4. Resp Phys

Front 1

Volume inspired/expired with each normal breath:

Back 1

Tidal volume

Front 2

Vol that can be inspired over and above tidal volume:

Back 2

Inspiratory reserve IRV

Front 3

Vol that can be expired after expiring TV:

Back 3

Expiratory reserve ERV

Front 4

Vol that remains after max expiration:

Back 4

Residual vol

Front 5

What is used during exercise?

Back 5

Insp reserve vol IRV

Front 6

What can't be measured by spirometry?

Back 6

Residual vol

Front 7

Anatomic dead space:

Back 7

Vol of the conducting airways

Front 8

How much is anatomic dead space normally?

Back 8

150 mL

Front 9

What is Physiologic dead space?

Back 9

The volume of the lungs that does not participate in any gas exchange

Front 10

What is Phys deadspace equal to in normals?

Back 10

Anatomic dead space - normally all the alveoli should be participating!

Front 11

What happens to Phys dead space in lung diseases? What kinds of disease?

Back 11

It increases - Ventilation/Perfusion defects

Front 12

How do you calculate physiologic dead space?

Back 12

TV x (Blood Co2 - Exp Co2)
---------------
blood co2

Front 13

What is Minute ventilation?

Back 13

TV x breaths/min

Front 14

What is Alveolar ventilation?

Back 14

(TV - Deadspace) x Breaths/min

Front 15

What is Inspiratory capacity

Back 15

IRV + TV

Front 16

What is FRC?

Back 16

Functional residual capacity
ERV + RV

Front 17

Can you measure ERV w/ spirometry?

Back 17

No - cant measure residual vol!

Front 18

What is Vital capacity?

Back 18

IRV + TV + ERV

Front 19

What if you force Vital capacity out?

Back 19

FVC - forced vital capacity

Front 20

How do you do a FVC measurement?

Back 20

By inhaling to maximal and then forcibly expiring

Front 21

Can you measure TLC with spirometry?

Back 21

Nope - can't measure residual volume with spirometry

Front 22

What is FEV1?

Back 22

Forced vital capacity in the first second of expiration

Front 23

Normally, how much of the forced vital capacity (VC) can be forced out in the 1st sec of breathing out?

Back 23

80%

Front 24

In what type of lung disease would the FEV1/FVC ratio be DECREASED?

Back 24

Disease that obstructs outflow - ASTHMA

Front 25

Why is the FEV1/FVC ratio decreased in asthma?

Back 25

Bc FEV1 is reduced MORE than FVC - both are reduced, just FEV1 is MORE reduced

Front 26

What kind of FEV1/FVC is seen in RESTRICTIVE lung diseases? Why?

Back 26

NORMAL or INCREASED - because both FEV1 and FVC are decreased.

Front 27

Inspiratory Muscles (which is most important?)

Back 27

-Diaphragm - most important
-External intercostals
-Accessory muscles

Front 28

When are the external intercostals and acc muscles used?

Back 28

Only in exercise

Front 29

What muscles are normally used in expiration?

Back 29

None - it's normally PASSIVE

Front 30

Why is expiration normally passive?

Back 30

Because of the lung-chest wall elasticity

Front 31

So when are expiratory muscles used?

Back 31

In exercise or diseases with increased air resistance like asthma

Front 32

What are the expiratory muscles?

Back 32

-Abdominal muscles
-Internal intercostals

Front 33

What does COMPLIANCE of the resp system describe?

Back 33

The DISTENSIBILITY of the chest wall and lungs

Front 34

How is distensibility related to elasticity?

Back 34

INVERSELY

Front 35

How do we evaluate Compliance?

Back 35

By looking at the SLOPE of Vol vs Pressure curve

Front 36

What is Hysteresis?

Back 36

The difference in compliance curves that are created on the V/P graph during inspiration vs expiration - not the same!

Front 37

What is PRESSURE on the VP graph?

Back 37

Transmural pressure - the pressure difference across the lung structures

Front 38

How is Ptp calculated?

Back 38

Ptp = Palv - Pintrapleural

Front 39

When is transmural pressure going to increase so you can inhale?

Back 39

When intrapleural pressure decreases so that Palv - (-Pip) makes Ptp increase above 0

Front 40

And how do you make Pip increase?

Back 40

By inhaling with the diaphragm

Front 41

What systems are coming into play when we talk about lung compliance?

Back 41

-Chest wall
-Lungs

Front 42

How does the combined compliance of the Chest wall + Lungs compare to each alone?

Back 42

Combined is LESS than compliance of just the chest wall or lungs alone!

Front 43

What 2 forces are equal and opposite at FRC?

Back 43

The chest wall expanding out and the lungs collapsing in.

Front 44

What pressure is created by these equal/opposing forces?

Back 44

Intrapleural pressure

Front 45

What is Pip normally at FRC?

Back 45

Negative

Front 46

What do you suspect if Pip becomes equal to Patm at rest?

Back 46

Pneumothorax!

Front 47

What is the alveolar pressure at rest?

Back 47

Equal to Patm = 0

Front 48

How is lung compliance changed in Emphesyma? What is the result?

Back 48

It is INCREASED due to loss of elastic tissue in the lungs; the lungs DON'T collapse inward as much so the chest wall EXPANDS

Front 49

How does FRC change in emphesyma?

Back 49

The lungs seek a new HIGHER frc

Front 50

How is lung compliance changed in Fibrosis/restrictive lung diseases?

Back 50

It is DECREASED - lungs tend to collapse MORE

Front 51

So what happens to FRC in fibrotic disease?

Back 51

Lung-chest wall system seeks a new LOWER FRC

Front 52

What creates surface tension in alveoli?

Back 52

Droplets of liquid on the alveolar surface, btwn which there are attractive forces

Front 53

What does surface tension create inside alveoli?

Back 53

Collapsing pressure!

Front 54

What law describes the collapsing P and how is it calculated?

Back 54

Laplace's Law
P = 2T/r

Front 55

So the collapsing pressure is proportional to:

Back 55

Directly ppl to Tension
Inversely ppl to alveolar radius

Front 56

What change in alveolar radius will REDUCE collapsing pressure?

Back 56

Making alveoli big lowers the collapsing pressure

Front 57

So what size of alveoli have a greater tendency to collapse?

Back 57

SMALL alveoli

Front 58

And how will changes in the surface tension of fluid in the alveoli change collapsing pressure?

Back 58

The higher the surface tension, the stronger the tendency of the alveolus to collapse

Front 59

How do we get around always having to have LARGE alveoli in order to reduce the tendency to collapse?

Back 59

SURFACTANT

Front 60

What does surfactant do?

Back 60

Reduces surface tension (T) without requiring change in r

Front 61

What is it called when small alveoli lack surfactant and tend to collapse as a result?

Back 61

Atelectasis

Front 62

How does surfactant reduce surface tension?

Back 62

By disrupting the intermolecular forces between liquid

Front 63

So how does surfactant affect lung compliance?

Back 63

It INCREASES lung compliance

Front 64

What cells secrete surfactant, and what is it composed of?

Back 64

Type II pneumocytes - composed of Dipalmitoyl Phosphatidylcholine

Front 65

So, Brian, what is the cause of acute resp distress syndrome in infants?

Back 65

Well, I believe it's a failure of type II pneumocytes to secrete dipalmitoyl phosphatidylcholine, resulting in decreased compliance of the lungs!

Front 66

When is the earliest secretion of surfactant in the fetus? When should it for sure be secreted?

Back 66

Early - week 24 (6 months)
For sure - week 35 (8mo+3wks)

Front 67

So the 3 things that an infant with ARDS will exhibit are:

Back 67

-Atelectasis
-Decreased compliance
-Hypoxemia

Front 68

What lab msmt indicates adequete and mature levels of surfactant in a fetus?

Back 68

L:S ratio - greater than 2:1

Front 69

What is the LS ratio?

Back 69

Lecithin: Sphingomyelin

Front 70

What drives AIRFLOW?

Back 70

Pressure differences between the mouth/nose and lung alveoli

Front 71

What is the equation for Airflow Q?

Back 71

Q = P/R

Front 72

What is R?

Back 72

The resistance of the airway

Front 73

What law describes airway RESISTANCE?

Back 73

Poiseuille's

Front 74

What is Resistance ppl to directly?

Back 74

8 x viscosity x length

Front 75

What is Resistance ppl to inversely?

Back 75

pi x radius^4!!!

Front 76

If the radius of the airways were to decrease by a factor of 4, how would resistance change?

Back 76

R would increase by 4^4 - 256!

Front 77

What is the major SITE of airway resistance?

Back 77

The medium sized bronchi

Front 78

How do we change the radius of the med sized bronchi?

Back 78

By contracting/relaxing bronchial smooth muscle

Front 79

What will constrict bronchial smooth muscle?

Back 79

PNS
Irritants
SRSA - slow reacting substance of anaphylaxis in asthma

Front 80

What will dilate/relax bronchial smooth muscle?

Back 80

SNS
Isoproterenol - B2 agonist

Front 81

Other than radius, what controls airway resistance?

Back 81

VOLUME

Front 82

How does lung volume alter airway resistance?

Back 82

By exerting radial traction

Front 83

So what type of lung volume has less vs more airway resistance?

Back 83

HIGH vol = LOW resistance

LOW vol = HIGH resistance

Front 84

What would increase vs decrease air viscosity and thus airway resistance to flow?

Back 84

Decrease = helium, low density gas

Increase = deep sea dive

Front 85

What is alveolar pressure at the start of a breath before inspiration?

Back 85

0 = Patm

Front 86

What happens to alveolar pressure during inspiration? After inspiring completely? During expiring? After?

Back 86

Inspire - becomes negative
Top of breath - 0
Expire - becomes positive, then back to 0 = Patm

Front 87

What is intrapleural pressure
-At rest
-After total inspiration
-After expiration

Back 87

At rest = -3
Total inspire = -6
After expire = -3 again

Front 88

How can intrapleural pressure be measured?

Back 88

With a balloon catheter in the esophagus

Front 89

What is lung volume at rest?

Back 89

FRC - 40% of tlc

Front 90

What is lung volume at the peak of inspiration?

Back 90

FRC + TV

Front 91

How do we measure lung DYNAMIC compliance?

Back 91

By the change in intrapleural pressure during inspiration

Front 92

And what causes air to flow during inspiration?

Back 92

Pressure GRADIENTS - between Palv and Pip

Front 93

What causes air to flow during expiration?

Back 93

Positive pressure in the alveoli so that the Ptp gradient is decreased

Front 94

When would intrapleural pressure become POSITIVE?

Back 94

During a FORCED expiration (not passive breathing)

Front 95

What does forcing airflow by increasing Pip actually do?

Back 95

Makes expiration more DIFFICULT due to compression of the airways

Front 96

What disease shows compensation by learned behaviors to decrease forced resistance to airflow?

Back 96

COPD - pink puffer - breathe through pursed lips

Front 97

So what disease is characterized by decrease in all lung volumes, but a normal or INCREASED FEV1/FVC ratio?

Back 97

Restrictive - Fibrosis

Front 98

In asthma what is the:
-FEV1
-FVC
-FEV1/FVC ratio
-FRC

Back 98

FEV1 = very decreased
FVC = decreased
Ratio = decreased
FRC = increased (can't blow it all out)

Front 99

What is COPD?

Back 99

A combination of Emphesyma and chronic bronchitis

Front 100

What are the findings in COPD?
-FEV1
-FVC
-FEV1/FVC ratio
-FRC

Back 100

All same as asthma! Obstructive outflow - less expiration

Front 101

What is worse; COPD dominated by Emphysema, or by Bronchitis?

Back 101

Bronchitis

Front 102

How do we differentiate Emphesyma-dom vs Bronchitis-dom COPD?

Back 102

Emphesyma = Pink puffer
Bronchitis = Blue bloater

Front 103

Why do we call Bronchitis-dom COPD patients blue bloaters?

Back 103

They can't adequetely perfuse, so become severely HYPOXIC, HYPERCAPNIC, and develop Right Ventricular failure, Systemic edema, and are Cyanotic

Front 104

What are the findings in Fibrosis?
-FEV1
-FVC
-FEV1/FVC ratio
-FRC

Back 104

FEV1 = decreased some
FVC = markedly reduced
FEV1/FVC = N or INCREASED
FRC = reduced (fibrosis fills up the space)