Exam 4: Respiratory L2 Flashcards

1
Q

Draw the graph that indicates lung volumes AND lung capacities all on one graph

(indicate Vt, IRV, ERV, RV, TLC, FRC, IC, VC)

A
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2
Q

Explain the following using words:

Tidal Volume

Inspiratory Reserve Volume (IRV)

Expiratory Reserve Volume (ERV)

Residual Volume (RV)

A

Tidal Volume: the volume inspired or expired during a normal breath (0.5 L)

Inspiratory Reserve Volume: the volume that can be inspired over and above the tidal volume (used during exercise) roughly 3 L

Expiratory Reserve Volume: the volume that can be expired after expiration of a tidal volume roughly 1.2 L

Residual Volume: volume that remains in lungs after maximal expiration (1.2 L)

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3
Q

Explain the following using words:

Inspiratory Capacity

Functional Residual Capacity

Vital Capacity

Total Lung Capacity

A

Inspiratory Capacity: sum of tidal volume and inspiratory reserve volume (Vt + IRV)

Functional Residual Capacity: sum of ERV and RV (it is essentially the volume remaining in the lungs after a tidal volume is expired)

Vital Capacity: sum of Vt + IRV + ERV (volume of air that can be forcibly expired after maximal inspiration)

Total Lung Capacity: IRV + Vt + ERV + RV (sum of all four lung volumes)

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4
Q

What three things cannot be measured with a spirometer in terms of lung volumes and capacities?

A

Residual Volume (RV), Functional Residual Capacity (FRC), and Total Lung Capacity (TLC) can NOT be measured with a spirometer

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5
Q

Measurement if RV, FRC, and TLC

What two things can we use to measure them?

A

Measurement of RV, FRC, and TLC:
Helium dilution vs body plethysmograph:

both use conservation of mass

helium dilution uses concentration and volume

plethysmograph uses pressure and volume

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6
Q

Explain essentially what body plethysmograph does

A

It measures lung volumes via pressure volume relationships

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7
Q

Explain the clinical importance of helium dilution vs body plethysmography

A
  • Should be equivalent in normal pts
  • Helium starts to fail with airway closure (obstructive respiratory disease)
  • Plethysmograph can overestimate VL in COPD
  • Some evidence that ratio of Helium: Pleth can diagnose severity of COPD (lung volume found via pleth much much higher in severe COPD pt’s than helium)
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8
Q

Draw the pressure volume loop for lungs:

explain all five parts of the graph

A
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9
Q

Draw the graph and explain the effect of saline inflation on the PV loop

A
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10
Q

Explain the effects of post-lavage inflation on the PV loop (essentially NO surfactant)

A
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11
Q

Draw the effects of surface tension and surfactant on the PV loop

A
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12
Q

Air flows through airways when there is a pressure gradient.

Air flow at a given pressure gradient is determined by:

1.

2.

A

Air flow at a given pressure gradient is determined by:
pattern of air flow

resistance to airflow by airways

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13
Q

Equation for Reynold’s number

Equation for flow rate

A

Reynold’s Number:

Re = ((diameter)(velocity)(density))/ (viscosity)

Flow Rate:

V = deltaP pi (r)^4 / 8nL

remember, flow is directly proportional to radius to the fourth power

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14
Q

Explain how flow relates to the increasing cross-sectional area of the airways

A
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15
Q

Explain airway resistance in the lungs as you go from the conducting zone into the respitatory zone

A

Airways in parallel

initially, the resistance increses because the CSA stays the same (radius decreases so resistance increases)

Then, as CSA increases more rapidly, there is a rapid decrease in resistance

There is no resistance in the respiratory zone

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16
Q

Draw the graph overlapping the velocity/resistance curve and the CSA curve

Airway CSA and velocity (or resistance) are ____ proportional

Even though the individual airways are getting smaller, the aggregate CSA is ____, thereby ___ resistance

A

Airway CSA and velocity/resistance are inversely proportional

Even though the individual airways are getting smaller, the aggregate CSA is increasing dramatically, thereby reducting the resistance

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17
Q

Factors Influencing Airway Resistance:
Eqn for Resistance

What are things that increase radius and decrease AWR

What are things that decrease radius and increase AWR

A

Equation for Resistance: R = 8nL/ pi r^4

Things that increase radius and decrease AWR: increasing lung volume, smooth muscle relaxation, sympathetic stimulation

Things that decrease radius and increase AWR: mucus, edema, smooth muscle contraction, vagal stimulation

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18
Q

Explain the following terms

FVC

FEV1

Ratio of FeV1/FVC

Normal range for that ratio?

How are they used for clinical markers

A

FVC: forced tital capacity (same as vital capacity)

FEV1: forced expiratory volume in 1 second

Ratio of FEV1/FVC is normally 75%

(so you can normally breathe out about 75% of what you can breathe in within a second)

Generally, if FEV1 is reduced in obstructive

FVC reduced in restrictive

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19
Q

Explain the flow volume loop.

Explain what PEFR, PIFR

Explain what happens to flow rate when you exhale

A

When you exhale: you initially get a high flow rate and then it tapers off

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20
Q

For expiratory flow rates:

At higher lung volumes it is effort ___

At lower lung volumes it is effort ___ and flow ___

A

At higher lung volumes, expiratory flow rates is effort dependent

At lower lung volumes, expiratory flow rate is effort independent and flow limited

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21
Q

Explain effort dependent and independent expiratory flow

A
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22
Q

Explain dynamic airway compression

A
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23
Q

Explain the idea of equal pressure point within dynamic airway compression

A
24
Q

Explain Restrictive Pulmonary Diseases

A

Restrictive Pulmomary Diseases:
- Collectively anything that makes the lungs difficult to inflate: could reduce FRC, vital capacity, TLC

  • Decrease in compliance…for example:
  • Decrease in surfactant (infant respiratory distress)
  • Increase in fibrosis
  • Pleural Effusion
25
Q

Explain Obstructive Pulmonary Diseases

A

Obstructive Pulmonary Diseases:

Collectively anything that increases airway resistance (reduction in FEV1)

For example: infection (build up mucus in airways), asthma (smooth muscle constriction of airways), COPD (increased compliance but less airway integrity resulting in airway collapse)

26
Q

Draw the lung compliance curve and the effects of emphysema and fibrosis on lung compliance

A
27
Q

Explain what happens to FEV1 and FVC in obstructive lung diseases (asthma and COPD) vs restrictive lung diseases (such as fibrosis)

A

FEV1 is reduced in obstructive lung diseases

FVC is reduced in restrictive lung diseases

Look at the graph

28
Q

Explain what happens to asthma FEV1s and FVC after treatment with albuterol

A
29
Q

Explain the changes in respiratory flow and lung volume in obstructuve vs restrictive disorders

A

Obstructive (COPD, asthma): cannot move air as quickly, flow reduced, volumes might be normal, FEV1/FVC ratio decreased and FEV1 decreased

Restrictive (fibrosis): cannot expand lungs, flow might be normal but volumes reduced (FVC, TLC, and RV all decreased)

30
Q

Summary:

What are the four primary non-overlapping lung volumes?

Lung capacities are comprised of ___ or more volumes

RV can/or cannot be measured with spirometry

A

Four primary non-overlapping lung volumes: tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume

Lung capacities are comprosed of 2 or more volumes

RV CANNOT be measured with spiometry (you need to use Helium or plethysmograph)

31
Q

Summary:

______ is a measure of the elastic properties of the lung (_______ increases it)

The lung PV lopp is ____ and shows ____

The elastic recoil of the lung is attributable to its _____ and ____ (COPD has ____ compliance and fibrosis has ____ compliance)

A

Compliance is a measure of the elastic properties of the lung (note: surfactant increases compliance)

The lung PV loop is linear and shows hysteresis

The elastic recoil of the lung is attributable to its elastic properties and surfactant (loss of elastic recoil of the lung occurs in COPD causing higher compliance, whereas fibrosis leads to decreased compliance)

32
Q

Air flow is largely ____ in larger airways, ____ in small airways of the conducting zone

AWR is highly dependent on the _____

AWR ______ with increasing lung volume and CSA of the airway generation

What is AWR dependent on?

A

Air flow is largely turbulent in larger airways, transitional and laminar in smaller airways of the conducting zone

AWR is highly dependent on radius (to the fourth power)

AWR decreases with increasing lung volume and CSA

note AWR stands for air way resistance; it is dependent on lung volume, smooth muscle , muscus/edema

33
Q

Restrictive lung diseases means lungs are ____ (display reduced ____ and ____)

Obstructive lung diseases mean _______

A

Restrictive lung diseases means lungs are difficult to inflate (display reduced compliance and volumes FRC, TLC, etc)

Obstructive lung diseases mean increased airway resistance (display reduced flow FEV1)

34
Q

_________ limits airflow during a forced expiration; airflow becomes independent of effort

(what is the equal pressure point)

Work of breathing is ____ at normal tidal volume

A

Dynamic compression limits airflow during a forced expiration; airflow becomes dependent of effort

The equal pressure point is the point at which pressure inside and surrounding the airways is the same

Work of breathing is minimal at normal tidal volume (pt will adjust breathing to minimize work of breathing)

35
Q

Explain the various gas law relationship:

V and P

V and T

P and T

P, T, and V (the combined gas law)

Avogadro’s Law

Ideal gas law

A

V and P are inversely proportional

V and T are directly proportional

P and T are directly proportional

(P1V1)/T1 = (P2V2)/T2

Avogadro’s: if the amount of gas in a container is increased, volume increases (V and n are directly proportional)

Ideal gas law: PV=nRT

36
Q

Law of partial pressires

Law of partial volmes

A

Total pressure of gas mixture is sum of partial pressures

Total volume of gas is equal to sum of component volumes

37
Q

Explain Ventilation

What is the normal ventilation of an adult vs child?

Explain what V/Q is

A

Ventilation is the frequency of breaths x volume (V = f x Vt)

Normal adults = 15 per minute x 500mL = 7.5 L/min

Child= 3-5 L/min

Q stands for perfusion so V/Q is the ventilation to perfusion ratio

38
Q

Explain the composition of atmospheric air

A

Ambient air is MOSTLY nitrogen and oxygen (a tiny bit of CO2)

At sea level the atmospheric pressure is 760 mmHg at sea level (standard)

The air is roughly 79% N2, so partial pressure of N2 is 600 mmHg

21% O2, so the partial pressure of O2 is 160 mmHg

Therefore, Patm at sea level is 760 mmHg and is essentially the sum of the partial pressures of N2 and O2

39
Q

What is the Patm of oxygen

Remember: our airways will always be ____

This water vapor will take up part of the pressure: ____

What is the partial pressure of O2 of inspired air in the trachea?

A

Patm of oxygen us essentially 160 mmHg

Our airways will always be humidified, so at 37 degrees celcius, the water vapor pressure is 47 mmHg

That value, 47 mmHg is TEMP DEPENDENT, so it does not change. Therefore, the partial pressure of O2 in the trachae is equal to the total atm pressure minus water vapor pressure multiplied by the fraction of oxygen. If we are at sea level, it’s 760-47

If we are in Denver it’s 630-47

If we are in Everest it’s 265-47mmHg

40
Q

Explain the alveolar gas equation using a very general description

Explain what R is

A

Alveolar gas equation measures the partial pressure of oxygen that enters the alveoli muis the pressure of oxygen that leaves the alveoli

R is the ratio of Co2 eliminated to O2 consumed (an R of 1 means one Co2 for every O2 consumed)

the standard R is 0.8

41
Q

What is the alveolar gas equation?

Explain each part

A
42
Q

Alveolar CO2:

The amount of CO2 in the alveoli is ______ to the amount of CO2 produced by the tissue

The amount of CO2 in the alveoli is ___ to the ventilation rate

A

Amount of CO2 in alveoli is directly proportional to amount of CO2 produced by the tissue

AND indirectly proportional to ventilation rate

think about it, the more metabolism, the more C02 produced by tissues, the more would be in blood and cross over into alveoli

AND we get rid of CO2 via breathing so increasing ventilations would expel more CO2 and there would be less in the alveoli

43
Q

Draw the graph relating alveolar CO2 and alveolar O2 levels to ventilation rate

A
44
Q

Explain the gravitational effects on the regional differences in ventilation

A

Gravity pulls down on the lungs, the gravitational effect is larger at the bottom of the lungs than the top

The lungs push down on the pleural space at the bottom. This creates a LESS negative pleural pressure at the bottom of the lungs relative to the top.

This then also means that the alveoli will have different volumes at differenct places due to the difference in pleural pressures. SO, the alveoli at the bottom cannot open as much during RV and FRC because of that gravitational effect. Some alveoli at bottom of RV can even be closed shut. Its not until TLC that both alveoli can open up to maximum radius.

45
Q

Explain the single breath nitrogen test and what it is essentially looking at

A

In the single breath nitrogen test, you have a pt who breaths in 100% O2.

Essentially you are seeing how much nitrogen is exhaled after breathing in that oxygen. Initially, there would be barely any N2 because you’re breathing out the air in the upper airways (“washout”). Then there is a plateau phase where there is uniform ventilation, and then near the right end of the graph, there are “slow emptying alveoli” that will start to leak out their nitrogen. A little but of this is normal. Thus section of RV will shift to the left in diseased states

46
Q

Total ventilation is the sum of ______ ventilation and _____ ventilation.

The first air to reach the deep alveoli during an inspiration is __________.

A

Total ventilation is the sum of wasted dead-space ventilation and alveolar ventilation.

The first air to reach the deep alveoli during an inspiration is “dirty” air from the previous exhalation.

47
Q

Anatomic dead space is _______

Explain how to measure anatomic dead space

A

Anatomic dead space is the volume of air that never gets perfused within the upper conducting zone in the airway. It is an inherent property, the volume of anatomic dead space does not change

(usually stays around 150 mL)

Anatomic dead space is measured with Fowler’s method: where a pt will breathe in pure oxygen, and then they will measure the amount of nitrogen the pt breathes out.

48
Q

Explain what physiological dead space is

How do we measure physiological dead space?

A

Physiological dead space is anatomic dead space PLUS alveolar dead space (which is ventilated but not perfused air)

It can be measured with Bohr’s method (looks at expired CO2)

49
Q

In a healthy patient what is the relationship between physiological dead space and anatomic dead space?

A

In a healthy patient, physiological dead space and anatomical dead space should be about the same. In pt’s with diseased lungs, physiological dead space will be much larger than anatomic dead space.

50
Q

The larger the tidal volume, the ____ the dead space ventilation.

To Increase Va (alveolar ventilation), an increase in respiratory rate is _____ than an increase in tidal volume.

Tidal ventilation is comprised of ________. TO increase alveolar ventilation, what is most effective way?

A

The larger the tidal volume, the smaller the dead space ventilation.

To increase alveolar ventilation, an increase in respiratory rate is LESS EFFECTIVE than an increase in tidal volume.

Tidal ventilation is comprised of dead space and alveolar ventilation. To increase alveolar ventilation, an increase in tidal volume is more effective than an increase in the frequency of breathing.

51
Q

The sum of the partial pressures and the partial volumes of a gas is equal to____

A

Sum of partial pressures and partial volumes of a gas equal to the total pressure and total volumes.

52
Q

_________ airways do not participate in gas exchange. Thus, the partial pressures of O2, N2, and water vapor in humidified air______ in the airways until gas reaches alveoli.

A

Conducting airways do not participate in gas exchange. Thus, the partial pressures of O2, N2, and water vapor in humidified air remain unchanged in the airways until the gas reaches the alveolus.

53
Q

The partial pressure of oxygen in the alveolus is given by the ______.

A

The partial pressure of oxygen in the alveolus is given by the alveolar gas equation.

Which is PA02 = Pio2 - (PAco2/R)

PA02 = ((Patm - Pwatervapor) x Fo2) - (PAco2 / R)

example = ((760 -47) x 0.21) - (45/0.8)

remember, water vapor pressure is always 47, and R is usually 0.8 unless stated otherwise

54
Q

The relationship between CO2 production and alveolar ventilation is given by the alveolar CO2 equation : what is the relationship between PCO2 and alveolar ventilation?

A

Inverse relationship between pressure of CO2 in alveoli and the ventilation rate

There is a direct relationship between metabolic CO2 levels (blood ) and levels of CO2 in alveoli

We get rid of that CO2 through breathing. SO if you increase your breathing, there would be less CO2 in lungs. and vice versa

55
Q

Regional differences in ventilation (base higher than apex) are due to ________

A

Regional differences in ventilation (base higher than apex) are due to gravitational effets and variable resistances/compliances of alveolar units.

56
Q

Anatomic dead space can be measured with ______

Physiological dead space can be measured with___

A

Anatomic dead space : Fowler’s method

Physiological dead space: Bohr equation

57
Q

Tidal ventilation is comprised of both ______ and _____. To increase alveolar ventilation, an increase in _____ is more effective than an increase in ______.

A

Tidal ventilation is comprised of both dead space ventilation and alveolar ventilation.

To increase alveolar ventilation, an increase in tidal volume is more effective than an increase in the frequency of breathing.