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CPR1 Exam 2 > 1 - Respiratory Cycle & Mechanics > Flashcards

1 - Respiratory Cycle & Mechanics Flashcards

1
Q

What does “P” stand for?

A

Partial pressure of a gas – you must specify which gas you are referring to. The units are mmHg.

  • **PO2 = partial pressure of oxygen
  • **PCO2 = partial pressure of carbon dioxide
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2
Q

What does “Q” (or “Q” with a dot over it) stand for?

A

Blood flow

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3
Q

What does “V” stand for?

A

Volume of gas (VT = Tidal Volume, or volume per breath)

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4
Q

What does “V” with a dot over it (named Vdot) stand for?

A

Airflow or volume per unit time

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5
Q

What does “F” stand for?

A

Fractional concentration of gas (again you specify what gas you are referring to). There are no units.

  • **FO2 = partial pressure of oxygen (100% oxygen = 1.0; 21% = 0.21)
  • **FCO2 = partial pressure of carbon dioxide
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6
Q

What does “A” (or ALV) stand for?

A

Alveolar gas.

***Conventional use: PAO2

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7
Q

What does “a” stand for?

A

Arterial gas.

***Conventional use: PaO2

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8
Q

What does “v” stand for?

A

Venous blood.

***Conventional use: PvO2

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9
Q

What does “E” stand for?

A

Expired gas. Can indicate that the volume in question was measured during expiration.

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10
Q

What does “I” stand for?

A

Inspired gas.

***FIO2 = Fraction of inspired oxygen

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11
Q

Which lung volumes change with aging naturally?

A

Residual Volume increases
FRC increases

***Remember, FVC decreases

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12
Q

Obesity can greatly reduce lung volumes. The main difference is no change between when they are ________ or ________.

A

Seated
Supine

***See Slide 14 for Figure!

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13
Q

_________ is the passive movement of air into the lungs.

A

Inspiration

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14
Q

During inspiration, the pressure of gas is inversely proportional to its volume. This is _______ ______.

A

Boyle’s Law

***P1V1 = P2V2

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15
Q

During inspiration, an increase in lung volume results in a (INCREASE/DECREASE) in pressure. This is when air (ENTERS/EXITS).

A

Decrease

Exits

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16
Q

During expiration, a decrease in lung volume results in a (INCREASE/DECREASE) in pressure. This is when air (ENTERS/EXITS).

A

Increase

Exits

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17
Q

During inspiration there is (CONTRACTION/RELAXATION) of inspiratory muscles.

A

Contraction

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18
Q

For inspiration, there is an increase in thoracic volume. The lungs and muscles/ribs are NOT directly connected. The chest wall wants to ________, while the lungs want to ________. There is interplay.

A

Expand

Collapse

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19
Q

Between the visceral and parietal pleura there is ________ ________ that is 5-35 um thick.

A

Parietal Fluid

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20
Q

__________ Pressure (P-PL) is less than atmospheric pressure (negative).

A

Intrapleural

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21
Q

It is helpful to think of P-IP as the _________ pressure. This is the pressure everywhere in the thorax except in the lumens of blood vessels, lymphatics, or airways.

A

Intrathoracic

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22
Q

Because the pressures we deal with are relatively small (plus some storied history), pressures in respiratory physiology are in ________ (NOT mmHg as in cardiovascular physiology).

A

cm H2O

***We normalize atmospheric pressure to 0 cm H2O (so PB 760 mmHg becomes 0 cm H2O, even if PB changes).

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23
Q

At rest, intrapleural pressure (P-PL) is near ______ cm H2O. During inspiration, volume increases and P-PL decreases to near _______ cm H2O. Because of ________ between lungs and chest wall, lungs expand as thorax expands.

A

-5
-8
Coupling

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24
Q

As thoracic cavity increases in size, pleural pressure (P-PL) – pressure within pleural space – will (INCREASE/DECREASE). It starts negative and becomes more negative.

A

Decrease

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25
Q

As thoracic cavity increases in size, alveolar pressure (PA) – pressure within alveoli – will (INCREASE/DECREASE).

A

Decrease

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26
Q

At rest, PB = PA = 0 cm H2O. At the end of inspiration, PA is now _______ cm H2O. This is due to the increase in alveolar size. This is what causes air to enter the lungs!

A

-1

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27
Q

This pressure is the difference between PA (alveolar pressure) and P-PL (intrapleural pressure).

A

Transpulmonary Pressure (P-TP)

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28
Q

Transpulmonary Pressure (P-TP) is _______ at rest.

A

5 cm H2O

***Transpulmonary Pressure = Alveolar Pressure - Intrapleural Pressure

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29
Q

What would happen if P-TP = 0?

A

PA and P-PL would be the same.

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30
Q

What are the values for the following when a person is at rest (between inspiration/expiration)?

    • Volume Change (liters)
    • Alveolar Pressure (cm H2O)
    • Intrapleural Pressure (cm H2O)
    • Air Flow (L/sec)
A

Volume = 0 L

PA = 0 cm H2O

P-PL = -5 cm H2O

Air Flow = 0 L/sec

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31
Q

What happens to the following when a person is at mid-inspiration?

    • Volume Change (liters)
    • Alveolar Pressure (cm H2O)
    • Intrapleural Pressure (cm H2O)
    • Air Flow (L/sec)
A

Volume = Increasing (from 0 L)

PA = Decreasing (from 0 cm H2O)

P-PL = Decreasing (from -5 cm H2O)

Air Flow = Flowing into lungs (going negative from 0 L/sec)

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32
Q

What happens to the following when a person is at the end of inspiration?

    • Volume Change (liters)
    • Alveolar Pressure (cm H2O)
    • Intrapleural Pressure (cm H2O)
    • Air Flow (L/sec)
A

Volume = Has reached peak increase (positive)
– Tidal Volume (VT = 500 mL)

PA = Returned to 0 cm H2O

P-PL = Decreased to -8 cm H2O

Air Flow = Has stopped (back at 0 L/sec)

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33
Q

During expiration, volume is decreased and P-PL is returned to its starting point, which is…

A

-5 cm H2O

34
Q

During expiration, PA increases due to recoil to about _______ at mid-expiration.

A

+1 cm H2O

35
Q

What happens to the following when a person is at mid-expiration?

    • Volume Change (liters)
    • Alveolar Pressure (cm H2O)
    • Intrapleural Pressure (cm H2O)
    • Air Flow (L/sec)
A

Volume = Decreasing (from positive)

PA = Rises (from 0 cm H2O)

P-PL = Begins to rise (from -8 cm H2O)

Air Flow = Exits the lungs (increasing from 0 L/sec)

36
Q

What happens to the following when a person is at the end of expiration?

    • Volume Change (liters)
    • Alveolar Pressure (cm H2O)
    • Intrapleural Pressure (cm H2O)
    • Air Flow (L/sec)
A

Volume = Returned to resting (0 L)

PA = Decreases to 0 cm H2O

P-PL = Returns to resting (-5 cm H2O)

Air Flow = Has exited the lungs (0 L/sec)

37
Q

At rest, what is the Transpulmonary Pressure (P-TP)?

A

+5 cm H2O

***Remember, Transpulmonary Pressure = Alveolar Pressure - Intrapleural Pressure

38
Q

What is the P-TP at mid-inspiration?

A

+5.5 cm H2O

***Because PA at this point is -1 cm H2O and P-PL is -6.5 cm H2O.

39
Q

What is the P-TP at the end of inspiration/start of expiration?

A

+8 cm H2O

***Because PA at this point is 0 cm H2O and P-PL is -8 cm H2O.

40
Q

What is the P-TP at mid-expiration?

A

+7.5 cm H2O

  • **Because PA at this point it +1 cm H2O and P-PL is -6.5 cm H2O.
  • **After this, we are back at rest values.
41
Q

This is the volume of air inhaled every minute.

A

Minute Ventilation (VE)

42
Q

This is the volume of air inhaled and exhaled in a single breath.

A

Tidal Volume (VT)

43
Q

What is the equation for Minute Ventilation (VE)?

A

VE = VT x Frequency

44
Q

A patient’s respiratory volume is 14 breaths per min (RR) and VT is 500 mL per breath. What is minute ventilation?

A

14 breaths/min x 500 mL/breath = 7,000 mL/min OR 7 L/min

***This is the normal value for VE, remember it!

45
Q

Regions of the lung that receive air, but not blood means that there is no ________ ________ occurring there.

A

Gas Exchange

***This is dead space!

46
Q

This is space in the respiratory system other than alveoli.

A

Anatomic Dead Space

***150 lb person = 150 mL of V-DS

47
Q

This is alveoli that receive air, but not blood.

A

Alveolar Dead Space

48
Q

This is abstract, but is considered air that functionally doesn’t participate in gas exchange. In healthy individuals, this is nearly zero.

A

Physiological Dead Space

49
Q

At the end of expiration, there is air left in the lungs. At the end of inspiration, the _________ ________ ________ air has entered the lungs.

A

Anatomical Dead Space

50
Q

Out of the 500 mL of Tidal Volume, how much is air from Anatomical Dead Space?

A

150 mL

51
Q

Alveolar Ventilation can be calculated by subtracting _______ _______ volume from _______ _______.

A

Dead Space
Tidal Volume

  • **Alveolar Ventilation = Tidal Volume - Dead Space Volume
  • **500 mL - 150 mL = 350 mL
52
Q

How is Minute Alveolar Ventilation calculated?

A

Alveolar Ventilation x Frequency

***V(dot)ALV = V-ALV x Frequency

53
Q

During inhalation at low lung volumes, you have to work hard to get a little increase in volume. It is much harder to _________ the lungs.

A

Stretch

54
Q

The more volume there is in the lungs, the (MORE/LESS) negative pressure there is around the lungs.

A

More

55
Q

During inhalation at normal lung volumes, once there is a little air in the lungs then a little pressure change will produce a large ________ change. It is easier to stretch the lungs!

A

Volume

56
Q

During inhalation at high lung volumes, as the lungs expand towards TLC, it again becomes difficult to ________ the lungs. A small pressure change produces a small change in volume.

A

Stretch

57
Q

T/F. The lung does NOT deflate the same way it inflates!

A

True

58
Q

When you inflate the lungs with ________ rather than air, the lungs almost inflate and deflate in the same way. The difference is _________ because it reduces tension in the smallest alveoli more than larger alveoli. This contributes to __________, which is the difference in compliance between inspiration and expiration.

A

Saline
Surfactant
Hysteresis

59
Q

This is the measure of stretch ability of the lungs. The higher it is, the easier it is to stretch/open.

A

Compliance

***To calculate take (∆ volume / ∆ pressure)

60
Q

When is compliance the highest and reduces the workload?

A

During normal breathing, normal VT

***At normal lung volumes

61
Q

What is compliance at high and low lung volumes?

A

At either extreme (too small or too large), the lung compliance is low. This makes it much harder work.

62
Q

Remember, compliance is the OPPOSITE of _________, which is “recoil ability”.

A

Elasticity

63
Q

At birth, a baby must inflate its lungs for the first time. What is the compliance of the lungs for this first breath? How hard does the baby have to work?

A

Prior to first breath, lung volume is very low. Compliance is low, so effort is high.

64
Q

Compliance changes in different conditions. ________ lowers compliance, and there is more change in pressure required for change in volume. People usually breath at shallower volume and more frequently.

A

Fibrosis

***Also occurs in obesity!

65
Q

Compliance (INCREASES/DECREASES) with age as elasticity (INCREASES/DECREASES) with age due to the loss of elastin and increased collagen.

A

Increases

Decreases

66
Q

_________ increases compliance, as it destroys alveolar septal tissue that normally opposes lung expansion.

A

Emphysema

67
Q

For the Relaxation Pressure-Volume Curve read Costanzo starting at pg. 201. She’s helpful, peace and blessings.

A

Read Me

68
Q

Lungs have a lot of elastic fibers, so they want to ________. The chest wall wants to ________. In the intact system, the elastic recoil of the lungs and chest wall exactly counter each other at ________.

A

Collapse
Expand
FRC

69
Q

When the volume in the system is less than FRC, what happens?

A

i.e., patient makes a forced expiration into the spirometer. There is less volume in the lungs and the collapsing force of the lungs is smaller. The expanding force on the chest wall is greater. The combined lung and chest wall overall wants to expand (moving negative on the graph).

70
Q

When the volume in the system is greater than FRC, what happens?

A

i.e., patient inspires from spirometer. There is more volume in the lungs and the collapsing force of the lungs is greater. The expanding force on the chest wall is smaller. The combined lung and chest wall overall wants to collapse (moving positive on the graph).

***At highest lung volumes, BOTH the lungs and chest wall want to collapse, that is why the combined curve is so large for collapsing.

71
Q

What happens in a pneumothorax?

A

There is no pressure equilibrium, so the chest wall actually expands and the lung collapses.

72
Q

Contraction of bronchial (airway) smooth muscle changes the radius of the airway and therefore the _________.

A

Resistance

73
Q

What is the equation for resistance?

A

R = 8nL/rˆ4

R = Resistance
n = Viscosity 
L = Length of tube 
r = Radius of tube
74
Q

Describe the FEV1/FVC ratio for an obstruction.

A

For an obstruction, FEV1 and FVC are both decreased but FEV1 is decreased MORE. So the overall ratio is decreased.

***i.e., Asthma or COPD

75
Q

Describe the FEV1/FVC ratio for a restriction.

A

For a restriction, FEV1 and FVC are both decreased but FEV1 is decreased LESS. So the overall ratio is actually increased.

***i.e., Fibrosis

76
Q

What is the normal FEV1/FVC ratio?

A

80%

***This means that 80% of the vital capacity can be expired in the first second of forced expiration.

77
Q

The elastic recoil of the lung would normally create collapse of the small airways and alveoli. Shared walls of alveolar and airways prevent collapse as recoil opposes each other. This is called…

A

Interdependence

78
Q

T/F. Losing some of the walls will alter or lose forces that normally would counter collapse. This can be caused by age, smoking, etc.

A

True

79
Q

As airway resistance increases, it takes a (GREATER/LESSER) pressure change to generate flow into the lungs. Therefore, it takes (MORE/LESS) pressure to generate a change in volume.

A

Greater

More

80
Q

What 2 forces does breathing overcome?

A

Elastic (expiration)

Resistance (inspiration)

81
Q

Work is done to overcome the elastic recoil (emphysema) of the lungs or work is done to overcome resistance to airflow. The greater effort (bigger area of the curve) is the…

A

Elastic Recoil

CPR1 Exam 2 (27 decks)

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