Pulmonary Function Tests Flashcards
(97 cards)
1
Q
What is the last set of organs to full develop?
A
- lungs
2
Q
When describing the developing of the lungs, what does antenatal refer to?
A
- pre embryonic - embryonic - foetal - everything prior to birth
3
Q
Babies are at an increased risk of death if they are born prematurely, before 28 weeks of gestation. What is one of the main factors contributing to this?
A
- lack of surfactant - lungs can collapse
4
Q
What is respiratory distress syndrome?
A
- babies born prematurely (28 weeks) - lungs unable to inflate and deflate unaided
5
Q
What is the growth phase in lung development?
A
- birth to young adulthood - grow until 23 generations are present
6
Q
What is the plateau phase in lung development?
A
- from mid 20s to late 30s
7
Q
What is the decline phase in lung development?
A
- lung function, compliance, elasticity all begin to decline
8
Q
What are a few factors that can influence antenatal development of the lungs?
A
1 - maternal smoking 2 - poor maternal nutrition 3 - placenta insufficiency
9
Q
What is placenta insufficiency?
A
- low nutrients supplied by placenta to foetus
10
Q
How can babies born prematurely affect lung development?
A
- ⬇️ surfactant
11
Q
What factors can influence the babies lung development postnatally (after birth)?
A
- maternal smoking - infections - allergens
12
Q
What are pulmonary function tests?
A
- tests designed to assess how well the lungs work
13
Q
When are pulmonary function tests used?
A
- to diagnose a respiratory disease - in patients presenting with respiratory symptoms
14
Q
What are some common respiratory symptoms that would initiate a pulmonary function test?
A
- cough - wheeze - shortness of breathe
15
Q
Are pulmonary function tests used in smokers to diagnose disease?
A
- generally no - can be used to identify high risk groups though
16
Q
In addition to diagnosing patients, can pulmonary function tests be used for prognosis?
A
- yes in chronic lung disease - asthma, COPD, pulmonary fibrosis - good for monitoring disease progression
17
Q
Are pulmonary function tests useful when assessing a patients treatment?
A
- yes - provide objective measures of lung function
18
Q
What do pulmonary function tests actually measure?
A
- airflow - lung volume - gas exchange - airway reactivity
19
Q
What is airway reactivity?
A
- how airways react to allergens - asthma has a high airway reactivity
20
Q
Roughly how much lung volume do we lose each each year in the decline phase of lung development?
A
- 30ml/year
21
Q
What are some basic things that affect lung function, not disease factors?
A
- gender - age - weight - ethnicity - height
22
Q
What are a patients lung function tests compared against?
A
- normative data collected over long periods
23
Q
What are some things that patients must not do prior to a lung function test as they may affect the test results?
A
- take bronchodilator medication - exercise (30 mins prior) - smoke (24 hours prior) - alcohol (4 hours prior) - caffeine (24 hours prior)
24
Q
What is the normal age patients can do lung function tests well?
A
- > 6 years old - < 6 years old are unable to do the tests
25
What is tidal volume?
- amount of air in and out of lungs at rest
26
What is inspiratory reserve volume?
- max air patient can inhale above tidal volume
27
What is expiratory reserve volume?
- max air patient can exhale below tidal volume
28
What is vital capacity?
- total air patient can breathe in and out maximally
- DOES NOT include residual volume
29
What is residual lung volume?
- air left in lungs after maximum exhalation
30
What is functional residual capacity?
- expiratory reserve volume (below tidal volume) + residual lung volume
31
What is total lung capacity?
- max air in and out of lungs including residual lung volume
32
What are dynamic lung volumes?
- those that are dependent on the rate at which they happen
- FORCED expiratory volume (FEV1)
- PEAK expiratory flow
33
Peak expiratory flow (PEF) is a common dynamic lung volume measured, what is it?
- maximum speed of expiration - measured in L/min
34
Forced expiratory volume 1 (FEV1) is a common dynamic lung volume measured, what is it?
- maximum air expelled in the first second
35
Forced vital capacity (FVC) is a common dynamic lung volume measured, what is it?
- total air exhaled
- following maximum inhalation
- FEV1 is measured from this
36
Relaxed vital capacity is a common dynamic lung volume measured, what is it?
- maximum air exhaled in a relaxed breathe - similar to a heavy sigh
37
What are some common conditions that are contradictions for completing dynamic lung volume tests?
- haemoptysis (coughing up blood)
- pneumothorax
- severe hypertension
- recent myocardial infarction
- tachyarrhythmia
- pulmonary embolism
- aortic aneurysm
- essentially anything involving high pressure
38
Why is a peak flow meter useful in a clinical setting?
- cheap - easy to use - portable
39
Peak expiratory flow measures the maximum speed of expiration, but what is it measuring in the airways that contributes to the rate of air?
- resistance in airways
40
Why can peak expiratory flow be reduced?
- increased resistance in airways - generally due to narrowing
41
What conditions would we expect to a reduction in peak expiratory flow?
- COPD - asthma - bronchiectasis
42
Why are routine measurements of peak expiratory flow not routinely conducted in patients with COPD?
- COPD is generally irreversible - may be used for prognosis - BUT will not get better
43
Why is peak expiratory flow measurement useful in self managed asthma?
- can see if patient is using inhales - can see if patient is responding to treatment
44
Why is peak expiratory flow used by occupational health in the workplace?
- good measure to identify risk of asthma
- asthma is most common respiratory occupational disease
- certain jobs ⬆️ risk of lung disease
45
How can neuromuscular disorders impair peak expiratory flow?
- unable to innervate muscles in chest properly
46
How does tracheal tumour or thyroid goitre (swelling of the thyroid gland) impair peak expiratory flow?
- ⬆️ resistance - block or narrow airways
47
What is diurnal peak flow monitoring?
- relates to the variation/fluctuation in peak expiratory flow rate
- measured over (24 hours)
- \>20% variation in day = diurnal variation
48
How is diurnal peak flow monitoring monitored and why?
- patients given a peak flow meter and diary - measure throughout the day
49
What is the hormone that has been linked with diurnal peak expiratory flow?
- cortisol
50
Spirometry is the most common method for assessing lung function, what is it?
- pulmonary function tests - measures the amount and/or speed of air that can be inhaled and exhaled
51
What 3 measures are given during spirometry?
1 - forced vital capacity (FVC) 2 - forced expiratory volume in 1 second (FEV1) 3 - FEV1/FVC ratio
52
When using spirometry how many measures are taken, and which value is used?
- 3 attempts - maximum value used
53
Why is the shape of the graph in spirometry important?
- it will vary depending on lung disease - restrictive vs. obstructive
54
Above what values is classed as a normal forced expiratory volume?
- \>80%
55
What is obstructive lung disease?
- inability to exhale
56
What is restrictive lung disease?
- inability to inhale
57
In obstructive lung disease, what happens to the forced expiratory volume 1 (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio?
- ⬇️ FEV1 - difficult to exhale (can take up to 15 seconds) - ⬇️ FVC - but will eventually get air out - ⬇️ FEV1/FVC ratio
58
In restrictive lung disease, what happens to the forced expiratory volume 1 (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio?
- ⬇️ FEV1 - ⬇️ FVC - ⬆️ FEV1/FVC ratio
59
In obstructive lung disease, does forced expiratory volume 1 (FEV1) or forced vital capacity (FVC) reduce more?
- FEV1 has larger ⬇️
- larger ⬇️ in FEV1 drives ⬇️ FEV1/FVC ratio
- FVC can actually increase due to trapped air
60
In restrictive lung disease, does forced expiratory volume 1 (FEV1) or forced vital capacity (FVC) reduce more?
- FVC has larger ⬇️ due to ⬇️ compliance - larger ⬇️ in FVC drive ⬆️ FEV1/FVC ratio
61
Is spirometry good for distinguishing between restrictive and obstructive lung disease?
- yes - BUT cannot confirm exact diagnose
62
What does GOLD stand for in COPD, and what are the 4 things the GOLD stage for COPD measures?
- Global initiative for Chronic Obstructive Lung Disease
1 - severity of current symptoms
2 - spirometry results
3 - COPD prognosis
4 - presence of comorbidities
63
In obstructive lung disease which airways are mostly affected?
- medium and large sized airways
64
In restrictive lung disease is the FEV1/FVC ratio always increased?
- no it can be normal as well
65
What are flow volume loops?
- inspiration and expiration plotted against volume and time on a graph
66
What are flow volume loops useful for?
- identify where an obstruction is - intra vs extrathoracic obstruction
67
What does extra-thoracic mean?
- outside of thoracic cavity - likely to be in thoracic wall or spinal problems
68
Why are flow volume loops not routinely used?
- hard to conduct - poor reproducibility - flow is dependent on high lung volumes
69
When are airways most dilated and airways resistance is at its lowest?
- at total lung capacity
70
During flow volume loop test, is inspiration or expiration more reproducible and energy dependent?
- inspiration = ⬆️ energy depended
- inspiration = ⬇️ reproducibility
- expiration is determined by elastic recoil, so good reproducability
71
What is static lung volume tests?
- test to measure total lung capacity - not dependent on flow rate
72
Are static lung volume tests able to make accurate diagnosis?
- yes
73
Why are static lung volume tests not used routinely?
- measured in a lab - not portable
74
How do static lung volume tests determine total lung capacity, including the residual lung volume?
- helium dilution method - whole body plethysmography
75
What is the helium dilution method?
- patient inhales known volume and concentration of helium - patient then exhales providing a final concentration and volume, including functional residual volume
76
Why is helium a good gas to use for determining static lung volumes?
- it is insoluble in blood and lung tissue - gas will not be absorbed and stays in the lungs
77
What is a plethysmograph?
- an airtight box - volumes and pressures in the box can be measured
78
How does plethysmography work?
- patients breathe normally in the airtight box - sensor in box measuring pressure change - sensor in mouth piece measuring pressure and air flow changes - changes in volume and pressure in the box can be used to determine functional residual volume
79
Is total lung capacity reduced in both restrictive and obstructive lung disease?
- both are affected, but in a different way
- restrictive = ⬇️ total lung capacity
- obstructive = ⬆️ total lung capacity
80
Why does obstructive lung disease cause an increase in total lung capacity?
- obstructive lung disease = inability to exhale - air is therefore trapped in the lungs
81
In restrictive lung disease, do intra and extra pulmonary pathologies reduce total lung capacity?
- yes - restrictive = inability to inhale
82
What is the transfer factor also commonly referred to as?
- diffusion capacity - DLCO or TLCO, used interchangeably
83
What is transfer factor used for?
- measured in a single breathe - ability of gas to diffuse between alveoli and capillaries
84
What is the A-a gradient?
- difference between alveolar (A) and arterial (a) concentration of oxygen
85
What can the transfer factor be used to estimate?
- A-a gradient
86
When using DLCO/TLCO, what is the transfer coefficient?
- transfer of a gas per unit of alveolar volume
87
How is the transfer coefficient calculated from the DLCO/TLCO?
- measures carbon monoxide in ventilated alveoli
- divided by the non ventilated alveoli
88
What must the transfer coefficient be corrected for?
- haemoglobin levels - anaemic patients would skew the results
89
What can reduce the TLCO/DLCO?
- ⬆️ ventilation/perfusion mismatch - ⬇️ blood flow (pulmonary embolism) - ⬇️ alveolar surface area (emphysema)
90
What can increase the TLCO/DLCO?
- ⬆️ pulmonary capillary blood flow - ⬆️ cardiac output (exercise) - polycythaemia (⬆️ red blood cells) - pulmonary haemorrhage
91
Do extra thoracic restrictive lung conditions affect TLCO/DLCO?
- no - lung tissue is not involved
92
Why do extra thoracic restrictive lung conditions not affect TLCO/DLCO?
- blood vessels vasoconstrict in unventilated section of the lungs
- blood flow is diverted from under ventilated part of lungs
93
In a patient who is a heavy smoker and has emphysema, would you expect to see a change in the TCLO/DLCO and transfer coefficient ?
- yes
- both would ⬇️
94
Why would a patient who is a heavy smoker with emphysema, be expected to have a low TCLO/DLCO and transfer coefficient ?
- emphysema = obstructive lung disease
- smoking is primary cause of obstructive lung disease (COPD)
- emphysema will ⬇️ surface area (SA) at alveoli
- ⬇️ SA = ⬇️ diffusion
- ⬇️ SA = ⬇️ ventilation
95
In a woman with suspected pulmonary fibrosis, which is a restrictive lung disease (inability to inhale) what would we expect to see in the forced vital capacity (FVC), forced expiratory volume 1 (FEV1) and the FEV1/FVC ratio?
- larger ⬇️ in FVC
- ⬇️ or normal FEV1
- ⬆️ FEV1/FVC ratio
96
When is the the DLCO/TLCO and transfer coefficient (KCO) especially useful when looking at a patient with restrictive lung disease?
- determine where restriction is intra or extra thoracic
- intra thoracic = ⬇️ TLCO/DLCO and KCO
- extra thoracic = normal TLCO/DLCO and KCO
97
What is the transfer coefficient (KCO) that is used in TLCO?
- KCO is the ratio between ventilated and non-ventilated lung tissue
- TLCO is then divided by VA which gives TLCO
