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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
Pulmonary resistance is usually 2 main types. Give percentages for the prevalence of each
Lung or chest wall tissue or airways to flow or air Pulmonary resistance is: 20% Pulmonary tissue resistance 80% Airway resistance
26
As lung volume increases with inspiration what happens to the zone of Apposition? What is it?
It Decreases. | Insert photo
27
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?
Intra-abdominal pressure rather than pleural pressure
28
List the muscles involves in inspiration and expiration *** edit this with more info
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
Define the concept of hysteresis in terms of lung pressure.
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
Define compliance and elastic recoil
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
what do the following stand for? | CL & Ccw
CL - lung compliance | Ccw-Chest wall compliance
32
What does Ppl stand for What is it's value?
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
What does PA stand for? | small A
Alveolar pressure Pressure inside the Alveoli Usually 0cm H2O at end expiration (same as atmospheric pressure)
34
What does Ptm (capitals) stand for? There are 2 types list them
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
Transpulmonary pressure | How is it calculated?
PA - Ppl Distending pressure | The difference in pressure b/n inside and outside of the lung (always positive)
36
Transairway pressure Define How is it calculated?
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
Explain the pressure changes that occur during inspiration that allow the lungs to fill with air
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
List 3 factors responsible for keeping the alveoli open
Surfactant- reduces surface tension Interdependance Functional Residual capacity- Resting lung volume
39
List 5 factors that Affect compliance
``` Lung volume Surfactant Pulmonary blood flow Age Disease ```
40
How does lung volume affect compliance?
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
How does Surfactant affect compliance?
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
How does pulmonary blood flow affect Compliance?
Increased capillary blood flow> decreased lung compliance. Left heart failure can lead to Acute pulmonary Oedema which > decreased lung compliance
43
How does Age affect compliance
Decreased chest wall compliance(joint ROM) | Increased lung compliance (reduced elasticity)
44
What diseases lead to Increased lung compliance?
OBSTRUCTIVE LUNG DISEASE- floppy lungs Emphysema -destroyed elasticity Floppy airways close early
45
What diseases lead to decreased lung compliance?
RESTRICTIVE LUNG DISEASE- stiff lungs FIbrotic lung disease Collapsed alveoli Obesity
46
What diseases lead to decreased chest wall compliance?
Musculoskeletal disorders | Obesity
47
Effect of increased compliance | Effect of decreased compliance e.g restrictive lung disease
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
Define closing capacity | Define closing volume
Closing capacity(CC)= lung volume at which some of the small airways begin to close Closing volume(CV)= Closing capacity- Residual volume
49
What does CC and CV stand for?
Closing capacity | Closing volume
50
List 4 factors that affect airflow resistance
Character of an airway (length& diameter) Pattern of airflow Density and viscosity of gas Lung volume
51
How does the character of airways affect the airflow resistance?
^ 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
Describe the causes of airway narrowing there are 3 main categories
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
How does the pattern of airflow affect airflow resistance?
Laminar (terminal bronchioles) min resistance Turbulent-(eg due to sputum) greatest resistance Transitional (Nose glottis, carina) great resistance
54
How does lung volume affect airflow resistance?
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
Explain the difference between static and dynamic hyperinflation
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
What are the affects of increased airway resistance
Increased resistance -Decreased airflow t/f Preferential ventilation of low resistance lung units -Dynamic hyperinflation
57
List the main causes of hypoxemia
Ventilation perfusion missmatch ** Hypoventilation Difusion abnormalities Shunt
58
What does V and Q stand for? What is an ideal VQ relationship What is a normal VQ relationship
V= ventilation Q=Perfusion Ideal V/Q= 1 Normal V/Q= 0.8
59
What does Dependent Non Dependent mean interms of lungs
Describes the position of the lung in relation gravity Standing- Upper lobes non dependent lower lobes dependant
60
Explain perfusion and ventilation in the dependent lung section Of a Normal person
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
Breathing at low lung volumes or being mechanically ventilated * expand on this if nescessary
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
What is it called when there is a HIGH V/Q ratio What is it called when there is a LOW V/Q ratio
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
If an individual is hypoxemic with LEFT SIDED pnuemonia which side would you lie them on and why?
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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