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Pulmonary Block > Mechanics > Flashcards

Mechanics Flashcards

1
Q

Intrapleural pressure

A

Pressure in the pleural space

Always neg in normal breathing but can become pos during forced, prolonged expiration

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2
Q

Intrapulmonary pressure

A

Pressure in the alveoli ranges from neg to pos during the different phases of respiration
(Neg in inspiration and pos in expiration)

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3
Q

Transpulmonary pressure

A

Intrapulmonary pressure - intrapleural pressure

Creates the suction to keep the lungs inflated:
Alveolar distention get pressure

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4
Q

Air flow from:

A

High to low pressure

If Palv = Patm no flow
Palv > Patm air flows out
Palv

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5
Q

Primary muscles of inspiration

A

Diaphragm

External intercostal muscles

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6
Q

Accessory muscles of inspiration

A

Sternocleidomastoid

Scalene

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7
Q

Inspiration causes an increase in pleural cavity volume which in turn causes

A

Intrapleural pressure to become more negative

Therefore, transpulmonary pressure increases - dis tending pressure causes alveoli to open

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8
Q

When alveoli expand, what occurs next?

A

Intrapulmonary pressure drops below atmospheric pressure and air flows into alveoli until Palv and Patm equilibrates

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9
Q

During expiration, pleural cavity volume decreased causing

A

Intrapleural pressure to increase

Transpulmonary pressure decreases and and the alveoli collapse

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10
Q

When the alveoli collapse during expiration, what happens next?

A

Intrapulmonary pressure increases above Patm and air flows out until Palv and Patm equilibrate.

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11
Q

What muscles are used during forced expiration

A

Internal intercostal, and abdominal wall muscles

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12
Q

What can cause a pneumothorax?

A

Trauma that penetrates/disrupts pleura

Bullouse emphysema- build up in pressure in bulla, burst -> air flows out into pleura

Procedures in which catheterize patients, may accidentally hit the lung.

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13
Q

Treatment for pneumothorax vs partial pneumothorax

A

Chest tub- hooked up to neg pressure

Partial- leave them be

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14
Q

Which factors affect ventilation

A

Compliance

Airway resistance

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15
Q

Compliance of lung and chest wall are ___ correlated with their elastic properties.

A

Inversely

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16
Q

When is compliance greatest

A

At lower lung volumes

Steeper slope in pressure volume loop

17
Q

Pressure volume loop

A

C (L) = change in volume / change in pressure

18
Q

Factors affecting compliance

A

Elasticity
Decrease in surface tension by surfactant
Mobility of the chest wall

19
Q

In emphysema, do you have increased or decreased compliance.

A

Increased
Destruction of alveolar septa and elastic tissue
Alveoli are floppy and collapse but are easily distendable

20
Q

Hysteresis

A

Caused by surface tension

Difference between inspiration and expiration curve on the volume pressure loop

21
Q

LaPlace law

A

Pressure in the alveoli is directly proportional to surface tension and inversely proportional to radius.

22
Q

The effect of surfactant is greater when

A

The alveolar are smaller because the ratio of surfactant to air is greater

23
Q

What are the two factors that stabilize the alveoli

A

Reduced surface tension

Alveolar interdependance

24
Q

respiratory distress syndrome of the newborn. Treatment?

A

More common in infants

25
Q

FRC

A

Volume left in lungs when lung and chest walls are balanced (equal and opposite)

26
Q

At what volume do the lungs feel most comfortable?

A

The lung wants to collapse- 0

27
Q

At what volume does the chest wall feel most comfortable?

A

Halfway between FRC and TLC
~70% of TLC
Below this value, it wants to expand

28
Q

When will the chest wall want to compress down

A

When the lungs are fully hyperexpanded

29
Q

Changes in chest wall compliance

A

Less common than changes in lung compliance

Causes:
Increase intra-abdominal pressure:
Pregnancy and ascites

Reduced movement of rib cage:
Kyphosis
Broken ribs

30
Q

Air flow =

A

Difference in pressure (alveoli and mouth) / airway resistance

31
Q

Laminar flow is seen in ___ airways and is more dependent on ___.

A

Smaller

Viscosity
Extremely dependent on radius

R = (8 X viscosity X length) / radius ^4

32
Q

Turbulent is seen in ____ airways and is more dependent on ___.

A

Larger

Density

Occurs when Reynolds number is high
Reynold number= (density X velocity X diameter) / viscosity

33
Q

What is transitional flow and where do you see it?

A

Combination of laminar and turbulent flow

Branch points

34
Q

Vast majority of flow in the lung is

A

Transitional

35
Q

Resistance is greatest at ____ lung volumes

A

Lower

36
Q

In emphysema, what happens to resistance

A

Resistance begins at higher lung volumes

37
Q

Work

A

Pressure needed to overcome resistance of airflow and elastic recoil of the lungs X volume of air moved in and out of the lungs (Vt)

Pulmonary Block (7 decks)

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