110714 spirometry Flashcards

1
Q

transpulmonary pressure equals

A

Palv-Ppl

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2
Q

what determines airflow, particularly during expiration?

A

flow = (Palv-Patm)/airway resistance

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3
Q

where is resistance largest along the respiratory tract?

A

medium sized bronchi

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4
Q

conductance and resistance relationship

A

inverse

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5
Q

the only lung pressure we can measure i

A

pleural pressure

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6
Q

how can we calculate lung compliance?

A

volume/pressure change for transpulmonary pressure

use points of zero alveolar pressure to find transpulmonary pressure

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7
Q

in emphysema, compliance is

A

increased relative to normal subject

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8
Q

in expiration, there are two phases called?

A

effort dependent

effort independent flow rate phase

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9
Q

indications for PFTs

A

diagnostic (symptoms, signs, abnormal labs)

assess effects of diseases and therapies

screening (smokers, occupational exposures, preoperative risk, disability, prognosis)

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10
Q

spirometry will never tell you the disease-true or false?

A

true

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11
Q

what kind of graphs are there in spirometry?

A

volume time curve

flow volume loop

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12
Q

what portion of flow volume loop is effort independent

A

btwn FEF25 and FEF75

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13
Q

inspiratory flow rate on flow volume loop measures what?

A

how well upper airway is doing

upper airway=what’s outside of the chest wall

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14
Q

expiratory flow rate on flow volume loops measures what?

A

what’s happening in the intrathoracic airways (anything affecting resp sys inside chest wall; not just lungs and airway)

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15
Q

with asthma, what would you observe in the mid lung volume range and where on the flow volume loop?

A

in the expiratory flow rates, you would see decrease in expiratory flow rate in mid lung volume range

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16
Q

FEF50 and FIF50 relationship in normal pts

A

normally equal

17
Q

hallmark of obstructive disease on flow volume loop

A

decreased flow rates

small airway–scalloping effect

18
Q

restrictive disease

A

you never get a lung capacity that goes out to normal because there’s scarring and not not expanding normally

total lung capacity is going to be too low

flow volume loop:
shape of curve is similar to normal curve

19
Q

FVC is expired in how many seconds normally

20
Q

keys to spirometry interpretation

A

FEV1/FVC ratio (must be close to 100% of predicted to be normal)
FEV1
FVC

21
Q

how do you interpret a NOT low ratio of FEV1/FVC?

A

normal ventilatory fxn and restrictive processes

22
Q

how do you interpret a LOW ratio of FEV1/FVC?

A

obstructive process

23
Q

what is normal FEV1/FVC ratio?

A

0.70-0.87, depending on demographics of pt

24
Q

what is considered normal spirometry result?

A

FEV1/FVC ratio is normal
AND
VC (FVC) is normal

25
what is considered a normal FVC
greater than or equal to 80% of predicted (within the 95% confidence level)
26
if FEV1/FVC ratio is low, how do you determine the degree of obstruction?
look at percent of predicted FEV1 see slide 20 for values
27
when should you assess bronchodilator responsivity?
for all pts with spirometry showing low FEV1/FVC ratio for all pts suspected of asthma or chronic obstructive lung dis
28
bronchodilator respponsivity
significant response to a bronchodilator is shown when the FVC or FEV1 increases at least 12% AND 200mL shows reversible obstruction--asthma
29
ex of restrictive ventilatory defects
interstitial lung disease: sarcoidosis, collagen vascular dis, pulmonary fibrosis penumonectomy pleural disease: pleural effusion chest wall dis: kyphosis, neuromuscular disorders extrathoracic conditions: obesity
30
true hallmark of restrictive ventilatory defect
reduced TLC
31
how to determine if supports restrictive ventilatory defect?
normal FEV1/FVC ratio reduced TLC--see slide 24 for values for degree of restrictive disease if cannot obtain lung volumes, then grade FVC via the obstructive FEV1 criteria--see slide 25
32
looking at shapes of flow volume loops-what to look for
beware of flattened inspiratory curve check FEF50/FIF50 ratio FEF50/FIF50 of 1 or less is normal FEF50/FIF50 greater than 1 is variable extrathoracic airway obstruction FEF50/FIF50 a little over 1 is fixed extrathoracic airway obsrtuction
33
FEF50
forced expiratory flow of 50%--look at y axis and halve it to determine