs are.
Worse
28
Which pulmonary function test does Schmidt think should be a part of every physical, and why?
Closing volume/capacity test.
It's very sensitive and can detect small changes in tissue behavior. Would be easy to do at a physical, because it only requires a nitrogen meter + a tank of oxygen.
This would allow people to know their lungs suck before it becomes an issue.
29
Compare the lung volumes/closing capacity between a 20y/o and a 70 7/o?
Standard volumes/capacities don't change very much
Same: TLC, IC
Very little change: VC
RV increases as we age due to parts of lungs being more difficult to empty as we get older.
30
At age 20, we ____ _____ any small airway collapse at RV.
Phase 4 is ____.
hardly have any
Phase 4 is small
Blue line = closing capacity
30
In a 70 y/o, closing capacity/volume is ____ than at age 20. What does this mean?
Much higher
Airways start collapsing before we even get to FRC due to loss of elastic tissue as a function of age.
31
The more elastic tissue we lose, the ___ elastic recoil we have, the ____ traction we have on small airways.
Why is this important?
Less
Less
Predisposes us to small airway collapse.
31
In a 20 year old patient, will the small airways collapse normally?
No. A 20 year old doesn't go below FRC often, and the. closing capacity is well below FRC
32
T/F
A 70 year old patient will have small airway collapse on every breath.
True: closing capacity exceeds FRC so it is reached on every breath. This increases work of breathing compared to younger people.
32
What old guy did Schmidt mention is in good shape, but has more work of breathing due to age?
Warren Buffet
33
What age, even in perfect health, will have small airway collapse with every breath?
55
33
What is the pleural pressure at RV at the apex of the lung? How about the base?
-2.2 cm H2O at the apex
+4.8 cm H2O at the base
34
At RV, how full is the apex of the lung? How about the base?
Apex 30%
Base 20% (as empty as the lungs can get before small airways collapse)
35
At RV, how much air can enter the apex/base of the lung?
The apex can accept 70% more capacity (30->100)
The base can accept 80% more capacity (20->100)
36
What is the partial pressure of nitrogen in the lung normally?
569 mmHg
37
If someone took a VC breath at RV from a 100% O2 source, how would the nitrogen content of the alveoli compare between the apex and base?
The nitrogen that was already in the lungs at RV would be diluted.
Since 70% capacity is being added to the apex, and 80% capacity is being added to the base, the base would be diluted slightly more.
The partial pressure of nitrogen in the base of the lungs would be slightly lower than the apex if someone took a VC breath at RV from a 100% O2 source. ****
38
What does a flow volume loop measure?
Top: Expiratory flow rates given different levels of effort between TLC and RV. The higher the curve, the more effort is being given to exhale.
Bottom: Inspiration, same concept
38
If expiring as hard as possible from TLC to RV, what is the peak expiratory flow rate?
10L/sec
39
With forced expiratory flow rates, airflow picks up rapidly but then trails off. Why?
Lower and lower lung volumes lead to a lower delta P, which decreases flow rates.
40
A flow volume loop shows the _______ flow rate between what two lung volumes?
Expiratory flow rate between TLC and RV
41
What is effort independence?
No matter how much harder we try to push air out of the lungs, the maximum expired flow rate will be capped by something. We won't expire any faster.
Takes place later in the expiration as there is less and less air to push out, lowering delta P thus decreasing flow.
Right side of graph shows this
42
What is effort dependence?
If someone tries to exhale faster, it will result in a faster air flow. This happens at the start of expiration when we have plenty of air. Flow is dependent on strength/effort of expiration.
Left side of graph shows this
43
For our purposes, which flow volume curve do we care about the most?
The maximal effort curve.
44
Flow volume loops:
How does the flow volume loop compare between inspiration and expiration?
The maximal flow rate happens before the halfway point of expiration assuming maximal effort. Note that if less effort is given, the maximal flow rate will be closer to the end of exhalation (see top of graph).
The maximal flow rate happens exactly at the halfway point on inspiration. Note there is no effort dependence/independence on inspiration, only expiration (See bottom of graph).
45
What did Schmidt say that the flow volume loop looked like?
An upside down ice cream cone.
46
Where are the internal intercostal muscles, and what do they do (think pleural pressure)?
Inside and between the ribs. When contracted, they pull the ribs closer together. This reduces the volume in the chest which increases pleural pressure.
46
If you do a flow volume loop on someone and there is less speed of expiration than expected, what does that indicate?
Problem with the lungs
47
What is peak expiratory flow rate dependent on?
Elastic recoil pressure: Transpulmonary pressure needs to be +30 cm H2O to fill lungs to TLC.
Pleural pressure: Very positive with maximal effort to push air out of the lungs. Use the diaphragm, internal intercostal muscles, and abdominal muscles to create this pressure.
48
What happens when the abdominal muscles contract in regard to pleural pressure?
Pushes stuff in abdomen to the bottom of the diaphragm, increasing pleural pressure.
49
What is an example of a disease that causes awful elastic recoil? What considerations need to be made in the OR?
COPD
Nearly entirely dependent on pushing the air out themselves rather than with elastic recoil. This will collapse the small airways and limit the rate that expiration can occur.
In the OR, there is no internal intercostal/abdominal muscle activity, meaning that patients are entirely dependent on whatever elastic recoil pressure they have.
More time needs to be allowed for expiration in these patients.
50
When doing a flow volume loop test, what do we care more about? Inspiration, or expiration?
Expiration most of the time, though inspiration can be useful in some cases.
51
What is the difference between a flow volume loop and an expiratory flow function curve?
It is only the expiratory flow curve that is plotted.
51
Whatever a patient looks like under maximal exertion (flow volume loop) is important. Why?
Tells us about lungs collapsing. Collapsed lungs will have air come out slower than usual.
52
What might an expiratory flow function curve look like in someone with COPD? Why?
The maximal flow rate would be less than usual, and the expiration would be longer than usual due to the loss of elastic recoil. There is a curve on the effort independent side of the loop. (right side of the left-most loop)
53
What is missing in obstructive lung disease?
Elastic recoil
54
What does the shape tell you about when talking about expiratory flow function curves?
Behavior of tissue
55
What is the problem in restrictive lung disease?
More scar tissue, more elastic recoil pressure
This makes it difficult to fill with air d/t increased tissue
Expiratory flow rate is reduced.
This is more of a fullness issue rather than elastic issue. The elastic pressure is there, but the air is not. Less air = not as fast expiratory rate.
56
Which peak expiratory flow is greater - obstructive disease or restrictive disease?
Restrictive flow is greater than obstructive
57
Which has a greater VC - restrictive or obstructive disease?
Obstructive disease
58
Order the following RV volumes greatest to least: Normal, obstructive disease, or restrictive disease. Provide volumes.
1) Obstructive 4.5L; d/t fuller lungs at higher pleural pressure, less springs.
2) Normal 1.5L
3) Restrictive 1L
58
Does obstructive disease have a greater VC than normal lungs?
No, normal lungs have a greater peak expiratory flow rate as well as a greater VC
59
Order the following TLC volumes greatest to least: Normal, obstructive disease, or restrictive disease. Provide volumes.
1) Obstructive; 8.5L
2) Normal; 6L
3) Restrictive; Just over 4L
60
What is FVC (forced vital capacity) almost always referring to?
Expired portion of a flow volume loop - we care more about how air gets out of a patient than in most of the time.
61
Order the following VC volumes greatest to least: Normal, obstructive disease, or restrictive disease. Provide volumes.
1) Normal 4.5L
2) Obstructive 3.5-4L ish
3) Restrictive 3L
62
The smaller the VC on an expiratory flow function curve, the ____ the disease.
Worse
63
Normally flow volume curves won't have volume and airflow plotted like in this graph.. what do they usually do?
Usually have a scale like on maps and you have to eyeball it.
64
What is one flaw of the flow volume loop compared to an expiratory flow function curve?
RV isn't plotted, so you wouldn't know what it was unless you did a helium dilution measurement with FRC/RV.
Without RV, you wouldn't know where to position the expiratory flow function curve, and wouldn't know that RV was huge (or small).
Can look at other things for abnormalities instead, such as max expiratory flow rate, the shape, and VC. RV will be missing.
Note: For test day, I bet he will give us a flow volume loop and make us figure out helium dilution/RV.. be prepared for that
65
What does the forced vital capacity maneuver look at?
Expiratory flow rate (normally.. can look at inspiration, but not often).
66
With forced expiratory maneuvers, what is the pleural pressure? What about the alveolar pressure?
Given this, why does air flow out of the lungs?
+25 cm H2O pleural pressure
+35 alveolar pressure
There is a pressure gradient (delta P) along the airways. +35 cm H2O within the alveoli, and 0 cm H2O in the environment. This allows for air flow from high pressure to low pressure areas.
(right picture)
67
Does pleural pressure change as you go up and down the airways? What about alveolar pressure?
Pleural pressure is uniform along the airways, while airway pressure changes (more positive in the alveoli while closer to 0 cm H2O outside of the airways)
68
The conducting zones (Upper airway) are supported by what? What is the purpose?
Cartilage (firm tissue)
Prevents collapse of upper airways during forced expiratory maneuvers.
69
Do lower airways have cartilage? What is the implication?
No
They are vulnerable to collapse, as evidenced by blue arrow on right picture.
Pressure in the airway and pleural pressure are the same. If the pleural pressure were to overcome the airway pressure, it would collapse.
70
How is passive expiration different than forced expiration?
Passive expiration relies only on elastic recoil to push air out, while forced expiration adds effort (positive pleural pressure)
71
In a normal patient, what is the pleural pressure on passive expiration?
-8 cm H2O
72
In a normal patient, what is elastic recoil pressure? Does this change with passive/forced expiration?
+10 cm H2O; does not change
Very important to help us get air out of the lung***
73
In a normal patient, what is the pleural pressure on forced expiration?
+25 cm H2O
74
In a normal patient, what is the net pressure within the alveoli with passive expiration? What does this mean?
+2 cm H2O
Positive value = outward airflow
75
Why do the airways stay open on passive expiration?
The pressure within the small lower airways (+1 cm H2O) is greater than the pleural pressure (-8 cm H2O)
76
Is there a choke point within the airways during passive expiration?
Not normally
77
With forced expiration, how would emphysema change pressures/chokepoints?
Loss of elastic recoil/tissue in alveoli results in a half normal recoil pressure of +5 cm H2O.
Pleural pressure remains at +25 cm H2O.
This makes alveolar pressure +30 cm H2O instead of +35 cm H2O like normal.
While delta P is still +30 cm H2O, the pressure in the small airways will be lower than normal.
i.e., pressure within the small airways might be +19 cm H2O, while pleural pressure is +25 cm H2O.
This results in collapse of the small airways in a patient with emphysema (obstructive lung disease) on forced expiration.
78
What can predispose us to collapsing airways?
Narrow airways as seen with asthma or low lung volumes.
79
What guards us from airway collapse?
Spongy recoil tissue of the alveoli. More tissue = more recoil pressure. Note recoil tissue/springs are in alveoli as well as small airways.
This provides traction on small airways and keeps them open.
80
What happens if we lose springi-ness of the small airways and alveoli?
What is an example of this?
Traction on small airways would be lost, resulting in airway narrowing. This causes susceptibility to airway collapse.
i.e. COPD/Emphysema d/t loss of elastic recoil and thus loss of small airway traction.
81
Can upper airways ever collapse?
Not usually, but if someone has loss of upper airway cartilage it can increase the risk of collapse.
81
What relationship does an ETT have with the trachea? What does this imply?
No matter what size the ETT is, it has to be smaller than the trachea. This leads to higher resistance to airflow (both inspiration and expiration)
82
What does an ETT do to the flow volume loop?
Cuts the top and bottom off of it due to extra upper airway resistance. (Both inspiration and expiration impacted).
This is fixed (intra- or extra thoracic). It is a continuous problem.
83
What is the difference between intrathoracic and extra thoracic?
Intrathoracic is in the chest, extra thoracic is outside the chest.
84
What kind of problems would cause a variable extra thoracic flow volume loop?
Obstruction outside chest
Weak point at top of upper airway, such as missing cartilage
Trachea removed
Paralyzed vocal cords
85
If there is a weak point in the upper airway, what can happen?
Negative internal airway pressure causes airways to collapse on inspiration, evidenced by bottom of flow loop being flat.
85
What does open/closed state depend on with vocal cords?
Pressures in and around the airway inside of the larynx. If the pressure in the larynx is negative, the cords are pulled closed.
On expiration (especially forced), the chest pressure is increased, which increases airway pressure. This will open the vocal cords/move the obstruction. There is no opposing environmental pressure outside of the thorax.
Note: This applies to NORMAL breathing.
86
How does the open/closed state of paralyzed vocal cords change with positive pressure ventilation?
The obstruction will be pushed out of the way (i.e vocal cords will be pushed open d/t positive pressure).
Note: Will cause other problems from PPV though.
87
Name the three variants of the flow volume loop.
Fixed (intra or extra thoracic)
Variable extra thoracic
Variable intrathoracic
88
What is a variable intrathoracic flow volume loop? Name some diseases that can cause it.
Not present all the time - variable.
Impacts expiration, especially forced. This cuts the top of expiration on a flow volume loop off.
This is due to loss of elastic recoil pressure. Not enough traction to keep airways open on forced expiration.
On inspiration, airways open since thorax pressure is very negative.
COPD, emphysema, asthma
89
What is FVC?
Forced vital capacity
89
What is FEV1?
Forced expiratory volume in 1 second with maximal effort
90
FEV1/FVC gives us what?
A ratio/fraction. We should be able to move 80% of our VC out of the lungs within 1 second during maximal forced expiration in a healthy lung.
Note: NOT TLC; this is talking about VC.
91
What does it mean if FEV1/FVC is lower than 80%?
Your lungs have a problem.
92
What does this graph mean?
Looking at how much air is coming out of the lung over time during a forced expiratory maneuver.
Note: RV is left out of this graph.
VC is 4.5L
Read right to left - lots of lung volume removed in 1 second, then trails off.
FEV1/FVC ratio is about 80% here.
93
This graph shows an airway obstruction. What does it tell you?
FVC lower than normal.
At 1 second, not much air has came out of the lung.
Slower expiratory rate, takes longer to get to RV than normal.
FEV1/FVC ratio less than 50%, which is lower than the normal of 80%.
94
This graph shows a normal FEV1/FVC ratio overlapped with the blue line, which is airway obstruction. Note differences.
Read left to right in this graph, as opposed to right to left in other FEV1/FVC graphs. Pay attention to this.
Normal:
FEV1 = 3.6L
FVC = 4.5L
FEV1/FVC = 80%
Airway obstruction:
FEV1 = 1.5L
FVC = 3L
FEV1/FVC = 50%
95
What is the difference between these graphs?
Left: FEV1/FVC ratio graph, read left to right. Can figure out how much air is coming out of the patient, but can't tell flow rate.
Right: No time axis here, just flow rate and volume. You cannot figure out how much air is coming out of the patient with this. Can tell flow rate with this graph.
96
What lung disease would have a normal FEV1/FVC ratio, but have a low VC?
Restrictive lung disease. Low VC, low FEV, but in proportion to VC you have a normal FEV1/FVC ratio.
Note: less flow rate d/t lower volumes in restrictive lung disease.
Max flow rate is under 6L/s, while normal is close to 10L/s
97
What kind of lung does the graph depict? Why?
Restrictive lung disease.
Normal FEV1/FVC ratio
Low VC, low FEV
98
What kind of lung disease does this graph show?
Advanced emphysema/bad COPD (Obstructive disease)
Note extended amount of time to get air out of lungs, so much so that the X axis of the left graph is cut off.
Only 1.5L out in the first second. Low FEV1/FVC ratio.
98
With PPV, what is expiration in obstructive lung disease (COPD/Emphysema) dependent on?
Elastic recoil (which they are lacking - need more time for expiration).
99
What is the hallmark shape/change indicating obstructive lung disease, or a problem getting air out?
Right graph
Note the peak of flow rate, followed by a curved line on the back end.
100
What are the 5 steps of the PFT algorithm?
1) Is FEV1/FVC <70%? --- if lower than 70%, it's a problem (like obstructive lung disease)
2) Evaluate FVC
3) Helium dilution/spirometry to find TLC/RV --- if RV increased, could be obstructive lung disease. Compare to TLC to find out what obstructive disease it is.
4) DLCO measurement, AKA CO diffusion test to measure gas exchange in the lungs --- don't need details here
5) FEV1 reversibility with bronchodilator - administer bronchodilator ----- if reversible, could be airway reactivity like asthma. If not, then there is an elastic tissue issue like emphysema.
101
Brushed over this, know this chart.
102
What is this?
Flow volume loop plot with FVC. Expiration starts at 5L with both X and Z (two different patients). Graph keeps track of how much patient expires.
Note that it starts at one second, so the two second mark would be FEV1.
103
What is the FEV1/FVC ratio of X?
FEV1 = 4L
FVC = 5L
FEV1/FVC = 4/5 --> 80%
This is normal.
104
What is FEV1/FVC of Z?
FEV1 = 3L
FVC = 5L
FEV1/FVC = 3/5 --> 60%
This is low. Could be restrictive lung disease OR someone who is just small.
105
What does this graph show?
Flow volume loop with different level of effort.
Z = normal FRC breathing.
Y = Little deeper inspiration/expiration than Z.
X = even more so
W = maximal effort inspiration/expiration.
106
What does "a" stand for on the top of this OxyHgb dissociation curve?
What is the PCO2 of "a?"
a = arterial blood sample. PCO2 on average in arterial blood is 40 mmHg with a higher pH compared to venous blood.
107
Why does venous blood have a lower pH than arterial blood?
Will this be a left or a right shift on the OxyHgb curve?
Finally, will all venous blood look the same?
It has picked up more CO2
Right shift (lower pH)
For the most part, there is little difference in behavior in different areas of systemic circulation when it comes to venous samples.
108
What is the optimal hypothetical number for venous saturation of oxygen?
What is it actually closer to?
What is it in the standard healthy person, and why would it be lower?
75% optimal
60% actual (he mentioned this but pivoted to 70%)
70% healthy person; lower with a sick/acidotic patient. More acidotic = less saturated Hgb
109
When might SVO2 be higher?
If tissue isn't extracting O2 d/t low metabolic rate (i.e. cold). Will have higher venous Hgb saturation
110
Regarding OxyHgb affinity values, what is P50?
P50 value refers to the partial pressure of oxygen (PO2) required to bring a Hgb oxygen saturation up to a level of 50%
111
What is the normal P50 of oxygen under normal conditions?
26.5 mmHg
112
What characteristics would Hgb have if P50 was right shifted?
Hgb is less prone to saturating with oxygen. More oxygen (PO2) is needed to reach 50% saturation.
Lower affinity = need more oxygen for the same (50%) result
113
What characteristics would Hgb have if P50 was left shifted?
Hgb more prone to saturating with oxygen. Less oxygen (PO2) is needed to reach 50% saturation.
Higher affinity = need less oxygen for the same (50%) result
114
The whole blood CO2 content is a combination of how many forms? What are they?
Three forms - all are needed to figure out CO2 content
Dissolved
Carbamino compounds
Bicarb
115
What is the normal OxyHb saturation of venous blood?
How about the PCO2 of venous blood?
Lastly, what is the whole blood carbon dioxide content in mL CO2/dL venous blood?
OxyHgb: 75% (for our class, 70% if healthy)
PCO2: 45mmHg
CO2 content: 52.5 mL CO2/dL
116
What is the normal OxyHb saturation of arterial blood?
How about the PCO2 of arterial blood?
Lastly, what is the whole blood carbon dioxide content in mL CO2/dL arterial blood?
97.5% (for our class, we'll use 100%) OxyHgb saturation
40 mmHg PCO2
Carbon dioxide content: 48 mL CO2/dL
117
In arterial blood, aside from gas exchange having occurred, why is CO2 in lower concentration than oxygen?
How does this change in venous blood?
Less room for CO2 if there is lots of oxygen floating around (arterial)
Less oxygen, more room for CO2 to be transported.
118
Why is it important to use both a OxyHgb/CO2 dissociation curve, and not just one or the other?
Oxygenation impacts carrying capacity of blood - they are related to one another.
119
120
121
Why is it that if we have a lot of oxygen that we have "less room for CO2?"
Why is it that if we don't have a lot of oxygen that we have "more room for CO2?"
R proteins can be Hgb. If it is OxyHgb and saturated with oxygen, there are not as many exposed terminal amine groups for CO2 to bind at.
As OxyHgb becomes DeoxyHgb, more terminal amine sites are exposed, allowing Hgb to do other things like bind to CO2 or buffer protons (HbH+).
Remember the acid/base equation on slide 15 (attached). If you have lots of CO2 producing lots of protons plus Hgb available to buffer said protons, you can fit more CO2 in blood.
122
What three things can Hgb do?
Bind and release O2
Form carbamino compounds
Buffer protons
123
What are the three forms of CO2, and what % of CO2 is in each?
Dissolved - 5%
HCO3 - 90%
Carbamino - 5%
Note: While composition is different in venous, Schmidt said to use this composition for both arterial and venous. This is the arterial composition.
124
How do you calculate dissolved CO2?
Solubility of CO2 x Partial pressure CO2 in solution = amount of CO2 dissolved in sample solution
125
What is the solubility of CO2?
0.06 mL CO2/mmHg partial pressure CO2/dL blood
126
What is carbamino, and how does CO2 get carried by it?
Proteins can have a terminal amine group. That is considered a carbamino. Note: Hgb is a type of carbamino group.
Terminal amine + CO2 = carbamino compound.
In good conditions, when lots of CO2 is around the terminal amine group, one proton (hydrogen) falls off of the terminal amine group. The hydrogen ion dissociates into solution.
127
If more CO2 exists in solution, what will happen to the level of carbamino compounds?
More CO2 concentration = more carbamino compounds
128
What is the molecular structure of a terminal amine group?
R-NH2
129
What is the chemical structure of a carbamino compound?
RNH-CO2 + H+
130
How does bicarb carry CO2? Does anything help this reaction along?
CO2 combines with water, forming carbonic acid (H2CO3).
Carbonic acid isn't stable, and falls apart into its components. It can go one or two ways depending on the pH.
1) Bicarb + Proton (blood in area that is high in CO2 will create this)
2) CO2 + H2O (Blood in area that is low in CO2 will create this)
This reaction gets help from carbonic anhydrase, an enzyme that pulls the water out of carbonic acid OR puts water and CO2 together for form carbonic acid. It works both ways.
131
How much mL O2/dL would be in solution if the PO2 was 1mmHg?
0.003 mL O2/dL per mmHg partial pressure of O2
132
Carbonic anhydrase can speed up the dissociation of carbonic acid into CO2/H2O and vice versa. What does speed of this depend on?
The amount of product/substrate in the area. Can't have a reaction if you don't have the pieces
133
When calculating CO2 in arterial/venous samples, what is the difference in the formula?
No difference other than the PCO2 value of the sample (40mmHg in arterial, 45mmHg in venous)
134
How many mL/dL of CO2 is in arterial blood with a standard PaCO2?
PaCO2 x CO2 solubility = mL/dL CO2 in arterial solution
Standard PaCO2: 40 mmHg
CO2 solubility: 0.06 mL CO2/mmHg PCO2/dL
40 mmHg x 0.06 mL CO2/mmHg PCO2/dL =2.4 mL CO2/dL arterial blood***
135
Knowing that 2.4mL CO2 is in the dissolved form in arterial blood with a standard PaCO2, calculate how much CO2 in mL/dL arterial blood would be in each of the following: Carbamino, HCO3, and dissolved.
Give the total CO2 in the arterial system as well.
2.4mL/dL dissolved = 5% of the CO2 in the arterial system
5% is also in carbamino compounds, meaning that 2.4mL/dL is there.
90% of bicarb is remaining.
20 x 5 =100%
so
2.4mL/dL x 20 = total CO2 content
Total CO2 content = 48mL CO2/dL arterial blood
48mL - 2.4mL - 2.4mL = 43.2 mL CO2/dL in bicarb
136
Why is there so much CO2/dL blood?
It's very soluble. More *dissolved* in blood than oxygen, while oxygen is bound to Hgb mostly
137
In arterial blood, CO2 is carried three ways:
Carbamino - 5%
Bicarb - 90%
Dissolved - 5%
How does this change in venous samples?
Carbamino - 30%
Bicarb - 60%
Dissolved - 10%
Note: He said just know the relationship, but we will use the arterial composition for the purpose of our class.
138
In venous samples, why is the % of CO2 dissolved higher than in arterial samples?
Have a higher PCO2, so more is in the dissolved state
139
In venous samples, why is the % of CO2 in bicarb lower than in arterial samples?
More protons in venous blood compared to arterial blood, so protons will consume some bicarb leaving less for CO2 to use
140
In venous samples, why is the % of CO2 in carbamino groups higher than in arterial samples?
Remember Hgb is a terminal amine group when desaturated. CO2 binds to Hgb and forms carbamino groups this way.
More CO2 = more carbamino
140
What is the difference between these lines?
Different OxyHgb saturation levels. These are CO2 venous curves at different levels of PCO2.
141
Deoxygenated blood has more room to transport CO2.
What is this known as, and what is the definition?
The Haldane Effect
The amount of CO2 transport we have is dependent on OxyHgb saturation.
142
Why don't we use the same curve for both of these samples?
If you use the same curve, (lower being 100% saturated with O2, upper being 70% saturated with O2), it would be inaccurate.
i.e. 100% saturated blood can't carry as much CO2, meaning that the CO2 content of the blood would be lower than in desaturated blood.
A second curve is used to show PCO2 levels at different levels of OxyHgb saturation.
143
A OxyHgb saturation of 100% would allow for how many mL of CO2 content?
2mL CO2
144
What is the CO2 content in blood that is 70% saturated with oxygen?
52.5mL/dL
145
What does A, B, and C show?
A - normal V/Q
B - shunt (low V/Q)
C - alveolar dead space (High V/Q)
146
Is the V/Q constant throughout the lung?
No - different in each area.
147
If your ventilation is higher than perfusion, how will the O/CO2 content change, and will the V/Q be high or low?
Higher O2 than usual
Lower CO2 than usual
Low V/Q
See B
148
If an alveoli had no ventilation, but there was perfusion (shunt), what is the VQ?
Zero (0/x = 0)
148
If your ventilation is lower than perfusion, how will the O/CO2 content change, and will the V/Q be high or low?
Lower O2 than usual
Higher CO2 than usual
Low V/Q
See C
149
If an alveoli had ventilation, but there was no perfusion (alveolar dead space), what is the VQ?
Higher than normal
150
Assuming alveolar dead space, what is the highest V/Q ratio possible?
Infinity
151
When sitting in a chair, where is most of the fresh air going? How about blood flow?
Both to the bottom of the lung
151
What happens to blood flow and ventilation as you go lower in the lungs?
The BOTH decrease
152
At the bottom of the lung, which is greater? Blood flow or ventilation?
How about the top of the lung?
Bottom - blood flow is greater
Top - ventilation is greater
Again, note BOTH decrease the higher in the lung you are.
153
What part of the lung in general is under ventilated?
Overventilated?
Bottom (meaning V/Q ratio is lower here than at the top of the lung normally)
Top (meaning V/Q ratio is higher here than at the bottom of the lung normally)
154
What is the PO2 at the base of the lung?
PCO2?
90 mmHg (lower than average)
Little higher than 40 mmHg (higher than average)
d/t having lower than average V/Q at base of the lung
155
What is the PO2 at the apex of the lung?
PCO2?
PO2 - 130 mmHg, higher than average
PCO2 - 30ish mmHg, lower than average
Higher V/Q ratio than average
156
More ventilation will result in a ___ PO2 and a ____ PCO2.
Less ventilation will result in a ___ PO2 and a ___ PCO2.
Higher; lower
Lower; Higher
156
Alveolar air should have PO2 of
100 mmHg
157
What is normal alveolar ventilation in mL/min?
4,200mL/min
VT = 500mL
VD = 150mL (anatomical)
VA = 350mL
RR = 12
VA x RR = VA/min
350mL x 12 = 4,200mL/min
Note: on test, be prepared to calculate alveolar dead space and incorporate it here.
158
What are normal factors that influence ventilation?
Intrapleural pressure
Transmural pressure gradient
Alveolar size
Ventilation/min
159
What are normal factors that influence perfusion?
Intravascular pressures
Recruitment distention
Resistance
Blood flow
160
What is the most important/largest factor that can cause problems with V/Q ratio?
Development of alveolar dead space
161
What do we do that increases alveolar dead space?
What can we do to "put a band aid on it?"
Anesthetize w/ positive pressure ventilation (abnormal for lungs)
More positive pleural pressures cause alveolar dead space.
Increase ventilation to maintain blood gas as more and more alveolar dead space develops.
162
What's the difference in these?
Right picture has atelectasis visible in the left lung lobe.
The left picture is an awake patient. The right picture is an anesthetized patient with zero PEEP. (aka ZEEP). No usage of PEEP results in lung collapse.
Note the large decrease in V/Q ratio. This is due to less ventilation relative to perfusion.
163
What happens over time as the lung is collapsed?
Longer it has been collapsed, harder it is to reopen.
163
How long does it take for lung collapse on induction without PEEP?
Is this an issue?
Instantly, causing a V/Q mismatch
20 minute procedure on a 20 y/o? Probably not an issue
Longer surgery on a 90 y/o or person in poor health? Apply PEEP as soon as possible, this won't be good for them.
164
What is LaPlace's Law?
If you had a two different sized balloons (spheres) connected via a pipe system and put air down it, the smaller balloon would deflate and move air to the larger balloon.
165
The pressure of a balloon is dependent on what?
Radius of a sphere
166
Regarding LaPlace's law, what formula is used to find pressure of a sphere?
Pressure in a sphere is related to surface tension divided by the radius
AKA
T/r = P1
For a sphere twice as big, it would be T/2r, since the radius is twice as large.
167
T/r = P1
vs
T/2r = P2
What would the formula above mean for air trying to enter two spheres, one with the first formula and one with the second?
The second sphere would have a lower pressure since the denominator is higher.
T = tension
This would mean air would want to go into the second sphere before the first one. Air would also leave the first sphere to enter the second one. (provided the second sphere is not full)
168
If you had two balloons of different sizes connected by a series of pipe, how full would the bigger balloon need to be before air would go to the smaller balloon?
80-100% full.
However, eventually pressure exceeds capacity and you can blow them out.
168
If LaPlace's law held true to the lungs ,what happens if you have one lung collapsed partially?
Air would move from the collapsed lung to the non-collapsed lung, worsening the bad lung. Will take a lot of pressure to re-recruit the affected lung.
169
What happens to surfactant concentration as we take a breath?
Unless we produce more surfactant, the biological concentration is reduced as alveoli get larger.
As alveoli get smaller, the biological concentration is increased d/t surfactant not being spread out as much.
169
LaPlace predicts that ventilation is uneven, fresh air goes to alveoli that are already open, and that closed alveoli just don't get air. Is this true? Why or why not?
Not true under normal circumstances.
Surfactant protects us by breaking surface tension, distributing pressure needed to fill with air.
170
In what cases might LaPlace's law hold true in the lungs?
Surfactant deficiency.
Any respiratory issue ever is known to cause surfactant deficiency.
171
The "effective surfactant concentration" describes what?
Small surface area with surfactant = more concentrated, making it easier to put air in
Large surface area with same amount of surfactant = less concentrated, making it harder to put air in
172
Why is it harder to open a lung that has been collapsed for awhile?
Alveolar macrophages eat up surfactant, making it harder to re-open the alveoli.
173
What information do you need to find the volume of a gas?
Size of the container
Concentration of the gas
174
If you have a pressure and need to know a volume, how can you find it?
Use concentration of the substance to figure out the volume.
175
What is physiological dead space?
TOTAL amount of dead space, consisting of alveolar and anatomical dead space.
176
How much anatomical dead space do we have?
~150mL
177
What does a healthy 20 y/o physiological dead space consist of?
Little to no alveolar dead space.
150mL anatomical dead space.
178
What things cause alveolar dead space?
Anesthesia exposure
Ventilators (PPV makes blood flow difficult)
Unhealthy environments
179
What is an easy way to calculate anatomical dead space?
1mL/lb of ideal body weight
180
What is mixed expired gas?
Collection of entire inspired breath & what was already in the lungs
(lungs + alveoli + dead space)
180
What happens with air in alveolar dead space?
Air isn't being used for gas exchange.. need more ventilation to make up for it
181
Will anatomical dead space have CO2?
No, but it will have high PO2. Air is getting there, but no exchange is happening.
182
PE(O2)
What does E stand for?
Mixed expired air
183
If you put mixed expired gas in a container, what would PO2 be? (think dead space)
Between PO2 of dead space and PO2 of alveolar air
184
What is the PO2 of alveolar air?
PO2 of dead space?
Alveolar air - 100 mmHg O2
Dead space O2 - 150 mmHg
185
If you put alveolar air and dead space air in a container, would the PO2 equilibrate closer to alveolar air or dead space air? Why?
What is the actual PEO2?
Closer to alveolar air as there is 350mL of that, vs 150mL dead space
^Careful on test if we end up having more dead space than alveolar air, one thing to think about. Know diseases that would change this.
PEO2 = 120 mmHg
186
What is PEH2O?
47 mmHg always for water
186
What is the CO2 in the dead space?
How about the alveolar air?
Finally, if allowed to equilibrate, would it be closer to dead space or alveolar air, and what would the value be?
Dead space CO2 - 0 mmHg
Alveolar air CO2 - 40 mmHg
Closer to alveolar air
PECO2 - 27 mmHg
187
Oxygen and CO2 mixed expired air numbers are different than atmospheric, but nitrogen is about the same. Why?
We don't really take up nitrogen, so what we breathe in is what we breathe out more or less. 569 mmHg is in the atmosphere, while we breathe out 566 mmHg
188
If dead space is developing in the lungs, how will mixed expired air change?
Lower than expected PECO2 d/t less surface area for diffusion
189
How are the mixed expired air concentrations found?
i.e. PECO2 = 27 mmHg
long card sorry; math
VT = 500mL (portion dead space, portion VA)
PCO2 in dead space should be 0 mmHg
Find alveolar air CO2, need concentration of CO2
PACO2 = 40 mmHg
Partial pressure of gas = concentration x total pressure
Total pressure = atmospheric = 760 mmHg
so
40 mmHg/760 mmHg = 0.053
or
5.3% is the concentration of CO2 in the alveolar air
190
How do you find how much CO2 in mL is in alveolar air?
The normal concentration of CO2 in alveolar air assuming 40mmHg PCO2 and standard atmospheric pressure is 5.3%.
Alveolar air volume is 350mL.
Concentration x volume = mL
5.3% x 350mL =18.42mL CO2 in alveolar air
191
If there is 18.42mL CO2 in alveolar air, 150mL dead space, and 350mL alveolar air, what would be the concentration of CO2 assuming alveolar air and dead space air were mixed? (i.e. mixed expired air)
Dead space + alveolar air = 500mL
Now find concentration by:
Volume gas/volume sample
18.42 mL CO2/500mL air = 0.0368
or
3.67% concentration of CO2 in the mixed sample.
Note, concentration in alveolar air went from 5.3% --> 3.67% when mixed with dead space.
192
How do you find the PCO2 of a mixed sample?
Take concentration x total pressure
i.e.
Concentration: 3.7%
Total pressure: 760 mmHg
3.7% x 760 mmHg = ~28 mmHg
^Note for our class we will use 27 mmHg CO2 in mixed expired air
193
As we have more dead space, how will PECO2 change?
It will get lower.
194
What two things in the chest are a barrier to putting air in the lungs?
The lungs themselves - d/t recoil; they like to be empty as can be
Chest wall - depends on lung volume/positioning/heaviness/tightness
I.e someone on their back has more weight on their chest, thus decreasing chest wall compliance
194
What are the steps to get to PCO2 of a mixed expired sample?
Not sure what concentration is to start, but can use formula for partial pressure of a gas.
Have partial pressure? Can then figure out concentration --> How much CO2 we have --> PCO2 of the total mixed sample --> Divide that by total size of the sample --> This gives the new concentration --> Multiply that by the total pressure = PCO2 of the mixed expired sample
195
Are the lungs/chest wall in series, or parallel when it comes to compliance?
In series. Both outward and inward recoil determine pleural pressure and lung volume. This decides what our FRC is.
(1/compliance of lung) + (1/compliance of chest wall) = (1/total compliance)
196
The apex of the lung sits where in relation to the ribs?
Above rib 1
196
Which way does the chest recoil?
How about the lungs?
Why is this important?
Chest - outward
Lungs - inward
Creates negative pleural pressure normally of -5 cm H2O
197
Elastic recoil pressure can be abbreviated how?
PER, or Pel
ER/el are subscripts
198
If you decided to take a saw to a chest, what would happen to the ribs? Why?
They would pop outwards d/t the chest walls natural tendency to recoil outwards.
199
What happens if lung recoil doesn't balance chest wall recoil, for example in severe emphysema?
There is less inward recoil of the lung, which allows the chest wall to expand.
The ribs then protrude outwards, leading to larger lungs + barrel chest.
Because of this shift, instead of a -5 cm H2O pleural pressure, people with severe emphysema have a more positive pressure (-2.5 cm H2O) since there is less opposition to the chest wall. Not as much pressure is needed to get air in the lung.
200
What happens to the lungs if someone gets shanked in the chest and it opens the chest wall? (i.e. pneumothorax/hemothorax)
Air/blood moves in to fill pleural space, making it equal to atmospheric pressure (so equilibrated at 0 cm H2O)
This leads to the lung deflating and difficulty filling with air since there is not a negative pleural pressure.
200
What is the TLC of emphysema with transpulmonary pressure of 10cm H2O? Why?
6L. Not as much pressure is required to get air in the lungs d/t lack of elastic recoil, leading to chest wall expansion.
Normally 6L TLC takes 30 cm H2O
201
How do you find lung compliance?
Compliance = delta V/Delta P
VT = 500mL
P1 = -5 cm H2O
P2 = -7.5 cm H2O
Delta V = 0.5L
Delta P = 2.5 cm H2O
Compliance = 0.5/2.5
Compliance of the lungs normally = 0.2 L/cm H2O
202
What is compliance of the lungs measured in?
L/cm H2O
203
Upright & at FRC, is the chest wall in the way of breathing?
No
204
Why are the lungs/chest wall considered a system in series?
What is lower compliance - the components, or total compliance?
When we breathe in, we're pushing against both elastic recoil of the lungs and the stiff chest wall.
1/n + 1/n =1/total compliance
Total compliance is lower than any single component. (about half)
205
Definition of resistance?
How hard it is to push something through a conduit
206
Compliance is a measure of what?
How easy it is (i.e. how much air can you put into the lungs with a given pressure)
206
Why do we use the formula for a system in parallel to find compliance of the lungs and chest wall if they are a system in series?
Want to know how easy it is to put air into the lungs
206
In a parallel system, is total resistance higher or lower than individual components?
Lower, as there are more pathways
207
Formula for parallel system resistance?
1/R total = (1/R1) + (1/R2) etc
208
What is the normal compliance of the chest wall?
And the lung?
0.2 L/cm H2O - chest
0.2 L/cm H2O - lungs
209
Find the compliance of the average lung/chest wall system.
Chest wall compliance = 0.2 L/cm H2O
Lung compliance = 0.2 L/cm H2O
(1/0.2 L/cm H2O) + (1/0.2 L/cm H2O = 1/x
5 + 5 = 1/x
10 = 1/x
Multiply both sides by X
10x = 1
Divide both sides by 10
(10x/10) = (1/10)
Total compliance of the system is:
X = 1/10
X = 0.1 L/cm H2O
210
What does the Bohr equation do?
Helps estimate alveolar dead space
211
What was the name of the guy who named the Oxyhemoglobin dissociation curve?
Bohr
He also named the Bohr equation, very original
212
Derive the Bohr Equation.
Just kidding, good luck
212
What is a common thing with both subtypes of physiologic dead space?
Alveolar and anatomical dead space both do not have CO2 in them since there is no gas exchange
213
What is a quick way to figure out anatomical dead space?
Fowlers test (review that)
214
All CO2 coming from a mixed expired air sample comes from where?
Alveoli that are both ventilated and perfused.
214
What can we do with this?
Scratch out the middle section. No CO2 comes from dead space, so it is not needed.
215
How do we find the amount of CO2 in a mixed expired sample?
If we know the fractional concentration of CO2 and the volume of air, we can multiple those together to get the quantity of CO2 in mixed expired air.
Size of sample x concentration of CO2 = amount of CO2
^Note that this amount of CO2 HAD to have came from good alveoli
216
Mixed expired air with CO2 in it had to have came from ____ alveoli.
Good/healthy
217
How do you find the amount of CO2 in mixed expired air that is coming from the alveoli?
All CO2 comes from good alveoli
Mixed inspired = mixed expired CO2
218
The most simple formula for finding alveolar deadspace is what?
What is the best formula?
Simple: VT = VDS + VA (rearrange and find VA)
Best: VA = VT - VDS
VA= alveolar ventilation
VT = tidal volume
VDS = dead space
219
Fractional mixed expired CO2 should be lower than what?
5%
40 mmHg/760 mmHg = ~5%
220
What would dead space divided by tidal volume give you?
Difference in gas fractions
220
What tool do we use that can tell us fractional inspired PCO2 if you're at utopia general?
Fancy ventilators
221
What's the easiest way to find fractional inspired PCO2?
Provided there is no shunt, look at a blood gas
222
What is the Bohr Equation that we need to have in our brains?
These 4
223
Assuming a healthy person, end tidal CO2 should be = to what?
Arterial PCO2
224
How can we find mixed expired PCO2 for this equation?
The ventilator can do it
Or
Do the math
^Need PaCO2 (blood gas works)
PECO2 = PaCO2 - (VD/VT) * PaCO2.
Figure out VD/VT
Plug it in to the equation
i.e.
VD = 150mL
VA = 350mL
VT 500mL
150/500 =0.3
PECO2 = PaCO2 - (VD/VT) * PaCO2.
VD/VT ratio = 0.3
40 mmHg - 0.3 x 40
40 mmHg - 12 mmHg
28 mmHg CO2 = PECO2
225
If you discover someone has alveolar dead space, what happens?
It continues to get bigger - need to give more ventilation to make up alveolar dead space.
Note: Can't do anything about physiologic dead space.
226
What kind of dead space does this solve for if you rearrange it?
TOTAL dead space
227
How can we find alveolar dead space from this?
Subtract anatomical dead space from VDCO2
228
What is the roof of the mouth called?
Hard palate
229
What is posterior/inferior to the hard palate?
Soft palate, hangs off the back of the hard palate and can create difficult airway if they have too much tissue.
Note: Soft palate typically is what makes people snore
230
What is the projection of the soft palate called?
Uvula
231
What sits right behind the uvula?
Tonsils
232
What are the two types of tonsils?
Palatine (visible just behind the uvula)
Pharyngeal tonsil, which is in the back of the nose
233
What's the danger of having large pharyngeal tonsils?
They are in the back of the nose, so if they are large they can push the soft palate forward and make the airway more difficult to keep open.
These people need tonsil removals.
234
Where are the salivary glands?
Oropharynx
235
How many salivary glands are there, and where are they?
Sublingual - under the front of the tongue
Submandibular - under mandible/base of jaw
Parotid - large gland on sides of face
235
Why do we want saliva?
To START processing food.
236
Salivary glands are in charge of making lots of fluid and saliva. What characteristic do these tissues have?
Highly vascular since it needs to secrete water.
237
Where do the lingual tonsils reside?
Back of the tongue, at base.
Note: With a MAC blade, you're between this and the epiglottis, which is the vallecula*
237
Your patient is a professional slapper, but unfortunately lost his slap match via KO. Why is their face so large?
The parotid gland has broken blood vessels. It is large, so by proxy it can get very large if vessels burst.
238
If you need to reposition the tongue, what blade should you use?
MAC
239
What is the top most piece of cartilage of the larynx?
Epiglottis - protrudes from behind the tongue
240
What are the two ways that the airway is protected from food stuffs?
Epiglottis is pulled back, which closes the opening.
Larynx also moves up when someone swallows which helps close the airway.
240
What lines the inside of laryngeal cartilage?
Biologically active soft tissue
Mucous to catch junk projected up through the airway.
241
If you clear your throat, what are you clearing?
Junk out of the larynx mucous, then down the esophagus for recycling.
242
What is the "big honkin' cartilage" in the larynx?
Thyroid cartilage.
243
Which laryngeal cartilage is a complete ring, and where is it?
Cricoid cartilage, bottom of larynx
244
Before 10 y/o, what is the most narrow point of the upper airway?
Cricoid cartilage
245
Where does pec minor attach to?
Corticoid process of the shoulder blade
Ribs 3-5
245
What can we do to prevent gastric contents from entering the larynx?
Is there any risk?
Cricoid pressure (taking a finger and pushing the front of the cricoid cartilage, compressing the esophagus)
If the patient is not fully paralyzed and has an abdominal contraction, the lower esophageal sphincter can get blown out and permanently lose function. It's not normally used to large pressures.
245
What is the greatest pressure the lower esophageal sphincter is normally subject to?
Vomiting, which is hopefully just a short period of time.
245
After 10 y/o, what is the most narrow point of the airway?
Space between the cords
245
What does the space between the cords allow for?
Air movement + phonation
246
What happens if pec minor contracts while upright?
Shoulder blades are pulled down
247
What happens if pec minor contracts while leaning on a desk? (hands resting on desk)
Scapula is secured, allows for better breathing.
248
What is an easy observation to make to see if someone is in terrible respiratory shape?
Watch for people constantly supporting themselves on things, or bad posture.
Note: If you're tall then maybe this doesn't apply as much, could just be desk height is uncomfortable.
249
What is the purpose of the Hyoid bone?
Attachment point for muscles in the floor of the mouth + cartilage in the larynx
250
What structure can be broken in the trachea with a swift karate chop to the neck?
Hyoid bone.
Cartilage typically will not break, only bend/distort
251
What is the largest cartilage in the larynx? What is it attached to?
Thyroid cartilage
Attached to the hyoid bone
Attached to the cricoid cartilage through the cricothyroid joint
252
What does the cricothyroid joint allow for?
Allows the thyroid cartilage to pivot down (inferior; pivots voice box forward)
253
What divides the cricoid cartilage into left/right?
Nothing. It's ringed, no opening to separate it.
254
Where does the thyroid cartilage inferior horn (AKA cricothyroid joint) connect to the cricoid cartilage?
Articular facet for thyroid cartilage
255
What are the sides of the cricoid cartilage called?
Lamina - singular
Laminae - pleural
255
Where else in the body do we use the term "facet" other than on the cricoid cartilage?
Thoracic spine for example
256
On the superior part of the cricoid cartilage, what small piece of cartilage attaches?
What is the purpose of this small piece of cartilage, and where does it connect?
Arytenoid cartilage
Purpose is to be one of the two connection points of the vocal cords (other connection point for the vocal cords is on thyroid cartilage).
Connects to the articular facet for arytenoid cartilage on the superior aspect of the cricoid cartilage.
257
What is the shape of the arytenoid cartilage?
Diamond
258
What is the projection point on the bottom of the thyroid cartilage that connects to the cricoid cartilage?
Inferior horn
^connection point for cricothyroid cartilage
259
A projection off of a structure in the nervous system/spine are called ____.
In the thyroid cartilage, a projection off of a structure is called ____.
Processes
Horns
260
The side of thyroid cartilage is called _____. What is special about this on the thyroid cartilage?
Lamina
This is where the thyroid gland sits.
261
What structure of the thyroid gland connects to the hyoid bone?
Superior horn of the thyroid cartilage.
262
What is another name for the Adams apple? What is special about it?
Laryngeal prominence
This is where the vocal cords attach to the front medial part of the larynx.
263
A larger laryngeal prominence results in what?
Reason mens voices are usually deeper than women
Larger prominence = longer cord = lower pitch
264
What are the two paired pieces of cartilage in the larynx?
Arytenoid
Corniculate
265
What are the three unpaired cartilages in the larynx?
Thyroid
Cricoid
Epiglottis
266
What is the cartilaginous appendage on the arytenoid cartilage?
Corniculate cartilage
267
What are the two points that the vocal cords connect to?
Laryngeal prominence
Arytenoid cartilage
268
What decides how open/closed, or how much tension is on the vocal cords?
Cricothyroid muscle, which is the most external laryngeal muscle. When contracted, pulls the front of the thyroid cartilage down. This tightens the vocal cords, raising pitch.
269
How many sets of muscles do we have that change vocal cord tightness, openness, or can close it?
6 sets of muscles allow us to speak through pivot/turning. (These muscles will be on test 4, not this one).
270
What can a carbamino group form on?
Anything with an exposed terminal amine group
271
Which is more soluble in solution, CO2 or oxygen?
CO2
272
If you have a solution + gas in a container, what should the partial pressure of a mystery gas be?
Partial pressure will be the same in solution as it is in gas. It will find equilibrium.
273
When carbonic acid dissociates into H+ + HCO3-, what happens to the protons?
Some float around in solution, dropping pH
Others are buffered by proteins (Hgb, immunoglobulins, clotting factors)
274
If you add a lot of CO2 here, what happens?
H + HCO3 is produced. Not all protons can be buffered, resulting in more free H+, which drops pH
275
What happens as blood goes through peripheral tissues to the lungs? (tissue gas transport)
Tissue produces CO2 ->
Enters CV system through capillary wall since it’s a gas ->
Some remains in plasma, but larger portion goes to red blood cell ->
Portion of that in dissolved state, but a larger portion combines with water ->
Forms carbonic acid ->
Dissociates rapidly into bicarb and a proton
276
What special transporter do we have inside the RBC?
Bicarb chloride exchanger.
As Chloride is produced in the RBC, a portion of bicarb is grabbed by transporter and exchanges for chloride. Bicarb out, chloride in. Chloride stays in RBC until blood gets back to lungs, where transporter works in opposite direction.
277
When carbonic acid dissociates to the right into H+ and HCO3, what happens to the protons?
Some hang out in solution, but larger portion is buffered by proteins.
277
What is the most notable buffer of protons inside a RBC?
Hemoglobin
278
Typically, saturated hemoglobin isn't a great proton acceptor. When can this change?
When it becomes deoxyhemoglobin, it can accept protons much more readily.
279
Which is more likely to accept a proton?
What about donate a proton?
Weak acid wants extra protons
Strong acid wants to give away protons
279
How does pH impact oxygen unloading?
Higher CO2 leads to lower pH/acidic environment in the RBC.
More protons decrease hemoglobin affinity for Oxygen, which helps with unloading oxygen.
280
How long does it take for gas exchange to happen in pulmonary capillaries?
0.25 seconds
Oxygen comes in, dissolves with blood, and is packed away to storage locations on hemoglobin in this time. CO2 is off gassed.
281
How long does blood hang out around the pulmonary capillaries at rest?
0.75 seconds.
281
PO2 entering pulmonary capillaries are usually
40 mmHg, but can be higher/lower in different circumstances
282
If we increase cardiac output, what happens to time spent in the pulmonary capillaries/oxygenation?
Is this a problem?
More recruitment/distention
but
Blood can spend as little as 0.25 seconds in the pulmonary capillaries.
Not a problem in a healthy person since it takes 0.25 seconds for gas exchange to occur.
In an unhealthy person (i.e. fluid in lungs, or something slowing gas exchange) this could be a problem.
283
Why might a diffusion problem not be discovered until picking up level of activity?
0.25 seconds for gas exchange normally
0.75 seconds spent in pulmonary capillaries normally.
With gas diffusion problems, gas exchange times increase.
Cardiac output increases can make blood spend as little as 0.25 seconds in the pulmonary capillary, creating a problem with diffusing enough gas.
284
If we breathe in N2O, why does it diffuse faster than 0.25 seconds? (or faster than oxygen)
Nitrogen doesn't have many places to go in the blood, it's very insoluble. Not much nitrogen will actually come on board, so equilibration happens quickly.
"Low permeability in blood"
285
Rank solubilities
Nitrogen
Oxygen
Nitrous Oxide (N2O)
Oxygen is the most soluble
Nitrous Oxide (N2O)
Nitrogen is the least soluble (so equilibrates the fastest)
286
Why is carbon monoxide used in the pulmonary function lab?
Diffusion is similar to O2.
Used as a diagnostic gas to look at diffusion capacity of the lung.
Faster we diffuse carbon monoxide, the better diffusion we have and vice versa.
287
What common environmental things can get carbon monoxide in your blood?
Sitting in the drive through
Changing oil
Smoking
288
How can you find out if your kiddos smoke?
Blood test - CarboxyHemoglobin.
Should be zero unless you work on machinery, drive thru, smoke
289
What should a healthy persons carbon monoxide level be?
Zero
290
If the diffusing capacity of the lungs is 1/4 normal, how long will it take for diffusion to occur?
0.75 seconds - we can live with this (minor pneumonia)
290
What is perfusion limited gas absorption, and what does it usually happen with?
Happens with oxygen diffusion
Amount of O2 absorption depends on how much blood is moving through the lungs, assuming equilibration time of 0.25 seconds.
To increase O2 absorption, we can increase blood flow through the lungs, thus perfusion limited.
291
If the diffusing capacity of the lungs were 1/8th normal, what is the problem?
At the 0.75 second mark, PO2 is not even to 60 mmHg yet.. usually a problem with fluid in the lungs. Water doesn't let oxygen diffuse very well. CO2 is also slowed.
292
What is diffusion limited gas absorption?
Not normal - getting enough blood flow, just don't have enough diffusion. Might have fluid in lungs, etc.
No equilibrium between capillary blood and alveolar air.
293
Would the 1/4th or 1/8th normal blue lines represent diffusion or perfusion limited gas exchanges?
Diffusion limited. Note that is does NOT reach the alveolar plateau.
If something DOES reach the alveolar plateau, it is perfusion limited. This means it is reaching equilibrium.
294
Label the following: Diffusion or perfusion limited?
Nitrogen
Oxygen
Carbon monoxide
Nitrogen - perfusion limited; plateau
Oxygen - perfusion limited; plateau
Carbon monoxide - diffusion limited; no plateau
295
What is the formula for Fick's Law for diffusion of gas?
296
Label the variables of Fick's law for diffusion of gas.
A - area
D - diffusivity
(P1 - P2) - pressure difference
T - Thickness of barrier
297
The thicker a barrier is, the ____ it moves across a barrier.
Slower; applies to gas exchange.
298
If someone is working out, what happens to area for diffusion?
Causes distention and recruitment, activating additional alveoli and gives us more surface area for gas exchange when needed.
298
The surface area of our gas diffusing areas of the lungs is about the size of what?
A tennis court, which is 70 m2 (2 is a superscript)
299
Area for gas exchange is dependent on ___.
Perfusion
Low perfusion = low recruitment = less gas exchange
High perfusion = high recruitment = more gas exchange
300
The greater the pressure difference, the _____ rate of diffusion.
The smaller the pressure difference, the ____ rate of diffusion.
Faster
Slower
301
What two things does diffusivity take into account?
Solubility of the gas
Square root of the molecular weight of the gas
An example of this is that CO2 is much more soluble in blood than O2 is.
302
How much more soluble is CO2 than O2 in blood?
CO2 is 24x more soluble than oxygen
303
Why does oxygen come into equilibration so quickly if you raise FiO2?
When OxyHgb is low, there are many places for oxygen to go hang out (i.e. binding sites on deoxyhemoglobin). Once at 100%, the small amount that gets absorbed happens very quickly.
303
The difference in the ratio between the square root of the molecular weight of O2 and CO2 is ___. This means that on the basis of molecular weight, ___ diffuses faster than ___.
0.85
Oxygen; CO2
However, CO2 is more soluble, leading to faster diffusion.
303
What formula can we use to see why CO2 diffuses better than O2?
304
If we based diffusion on size, which would move faster? Oxygen or CO2?
Oxygen since it's smaller, however this is not the case. We have to take solubility and the square root of the molecular weight into account.
305
What is our normal alveolar ventilation?
Perfusion?
How about VQ ratio?
V = 4,200mL/min (350ml x 12RR)
Q = 5,000mL/min (Cardiac output)
VQ = 4,200/5,000 =0.84
However - Schmidt says 80%, but that anything between 80-85% is fine for us.
306
Normal VQ ratio will have what level of PO2 and PCO2 post alveoli?
100mmHg O2
40mmHg CO2
307
If you have a block of ventilation to the alveoli, what will the gasses look like?
Similar to what the pulmonary artery looks like.
PO2 will be 40 mmHg
PCO2 will be 45 mmHg
308
If you have a block of perfusion to the alveoli, what will the gas look like?
What will the body do to fix this?
Alveolar air will look close to inspired air.
PO2 150mmHg @sea level
PCO2 will be 0mmHg
Body will put more ventilation to other parts of the lungs to bridge the gap
309
Less ventilation than normal will result in a ___ VQ ratio.
Less perfusion than normal will result in a ___ VQ ratio.
Lower
Higher
310
What is a word to describe blood flow through non ventilated alveoli?
Shunt
311
When finding the partial pressure of a gas in a mixed sample, what two things do you need to take into account?
Alveolar and anatomical dead space
312
Gas coming from alveolar air will have a ____ PCO2 than dead space air.
PO2 of alveolar air will be ___ than what PO2 would be in dead space air.
Higher
Lower
312
Why are partial pressures of gases lower after inspiration?
Take into account water vapor diluting gasses within the respiratory system.
313
What area of this flow volume loop are we most interested in? Why?
Effort independent phase
If abnormal, it means that there is trouble getting air out of the lungs. Tells us how easy it is to collapse small airways, and shows small airway disease.
314
Why is the FEV1/FVC ratio important?
If low, tells us that there is a harder time getting air out of the lungs.
315
What is FEF 25-75%?
Forced expiratory flow rate during the middle of the breath.
Note: This will be on the final exam, but not this exam. It's a measure of small airway reactivity.
316
What volume/capacity would change the most if someone went upright to supine?
FRC has the biggest change.
317
FRC being reduced is a function of what volumes changing?
What does not change?
ERV reduction
IRV increase
TLC doesn't change as far as our class goes, though Levitski says it decreases a little.
317
What is ME an abbreviation for?
Mixed expired air
318
What are capnographs really sensitive to? What can we do to fix this?
Moisture
The sampling line usually has a moisture trap. If we don't use it, the machine won't work right.
318
Alveolar air should be roughly equal to what?
Arterial blood gas, assuming you're healthy.
319
What does the plateau of this capnograph describe?
Composition of lung air; lines up with ABG assuming no shunt/dead space problem.
End tidal CO2 should be roughly 40 mmHg
320
Why is there a slope in the plateau of the capnograph?
As we expire, we still are passing deoxygenated blood through the alveolar capillaries, meaning we are offloading additional CO2.
321
PCO2 should be about 40 mmHg.
When is it at its lowest point?
Highest point?
Lowest - when fresh air hits the lungs.
Highest - no fresh air, end of expiration where CO2 is still offloading into alveoli (top of plateau)
321
How many seconds do we have during inspiration?
Expiration?
Nothing?
Average RR?
2 seconds in
2 seconds out
1 seconds nothing
RR = 12
322
How do you find what alveolar PCO2 fluctuation is between breaths in mL?
How about the new PCO2 after a breath?
Expected to know:
Alveolar PCO2 = 40 mmHg
FRC = 3L
Alveolar air = 350mL
Get fraction of CO2 in the lungs between breaths:
FACO2 = partial pressure of gas/total pressure
5.263% = 40 mmHg/760 mmHg
Fraction CO2 x FRC = amount of CO2 in mL
5.263% x 3,000mL = 158mL CO2 between breaths
To get alveolar CO2 in mL after a fresh breath:
FRC + alveolar air = Total air in lungs
3,000mL + 350mL = 3,350 mL
Then, get new fraction of CO2 in alveolar air.
(Quantity of CO2 in alveoli before breath)/total volume = concentration CO2
158mL/3,350mL =0.0472, or 4.7% CO2
Finally, to get PCO2 after taking a breath in:
(New concentration CO2 in alveolar air after breath) x (total pressure) = PCO2
4.7% x 760 mmHg = 35.8 mmHg CO2 after a breath of fresh air in alveolar air
323
How many seconds do we have to unload CO2 into lung air?
What is CO2 unloading a function of?
5 seconds
Function of time
323
As CO2 unloads in lung air, we get closer to 40 mmHg. What is the lowest alveolar PCO2 usually gets?
~36 mmHg PCO2.
324
What area of the capnograph is used to approximate conditions in the lungs?
End of the plateau will be roughly what arterial blood gas is like
324
Why would we have a reverse slope on a capnograph? (i.e., highest CO2 was first, then decreased throughout the expiration)
Late stage emphysema. Lung compliance is really high, so they are prone to small airway collapse.
Thinking about different VQ qualities of different areas of the lungs, we know that PCO2 on the top of the lungs is lower than average, and PCO2 out of the base is higher than average.
In emphysema, lower airways collapse first, leaving the top of the lung open longer. The longer the expiration lasts, the more air comes from the top of the lungs, leading to a lower PCO2.
324
Does a reverse slope capnograph happen in mild COPD?
No. Only severe late stage emphysema.
325
Given this capnograph, why is there a delay in CO2 showing up from expiration?
This patient is on a ventilator. Capnograph pulls off luer on the Y piece of the circuit, which is long. This results in a delay on the capnograph due to the length of the respiratory circuit.
326
How does alveolar dead space impact capnography?
Alveolar dead space will not have CO2, and empties at the same time as functioning alveoli.
More alveolar dead space = lower PCO2 on capnography, and reduces the slope.
327
Looking at a capnograph, how can you determine a relative amount of alveolar dead space someone has?
Look at end tidal CO2 and arterial blood gas PCO2. These should be close together. If not, this tells you that you have alveolar dead space. The bigger the difference, the larger the alveolar dead space.
328
Longer ventilator use = ___ pressure needed to keep the lungs open
Higher
329
How much O2 is in the lungs in between breaths in a healthy adult @ rest, upright in mLs?
Expected to know:
Total (atmospheric) pressure = 760 mmHg
PAO2 (aka oxygen tension) = 100 mmHg
FRC = 3L
Take partial pressure and figure out concentration of oxygen in alveoli.
100 mmHg/760 mmHg = 13.16% O2 concentration
To find volume in mLs,:
Concentration x volume
13.16% x 3,000 mL = 395 mL O2 in the lungs at FRC
330
When taking a breath of fresh air in, how much does PCO2 drop?
4mmHg (from 40 to 36)
331
In dry atmospheric air, what is the oxygen concentration?
What happens when we breathe it in, and what is the new concentration as we go deeper in the respiratory system?
21%
It gets humidified, which brings it to 19-20% concentration.
As we go deeper in the respiratory system, it gets lower until ~13% concentration which gives us a PO2 of 100 mmHg (~13% x 760 = about 100)
332
How much oxygen do we use per minute?
250mL O2/min
333
Given a normal amount of oxygen in mL in the alveoli at FRC, how long can we hold our breath?
When may this change?
Use 250mL O2/min
Have 395mL O2 in the alveoli
This gives us a little under two minutes of oxygen available if we are holding our breath normally.
The above assumes an upright awake patient. We anesthetize and lay our patients supine, which reduces FRC, thus reducing the amount of O2 in the alveoli. If we paralyze our patient, they can drop BELOW RV. This decreases our buffer significantly, which is why we pre oxygenate to pack more air into the lungs for if something goes wrong.
334
When paralyzing a patient, how low can lung volumes get?
Less than 1L, below RV (normally 1.5L)
335
Will hyperoxygenating a patient hurt them for pre-intubation?
Not for short term, OK for intubation especially after paralyzing to buy you time before the patient goes anoxic.
336
Which lung is bigger and why?
Right lung is bigger and heavier than the left lung.
Left lung has space carved out for the heart.
337
How many lobes does each lung have?
Left - 2 lobes
Right - 3 lobes
338
Which lung is taller?
Left is taller than the right lung
339
How many fissures does the right lung have, and what are they called?
2
Horizontal & oblique fissures
339
What are the lines that separate lung lobes called?
Fissures
340
What are the subdivisions within the lungs called?
Bronchopulmonary segments
341
How many bronchopulmonary segments does each lung have?
Total amount?
Right - 10
Left - 8 since it's a smaller lung
Total - 18
342
What connective tissue is there outside of the lung, and what is the purpose?
What problems can occur?
Visceral pleura – attached to organ
Parietal pleura = on chest wall
Thin layer of fluid that helps lungs slide without friction
Infection causes friction which makes breathing painful. Note that pain can be from large airways as well.
343
The pleural space is a potential space for fluid, not much else.
What is the exception?
Little pocket of air at the lower side of the diaphragm under the left lung called the costodiaphragmatic recess.
If we have air, will likely be there.
344
The diaphragm is fastened to what, and what shape is it?
Where does it connect to?
Base of the thorax, shaped like a dome on each side of the abdomen.
Connects to the central tendon
345
As we breathe, why does the heart move around?
The heart sits on the central tendon, so when the diaphragm contracts the heart moves up and down.
345
Why is the left lung taller than the right?
The heart sits on the central tendon on the left side of the diaphragm, which depresses it slightly down. The left lung also sits on the central tendon, so it's taller.
346
Inferiorly, where does the diaphragm anchor?
L spine vertebral bodies
347
Getting air out of the lung is a result of what?
How about getting air in (normally)?
Passive recoil of the lung. - out
Contracting the diaphragm drops it, stretching the lung out, pulling in lots of air.
348
How many scalene muscles do we have, and where are they?
3 sets of scalene muscles on connecting on either side of the neck and top two ribs
348
If we want to get a deeper breath in, what muscle do we rely on? Why?
Scalene muscles (3 sets, 6 total)
Helps hold the top of the thorax in position as the diaphragm drops. Without these, breathing in would drop the rib cage down, not allowing for air to enter lungs.
349
What are the three parts of the pharynx?
Nasopharynx - opening in nose
Oropharynx - oral cavity
Laryngopharynx - everything below oral cavity; portion of the pharynx that attaches to the trachea
350
Why is the tongue striated in this picture?
Why is this significant?
The tongue & floor of the mouth that it's attached to is skeletal muscle, which means paralytics will work on it.
if supine and paralyzed, the tongue will occlude the opening of the larynx and block the airway.
351
Notice that the bone is porous in the center of this picture. Why?
Blood vessels run through the pores. This area needs to be vascular because it is constantly heating/humidifying the airway as soon as it is inspired. You need blood flow to areas that are responsible for producing moisture.
352
If you for whatever reason lost blood flow to your nose, would the larynx dry out?
What about the lungs?
The larynx would dry out, but the lungs would remain humidified.
353
We have three sets of bony projections in the nose. What are they? Any special shapes?
Superior concha - 2 total, curved
Middle concha - 2 total
Inferior concha - 2 total, even more curved than the superior concha
354
Why are concha curved in the nasal sinus?
Concha are used to make turbulence as we inspire so air hits the walls of the nose, trapping foreign bodies in mucous
355
What ratio of breathing is through the nose vs the mouth?
50/50
356
What is the other name for concha?
Turbinates
356
The concha/turbinates cause turbulence and catch particulate matter into mucous.
What types of things can get caught?
Anything that can't get caught?
Pollen, dust - can get trapped
Smoke - does not get trapped, just goes to the lungs
357
What bone do the top two concha come off of, and what's special about it?
Ethmoid bone (red color in pic), which sits right in the middle of the face behind the opening of the nose.
It's fragile. Punch someone in the face and this is likely to break, causing lots of bleeding.
358
_____ concha are continuous with the ___ ____ which are projections of the ____ bone, which is the top part of the jaw/mouth where teeth are anchored in.
Inferior
Hard palate
Maxillary bone
359
What kinds of patients will be at greater risk for ethmoid bone fracture (or concha fracture)?
Osteoporosis
Nasal intubation
Punched in the face
Note: Bleeding in the airway can be caused by this, which isn't great
360
Which concha are the most sturdy? How should you nasally intubate people if you have to?
Inferior concha are the most sturdy. Aim for the floor of the nose (which is fairly flat) when nasally intubating to avoid bleeding and potential fractures.
361
The majority of the face has sensory function relayed through the _____ nerve. This is cranial nerve _.
Trigeminal; V
361
What is the upward projection on the ethmoid bone? What's that do?
Crista Gali; connection point for the fall cerebri, the connective tissue in the brain that separates the left and right hemisphere
362
How many divisions are there of the trigeminal nerve (CN V), and what are they/what do they do?
Ophthalmic (V1)
Forehead sensory
Maxillary (v2)
Upper part of mouth sensory
Mandibular (v3)
Jaw sensory
363
Where does the sternocleidomastoid muscle attach?
Right behind the external acoustic meatus, or ear opening.
364
What mouth structure is seen here?
Hard palate, which is the bony top of the mouth.
365
Note the crista gali (superior projection off of the ethmoid bone). This is where the falx cerebri attaches, which separates the left and right cerebral hemispheres.
Note also that the ethmoid bone is porous. Why?
Gives us route for smell sensors to pick up scents from nose and relay it to the brain.
366
Where are smell sensors located? How do they get to the nose?
Smell sensors themselves are located at the top of the ethmoid bone. Growth projections wind through the pores of the ethmoid bone to the top of the nasal cavity.
367
When growth projections from smell sensors reach the top of the nasal cavity, they have to route through what structure (other than the ethmoid bone).
Cribiform plate
368
What's another name for smell sensors?
Smell sensors = olfactory neurons
They wind through the ethmoid bone and cribriform plate to get to the top of the nasal cavity
369
Why is the nose a great place to absorb drugs?
Lots of blood flow given porous bone, and has lots of neurons that take a direct route to the brain.
370
Within the upper airway, what does the trigeminal nerve (CN V) innervate?
Oropharynx + a little bit of nose
371
What is cranial nerve IX, and what does the it take care of in the upper airway?
Glossopharyngeal nerve
Back of the mouth (just anterior to the epiglottis)
yellow places in this picture
372
What cranial nerve is CN 10? What does it take care of in the upper airway?
Vagus nerve is CN 10. It takes care of the back of the oropharynx (including the epiglottis) down through the larynx, as well as the trachea.
In other words, from the back of the mouth (oropharynx) through the larynx (laryngopharynx) and down to the lungs/trachea
373
What is somatic sensation typically?
Tickle/itch
373
Why do we get the dreaded "ice cream headache?"
How can you stop it quick?
We have a ton of nerves under the roof of the mouth.
Nerves in the mouth sense the cold, but get confused where the pain is coming from. We get pain on the forehead because the trigeminal nerve gets confused.
Stop it by pushing your tongue on the roof of your mouth. This warms up the nerves, causing the pain to go away.
374
What cranial nerve is responsible for the epiglottis closing the larynx to direct food to the esophagus when swallowing?
Vagus nerve (CN X)
375
What cranial nerve handles touch/irritation to the back 1/3 of the tongue?
CN IX, glossopharyngeal nerve
375
What cranial nerve takes care of pressure, pain, tickle, and itch on the front anterior tongue?
The mandibular division of Cranial nerve V, which is the trigeminal nerve
"CN V 3"
376
Do we have taste sensation on the epiglottis?
Maybe a little, but for our class, no. If we did, it would be controlled by the vagus nerve.
377
Which cranial nerve takes care of taste at the back of the tongue?
CN IX, glossopharyngeal nerve
378
Which cranial nerve takes care of taste on the front 2/3rds of the tongue?
CN VII, facial nerve via corda tympani
