4/1 Lecture Flashcards by TWU .

Mixed expired gas is combination of gasses from what 2 places?

Dead space gas

Good alveolar gas

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Dead space air in a normal healthy patient should be ____________

150 mL or 1 mL per lb of IBW

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Good alveolar air in a normal healthy patient should be ____________

350 mL

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P_{E_CO₂} should have a ________ PCO₂ than dead space air

higher

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P_{E_O₂} should have a ________ PO₂ than dead space air

lower

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What is the P_{E_O₂} based off the math we learned with Dr. Schmidt?

115 mmHg

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When anaylyzing a flow volume loop, a “goofy” or abnormal ________________ indicates that the patient is having a hard time getting air out of the lungs because the airways are collapsing

effort independence phase

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The one thing that forces the airway to collapse is a _____________

maximal force effort

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Maximal force causes ____________ in the chest and collapses the alveoli. This increases alveolar pressure and also acts on the small airways

positive pressure

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When moving from upright to the supine position, what is the volume or capacity that has the biggest change?

FRC

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T/F: TLC is slightly reduced when a person changes frmo the upright to supine position

Schmidt said this is not true despite the practice quesiton in the Lange book

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In a normal, healthy patient, expired air should be similar to the ____________ unless something is really wrong.

arterial blood gasses (ABG)

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CO₂ Capnography

What is the PCO₂ of point A? What part of the lung is air coming from at that point?

PCO₂ = 0 mmHg

Air is coming from dead space

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CO₂ Capnography

Where letter reflects the transitional phase of the graph? Where is

B this is when CO₂ starts to show up on the graph

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CO₂ Capnography

This part of the graph is similar to what occurs in Fowler’s test.

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CO₂ Capnography

Which letter would reflect the arterial PCO₂ if the patient is normal and healthy?

E or F

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CO₂ Capnography

Which letter relects where PCO₂ would be highest right before fresh air comes in?

E or F

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CO₂ Capnography

Which letter relects where PCO₂ would be lowest when fresh air is hitting the lung?

A or I

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CO₂ Capnography

Where does expiration begin?

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CO₂ Capnography

Where does inspiration being?

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CO₂ Capnography

Which letter reflects what the end-tidal CO₂ would be?

E or F

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CO₂ Capnography

The PCO₂ will be at the ________ point when the fresh air hits the lung

lowest
(A or I)

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CO₂ Capnography

The PCO₂ will be ________ at the end of the cycle right before the fresh air comes in

highest

(E or F)

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T/F: Blood flow is continuous & doesn’t stop during breaths

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What would an inverted slope on capnography indicate?

Late-stage emphysema

In emphysema, the small airways collapse earlier, starting at the ____________ of the lungs. In this situation, CO₂ from the top of the lung has a ____________ concentration than CO₂ from the base.

base; lower ____________

At the base of the lungs, the V/Q ratio is ____________ than average, leading to ____________ CO₂ concentrations.

lower; higher

At the apex of the lungs, the V/Q ratio is ____________, which results in ____________ CO₂ concentrations.

higher; lower

If someone has severe emphysema, the small airways are collapsing at a crazy pace during expiration. What part of the lungs will collapse first?

Base The apex will collapse later

Why does the base of the lung collapse before the apex?

The base of the lung has smaller alveoli so the airways are smaller so if an area of the lung is going to collapse, it would probably be the base of the lung first. Think of LaPlace's Law!!!!

T/F: During airway collapse, the concentration of CO₂ coming from the top of the lung will be a lot higher than concentration of CO₂ coming from the bottom of the lung.

F During airway collapse, the concentration of CO₂ coming from the top of the lung will be a lot **lower** than concentration of CO₂ coming from the bottom of the lung. At the apex of the lungs, the V/Q ratio is higher, which results in lower CO₂ concentrations.

T/F An inverted slope on capnography can be observed in patients with mild COPD.

F This is only seen in patients with severe emphysema

Where does inspiration begin on the graph?

Why is there a slight delay for the start of inspiration (H) on the graph?

The capnograph doesn’t instantly detect the expired air coming from the patient because **the exhaled air has to travel through the tubing**, causing a staggered offset.

Capnographs are highly sensitive to ________ in the system.

moisture

Without a ________________, the capnograph readings becomes unreliable

moisture trap

The first portion of expired air comes from anatomical dead space. What should be the PCO₂ here?

PCO₂ = 0 mmHg No gas exchage happens here

As expiration continues, air moves from the anatomical dead space into the alveoli, where gas exchange occurs. What should be the PCO₂ here?

The concentration of CO₂ increases as the exhaled air begins to include air from the alveoli, which has a higher CO₂ concentration due to the exchange of gases with the blood.

________________ refers to areas of the lung where ventilation occurs but no effective perfusion (blood flow) happens, such as in cases of pulmonary embolism or certain lung diseases.

Alveolar dead space

T/F: Alveolar dead space air should contain CO₂.

F Alveolar dead space air should ideally not contain any CO₂, because there is no exchange of gases between the alveoli and the blood (due to the lack of blood flow).

How would the presence of alveolar dead space air effect end-tidal CO₂? How would this effect capnography?

It would dilute/reduce the end-tidal CO₂ Alveolar dead space air lacks CO₂ this mixes with the alveolar gas from alveoli that are particpiating in gas exhange which dilutes the overall CO₂ levels This will reduce the slope on capnography

What does a reduced slope (orange line) on capnography represent?

The presence of alveolar dead space

How can you quickly detect how much alveolar dead space a patient by looking at the capnography?

Look at the ETCO₂ and P_{A_CO₂} (arterial blood gas), they should be similar values in a normal healthy patient. ETCO₂ will be **a lot lower** than P_{A_CO₂} (arterial blood gas) if is a lot of alveolar dead space present. The greater the difference between the two values, the more alveolar dead space that is present.

What is one way alveolar dead space can develop?

Prolonged mechanical ventilation (will cause atelectasis leading dead space)

The Bohr equation was made by the same guy that made __________________

oxyhemoglobin dissociation curve shift.

____________________ = Anatomical DS + Alveolar DS

**Physiologic Dead Space** = Anatomical DS + Alveolar DS

In the chest, what are the 2 barriers to putting air into the lungs?

The lungs themselves The chest wall can get in the way

The apex of the lung sits above ____________ (lungs are very high up in chest)

rib 1

The lungs have a natural tendency to recoil ________ and the chest wall has a natural tendency to recoil ________

In; out

What are the abbreciates for elastic recoil pressure?

P_ER P_EL

The lung favors being ________ as possible, it would be happy if it were ________

empty

The chest wall at a normal FRC has the tendency to recoil ________

outwards

How is the negative pleural pressure in the lungs made?

The chest wall and lung recoiling in different directions creates negative pressure

The only thing that holds the chest wall into place is the lung’s _______________

inward elastic recoil

T/F: The chest wall is normally opposed the opposite forces of the lungs tissue.

The chest wall is normally opposed by elastic lung tissue and if some of that is lost, there's less opposition to the chest wall which will cause ____________ (3 things)

1. barrel chest, a protuding chest, larger lungs 2. More positive pleural pressures

With COPD or emphysema, the lung lacks elastic recoil and become very full/large and P_IP is going to be more ________________

positive

For a normal, healthy patient to reach total lung capacity, what does the the transpulmonary pressure need to be? What about a patient with an obstructive disorder? What about a patient with a restrictive disorder?

Normal = 35 cmH₂O Obstructive = 10 cmH₂O Restrictive = 40 cmH₂O

What is another term for "normal end-expiratory lung volume"?

FRC

What is the pulmonary compliance for a normal, healthy patient at FRC?

0.2 L/cmH₂O

What is the total compliance for a normal, healthy patient at FRC?

0.1 L/cmH₂O

What is the chest wall compliance for a normal, healthy patient at FRC?

0.2 L/cmH₂O

____________if something fills the potential space, this is a loss of the integrity of the chest wall is how hard it is to push current through some kind of conduit

Resistance

If something fills the potential space, this causess a loss of the integrity of the chest wall and the lung will ____________

collapse