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Cardiopulmonary Science > Week 1 Compliance, Resistance and WOB VQ missmatch > Flashcards

Week 1 Compliance, Resistance and WOB VQ missmatch Flashcards

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1
Q

TV
Define
How much is it
how is it calculated

A

Tidal volume
Volume air inspired and expired with a normal breath
500ml
Tv=Total dead space(VD) + Alveolar volume (VA)

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2
Q

ERV &; RV

Define

A

Expiratory reserve volume
extra air that can be expired after normal tidal expiration
1200ml

Residual volume
Vol of air remaining after max expiratory effort(ERV)
RV=FRC + ERV or RV=TLC-VC

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3
Q

IRV
Define
How much is it

A

Inspiratory reserve volume
Extra air that can be inspired after normal tidal inspiration
3000 ml

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4
Q

VC

A

Vital capacity

Volume of gas that can be expired following maximal inspiration (Deep breath+ deep inhale)

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5
Q

TLC
Define
How is it calculated

A

Total lung capacity
Gas contained within lungs at end of max inspiration
Total amount air that lungs can hold
RV+ERV+TV+IRV

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6
Q

FRC & IC
Define each
Give calculation for each

A

(FRC) Functional residual capacity
Volume of gas remaining in lungs at the end of normal exhalation
FRC= Expiratory reserve volume+Residual volume

(IC) Inspiratory capacity
Max volume of gas that can be inspired from resting end-expiratory level (of normal breathing)
IC= Inspiratory reserve volume + Tidal volume

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7
Q

Define VE

How is it calculated

A

(VE) Expired total ventilation= Tidal volume X frequency

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8
Q

VA
Define
What does it mean
How is it calculated

A

Alveolar ventilation (Actual vol ventilated per min)
VA = (VT-VD) x f
=(Tidal volume - Total dead space) x frequency

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9
Q

VD
Define
What is it’s significance

A

Total dead space/Physiologic dead space
volume of gas that does not eliminate co2
composed of:
Anatomical dead space and Alveolar dead space

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10
Q

Anatomical dead space
Define
How big is it?

A

The volume of the conducting airways (eg trachea ect)

approx 150 ml

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11
Q

Alveolar dead space

Define

A

Ventilated alveoli which are NOT perfused or relatively underperfused with blood. (t/f no gas exchange)

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12
Q

List 5 basic functions of the lung

A 
Gas exchange
Defence against invading microorganisms
Resevoir of blood
Filtering blood
Metabolism
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13
Q

Define partial pressure

A

The pressure exerted by a gas on the walls of it’s container. Dependant on temp & # molecules

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14
Q

PaO2

A

Partial pressure of oxygen in arterial blood

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15
Q

PAO2

A

Partial pressure of oxygen in Alveolar gas

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16
Q

PaCO2

A

Partial pressure of CO2 in arterial blood

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17
Q

PACO2

A

Partial pressure of CO2 in Alveolar gas

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18
Q

List 3 main metabolic functions of the lung

A

Synthesis
Biological activation
Inactivation

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19
Q

Where do the majority of metabolic processes occur in the lungs?

A

Endothelial cellWs in the lung’s vascular bed

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20
Q

What substances does the lung synthesise?

A

Phospholipids ( components of pulmonary surfactant)

Proteins (collagen & elastin)formstructural framework

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21
Q

What molecules are activated in the lung?

A

Polypeptide: Angiotensin I is converted to AngiotensinII by ACE (angiotensin converting enzyme)

AngiotensinII is a BP regulator

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22
Q

What substances are inactivated in the lung?

A

Bradykinin is inactivated by
ACE(angiotensin converting enzyme)

Prostaglandins from E&;F groups released from damages tissues are also broken down

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23
Q

List 3 forces

Respiratory muscles must overcome for respiration

A

ELASTIC RECOIL (of the chest wall and lungs)
FRICTIONAL RESISTANCE
(lungs&chest wall + airways to flow of air)
INERTIA (Negligable)

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24
Q

Elastic recoil is one of 3 forces that must be overcome for respiration

Explain elastic recoil of chest wall
Explain elastic recoil of lung

A

Elastic recoil of chest wall connective tissues:
Diaphagm, Abdomen, Ribcage joints

Elastic recoil of lung:
Surface tension of lungs & elastic fibres of lungs

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25
Q

Pulmonary resistance is usually 2 main types. Give percentages for the prevalence of each

A

Lung or chest wall tissue or airways to flow or air

Pulmonary resistance is:
20% Pulmonary tissue resistance
80% Airway resistance

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26
Q

As lung volume increases with inspiration what happens to the zone of Apposition?
What is it?

A

It Decreases.

Insert photo

27
Q

At very low lung volumes(When you’ve taken a deep breath out) what kind of pressure may the lower rib cage be exposed to?

A

Intra-abdominal pressure rather than pleural pressure

28
Q

List the muscles involves in inspiration and expiration

*** edit this with more info

A

Inspiration:
Parasternal muscles, scalenes- ^ AP diameter
Diaphragm, lower intercostals- ^ Lat expansion
Accessory muscles recruited in heavy breathing

Expiration:
Rectus abdominus,internal and external obliques, transversus abdominus

29
Q

Define the concept of hysteresis in terms of lung pressure.

A

The nonlinear pressure-volume curve of the lung in which transpulmonary pressure at a given volume during inflation is LESS than the transpulmonary pressure at the same volume during exhalation.

30
Q

Define compliance and elastic recoil

A

Compliance:The ease at which the lung is stretched to expand
Compliance= change in V/ change in Pressure
* insert picture of pressure volume curve

Elastic recoil: Tendency for lung to return to resting volume after distention

INVERSELY PROPORTIONAL

31
Q

what do the following stand for?

CL & Ccw

A

CL - lung compliance

Ccw-Chest wall compliance

32
Q

What does Ppl stand for

What is it’s value?

A

Intrapleural pressure
Pressure in the thin space b/n the visceral and parietal pleura.

usually more negative at top of lung and less neg at bottom, unless low lung volume or on artificial ventilation

Usually -5 cmH20 at end expiration
(subatmospheric)

33
Q

What does PA stand for?

small A

A

Alveolar pressure
Pressure inside the Alveoli

Usually 0cm H2O at end expiration
(same as atmospheric pressure)

34
Q

What does Ptm (capitals) stand for?

There are 2 types list them

A

Transmural pressure:The pressure diff across airway or lung wall

> Transpulmonary pressure-diff b/n inside and outside lung

> Transairway pressure- diff pressure b/n airway opening and alveolus. Important to keep airways open

35
Q

Transpulmonary pressure

How is it calculated?

A

PA - Ppl Distending pressure

The difference in pressure b/n inside and outside of the lung (always positive)

36
Q

Transairway pressure
Define
How is it calculated?

A

PAW - Ppl
transairway pressure is the pressure difference (gradient) between the airway opening and the alveolus. this is the pressure gradient required to produce airflow in the conductive airways, and therefore represents the pressure that must be generated to overcome airway resistance

37
Q

Explain the pressure changes that occur during inspiration that allow the lungs to fill with air

A

At End expiration
Pal= atmospheric pressure= 0cm H2O t/f no airflow
Ppl= subatmospheric = -5 cm H2O

Transmural pressure= 0- (-5) = +5

During Inspiration
Ppl= -8 cm H20
Pal= -1 cm H20 = below atmospheric pressure t/f air in

Transmural pressure= -1 - (-8) = +7

38
Q

List 3 factors responsible for keeping the alveoli open

A

Surfactant- reduces surface tension
Interdependance
Functional Residual capacity- Resting lung volume

39
Q

List 5 factors that Affect compliance

A 
Lung volume
Surfactant
Pulmonary blood flow
Age
Disease
40
Q

How does lung volume affect compliance?

A

The greater the volume the lower the compliance
eg compliance is better at RV than TLC

Compliance is the pressure volume curve. Blowing up a balloon LOW COMPLIANCE at lowest and highest volume.

41
Q

How does Surfactant affect compliance?

A

Reduces surface tension
low ST> increased lung compliance (expansion) t/f –reduces muscular effort of breathing

Reduces elastic recoil of lungs at low volume (Preventing collapse)

As alveoli become smaller surfactant molecules are squeezed together lowering the surface tension t/f smaller alveoli are easier to inflate

*Prem babies b4 30 weeks, no surfactant t/f stiff lungs (not compliant)

42
Q

How does pulmonary blood flow affect Compliance?

A

Increased capillary blood flow> decreased lung compliance.

Left heart failure can lead to Acute pulmonary Oedema which > decreased lung compliance

43
Q

How does Age affect compliance

A

Decreased chest wall compliance(joint ROM)

Increased lung compliance (reduced elasticity)

44
Q

What diseases lead to Increased lung compliance?

A

OBSTRUCTIVE LUNG DISEASE- floppy lungs
Emphysema -destroyed elasticity
Floppy airways close early

45
Q

What diseases lead to decreased lung compliance?

A

RESTRICTIVE LUNG DISEASE- stiff lungs
FIbrotic lung disease
Collapsed alveoli
Obesity

46
Q

What diseases lead to decreased chest wall compliance?

A

Musculoskeletal disorders

Obesity

47
Q

Effect of increased compliance

Effect of decreased compliance
e.g restrictive lung disease

A

Increased lung compliance
Less elastic support
Early airway closure
Reduced airway diameter- increased resistance to flow

Decreased lung & CW compliance
Decreased airflow
t/f preferential ventilation of compliance lung units

48
Q

Define closing capacity

Define closing volume

A

Closing capacity(CC)= lung volume at which some of the small airways begin to close

Closing volume(CV)= Closing capacity- Residual volume

49
Q

What does CC and CV stand for?

A

Closing capacity

Closing volume

50
Q

List 4 factors that affect airflow resistance

A

Character of an airway (length& diameter)
Pattern of airflow
Density and viscosity of gas
Lung volume

51
Q

How does the character of airways affect the airflow resistance?

A

^ length of tube > ^ resistance
^ length by 1.5 > ^ resistance x 2

Decreased diameter > ^ resistance
decreased radius by 0.5 > ^ resistance x 16

Peak airway resistance occurs in BRONCHUS decreasing as you go down the tract.

low trachea,high bronchus, decreasing as you go on.

52
Q

Describe the causes of airway narrowing

there are 3 main categories

A

Within the airway lumen
partial occlusion by secretions or foreign material
e.g. chronic bronchitis

In the lumen wall
-hypertrophy of mucous glands
-odema of bronchial walls
-Contraction of smooth mms 
(asthma)
Outside the airway
-loss radial traction due to destroyed lung parechyma
(floppy airways)
-lung compression
-Peribronchal odema
53
Q

How does the pattern of airflow affect airflow resistance?

A

Laminar (terminal bronchioles) min resistance

Turbulent-(eg due to sputum) greatest resistance

Transitional (Nose glottis, carina) great resistance

54
Q

How does lung volume affect airflow resistance?

A

Airways more distended(open) at higher lung volumes

Low lung volumes-airway closure will occur which leads to increased resistance

Low V= high resistance High V= low resistance
Think how ppl w COP will hyperinflate on purpose

55
Q

Explain the difference between static and dynamic hyperinflation

A

Static hyperinflation:occurs at rest due to floppy airways leading to early airway closure t/f gas trapping.
Also
Increased resistance (from floppy airways)
decreased expiratory flow& ^ expiratorytime (splinting)

Dynamic hyperinflation: Compensatory mechanism to overcome airway resistance.

Normally RR & TV increase during excercise. but coz lungs are hyperinflated only RR can increase.
Patient also spends LESS time in expiration (^ FRC)
to hyperinflate coz ^ Vol decreases airway resistance.

56
Q

What are the affects of increased airway resistance

A

Increased resistance
-Decreased airflow
t/f Preferential ventilation of low resistance lung units
-Dynamic hyperinflation

57
Q

List the main causes of hypoxemia

A

Ventilation perfusion missmatch **
Hypoventilation
Difusion abnormalities
Shunt

58
Q

What does V and Q stand for?
What is an ideal VQ relationship
What is a normal VQ relationship

A

V= ventilation
Q=Perfusion
Ideal V/Q= 1
Normal V/Q= 0.8

59
Q

What does
Dependent
Non Dependent
mean interms of lungs

A

Describes the position of the lung in relation gravity

Standing- Upper lobes non dependent
lower lobes dependant

60
Q

Explain perfusion and ventilation in the dependent lung section

Of a Normal person

A

DEPENDENT
Preferential perfusion
- high hydrostatic pressure (gravity) capilliaries filled
- alveoli compressed t/f no capillary collapse

Preferential ventilation

  • compressed alveoli (low volume) t/f high compliance
  • Intrapleural pressure less negative
  • t/f low transpulmonary pressure (distending pressure)
  • in sidelying abdominal contents fall onto dependent side of diaphragm putting it on stretch t/f stronger contraction

NON DEPENDENT
Well expanded alveoli
low compliance
more neg intraplural P, high transpulmonary P
high recoil pressure
high V t/f compressed capillaries & low perfusion

61
Q

Breathing at low lung volumes

or being mechanically ventilated

  • expand on this if nescessary
A

POS PRESSURE SYSTEM
Preferential ventilation to Non-Dependent areas
Lungs not well expanded(Low compliance)

Lungs So uninflated that airway closure occurs in dependent areas.

62
Q

What is it called when there is a HIGH V/Q ratio

What is it called when there is a LOW V/Q ratio

A

High V/Q ratio- high ventilation, low perfusion
=SHUNT blood entering arterial system without passing through ventilated areas of lung

Low V/Q ratio- low ventilation, high perfusion
=DEAD SPACE

63
Q

If an individual is hypoxemic with LEFT SIDED pnuemonia which side would you lie them on and why?

A

Lie them on their good RIGHT side. So that their good right side is in the dependant position and is preferentially ventilated

Cardiopulmonary Science (6 decks)

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