lecture 3: pulm function test Flashcards
what are 3 reasons for performing pulm function tests
1) Diagnossi (allegrgies, resp infections, chronic disease ex: COPD)
2) Presurgery screening (for lung function)
3) Assess treatment of current condition
=quick way to assess pulm health
what are 3 different methods of measurement for pulm fucntion test
1) plethysmography (measures changes in pressure)
2) gas dilution test (ex: nitrogen washout, helium dilution)
3) Spirometry (measures changes in vol)
what are some factors that affect PFT results
age
height
sex
ethniticty
explain how age can affect PFT results
increase age=decrease elasticity of lungs
=decreaese PFT values
explain how height can affect PFT values
if you have a larger height= larger PFT values
larger lung size
explain how sex can affect PFT values
males have larger PFT values than females
explain how ethnicity can affect PFT values
there are anthropometric differences across ethnicities that will affect it
what are the indications for before doing PFT
1) no smoking within 1 hour of test
2) no alchohol consumption within 4 hours of test
3) no vig exercise 30 minutes before test
4) no large meals within 2 hours of test (stom will take more space)
what are the 4 static luung valomes
tidal vol
inspiratory reserve volume
expiratory reserve volume
residual volume
explain tidal volum
the volume of air inhaled/exhaled during a nromal breath
=without concious effort
(normally 200-500 ml but can increase to more than 3L)
does IRV decreaese or icnrease with exrcise and why
it decreases because tidal volume increases
explain inspiratory reserve volume
the vol of air that can be maximally inhaled at the end of a normal tidal inspiration
(end todal to max inhale)
normally approx 1900 in fem
3000 in men
explain Expiratory reselve volume
the vol of air that can be maximally exhaled after a normal tidal exhalation
(end tidal to max exhale)
normal: 700 ml in fem
1100 in males
does ERV increase or decrease with exrecise and why
it decreases bceause tidal vol increases
what is residual vol
vol of gas remaining in the lungs after a forced/maximal exhalation
what is the function of residual vol
The residual lung volume is important for helping pulmonary function since it allows the gas exchange between the blood and the alveoli to be uninterrupted even between breaths
prevents fluctuations and variations of the gases and present in the blood and their concentrations during the entire breathing cycle
the residual volume allows the alveoli to remain open between breaths, to allow for continual gas exchange at all times
what are the 4 lung capacites
inspiratory capacity
function residual capaicty
vital capacity
total lung capcitty
explain inspirtaoty capcity
Inspiratory capacity (IC): The maximum volume that can be inhaled from the end of a normal resting exhalation (IC = VT + IRV).
explain functional residual capacity
Functional residual capacity (FRC): The volume of gas remaining in the lungs at the end of a normal resting exhalation (FRC = ERV + RV).
explain vital capacity
- Vital capacity (VC): The greatest volume of gas that can be exhaled by maximal effort after a maximum inhalation (VC = IRV + VT + ERV).
explain total lung capacity
- Total lung capacity (TLC): The volume of gas in the lungs at the time of maximal inhalation. It is the sum of VC and RV (TLC = IRV + VT + ERV + RV).
how do you mark off the volumes and capacities on a graph
1) choose the smallest tidal vol before maneuver (but not the first one right before test)
(from end of tidal to end of inhale)
2)
in the lung volumes tset, each box is how many liters
0.1 L
how do you measure inspiratory server volume off graph
from the end of the tidal inhale all the way to the max inspiration
how do you measure expiratory server volume off graph
measure from end of the tidal breath to end of expiration
how do you calculate RV
usually just estimated at 1 L
what does the forced expirations test measure
dynamic lung volume (allows us to observe air flow, compliance of chest and lungs)
what are the 3 exhale cirtearia inn the forced expirations test
1) exhale needs to be quick
2) exhale should be fprceful
3) exhaule sould be held as long as possible
(at least 6 seconds)
what are the variables we are measureing in the forced expirations test
1) forced expiratory volume in 1 sec
2) forced vital capacity
3) FEV1/FVC
how many times is the forced expiration test completed and how do you know which test to choose
done 3 times but choose the one with the longest duration for exhale
explain how to mark the graph for forced expiration test
1) mark time 0 (where exhale begins)
=start where dramatic downslope starts
2) mark 1 sec over to establish FVC
3) mark from the max (the beg of exhale) all the way down to lowest point in exhalation
what is considered a normal FEV1.FV ration
greater than 0.7
what is considered a low FEV1/FVC ratio
less than or equal to 0.70
how do you calculate % preduced FVC
FVC measured/FVC predicted
if someone has a normal ratio, and a predicted FVC that is greater or equal to 0.8, what does that indicate
indicates normal FEv1 and normal FVC
if someone has a normal ratio, and a predicted FVC that is less than 0.8, what does that indicate
that the FVC only is reduced
(restrictive)
=difficult to expand the lungs (it is a volume limitation)
if someone has a low ratio, and a predicted FVC that is less than 0.8, what does that indicate
both FEv1 and FVC are reduced, you have mixed disorders
if someone has a low ratio, and a predicted FVC that is equal or greater than 0.8, what does that indicate
only fev1 is reduced
=obstructive
=limiated to flow (harder to expty lungs)
know the forced expiration interpretation chart
.
what is the main symptoms shared between obstructive and restrictive breathing disorders
dyspnea
how can you calculate the severity of the obstruction
calculate the % predicted FEv1
%FEV1 meaured/predicted
explain obstructive lung disordderes
they have an airflow limitation caused by some sort of obstruction (sometimes inflammation of airways)
=cannot exhale/push out air quickly
=bad Fev1
give some examples of obstructuve lung dieases
COPD Emphysema Bronchitis Asthma cystic fibrosis
epxlain resisttrictive lung disorders
difficult to expand lungs(volume limitation)
=lungs cannot expand well due to compliacne issues (sometimes scar tisse and inflammation)
what are some examples of restrictive lung disorders
Obseity
scoliosis
neuromuscular disease
intersitial lung disease
If a subject’s VC is in the normal range for his/her
age, size and gender, the subject likely has no BLANK
Pulm disease
what is FEV1
the forced expiratory volume in 1 second (FEV1 –
volume that the subject is able to exhale in the first second of the FVC maneuver, expressed in L
wha t is FVC
volume of gas that is expired by maximal effort after a maximum inhalation, expressed in L)
explain what happens to FEV and FVC in airway obstructions
In conditions where the airways are obstructed (i.e., such as in asthma and chronic obstructive pulmonary disease (COPD), which includes emphysema and chronic bronchitis)
the FVC is normal (> 80%). However, the rate of expiratory flow (and thus the FEV1) is reduced (< 80%)
explain what happens to FVC and FEV1 in restrictive diseases
In conditions where the lung volume is reduced (i.e., restrictive diseases such as pulmonary fibrosis, scoliosis, and tuberculosis)
the FVC is compromised (< 80%). However, the FEV1/FVC ratio may be
normal or even greater than normal due to the normal FEV1 value
what is the def of MVV (max voluntary ventilation)
It is defined as the maximum volume of air that can be exhaled over a specified period of time
=largst amount of air that can move in and out of lung in one minute)
the MVV test provides information on what
measures respirtatory muscle stregnth
=provides info on airway resistance, lung elasticity, lung compliace, and respiratory muscle mechanics
what is the goal in terms of breaths/min and vol for the MVV test
90 breaths/min
about 50% of VC
how do you extract data for MVV test
mark off center (start of exhale of first maneurveer)
=measureeing all of the exhale volumes up until the last one
(do not inlclue last one that has normal breath)
sum all the volumes and measure the time from begining of first exhale to end of last exhale
=calcualte MVV
what does it mean if the MVV graph has a downward trend
person is breathing out more than they are breathinging in
=respiratory muscle fatigue/increase work of breathing
what does it mean if MVV graph has upward slope
indicates air trapping
not exhaling as much as inhaling
what is the MVV interpresation equation and the norm values
MVV measured / (40 * FEV1 measured)
if ration < 0.80, this indicates MVV is low relative to FEV1, which suggests disease or poor effort
