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AP (2) > Exam 2 Lecture 10 (2-28-23) Pulmonary (HPV, Inspired Partial Pressures, Aveolar Compliance Chart) > Flashcards

Exam 2 Lecture 10 (2-28-23) Pulmonary (HPV, Inspired Partial Pressures, Aveolar Compliance Chart) Flashcards

1
Q

What happens to FRC when we sit?

What happens to FRC when we are supine?

A

FRC decreases slightly when we sit.

FRC decreases significantly when we are supine.

(8:00)

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2
Q

So typically at rest, under normal conditions in somebody who’s young and healthy. We have excess ____________ in our lungs that aren’t always being used.

A

blood vessels/capillaries

Increasing cardiac output will utilize these blood vessels in the lungs. This is called recruitment. Blood vessels that are already recruited can also become larger (distension).

(12:30)

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3
Q

How will recruitment and distention affect pulmonary vascular resistance?

A

Lower Pulmonary Vascular Resistance

As more blood is pumped into the lungs, more parallel pathways (recruitment) are utilized decreasing resistance. With distention, wider blood vessels will decrease resistance.

(14:45)

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4
Q

What is the relationship between pulmonary blood flow (PBF) and pulmonary vascular resistance (PVR)?

A

There is an inverse relationship between PBF and PVR. As PBF increases, PVR decreases.

Low PBF will increase PVR. (This will be bad for someone with a failing right heart, b/c the right heart will have to pump blood against a high-resistance pulmonary system)

(16:00)

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5
Q

Flow in the lungs depends on ________.

A

Pressure

More pressure, more flow, more perfusion.
(18:09)

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6
Q

Pressure at the base of the lung tends to be _______ than the pressure at the apex of the lung.

A

higher (due to gravity)

(19:30)

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7
Q

In regards to the lungs, what zone number will have continuous blood flow?

A

Zone 3 (base of the lung)

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8
Q

As you go above zone 3 to zone 2 in the lungs, blood flow tends to be more _________.

A

Pulsatile (Variable blood flow only occurring during the middle of systole where there is the greatest pressure.)

(21:00)

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9
Q

What are the two types of blood flow in a healthy lung?

A

Continuous Blood Flow (Zone 3)
Pulsatile Blood Flow (Zone 2)

(21:15)

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10
Q

In a pathological condition, what zone in the lungs will have no perfusion during any part of the cardiac cycle?

A

Zone 1 (In a normal healthy adult, there will not be a zone 1 because there will be perfusion to the top of the lungs)

(23:30)

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11
Q

List Alveolar Pressure (PA), Pulmonary arterial pressure (Pa), and Pulmonary venous Pressure (Pv) from highest to lowest in Zone 1, Zone 2, and Zone 3.

A

Zone 1: PA > Pa > Pv (no perfusion)
Zone 2: Pa> PA > Pv (pulsatile perfusion)
Zone 3: Pa > Pv > PA (continuous perfusion)

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12
Q

What conditions can cause lungs to have zone 1?

A

Positive Pressure Ventilation
Pathological Conditions (Low pulmonary arterial pressures)

(26:00)

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13
Q

This graph shows the relationship between pulmonary blood flow and lung distance below rib 2 (apex). Blood flow tends to increase as lung distance increases below rib 2. What causes the decrease in blood flow at the base/bottom of the lungs? What is this region called?

A

The bottom of the lung is supporting the weight of the organ and because we have compression at the base of the lungs, we tend to have lower perfusion. John West calls this region Zone 4.

(30:00)

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14
Q

Pulmonary blood capillaries are regulated by what blood vessels upstream?

A

Pulmonary arterioles

Constricted upstream arterioles will increase PVR. Relaxed upstream arterioles will decrease PVR.

(32:00)

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15
Q

What are the active influences that increase pulmonary vascular resistance?

A

Stimulation of SNS
Pressors (alpha agonist, NE, EPI)
Inflammatory Agents (PGFA2, PGE2)
Thromboxane
Endothelin
Angiotensin
Histamine
Alveolar Hypoxia (Low O2)
Alveolar Hypercapnia (High CO2)
Low pH of mixed venous blood

(34:00)

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16
Q

What are the active influences that decrease pulmonary vascular resistance?

A

Stimulation of PNS
Prostacyclin (PGI2)
Acetylcholine
Nitric Oxide
Bradykinin
Beta-adrenergic agonist

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17
Q

What is Hypoxic Pulmonary Vasoconstriction (HPV)?

A

Decreased levels of O2 and Increase CO2 in the alveoli will cause vasoconstriction to direct pulmonary perfusion to areas where there’s better ventilation.

(36:00) (47:00)

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18
Q

Airway smooth muscles tend to _______ with ACh.
Pulmonary vasculature tends to __________ with ACh.

A

Airway smooth muscles tend to constrict with ACh.
Pulmonary vasculature tends to relax with ACh.

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19
Q

Blood Gas Value in a Systemic Venous Blood Draw
O2:
CO2:

A

O2: 40 mmHg
CO2: 45 mmHg

(42:45)

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20
Q

What is the value of the following pulmonary arterial blood gases?
O2:
CO2:

A

O2: 40 mmHg
CO2: 45 mmHg

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21
Q

Blood Gas Value in a Systemic Arterial Blood Draw
O2:
CO2:

A

O2: 100 mmHg
CO2: 40 mmHg

(43:45)

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22
Q

What is the value of the following pulmonary venous blood gases?
O2:
CO2:

A

O2: 100 mmHg
CO2: 40 mmHg

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23
Q

Describe the gas exchange process in a normal condition.

What happens to CO2?

A

Oxygen from the outside environment will into the alveoli, and then across the capillary wall, and we have oxygenation of mixed venous blood.

CO2 will be unloaded into the alveoli and escapes into the outside environment during expiration.

(44:30)

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24
Q

What happens to the O2 and CO2 values in the alveoli if there is some sort of obstruction upstream to it?

A

The O2 value of the alveoli will drop to 40 mmHg.
The CO2 value of the alveoli will increase to 45 mmHg.

The gases in the alveoli will be equal to pulmonary arterial gases

25
Q

In regards to pulmonary blood vessels, Hypoxic Pulmonary Vasoconstriction is _________than the constriction to the elevated CO2.

A

Stronger/Greater

(48:30)

26
Q

What is the downside of HPV?

A

There will be an increased workload on the right heart.

(49:00)

27
Q

If you climb a really high mountain, where the air is thin, and atmospheric pressure is low. What will our lungs look like?

How can this affect the heart?

A

Lungs will appear hypoxic d/t decreased partial pressure in the atmosphere. This will result in less O2 coming into the alveoli.

There will be HPV throughout the entire lung. The increase in pulmonary vasculature resistance will significantly increase the workload on the right heart, which can result in a heart attack.

The partial pressure of oxygen on Mt. Everest is 30 mmHg, according to Dr. Schmidt.

(50:00)

28
Q

Why would it be a bad idea to give someone high-inspired oxygen if they have an obstruction to the alveoli?

A

Giving someone high-inspired O2 will increase the amount of O2 in the alveoli, but it might not be enough to provide an adequate gas exchange. Instead, there will be a decrease in HPV, resulting in poorly oxygenated blood making it through areas that really shouldn’t be perfused.

Furthermore, giving high-inspired O2 will not fix the increased retention of CO2 levels in the alveoli.

(52:00)

29
Q

What three examples did Dr. Schmidt use where giving 100% FiO2 can be detrimental?

A
  1. Obstruction to the Alveolus (Decrease HPV)
  2. COPD (Decrease Ventilation/ Hypercapnia)
  3. Prolong use of 100% FiO2 will shred the lungs (Oxidation)

(73:00)

30
Q

What gases make up the dry gas mixture?
What are their concentrations?
What are their partial pressures?

A
31
Q

What is the formula for partial pressure?

A

Partial Pressure = Total Pressure x Concentration of Gas

Example:
What is the partial pressure of O2?
Total Pressure = 760 mmHg (At sea level/normal)
O2 concentration = 21%

760 x 0.21 = 159.6 mmHg

32
Q

So as soon as air enters the body, what happens is that it’s typically warmed and humidified. How does humidity affect inspired gas?

A

Humidity will cause displacement of some of the inspired gas. (81:15)

33
Q

What is the partial pressure of humidified water vapor?

How does this affect the displacement of inspired gas?

Which inspired gas will be displaced the most?

A

47 mmHg

The water vapor has to take up some room, resulting in less space for the inspired gas.

Nitrogen will be displaced the most (Gas with higher concentration at 79%)

(83:00)

34
Q

What is the formula to determine the partial pressure of the inspired oxygen?

A

PIO2 = FIO2 (PB – PH2O)

Partial Pressure of Inspired O2 = Concentration of O2 x (Atmospheric Pressure - Partial Pressure of Humidified Water Vapor)

FIO2 = 21%
PB (atmospheric pressure) = 760 mmHg
PIH2O = 47 mmHg

PIO2 = 0.21 (760 - 47)
PIO2 is appx. 149 mmHg (Inspired gas is diluted by water vapor)

(85:00)

35
Q

What are the partial pressures of the following inspired gas at Standard Barometric Pressure?
PIO2:
PICO2:
PIN2:
PIH20:

A
36
Q

For this figure:
What is the change in the oxygen partial pressure in the alveoli after equilibrium?

What is the change in carbon dioxide partial pressure in the alveoli after equilibrium?

A

The partial pressure of O2 will decrease by 50 mmHg. The partial pressure of O2 in the alveoli will drop from 150 mmHg to 100 mmHg.

The partial pressure of CO2 will increase by 40 mmHg. The partial pressure of CO2 in the alveoli will increase from 0 mmHg to 40 mmHg.

(89:00)

37
Q

What will be our alveolar gas partial pressure (PA) after equilibrium for the following gases?
PAO2:
PACO2:
PAN2:
PAH2O:

A

Note: PAO2 of 100 mmHg will be acceptable

38
Q

The alveolar gas partial pressure of O2 and CO2 should be ____________ partial pressure of the O2 and CO2 leaving the pulmonary capillaries.

A

The alveolar gas partial pressure of O2 and CO2 should be equal to partial pressure of the O2 and CO2 leaving the pulmonary capillaries.

O2 = 40 mmHg
CO2 = 100 mmHg

39
Q

How much O2 is absorbed per dL of blood by the pulmonary capillaries as it passes through the lungs?

How much CO2 is unloaded per dL of blood by the pulmonary capillaries as it passes through the lungs?

A

5 mL O2/dL of blood is absorbed by the pulmonary capillaries.

4.5 mL CO2/dL of blood is unloaded by the pulmonary capillaries.

(93:00)

40
Q

Despite having a similar amount of gas being picked up (5 mL of O2/dL of blood) and unloaded (4.5 mL of CO2/dL of blood) by the pulmonary capillaries. Why is there a smaller change in the partial pressure of CO2 (45 mmHg to 40 mmHg) in the blood vessels compared to the partial pressure of O2 (40 mmHg to 100 mmHg)?

A

CO2 is very soluble and likes hanging out in water, it typically doesn’t exert a lot of partial pressure. Partial pressure tends to be high in gases that do not like to be in water (oxygen).

(94:00)

41
Q

What are the values of all four pressure?

A

Pulmonary Capillary Hydrostatic Pressure (PC): 8 mmHg (value needs to be confirmed.)

Pulmonary Capillary Oncotic Pressure (π Cap): 28 mmHg

Interstitial Capillary Hydrostatic Pressure (Pis): -4 mmHg (corresponds with intrathoracic pressure)

Interstitial Capillary Oncotic Pressure (πis): 8 mmHg (value needs to be confirmed.)

(96:00)

42
Q

What will happen to the pressure in pulmonary capillaries if there is a bad left heart?

How does this affect oxygen absorption in the lungs?

A

Pressure will back in the pulmonary capillaries which will cause fluids to be pushed into the lungs resulting in pulmonary edema.

Oxygen does not like water. So if there is a water barrier in the lungs, the lungs will have trouble absorbing oxygen.

(97:00)

43
Q

What will be the result if the pulmonary capillaries lose all their oncotic pressure (π Cap)?

What can cause a decrease in π Cap?

A

Fluids will move out of the pulmonary capillaries and into the lungs.

Plasma colloids can be lost during hemorrhaging, over-dilution, and sepsis.

(98:30)

44
Q

If there is some kind of obstruction for a young healthy patient emerging from anesthesia, what will happen to Interstitial Capillary Hydrostatic Pressure (Pis) as they develop an urge to breathe?

What can this cause?

A

Our interstitial pressure is normally negative (-4 mmHg) which is equivalent to thoracic pressure. The urge to breathe is going to generate an awful lot of effort and pressure changes inside the chest (much more negative pressure). This will result in extra fluid being pulled into the lungs.

Flash Pulmonary Edema - There will be so much fluid that it impedes O2 absorption.

(100:00)

45
Q

What is the purpose of a capillary filtration coefficient (Kf)?

A

The capillary filtration coefficient (Kf) is responsible for the conversion of mmHg into some type of capillary flow rate (Qf = ml/min).

(101:00)

46
Q

How does capillary permeability affect the capillary filtration coefficient (Kf)?

A

Increase permeability will increase the capillary filtration coefficient (Kf).

If we have infections or damage inside the lungs, Kf can get quite high which can lead to increased fluid movement into the lungs.

(103:00)

47
Q

What do the thick alveolar walls at the base of the lung mean?
What do the thin alveolar walls at the apex of the lung mean?

Where do you want ventilation?

A

Thick walls = higher pressure, high perfusion
Thin walls = lower pressure, lower perfusion

You would want to have more ventilation (free air) into areas where you have the most deoxygenated blood flowing through so oxygen can be absorbed more efficiently. (Ventilation to Perfusion Matching)

(41:00) (105:00)

48
Q

The minimum volume of a lung is usually about _____% of its total capacity

A

20%

(107:00)

49
Q

This is a graph showing alveolar compliance at FRC.
What do the two blue circles in this graph represent?

A

The blue circles represent alveolus filled to varying degrees.

(108:00)

50
Q

This is a graph showing alveolar compliance at FRC.

At a pleural pressure of -8.5 cmH2O, what will be the percent fullness of the alveolus?

At a pleural pressure of -1.5 cmH2O, what will be the percent fullness of the alveolus?

A

Pleural pressure of -8.5 cmH2O, will correspond to a transpulmonary pressure of +8.5 cmH2O and will result in 60% fullness of the alveolus.

Pleural pressure of -1.5 cmH2O will correspond to a transpulmonary pressure of +1.5 cmH2O and result in 25% fullness of the alveolus.

(114:00)

51
Q

This is a graph showing alveolar compliance at FRC.

Explain why the pleural pressure will be more positive at the base of the lung compared to the apex of the lung.

A

There is a pressure gradient that results from the lungs hanging out attached to the mediastinum. The weight of the lung is supported by the base and sits on top of the diaphragm. Because of this, we would expect to find a more positive pressure in the lower parts of the chest compared to the apex.

(110:00)

52
Q

This is a graph showing alveolar compliance at FRC.

Given these circumstances, where will fresh air be more likely to go during inspiration (higher regions of the lung or lower regions of the lung)?

A

Air will like to go to the lower region of the lung because they are not as full. It will also take less transpulmonary pressure to get air into the base of the lungs (1.5 cmH2O).

So if our transpulmonary pressure is the pressure available to fill parts of the lungs. That means areas of higher transpulmonary pressure will have fuller alveolus and areas of lower transpulmonary pressure would have more empty alveolus.

(115:00)

53
Q

This is a graph showing alveolar compliance at FRC.
Determine the average pleural pressure from this graph.

A

-5 cmH2O

((-1.5 cmH2O) + (-8.5 cmH2O)) / 2 = -5 cmH2O

(119:45)

54
Q

The graph shows alveolar compliance at RV.

Explain why pleural pressure is more positive than compared to the graph of alveolar compliance at FRC.

A

The only way to get to RV is the increase pleural pressure. The contractions of the abdomen and accessory muscles will increase thoracic pressure.

(121:00)

55
Q

Transpulmonary pressure needs to be _______ to get air into the lungs.

A

positive

(122:00)

56
Q

The graph shows alveolar compliance at RV.

Given these circumstances, where will fresh air be more likely to go during inspiration (higher regions of the lung or lower regions of the lung)?

A

If we inspire from RV, air will go to the top of the lungs first.

If our transpulmonary pressure is the pressure used to inflate the lungs, subzero transpulmonary pressure will not pull any air to the lower region. As pleural pressure becomes more negative, transpulmonary pressure will become more positive and air will eventually be placed in the base of the lungs.

(123:00)

57
Q

This is a graph showing alveolar compliance at FRC.

Where will you have the most compliance?

A

The most compliance (steepest slope) will be in the early part of the graph. This indicates for a change in pressure, more volume can be placed in that region of the lung.

(125:00)

58
Q

Transpulmonary pressure is also known as what?

A

Alveolar Distending Pressure

(126:30)

AP (2) (5 decks)

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