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27 Cards in this Set

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what are the indications for performing pulmonary fxn tests
- to eval pts with resp dz
- to assess resp involvement in pts with CV dz
- to evaluate impairment/response to therapy
- screen of high risk pts (ie. smokers)
what is the forced FVC maneuver (using spirometry)?
pt inspires maximally to total lung capacity, then exhales into spirometer as forcefully, as rapidly and as completely as possible

FVC = forced (expiratory) vital capacity
what is the most important volume examined in a spirometry test? what's the second most important?
#1 the volume that's exhaled in teh first second (FEV1)

#2 the total amt of air that pt can exhale (FVC)
which loop -- expiratory or inspiratory -- do you usually look at for dz process with spirometry?
expiratory loop
a healthy FEV1/FVC ratio is greater than ___%.
70%; basically, if you can exhale more than 70% of the air out in the first second, relative to the total amt of air you exhale...then you're a healthy person. if not, then you have an obstructive pathology that's keeping you from doing so.
which is the best measure of severity of airflow obstruction?

a. FEV1
b. FVC
c. FEV1/FVC
a. normal FEV1 > 80% of predicted for age, sex and height
FEV1 indicates:

a. large and small airway function
b. degree of lung and chest expansion
c. amount of total lung capacity for a given patient
d. none of the above
A
FVC indicates:

a. large and small airway function
b. degree of lung and chest expansion
c. how much air patient can blow out very rapidly
d. two of these (name em)
B,C
if FEV1/FVC is less 70%, it's:

a. airway obstruction
b. airway restriction
A. however, this is only true if FVC is not too small...otherwise you can't really distinguish b/w restrictive and obstructive lung dz
a low FEF usually reflects:
reflects small airway dz
how do you dx obstruction on spirometry?
- decreased FEV1, normal or slightly decreased FVC
** FEV1/FVC < 70% = obstruciton **
if FVC is decreased alot, may have combined restriction
how do you dx restriction on spirometry?
- reduced FVC and FEV1
** normal or INCREASED FEV1/FVC **
what are some causes of restrictive lung dz?
scarring, fibrosis of lung, chest wall problems (guillan-barre, myasthenia gravis)
if a pt's FEV1 and/or FVC improve by >12% AND 200 mL from baseline after bronchodilator administration, what is this suggestive of?
asthma (this tells us the airways are responsive to bronchodilators or not)
when is the only time you look at inspiratory loop?
to check for upper airway pathology
truncation of expiratory loop =

truncation of inspiratory loop =
intrathoracic obstruction (tracheal tumor above carina)

extrathoracic obstruction (vocal cord paralysis)

remember it's "E for I, and I for E"
what if you have truncation of expiratory and inspiratory loop in spirometry?
that means fixed obstruction (like in tracheal stenosis)
hat 2 pts would you want to measure lung volume w/ body plethysmograph?
- Pts with restrictive dz
- Pts with FVC so low that you can’t tell wther its obstructive or restrictive dz
LARGE/SMALL lung volumes are caused by increase in compliance of lung (decrease in stiffness and elastic recoil)
large (eg. emphysema)
LARGE/SMALL lung volumes are caused by either a decrease in lung compliance or a decrease in chest wall compliance
small (eg. parenchymal lung dz or chest wall disorders)
in small volume lungs, you can have either a problem with decrease compliance of lung itself or a decreased chest wall compliance. how do you differentiate b/w lung problems or chest wall problems?
diffusion capacity (DLCO) - which measures how well oxygen diffuses across alveolar-capillary membrane.

so if you have low DLCO, then you most likely have a lung problem bc most lung dz's decrease this diffusion capability by definition
pt has normal FEV1/FVC ratio on spirometry. but the values for both FEV1 and FVC are below 80% of expected. patient is given lung volume and DLCO tests. what would you expect the results to be if pt had a chest wall problem? what would you expect if pt had a lung dz?
In chest wall dz, you’ll have low lung volume and normal DLCO, whereas in lung dz, you’ll have both low lung volume and low DLCO.
what is the mechanism for DLCO test?
Single-breath technique for measurement of DLCO. The subject inhales a gas mixture containing a low concentration of CO and a tiny amount of helium. At end-inspiration the subject holds his or her breath for 10 seconds. During exhalation, the expired gas is analyzed for CO and helium concentration. During the breathhold period, some CO diffuses from the alveoli to the blood; the amount can be calculated from the measurements of the CO concentration in alveolar gas at the beginning and end of the 10-second interval
pt has isolated low DLCO. possible dx?
pulmonary vascular dz
anemia
pt has reduced DLCO with abnormal spirometry (with obstructive pattern). dx?
emphysema
pt has reduced DLCO with abnormal spirometry (with restrictive pattern). dx?
interstitial lung dz
when and how do you do a bronchoprovocation test?
do it when you want to support dx for asthma or hyperactive airway dz in the presence of normal spirometry(normal lung fxn)

You do spirometry, then you ask patient to inhale chemical, start with low dilution, then go up…then see at what point does pt’s FEV1 drop. Pts with asthma, once you start giving them even low dose methacholine, their FEV1 drops a lot. This doesn’t happen in normal people.