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Block 2 > Lungs > Flashcards

Lungs Flashcards

0
Q

What is pressure?

A 
P = F / A
Pressure
Force 
Area 
Unit is Pa
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1
Q

What is Boyles law? And how does it influence gas exchange?

A

Absolute pressure exerted by gas is inversely proportional to volume it occupies if temp and amount of gas remain unchanged in closed system
P1V1 = P2V2
Creates the pump and vacuum activity in lungs that allows us to breathe

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2
Q

What is Charles’ law?

A

At constant pressure, the volume of gas changes in direct proportion to its temperature on the absolute temperature scale
V = KT (K is a constant)
V1/T1=V2/T2

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3
Q

What is the universal gas law?

A 
PV = nRT
P is pressure
V is volume
n is number of moles of gas
R is gas constant
T is temperature
Allows calculation of volume changes with pressure and temperature changes
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4
Q

What is a partial pressure?

A

When two gases in a mixture do not interact, they behave independently and each exerts its own pressure

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5
Q

What is Dalton’s law?

A

In a mixture of non reacting gases, total pressure exerted is equal to sum of partial pressures

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6
Q

What is the partial pressure of O2 in air?

A

21.1 kPa

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7
Q

What factor is saturated vapour pressure dependent on?

A

Temperature

Increased kinetic energy allows more vapour to escape the surface of the liquid

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9
Q

What is Henry’s law?

A

Number of molecules of gas dissolving in solvent is directly
proportional to the pressure of the gas at the surface of the
liquid

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10
Q

What happens to tension of a gas dissolving in water at equilibrium?

A

Tension proportional to partial pressure of that gas in adjacent gas mixture

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11
Q

What does gas tension indicate?

A

How readily a gas will leave a liquid

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12
Q

What is gas tension measured as?

A

Partial pressure of solute in solvent in kPa

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13
Q

What is the content of a gas in a liquid?

A

Proportional to its solubility in that liquid and the gas tension at
equilibrium

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14
Q

What is saturated vapour pressure at 37 degrees?

A

6.28 kPa

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15
Q

What is a difference between convection and diffusion?

A

No net transport of matter in diffusion

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16
Q

How much oxygen is picked up by the blood in health?

A

12 mmol O2 per minute

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17
Q

What is an alveolus?

A

Thin spherical structure where gas exchange occurs
Surrounded by capillary plexus
Fed through tiny bronchiole called alveolar duct

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18
Q

What constitutes total content of gas in a liquid?

A

Total reacted gas and gas dissolved in liquid

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19
Q

In blood, final gas content is determined by…

A

Gas tension
Solubility of gas in liquid
Avidity of haemoglobin for oxygen

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20
Q

Where does gas exchange occur?

A

At alveolar membrane

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21
Q

How does the composition of alveolar gas differ from atmospheric?

A

Lower pO2 - 13.3 in alveolar, 21.1 kPa in atmosphere

Higher pCO2 - 5.3 in alveolar, minimal in atmosphere

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22
Q

How does mixed venous blood gas composition vary from alveolar?

A

pO2 - 6 kPa venous, 13.3 alveolar

pCO2 - 6.5 kPa venous, 5.3 alveolar

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23
Q

What factors affect diffusion rate?

A

Surface area of alveoli
Concentration gradient caused by differences in partial pressures
Resistance of alveolar capillary membrane - thickness
Solubility of gas
Molecular weight of gas
Diffusion rate = D x A x (difference in PP/thickness)
D is proportional to solubility / root of MW

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24
Q

What constitutes the diffusion barrier of the alveolar membrane?

A 
Diffusion through gas to alveolar wall
Epithelium of alveolus
Tissue fluid and connective tissue 
Endothelium of capillary 
Plasma 
Red cell membrane
Cytoplasm
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25
Q

What is solubility?

A

Amount of solvent that can dissolve in unit volume of solute

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26
Q

Which diffuses faster, O2 or CO2?

A

CO2

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27
Q

Is oxygen transfer perfusion or diffusion limited?

A

Perfusion

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28
Q

What may cause a change from perfusion limited oxygen delivery to diffusion limited?

A

Thickening of diffusion barrier - alveolar membrane

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29
Q

Other than gas exchange, what functions does the respiratory system have?

A

Reservoir for blood and oxygen
Metabolism of circulating compounds eg ACE
Filter blood

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30
Q

Which part of the airways form the anatomical dead space?

A

Conducting airways - bronchi and bronchioles

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31
Q

Which parts of the airways form the respiratory airway?

A

Respiratory bronchioles
Alveolar ducts
Alveolar sacs

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32
Q

What name is given to each level of branching of the bronchial tree?

A

Generation

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33
Q

What is hypoxic vasoconstriction?

A

In alveoli with low pO2 due to lower ventilation levels, pulmonary arterioles can be constricted to reduce blood flow to this area where it is not needed

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34
Q

Give an example of a disease which increases the thickness of the diffusion barrier

A

Pulmonary fibrosis

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35
Q

Give an example of a disease which reduces the surface area available for diffusion

A

COPD - chronic obstructive pulmonary disease

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36
Q

What non disease state can cause a switch from perfusion to diffusion limited oxygen delivery?

A

High levels of exercise as the perfusion rate is so fast that the diffusion rate cannot keep up

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37
Q

What can be used as lung function test to determine the thickness of the alveolar membrane?

A

Carbon monoxide as its delivery is diffusion limited

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38
Q

How can rate of gas exchange be increased when a gases delivery is diffusion limited?

A

Increase pO2 in alveoli

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39
Q

Which muscles are involved in ventilation?

A

Diaphragm

Intercostal muscles

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40
Q

What do you use spirometry for?

A

Measure lung volumes

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41
Q

What 4 parts make up total lung capacity?

A

Tidal volume
Residual volume
Inspiration reserve volume
Expiratory reserve volume

Maximum force generated by inspiratory muscles balanced by opposing forces

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42
Q

In spirometry, what is the difference between lung volumes and lung capacities?

A

Lung volumes change with breathing pattern

Lung capacities do not

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43
Q

What factors determine an individual’s lung capacities?

A

Properties of lung, chest wall and muscles

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44
Q

Which lung volumes make up inspiratory capacity?

A

Tidal volume and inspiratory reserve volume

Biggest breath that can be taken from resting expiratory level (lung
volume at end of quiet expiration) Inspiratory capacity typically ~3l

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45
Q

Which lung volumes form the vital capacity?

A

Tidal volume
Inspiratory reserve volume
Expiratory reserve volume

Biggest breath that can be taken, often changes in disease

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46
Q

Which lung volumes make up the functional residual capacity?

A

Residual volume
Expiratory reserve volume

Volume of air in the lungs at resting expiratory level
Typically ~2 litres Determined by the balance of elastic resistance
between lung and chest wall

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47
Q

What is a normal value for vital capacity?

A

5L

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48
Q

What is minute ventilation (MV)?

A

Amount of air moved into and out of the lungs or minute
Product of tidal volume and respiratory rate
MV=Vt x RR
Typically 6-8 L/min at rest

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49
Q

What must be calculated to work out the alveolar ventilation rate?

A

Amount of wasted ventilation into dead space

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50
Q

What volume of inspired air is within the serial dead space and therefore doesn’t take part in gas exchange?

A

150 ml

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51
Q

What is the distributive dead space?

A

Dead or damaged alveoli

Alveoli with poor perfusion

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52
Q

What is the physiological dead space?

A

Serial and distributive dead spaces combined

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53
Q

What type of breathing amplifies dead space effect?

A

Rapid and shallow

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54
Q

What is the ideal V/Q ratio?

A

1

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55
Q

What is the main reason for defective gas exchange in disease?

A

V/Q mismatch

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56
Q

What would total lung V/Q mismatch cause?

A

Arterial hypoxaemia

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57
Q

Give an example of a disease which causes a decrease in ventilation and therefore gives a lower V/Q ratio?

A

Pneumonia

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58
Q

Give an example of a disease which causes decreased perfusion and therefore increases the V/Q ratio

A

Pulmonary embolus

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59
Q

Describe the V/Q ratio in the apex of the lung and how this differs to the base

A

In the apex, the ventilation rate is greater than the perfusion so the V/Q ratio is above 1
In the base, perfusion (gravity dependent) is greater than ventilation rate and so the V/Q ratio is below 1

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60
Q

Why is perfusion of the central part of the lung sporadic?

A

Systole and diastole of the heart mean that pressure changes

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61
Q

What causes the reduction in pH as you move down from apex to base of lungs?

A

Increasing CO2 levels in alveoli and capillaries. CO2 transfer is ventilation dependent

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62
Q

Why is apical alveolar pO2 relatively high?

A

Less perfusion

O2 transfer is perfusion dependent

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63
Q

What happens in the lung during exercise to accommodate increased CO?

A

Distensible apical blood vessels that are usually collapsed, open. This increases oxygen uptake at the top of the lung

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64
Q

What 5 things can cause hypoxia?

A 
Shunt
V/Q mismatch
Limited diffusion
Hypoventilation
Decreased O2 in inspired air
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65
Q

Which pathological cause of hypoxia cannot be corrected with increasing inspired oxygen?

A

Pulmonary shunt

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66
Q

What factors does oxygen delivery to tissues rely on?

A 
Cardiac output
Haemoglobin concentration
Oxygen saturation 
Dissolved oxygen 
DO2 = CO x (( Sa02 x Hb x k) x ( PaO2 x 0.023 ))
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67
Q

Which ribs end in costal cartilage?

A

1-10

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68
Q

What is flail chest?

A

When a segment of thoracic cage is separated from rest of chest wall. At least 2 fractures per rib which produces a free segment. This segment is unable to contribute to lung expansion, paradoxical movement

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69
Q

What can be a consequence of having an additional cervical rib?

A

Thoracic outlet syndrome
Brachial plexus gets squashed
Muscle wasting in the hand

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70
Q

What 3 parts make up the sternum?

A

Manubrium
Body
Xiphoid process

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71
Q

At what thoracic level would you find the sternal notch?

A

T2

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72
Q

What do you find at the sternal angle?

A

T4

2nd rib

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73
Q

What level do you find the xiphoid process at?

A

T9/10

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74
Q

Which part of the ribs forms a joint with the vertebrae?

A

Articular facets of head

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75
Q

Which ribs connect directly to the sternum?

A

Ribs 1-7

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76
Q

Which ribs connect to the sternum via the costal cartilage of the ribs above?

A

Ribs 8-10

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77
Q

What are the 3 layers of intercostal muscle?

A

External intercostal
Internal intercostal
Innermost intercostal

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78
Q

Where would you make an incision in the intercostal space?

A

Just above the rib to avoid the neurovascular bundle at the top of the space

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79
Q

What does an intercostal nerve supply?

A 
Skin
Muscle
Bone
Cartilage
Parietal pleura
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80
Q

Where can pleuritic pain and shingles refer to?

A

Dermatome of the spinal nerve of origin

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81
Q

Where does the sympathetic chain lie in the thoracic cavity?

A

Posterior thoracic wall

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82
Q

What can a pancoast tumour cause?

A

Compression of the sympathetic chain in the apical region of the lung
Can cause Horner syndrome due to compression of the T1 spinal nerve

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83
Q

Which artery can be harvested for coronary artery bypass graft?

A

Internal thoracic artery

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84
Q

Where does the blood supply to the thoracic wall derive from?

A

Intercostal arteries which form anastomotic loops

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85
Q

Where do posterior intercostal arteries branch from?

A

Descending aorta

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86
Q

Where do anterior intercostal arteries branch from?

A

Internal thoracic artery

Musculophrenic artery

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87
Q

Where does the internal thoracic artery branch from?

A

Subclavian artery

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88
Q

What is the venous drainage of the thoracic wall?

A

Azygous venous system
Azygous vein on right
Hemiazygous on left

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89
Q

What does the azygous vein drain into?

A

Superior vena cava

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90
Q

What can damage of the thoracic duct lead to?

A

Chylothorax

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91
Q

Which areas of mediastinum does thoracic duct run through?

A

Posterior

Superior

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92
Q

Where does the thoracic duct start and finish?

A

Starts at cisterna chyli

Ends at left subclavian vein

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93
Q

Where does the diaphragm attach?

A

Costal margin
Ribs 10-12
Lumbar vertebrae

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94
Q

Name 2 types of congenital diaphragmatic hernia

A

Bochdalek hernia - posterior left sided

Morgagni hernia - retro sternal

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95
Q

Which nerve innervates the diaphragm?

A

Phrenic nerve C3-5

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96
Q

What can unilateral damage to the phrenic nerve cause?

A

Hemidiaphragmatic palsy

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97
Q

Which 3 structures pierce the diaphragm and at what levels?

A

Inferior vena cava T8
Oesophagus T10
Descending aorta T12

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98
Q

At what time during development does the respiratory diverticulum form as an outpouching of the gut tube?

A

4 weeks

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99
Q

What developmental tissue type are the lining of lungs and glands derived from?

A

Endoderm

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100
Q

What developmental tissue type are the blood vessels, cartilage, smooth muscle and visceral pleura derived from?

A

Mesoderm

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101
Q

During development, what divides the oesophagus and trachea?

A

Tracheo-oesophageal septum which forms weeks 4-5

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102
Q

What 2 developmental defects can occur if septation of the trachea and oesophagus fail?

A

Blind ended oesophagus

Fistula

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103
Q

How many bronchial buds form?

A

3 on right, 2 on left

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104
Q

At what time during development do segmental bronchi form?

A

Week 7

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105
Q

What part of respiratory development occurs at week 26? And what consequence can this have for premature babies?

A

Initial development of respiratory epithelia

Premature babies lungs are not fully developed and so survival rates are lower

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106
Q

What does the horizontal fissure divide?

A

Right middle and superior lobes

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107
Q

Which structures are closely related to the right lung?

A

Oesophagus
Azygous vein
Brachiocephalic vein
SVC and IVC

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108
Q

Which structures are closely related to the left lung?

A 
Aortic arch
Descending aorta
Cardiac impression
Subclavian artery
Brachiocephalic vein
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109
Q

Where does the phrenic nerve pass in relation to the hilum of the lung?

A

Anterior

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110
Q

Which structures pass through the hilum of the lung?

A

Main bronchi
Pulmonary artery
Autonomic nerves
Pulmonary vein

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111
Q

What is the pulmonary ligament?

A

Fold of parietal pleura at hilum

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112
Q

What occurs if a venous thrombus passes into the lungs via pulmonary artery?

A

Pulmonary embolism

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113
Q

What does the parietal pleura line?

A

Thoracic cage (costal)
Mediastinum
Cervical region
Diaphragm

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114
Q

What holds together the pleural layers at rest?

A

Surface tension

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115
Q

What signs will you see with a tension pneumothorax?

A 
Mediastinal shift away from pneumothorax 
Tracheal deviation 
Diaphragmatic depression
Unilateral hyperinflation 
Increased intercostal space size
Hyper resonant
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116
Q

At what point does the trachea bifurcate?

A

T4 - sternal angle

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117
Q

What vertebral level is the horizontal fissure located at?

A

4th costal cartilage, horizontally to join the oblique fissure

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118
Q

Where does the oblique fissure start and finish?

A

T3 spinous process posteriorly

6th costal cartilage anteriorly

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119
Q

Which spinous process is the most prominent in the neck?

A

C7

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120
Q

Biopsy of which structures will require crossing through the costodiaphragmatic recess?

A

Liver, spleen, kidneys

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121
Q

Where are chest tubes classically inserted?

A

Triangle of safety

Bordered by posterior, anterior axillary lines and nipple line (4-5th intercostal space)

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122
Q

Where does the trachea start?

A

Cricoid cartilage in larynx C6/7

123
Q

What are the walls of the trachea supported by?

A

Hyaline cartilage

124
Q

What happens to carina if the lymph nodes below it are enlarged? (Tracheobronchial nodes)

A

Become more rounded in shape

125
Q

Which bronchus is more likely to get aspirated food entering it and why?

A

Right main bronchus because it is more vertical

126
Q

Where do pulmonary arteries and veins run in relation to pulmonary segments?

A

Pulmonary arteries run with bronchi and bronchioles

Pulmonary veins run between segments

127
Q

How many segments does each lung have?

A

Right - 10

Left - 9

128
Q

What is atelactasis?

A

Collapse or closure of lung

129
Q

Which segment is least well drained in the supine position and so a likely site for hospital acquired pneumonia?

A

Superior bronchopulmonary segment of inferior lobe because it’s bronchus has to drain against gravity in this position

130
Q

Where does the left upper lobe drain to?

A

Bronchomediastinal duct –>thoracic duct and left subclavian vein

131
Q

Where does lung lymph drainage go to (apart from the left upper lobe)?

A

Bronchomediastinal duct –> right lymphatic duct to right subclavian vein

132
Q

When does acute respiratory failure occur?

A

When pulmonary system is unable to meet metabolic demands of the body

133
Q

What is hypoxaemic respiratory failure?

A

PaO2 < or equal to 8kPa when breathing room air

Type 1

134
Q

What is hypercapnic respiratory failure?

A

PaCO2 > or equal to 6.7kPa

Type 2

135
Q

What is the alveolar gas equation?

A 
PAO2 = (FiO2 x (P atmos - P H2O)) - (PaCO2 / RQ)
FiO2 - fraction of inspired oxygen
P atmos - atmospheric pressure 
P H2O - water vapour pressure 
RQ - respiratory quotient (0.8)
136
Q

What are the levels of expired CO2 largely dependent on?

A

Alveolar ventilation

137
Q

How can alveolar ventilation be calculated?

A

Alveolar ventilation = respiratory rate x (tidal volume - dead space)

138
Q

Which dead space is constant? And which can vary and why?

A

Anatomical dead space constant

Physiological dead space can vary depending on ventilation perfusion matching

139
Q

What mechanism tries to maintain ventilation perfusion matching?

A

Hypoxaemic pulmonary vasoconstriction

140
Q

In what circumstances will supplemental oxygen not be beneficial?

A

Absolute shunt where ventilation is blocked

When someone has chronically high levels of CO2 and therefore hypoxaemia is driving their breathing

141
Q

What factors could cause hypoxaemia?

A

Low levels of inspired O2
Hypo ventilation
V/Q mismatch - shunt
Diffusion abnormality

142
Q

At what sites may disease cause hypo ventilation?

A 
Brainstem - head injury, drug overdose
Spinal cord - sci c3-5
Spinal nerve root - guillain barré syndrome 
Nerve - demyelination 
Neuromuscular junction - myesthenia gravis
Respiratory muscle - muscular dystrophy 
Chest wall
Pleura
Lung
Airway
143
Q

What can cause shunts in the lung?

A 
Pneumonia
Pulmonary oedema
Atelactasis 
Collapse
Pulmonary haemorrhage or contusion
Right to left shunt of heart - congenital heart disease, pulmonary hypertension
144
Q

What can be a cause of diffusion abnormality?

A

PCP - pneumocystis pneumonia in immunosuppressed patients
Acute respiratory distress syndrome - widespread inflammation
Alveolitis

145
Q

What is a hallmark sign of diffusion abnormality?

A

Desaturation on exercise

146
Q

What is a normal venous oxygen saturation?

And what happens to this value if you half cardiac output?

A

Normal value 75%

Reduced to 50% if CO is halved

147
Q

What are signs of respiratory compensation?

A

Tachypnoea
Use of accessory muscles
Nasal flaring
Recession (gaps between ribs get sucked in)

148
Q

What can tissue hypoxia result in?

A

Altered mental state
Lactic acidosis
Decrease HR and decrease BP (late)

149
Q

What can be sources of error in using pulse oximetry to measure sats?

A 
Poor peripheral perfusion
Poorly adherent or positioned probe
False nails or nail varnish
Lipaemia
Bright ambient light
Excessive motion
Carboxyhaemaglobin or methaemoglobin
150
Q

What can hypercapnia result in?

A

Sympathetic stimulation
Respiratory acidosis
Flapping tremor
If severe (>10 kPa) unconsciousness and respiratory depression

151
Q

What are signs and symptoms of severe respiratory failure?

A 
RR > 30 /min or < 8 /min
Difficulty completing sentences 
Agitated, confused or comatose
Cyanosed
SpO2 <90% 
Deterioration despite therapy
152
Q

What are treatment options with respiratory failure?

A

Oxygen therapy
CPAP - continuous positive airway pressure to open collapsed alveoli
Mechanical ventilation

153
Q

What could you do to help with pneumonia?

A

Antibiotics

Physiotherapy

154
Q

What can be done to help with pulmonary oedema?

A

Vasodilators

Diuretics

155
Q

What can you do to help with a pneumothorax?

A

Chest drain

156
Q

What can be given in an opiate overdose?

A

Naloxone

157
Q

What are the 2 types of oxygen delivery devices?

A

Fixed and variable performance devices

158
Q

What is a disadvantage of mechanical ventilation?

A

Requires sedation and an endotracheal tube

159
Q

What factors affect the decision to ventilate or not?

A 
Severity of respiratory failure
Cardiopulmonary reserve
Adequacy of compensation
Expected speed of response -underlying disease, treatment
Risks
160
Q

What are the risks of mechanical ventilation?

A

Secondary infection
Pneumothorax
Ventilator induced lung injury
Risks from immobility - venous thromboembolism, pressure ulceration

161
Q

What is PEEP?

A

Positive end expiratory pressure
Alveolar pressure above atmospheric pressure that exists at end of expiration. Can be applied in ventilated patients to prevent collapse of alveoli at end of expiration

162
Q

What is lung volume determined by?

A

Elasticity of lungs

Properties of chest wall

163
Q

What is compliance?

A

Measure of stiffness of the lung

164
Q

What lung volume is represented when the forces inflating and deflating the lungs are equal?

A

Forced residual capacity

165
Q

The lungs are not adherent to the inside of the thoracic cavity. What stops themfrom collapsing away from the chest wall?

A

Negative pressure in chest that keeps lungs inflated

166
Q

Where are alveoli the biggest and why?

A

Higher negative pressure at top of lungs

167
Q

Which parts of the lung move the most during inspiration?

A

Bigger volume change at bottom of lungs due to the way the ribs move

168
Q

What effects do the shape of the ribs have on the way they move?

A

Upper ribs move like pump handle

Lower ribs move like bucket handle so allow for greater expansion

169
Q

Which muscles are used during inspiration?

A

Scalenes - fix thorax
External intercostals - posterior
Internal intercostals - anterior
Diaphragm

170
Q

Which muscles are used in active expiration?

A

Abdominal muscles
Intercostals
Pectoral girdle muscles

171
Q

Explain how the respiratory pattern of a patient with a low cervical spinal injurydiffers from a patient with a low thoracic spinal injury?

A

Cervical SCI - loss of use of intercostal muscles and accessory muscles so see saw breathing where diaphragm is pulled down but chest cannot expand sufficiently. Abdomen distends and chest caves in.
Thoracic SCI - all muscles of breathing will be able to function so normal breathing

172
Q

How do you measure compliance?

A

Change in volume / change in pressure

173
Q

What is specific compliance?

A

Relates compliance to actual volume
Volume change per unit pressure change / starting volume of lung
Babies lungs, not stiffer but compliance would give incorrect value, specific compliance gives more accurate measure

174
Q

What is hysteresis?

A

Difference in lung compliance due to additional energy required during inspiration to recruit and inflate additional alveoli

175
Q

What is LaPlace’s law?

A

Larger vessel radius, larger wall tension required to withstand a given internal fluid pressure. For a given vessel radius and internal pressure, a spherical vessel will have half the wall tension of a cylindrical vessel
For an alveolus - P=2T/r

176
Q

What is surface tension?

A

At a surface: attractive forces between molecules of a liquid are much stronger than those between liquid and gas. Surface becomes as small as possible. Measured as force required to change surface area per unit length

177
Q

What does surfactant do?

A

Lines the alveoli and reduces surface tension which prevents small alveoli emptying into large

178
Q

Which cells secrete surfactant?

A

Type II cells lining alveoli

179
Q

What is surfactant?

A 
Mixture of phospholipid compounds, principally dipalmitoyl phosphatidylcholine
Hydrophobic, projects into the gas phase of the alveolus
Surfactant proteins (SP-A, B, C, D)
180
Q

What can lead to a depletion of surfactant?

A

Lack of blood supply

181
Q

What effects does surfactant have?

A

Reduces work of breathing by reduction in surface tension and increasing compliance
Reduces the likelihood of tissue fluid transudation
The lipid component of surfactant has an antioxidant activity
SP-A and D can bind a wide range of pathogens
SP-A and D can activate macrophages and neutrophils via specific receptors

182
Q

When are the airways narrowest?

A

During expiration as positive intrathoracic pressure decreases diameter

183
Q

Where in the lungs does turbulent flow occur?

A

Trachea

184
Q

Where in the lungs does laminar flow occur?

A

Terminal bronchioles

185
Q

What factors affect compliance?

A

Lung volume
Diameter of alveoli
Content of alveoli
Integrity of surfactant production

186
Q

What factor of hysteresis allows V/Q matching?

A

Alveoli at bottom of lung are smallest, but are on most compliant part of hysteresis curve and so when pressure is increased, they can expand more to match perfusion

187
Q

Which category of lung defect will result in an almost normal FVC but a largely reduced FEV1?

A

Obstructive defect eg COPD

188
Q

Which category of lung defect will result in a reduced FEV1 and a largely reduced FVC?

A

Restrictive defect eg pulmonary fibrosis

189
Q

Where does automatic control of breathing originate?

A

Dorsal respiratory group - inspiration
Ventral respiratory group - expiration and inspiration
Sensory nerves IX and X send chemoreceptor, baroreceptor and stretch receptor signals to dorsal respiratory group

190
Q

Where does the ventral respiratory group signal to?

A

Accessory muscles in active respiration via u opioid receptors

191
Q

What does the pneumotaxic centre do?

A

Switch of inspiratory ramp

Control respiratory rate

192
Q

What is the Hering Breuer reflex?

A 
Stretch receptors in airways 
Signal travels via vagus nerve afferents
Respiratory centre in medulla
Inhibits inspiratory neurones
Inspiration is ended, allowing expiration
193
Q

Where are peripheral chemoreceptors located?

A

Carotid bodies

Aortic arch

194
Q

Via what nerve do the peripheral chemoreceptors in the carotid bodies signal to the medulla?

A

CN IX

195
Q

Where are central chemoreceptors located and what do they detect?

A

2mm below ventral surface of medulla

Detect pH of CSF

196
Q

What can prolonged vomiting cause in terms of acid base balance?

A

Metabolic alkalosis

197
Q

A 24yr old woman is hyperventilating. If she continues what will the physiological consequences be and why does she appear to have a ‘cardiac arrest’ before making a spontaneous recovery?

A

Low CO2. Becomes alkalotic. Calcium levels go up so nerves and muscles become more active - spasm
Brains response tells respiratory system to slow down but higher systems are overriding signal. Eventually response becomes overwhelming and cant override it, so she stops breathing. CO2 level rises. Paper bag works because she rebreathes expired gas and increases CO2

198
Q

A 76 yr old man is given morphine for post operative pain relief following an elective abdominal aortic aneurysm repair. Explain the physiological consequences that may occur in this situation

A

Breathing decreased so CO2 levels increase. So tachycardic, sweating etc due to sympathetic stimulation. Continued CO2 increase - respiratory depression so can become comatosed - overdose
Supplemental morphine in hospital, given supplemental oxygen to compensate for modest hypoxia

199
Q

Give 4 reasons for doing lung function tests

A

Provides aid to diagnosis
Can follow changes in lung function over time
Can assess those at risk of pulmonary disease and those with symptoms
Can assess changes in response to specific stimuli

200
Q

What is air flow rate a good measure of?

A

Diameter of airways

201
Q

What does measuring vital capacity tell us?

A

A measure of total lung volume

202
Q

What is carbon monoxide used for as a lung function test?

A

Measures permeability of lung membranes

203
Q

What 2 factors can the peak flow meter tell us about?

A

Diameter of bronchial tree

Muscle power available to blow air out of lungs

204
Q

What factors are important when taking a peak flow meter reading?

A

Pointer at zero to start
Stood or sat in comfortable position
Peak flow meter horizontal
Deep breath out, deep breath in then wrap lips tightly around mouthpiece
Blow as hard as possible using maximum force
Repeat 3 times and record highest value

205
Q

What peak flow results would you expect to see from an asthmatics peak flow diary?

A

Diurnal variation with lower values in the morning

>20% variability in readings over time in untreated or poorly controlled asthma

206
Q

What information can be discerned from a flow volume loop?

A

Peak expiratory flow PEF
Forced vital capacity FVC
Forced expiratory volume in 1 second FEV1

207
Q

What does a time volume loop show?

A

Forced vital capacity FVC

Forced expiratory volume in 1 second FEV1

208
Q

Which is the best index of lung restriction?

A

Reduced forced vital capacity

209
Q

Which is the best index for measuring lung obstruction?

A

Reduced FEV1

210
Q

Why will airway obstruction make the residual volume increase?

A

Air gets trapped at end expiration

211
Q

What are normal FEV1 and FVC values?

A

Over 80% of predicted values

212
Q

What happens to the ratio of Fev1/ FVC in obstructive airways?

A

Reduces below 0.7

213
Q

What happens to the ratio of Fev1/ FVC in restrictive airway disease?

A

Increase above 0.7

214
Q

What are contraindications to lung function tests?

A

Haemoptysis
Closed or recent (within 2 weeks) pneumothorax
Unstable CV status
Pre eclampsia
Hypertension (MAP above 130mmHg)
Thoracic, abdominal or cerebral aneurysms
Acute illness that may interfere with results
Recent thoracic, ear, eye or abdo surgery
Active communicable diseases eg TB

215
Q

What is bronchitis?

A

Infection and inflammation of the airways

216
Q

What are symptoms of bronchitis?

A

Dyspnoea
Cough
Wheeze
Sputum

217
Q

What are signs of bronchitis?

A

Fever
Tachypnoea
Crackles
Wheeze

218
Q

What would you see from investigations of a patient with bronchitis?

A

Hypoxia

Normal chest X-ray

219
Q

What is pneumonia?

A

Infection and inflammation of the alveoli

220
Q

What are the symptoms of pneumonia?

A

Dyspnoea
Cough
Sputum
Pleurisy

221
Q

What are signs of pneumonia?

A

Fever
Tachypnoea
Crackles
Decreased or bronchial breath sounds

222
Q

What would you see from investigations of a patient with pneumonia?

A

Possible hypoxia

Visible consolidation on chest X-ray

223
Q

Why do you hear abnormal breath sounds in pneumonia patients?

A

Fluid filled area does not attenuate sound as much as air

Pneumonia there are areas of pus in the alveoli

224
Q

What types of infection generally cause acute and chronic bronchitis?

A

Acute - viral typically: rhinovirus, flu virus

Chronic - bacterial: strep pneumoniae, Haemophilus influenzae

225
Q

Which microbes typically cause pneumonia?

A

Influenza virus
Strep pneumoniae
Staph aureus

226
Q

What respiratory condition does TB cause?

A

Bronchopneumonia with or without haemoptysis

227
Q

What investigations might be ordered for a suspected lower respiratory tract infection?

A 
PEF
FBC
U&Es
CRP
Lactate
ABGs
CXR
Nose and throat swabs
Sputum
228
Q

What treatment can be provided for a lower respiratory tract infection?

A 
Sepsis care package if sepsis
Oxygen if hypoxic
Antimicrobials
IV fluids if signs of AKI
Bronchodilators and steroids for bronchitis
Saline nebuliser for expectoration
Chest physio for expectoration
Ventilatory support if respiratory failure
229
Q

What is CURB 65?

A 
Confusion
Urea > 7mmol/L
RR > 30/min
BP < 90 mmHg systolic 60 mmHg diastolic 
Age > 65
If score >1 admit, if >2 IV treatment
230
Q

What antimicrobial would be used against influenza in acute bronchitis?

A

Oseltamivir

231
Q

What antimicrobial would be used against H. Influenzae in chronic bronchitis?

A

Co amoxiclav

232
Q

What antimicrobial(s) would be used against community acquired pneumonia?

A

Amoxicillin and Clarithromycin

233
Q

What antimicrobial would be used against hospital acquired pneumonia?

A

Piperacillin-tazobactam
Piperacillin is antibiotic
Tazobactam is beta lactamase inhibitor

234
Q

What antimicrobial should be used against staph aureus, particularly if there are concerns over MRSA?

A

Linezolid

235
Q

What would you expect to see on a chest X-ray of a patient with COPD?

A

Hyper inflated thorax
Flattened diaphragm
Increased hilar shadow
Bullae (in emphysema)

236
Q

What are symptoms of asthma?

A

Cough
Wheeze
SOB - worse at night
Chest tightness

237
Q

What are causes and triggers of asthma?

A 
Environmental allergen
Viral infection
Cold air
Emotion
Irritant vapours and fumes
Genetic factors 
Drugs - NSAIDs, B blockers
Atmospheric pollution 
Exercise
Occupational sensitisers
238
Q

What are 3 key features of asthma?

A

Airway obstruction - reversible
Airway hyper responsiveness
Airway inflammation

239
Q

What may be visible with histology of asthma airway?

A

Thickened basement membrane
Mucus plug with eosinophils and desquamated epithelial cells
Infiltration of mast cells, mononuclear cells, eosinophils in mucosa and submucosa
Oedema in mucosa and submucosa
Hypertrophied smooth muscle
Vasodilation

240
Q

What events happen in the immediate/early phase of asthma pathogenesis?

A

Pre sensitised mast cells encounter allergen and release histamine and other mediators which cause bronchoconstriction

241
Q

What events happen in the late phase of asthma pathogenesis?

A

Factors released from mast cells and T helper cells recruit other eosinophils and neutrophils
Cells infiltrate the mucosal layers, vascular leak occurs, mucus secretion increases
Mucus plugs cause a second wave of airway obstruction

242
Q

What events happen in the chronic/remodelling phase of asthma pathogenesis?

A 
Eosinophils cause damage due to repeated attacks
Smooth muscle hypertrophy
Smooth muscle and epithelial hyperplasia
Epithelial damage
Basement membrane thickening
243
Q

Which drugs are used to treat the immediate phase of asthma?

A

B2 agonists
CysLT antagonists
Theophylline

244
Q

What drugs are used to treat the late phase of asthma?

A

Glucocorticoids

245
Q

What is type 1 brittle asthma?

A

Wide PEF variability

>40% diurnal variation for 50% of time over >150 days despite therapy

246
Q

What is type 2 brittle asthma?

A

Sudden severe attacks on background of well controlled asthma

247
Q

What is acute severe asthma?

A

PEF 33-50% of best or predicted
Respiratory rate >25 / min
Heart rate > 110 / min
Inability to complete sentences in one breath

248
Q

What are signs of life threatening asthma?

A 
Altered consciousness
Exhaustion
Arrhythmia
Hypotension
Cyanosis
Silent chest
Poor respiratory effort 
PEF <8kPa
249
Q

What treatments can be used in acute asthma management?

A

Oxygen to maintain sats above 94%
B2 agonist nebuliser or MDI (metered dose inhaler) via spacer, repeat at 15-30 min intervals
Glucocorticoids to reduce late phase - prednisolone 40-50mg, hydrocortisone 100mg QDS (4x day) IV, continue for 5 days
Ipratropium bromide or magnesium sulphate if poor response to bronchodilators
Antibiotics where infection present

250
Q

What is COPD?

A

Umbrella term for chronic irreversible obstructive airway disease

251
Q

What are the clinical features of COPD?

A

Productive cough
Wheeze
Dyspnoea
Frequent infective exacerbations with purulent sputum
Cyanosis and oedema - blue bloater - insensitive to CO2 or
Tachypnoeic and pink - pink puffer - responsive to CO2
Signs of respiratory failure

252
Q

Describe COPD pathophysiology

A

Alveolar macrophages and damaged epithelial cells stimulate release of cytotoxic T cells and neutrophils
This causes airway inflammation, remodelling, parenchymal destruction, loss of alveolar attachments and decrease of elastic recoil

253
Q

What are the reversible causes of airway obstruction in COPD?

A

Accumulation of inflammatory cells, mucus and plasma exudate in bronchi
Smooth muscle contraction
Dynamic hyperinflation during exercise

254
Q

What are the irreversible causes of airway obstruction in COPD?

A

Fibrosis and narrowing of airways
Loss of elastic recoil due to alveolar destruction
Destruction of alveolar support that maintains latency of small airways

255
Q

Describe pathophysiology in large airways in COPD

A 
Mucus hyper secretion
Goblet cell hyperplasia
Mucus gland hyperplasia
Increased cytotoxic T cell and macrophage infiltration 
Squamous metaplasia of epithelium 
Neutrophils in sputum
256
Q

Describe pathophysiology in small airways in COPD

A 
Inflammatory exudate in lumen
Disrupted alveolar attachments
Thickened wall with cytotoxic T cells, macrophages and fibroblasts
Peribronchial fibrosis 
Lymphoid follicle 
Destruction of pulmonary capillary bed
Loss of elasticity
257
Q

What can be done to manage COPD?

A

Smoking cessation advice
Bronchodilator therapy - short acting
Combination therapy - long acting B2 agonist, inhaled steroid, long acting anticholinergic
Oral theophylline if others unsuccessful
Home oxygen

258
Q

Give 2 examples of short acting and 2 long acting B2 agonists

A

Short: salbutamol, terbutaline
Long: salmeterol, formoterol

259
Q

Describe the mechanism of action of B2 agonists

A

Bind to B2 receptor and activate it which activates adenylate cyclase via G-aS
This increases cAMP levels which activates PKA
This causes phosphorylation of myosin light chain kinase which inactivates it so reducing smooth muscle contraction

260
Q

What are side effects of drugs such as salbutamol?

A 
Tremor
Headache
Tachycardia
Cardiac arrhythmia 
Peripheral vasodilation
Hypokalaemia
261
Q

How can desensitisation of the B2 receptor occur?

A

Overuse of B2 agonists

Increased expression and activity of phosphodiesterase which breaks down cAMP

262
Q

Name a short acting and a long acting anticholinergic drug used as bronchodilators

A

Short: Ipratropium
Long: tiotropium

263
Q

Describe the mechanism of action of anticholinergic drugs as bronchodilators

A

Antagonist at muscarinic ACh M3 receptor
This prevents Gq from activating phospholipase C
Less PIP3 is converted to IP3 and so less Ca is released from the endoplasmic reticulum
Less Ca available to bind to calmodulin so myosin light chain kinase is not activated and therefore smooth muscle contraction is prevented

264
Q

What are side effects of drugs such as Ipratropium?

A 
Dry mouth
Constipation
Cough
Headache
Nausea
Paradoxical bronchospasm
Urinary retention
Glaucoma
265
Q

Name 2 methylxanthines used as bronchodilators

A

Aminophylline, theophylline

266
Q

Describe the mechanism of action of theophylline

A

Inhibit phosphodiesterase so prevent breakdown of cAMP

So more PKA can be activated and therefore phosphorylate more myosin light chain kinase

267
Q

What are the side effects of theophylline?

A 
Insomnia 
Nausea
Vomiting
Cardiac arrhythmias
Seizures
268
Q

Why do serum theophylline levels have to be carefully monitored?

A

Narrow therapeutic range

Side effects outside this range are toxic

269
Q

What could increase clearance of theophylline from your patient?

A 
Drugs: rifampicin, anticonvulsants, phenobarbitone
Ethanol
Tobacco smoking
Childhood
High protein diet
270
Q

What could decrease clearance of theophylline from your patient?

A 
Drugs: cimetidine, erythromycin, zafirlukast 
Old age
Congestive heart failure
Liver cirrhosis 
Respiratory acidosis and pneumonia
Viral hepatitis
High carb diet
271
Q

Name 2 leukotriene antagonists used as bronchodilators

A

Montelukast

Zafirlukast

272
Q

Describe how leukotriene antagonists work

A

Block CysLT1 receptors
Leukotrienes cause airway inflammation and bronchospasm so antagonises this
Reduce exercise induced symptoms in asthma
Reduce inflammatory response
Used as a preventer

273
Q

Name 2 inhaled, 1 oral and 1 IV glucocorticoid used in treatment of asthma

A

Inhaled: Beclomethasone, Fluticasone
Oral: prednisolone
IV: hydrocortisone

274
Q

Describe the mechanism of action of glucocorticoids in treatment of asthma

A

Activate intracellular glucocorticoid receptor which interacts with DNA and influences gene expression
Inhibits formation of pro inflammatory products - cytokines, IL3/5, PGE2
Increases expression of anti inflammatory products - upregulates B2 receptor

275
Q

What are side effects of glucocorticoids?

A 
Central weight gain
Moon face 
Easy bruising
Poor wound healing
Muscle wasting of arms and legs
Thinning of skin
Hypertension
Buffalo hump
Euphoria
276
Q

What are mast cell stabilisers?

A

Sodium cromoglicate and nedocromil
Stabilise membranes of mast cells to prevent histamine release
Useless in acute exacerbation
Side effect - bitter taste

277
Q

What is Omalizumab?

A

Monoclonal anti- IgE antibody
Useful to prevent allergic asthma
Expensive so only used if patient on regular corticosteroids and if manufacturer gives agreed discount in patient access scheme

278
Q

How big is the anatomical dead space/conducting airways?

A

150ml

279
Q

How big are the respiratory parts of the lungs?

A

3L

280
Q

What parts of the respiratory system make up the conducting airways?

A 
Nasal cavities 
Nasopharynx 
Oropharynx 
Larynx 
Trachea 
Bronchi 
Bronchioles 
Terminal bronchioles
281
Q

What parts of the respiratory system make up the respiratory airways?

A

Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli

282
Q

What are keratinised squamous epithelium?

A

Protected from abrasion by keratin and kept hydrated by glycolipids produced in stratum granulosum
Lines vestibules - first 1.5cm of conductive portion following nostrils

283
Q

What is non-keratinised squamous epithelium?

A

Oropharynx and larynx lined with this cell type

Must be kept moist by bodily secretions to prevent drying out

284
Q

What is another name for pseudostratified ciliated epithelium?

A

Respiratory epithelium

285
Q

What are the layers of the trachea?

A

Mucosa
Submucosa
Muscularis
Cartilaginous rings

286
Q

Which side of the trachea is flattened?

A

Posterior, facing oesophagus

287
Q

How long is the trachea?

A

10cm

288
Q

What type of cartilage is tracheal cartilage?

A

Hyaline

289
Q

What type of epithelium lines the trachea?

A

Pseudo stratified ciliated epithelium, respiratory epithelium

290
Q

What cell types are present in bronchi?

A 
Respiratory epithelium
Goblet cells
Submucosal glands
Smooth muscle between mucosa and cartilage plates
Cartilage plates
291
Q

Describe the structure of the bronchioles

A 
Less than 1mm in diameter & no cartilage
No mucous glands 
Ciliated low columnar 
Epithelium 
Increasing numbers of clara cells distally (dome shaped cells with small microvilli, simple epithelium, protect bronchioles)
Smooth muscle is major wall component
292
Q

Describe structure of terminal bronchioles

A

Cuboidal epithelium with few ciliated cells and abundant Clara cells
Smooth muscle knobs

293
Q

What non respiratory cells are present in conducting airways?

A

Neuroendocrine cells - Scattered throughout the basal layer, Dense core granules, Bombesin, substance P, calcitonin an leu-encephalin, Involved in development and regeneration / repair
Brush cells - Microvilli resemble small intestinal enterocytes, Function not entirely clear ?absorb water
Basal cells - Stem cells of airway, adhesion to basement membrane
Clara cells - Terminal bronchioles, Act as stem cells, modulating inflammation, anti-oxidant andanti protease activity

294
Q

Describe the different roles of type I and type II pneumocytes

A

Type I pneumocytes - gas exchange

Type II pneumocytes - Regeneration and surfactant production

295
Q

What cells are present in alveoli?

A

Type I and II pneumocytes, endothelium, alveolar macrophages

296
Q

What is surfactant?

A

Lipid rich secretion reducing surface tension

Recycled by type 2 pneumocytes

297
Q

What do alveolar macrophages do?

A 
Recruited from blood as monocytes 
Main phocytic cell of the lung 
Remove the majority of foreign material entering alveoli 
More numerous in smokers 
Aerobic metablolism 
Dense lysosomal bodies 
Phagocytic vacuoles 
Most removed by mucociliary escalator 
Some migrate to hilar nodes
298
Q

What is chronic bronchitis?

A

Clinical diagnosis productive cough 3 months of the year 2 consecutive years
Hypersecretion of mucus
Hypertrophy of bronchial mucus glands (Reid Index postmortem)
Hyperplasia of goblet cells
Mild dilatation of bronchi

299
Q

What effects does smoking have on the lungs?

A 
Loss of cilia 
Squamous metaplasia 
Mucous hypersecretion 
Goblet cell hyperplasia 
Individual factors affect the extent and rate of these changes
300
Q

What is smog and what effect can it have on the lungs?

A

Industrialisation
Increase in particulate matter in the atmosphere
Irritation of the bronchial epithelial lining leading to brochitis

301
Q

What is small airways disease?

A

Chronic obstructive bronchiolitis
Small bronchi and proximal bronchioles 9th order airways 2mm diameter
Goblet cell hyperplasia of bronchioles
Loss of clara cells (secrete protease inhibitors) Smoking related
Fibrosis, wall thickening and focal stenoses

302
Q

What is emphysema?

A 
Bronchioles collapse due to loss of parenchyma 
Air trapping on expiration 
Exacerbated by airway secretions 
Barrel chest 
Flattened diaphragm
303
Q

What patterns of emphysema are there?

A

Centriacinar
Paraseptal
Pan acinar
Irregular

304
Q

What is aspiration pneumonia?

A

Lower respiratory tract infection resulting from the inhalation of material, e.g. food/drink, from oropharynx and gastrointestinal tract into the respiratory tract (aspiration). The lungs are normally protected against aspiration by protective reflexes such as coughing

Block 2 (9 decks)

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