assessment of lung function
- vol
-flow
lung plethysmograph
MIR Spirolab
oximetry
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electronic spirometry- MIR Spirolab
portable equipment
clip put on nose and patient breathes into a machine
Expiratory Flow curve assessed
patient performance compared w predicted values
- height (a big person will have big lungs!)
- age (lung capacity declines w age)
- sex (thoracic dimens
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spirograms
two diff curves are produced:
1/ vol/ time curve
2/ flow/ time curve
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what is the standard way to measure lung vol?
electronic spirometry
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lung plethysmography
accurate determination of lung vols (more accurate than electronic spirometry)
expensive equipment
not portable
may be combined with gas dilution methods
Boyle's Law (states that if temp remains the same you can use the vol of a gas to work out its pressu
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what measurements does lung plethysmography allow for?
- total air capacity
- functional residual capacity (the total amount of air left in your lungs when you breathe out normally)
- residual capacity (the amount of air left in your lungs when you breathe out as much as possible)
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breathing changes the pressure in the lungs because the volume changes
changes in the pressure against the mouthpiece
this is what allows for the measurements stated above
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average TLC of an average male
about 6L of air
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average human respiratory rate (at birth) is
30- 60 breaths per min
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average human respiratory rate in adults in
12- 20 breaths per min
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what can be measured using spirometry?
IRV, VT, TV and IC
all basic elements of a pulmonary function test
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why is determination of RV more diff?
because it is impossible to completely breathe out
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how is determination of RV achieved?
by indirect methods
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TLC
Total Lung Capacity
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RV
Residual Volume
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IC
Inspiratory Capacity
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VC
Vital Capacity
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IRV
Inspiratory Reserve Volume
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ERV
Expiratory Reserve Volume
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FRC
Functional Residual Capacity
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positive FVC values on a spirometer output flow curve represent what?
expiration
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forced expiratory volume (FEV1)
this is the amount of air expired during the first seconds of the FVC test
(Forced Expiratory Volume in 1 second)
Litres
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peak expiratory flow rate (PEFR)
this is the fastest rate that you can force air out of your lungs
L/ min
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forced vital capacity (FVC)
this is the amount of air exhaled forcefully and quickly after inhaling as much as you can
Litres
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FEV1/ FVC ratio
declines w age
a v important measure
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Indicators of lung health
PEFR, FEV1, FVC
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restrictive diseases
pulmonary fibrosis, Infant Respiratory Distress Syndrome, weak respiratory muscles, pneumothorax
vols are dec
FEV1/ FVC- often in a normal range (0.8-1.0)
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obstructive diseases
asthma, COPD, emphysema
vols are essentially normal but flow rates are impeded
often low (asthma can reduce the ratio to 0.6, emphysema can reduce the ratio to 0.78-0.45)
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when FEV1 values make up less than 80% of the FVC,
an obstructive lung disease is likely present
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in restrictive diseases however, both the FEV1 and FVC measurements
decrease proportionally
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an obstructive pattern is defined when
FEV1/ FVC is less than or equal to 70% in adults and less than 85% in children
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FEV1 % predicted
Stage
> 80% mild
50 - 79% moderate
30 - 49% severe
<30% very severe
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contraindictions
forced expiratory manouvers may aggravate some medical conditions
Spirometry should not be performed when the individual presents with:
- hemoptysis of unknown origin
- pneumothorax
- unstable cardiovascular status (angina, recent myocardial infarction et
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wright flow meter
cheap
simple
single variable measured: PEFR
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peak flow readings are often classified into 3 zones of measurement according to the American Lung Association
green zone
yellow zone
red zone
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Pulse Oximetry
oximeter add-on to spirometer or stand- alone device allows measurement of blood oxygen saturation and HR
uses pulses on your thumb to gather basic info about your blood
non- invasive
measured O2 saturation of haemoglobin (effectiveness of ventilation)
as
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breathing sounds
auscultation
- using stethoscope to listen to internal sounds
- normal
- crackles (small airways and alveoli popping open, infection)
- wheeze (asthma, COPD)
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other measures (diffusion capacity)
measures gas transfer
patient empties lungs
fills lungs w 0.3% carbon monoxide (!)
breath held (10 sec)
CO in exhaled breath measured to estimate uptake
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Other cards in this set
Card 2
Front
electronic spirometry- MIR Spirolab
Back
portable equipment
clip put on nose and patient breathes into a machine
Expiratory Flow curve assessed
patient performance compared w predicted values
- height (a big person will have big lungs!)
- age (lung capacity declines w age)
- sex (thoracic dimens
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