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FHB > Pulmonary > Flashcards

Pulmonary Flashcards

0
Q

What is tidal volume?
Inspiratory reserve volume?
Residual volume?

A

Tidal = 500 mL
Inspiratory reserve = 3000 mL
Residual = 1200 mL

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1
Q

Where are the terminal bronchioles?

A

Generation 16

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2
Q

What is functional residual capacity?

A

FRC = volume in lungs when all muscles are at rest = 2500 mL
Inspiratory capacity = TV + IRV = 3500
Vital capacity = TV + ERV + IRV = 4800 mL

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3
Q

What is the total lung capacity?

A

6000 mL

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5
Q

What is physiologic dead space?

What is its value?

A

It is anatomic dead space plus alveolar dead space (volume that is poorly perfused)

150 + 10 = 160 mL

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6
Q

What is used to measure anatomic dead space?

A

Nitrogen washout

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7
Q

What is the equation for volume of gas transferred across the lung epithelium?

A

V = A/T * (sol/[MW]^1/2) * (P1-P2)

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8
Q

Is CO diffusion or perfusion limited?
N2O?
O2?

A

CO is diffusion limited. It is quickly taken up in to RBC’s so it never reaches partial pressure equilibrium.

N2O is perfusion limited. It quickly equilibrates and new blood is needed for more to be added.

O2 = normally perfusion limited but can become diffusion limited in pathology.

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9
Q

What PO2 does blood have when it enters the capillary?

When it leaves?

A

46 mmHg

100 mmHg

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10
Q

How much time does O2 equilibrium usually take?

How much time is allowed by bloodflow?

A
  1. 25 sec

0. 75 sec

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11
Q

How does pulmonary vascular resistance compare to systemic vascular resistance?

A

Pulmonary is much lower, which is why pulmonary blood pressures are much lower (25/8)

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12
Q

Why does increased arterial or venous pressure decrease pulmonary vascular resistance?

A

Recruitment of new vessels and distension of other vessels.

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13
Q

What is Fick’s Principle?

A

Pulmonary Blood Flow = O2 consumption/(PaO2 - PvO2)

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14
Q

What are the 3 zones of pulmonary bloodflow?

A

Zone 1 = apex. Pulmonary artery perfusion pressure is too low to push blood to this height. No bloodflow.

Zone 2 = middle. Pulmonary arterial pressure exceeds alveolar pressure but venous pressure does not. Flow depends only on arterial-alveolar gradient.

Zone 3 = base. Both arterial and venous pressures exceed alveolar pressure. Flow depends on AV gradient.

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15
Q

What is hypoxic vasoconstriction?

A

The lung vasoconstricts portions of it that aren’t being perfused effectively.

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16
Q

What is the relationship between pulmonary vascular resistance and lung volume?

A

It increases at very low or very high lung volumes due to compression of extra-alveolar and alveolar vessels, respectively.

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17
Q 
What is PAO2?
PaO2?
PvO2?
PaCO2?
PvCO2?
A

PAO2 = 100 mmHg

PaO2 = 95 mmHg
PvO2 = 40 mmHg
PaCO2 = 40 mmHg
PvCO2 = 46 mmHg
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18
Q

What causes the PaO2 to be lower than PAO2?

A

Ventilation-Perfusion mismatch = 2 mmHg
Bronchilar vein drainage = 3 mmHg

Diffusion, and shunt, respectively.

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19
Q

How do emphysema and pulmonary fibrosis each affect diffusion?

A 
Emphysema = reduced area (A)
Fibrosis = increased thickness (T)
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20
Q

Why can shunt patients not be loaded with O2 when breathing pure O2?

A

The O2/Hb curve is flat-topped, so the blood receiving 100% O2 cannot make up for the shunted blood.

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21
Q

What is the most common cause of arterial hypoxemia?

A

Va/Q mismatch

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22
Q

Does shunt or dead space blood have higher O2?

A

Dead space blood. It is a small amount of blood and is allowed to equilibrate fully with the air (PaO2 = 150 mmHg, PaCO2 = 0)

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23
Q

What is the Va/Q of shunt alveoli?

Dead space alveoli?

A

Shunt = 0 = blood flow but no ventilation

Dead space = infinity = ventilation but no bloodflow

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24
Q

How do Va/Q ratios differ in the lung?

O2?

A

Va/Q and PaO2 levels increase going up the lung.

PaCO2 levels decrease going up the lung.

25
Q

Does Va/Q mismatch affect O2 or CO2 levels more?

A

O2 levels since CO2 can diffuse so much easier and make up for shunt alveoli with dead space alveoli.

Thus, patients with Va/Q mismatch can often be hypoxemic but normocapnic.

26
Q

What are the 4 causes of arterial hypoxemia?

A

Hypoventilation
Diffusion limitation
Shunt
Va/Q mismatch

27
Q

If a patient is given 100% O2 but PaO2 levels cannot be risen to the expected level, what is the diagnosis?

A

AV shunt

28
Q

What is the typical hemoglobin concentration in the blood?

O2 capacity?

A

15 g/dL of Hb

20 mL/dL of O2

29
Q

What is the equation for the cyanotic threshold?

A

CT = (Hb - 6g)/Hb

30
Q

What is a normal P50 for the O1/Hb curve?

A

25 mmHg

31
Q

What enzyme catalyzes the change between CO2 and carbonic acid, and vice versa?

A

Carbonic anhydrase

Located in RBC’s

32
Q

What are the three ways of storing CO2 in the blood?

What is the main way?

A

Dissolved CO2, carbonic acid, and carbamino groups.

The most important one is carbonic acid (90%)

33
Q

Why do RBC’s swell in venous blood?

A

Take up CO2 –> HCO3- & H+ –> HCO3- diffuses out but H+ can’t –> Cl- diffuses into RBC –> ^ osmolarity of RBC –> swelling.

34
Q

Why is there no P50 for CO2 in the blood?

A

There is no (forseeable) maximum CO2 content.

35
Q

Why can venous blood hold more CO2 than arterial blood?

A

Deoxygenated blood is a weaker acid.

36
Q

What is O2 extraction at rest?

A

5 ml/dL or 25%

37
Q

What are the muscles of expiration?

When are they used?

A

Abdominus rectus & internal intercostals

Only used during exercise.

38
Q

What changes take place in lung ventilation upon breathing at volumes below FRC?

A

Basal alveoli collapse, so that apical and middle alveoli do the majority of ventilation.

39
Q

What is a pneumothorax?

A

When air is allowed into the intrapleural space. The chest wall cannot exert force onto the lung in this case.

40
Q

What occurs to the chest wall & to the lung upon inspiration?

A

The chest wall relaxes while the lungs stretch. At very high volumes both the chest wall & lung fight expansion.

41
Q

What causes the recoil of the lung?

What does this mean for expiration?

A

Its elasticity and surface tension cause recoil.

This means that at rest, expiration is passive.

42
Q

What generation is the airway resistance highest?

A

Generation 4 because the airways are short and velocity is high. This leads to more turbulent flow.

In the smaller airways, laminar flow is seen more often. The nasal airways actually contribute half of the total airway resistance due to their turbulent flow (to warm/humidify)

43
Q

Is airway resistance higher or lower at high lung volumes?

A

Lower, because the airways are tethered open.

44
Q

What is dynamic compression of airways?

A

During a forced expiration below FRC, expiration is effort-independent because increased intra-thoracic pressure causes compression of the airways.

45
Q

What are normal FEV1/FVC ratios?

What does it mean if the ratio is above/below this?

A

Normal = 75-90%

>90% = restrictive disease (fibrosis)
<75% = obstructive disease (asthma)
46
Q

What are the two main factors that determine the work of breathin?

A

Compliance of the respiratory system and resistance to airflow.

47
Q

When is the work of expiration performed?

A

Upon inspiration, since inspiration fights the elasticity of the chest wall, which can then passively push air out of the lungs upon expiration.

50
Q

How large is the anatomic dead space?

The alveolar volume?

A

Anatomic dead space = 150 mL

Alveolar volume = 2.5-3 L

51
Q

Where in the brain is the site of respiratory rhythm generation?
What area speeds up breathing?
What area slows breathing?

A

Rostral Medulla

Rostral Pons = faster

Caudal Pons = slower

52
Q

What is the normal range of systemic blood CO2 content?

A

35 mmHg < PaCO2 < 45 mmHg

Less than 35 –> Respiratory alkalosis (hyperventilation)
More than 45 –> Respiratory acidosis (hypoventilation)

53
Q

What do the central chemoreceptors primarily detect?

Peripheral chemoreceptors?

A 
Central = CO2 ONLY (through H+ sensitivity)
Peripheral = O2, then CO2 secondarily
54
Q

What PaO2 level will elicit a response from the carotid bodies?

A

50-70 mmHg

55
Q

What is hypoxic drive?

A

When CO2 levels are low but low O2 levels (below 70 mmHg) stimulate respiration.

56
Q

What is normal breathing called?

What is Cheyne-Stokes breathing?

A

Normal = eupnic breathing

Cheyne-Stokes is indicative of cardiovascular deficit, and presents as rapid swings between hyperventilation and hypoventilation

57
Q

Where are the central chemoreceptors located?

What do they detect?

A

They are on the ventrolateral medulla & detect changes in the pH of CSF.

58
Q

What is the anaerobic threshold?

A

It is the point at which lactate begins to form in the tissues. This is another stimulus for breathing, so ventilation is increased at an even higher rate (greater slope).

59
Q

What changes are seen at high altitude?

A

People have a respiratory alkalosis from hypoxic drive.

EPO is stimulated –> higher HCT over the course of weeks

More 2,3 DPG is released –> easier O2 unloading in tissues

60
Q

What is a danger for the lung that can develop in high altitudes?

A

High Altitude Pulmonary Edema (HAPE)
also
High Altitude Cerebral Edema (HACE)

FHB (8 decks)

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