Interpretation of Pulmonary
Function Tests
Ken Kunisaki, MD
Pulmonary, Critical Care, Sleep
St ff Physician,
Staff
Ph i i
Mi
Minneapolis
li VAHCS
Assistant Professor, University of Minnesota
Outline





Indications
Spirometry
 ATS/ERS criteria
 Interpretation and Limitations
Lung Volumes
Diffusing
ff
Capacity
C
Methacholine Challenge
Overview

Lung
g function has both mechanical and g
gas exchange
g
components

PFT’s can quantify both
PFT’
 Mechanics: Spirometry, Lung volumes, Maximal
pressures MVV
pressures,
 Gas exchange: DLCO, (ABG)
 Gross composite:
p
6MWD ((?P
(?PFT
FT’’s or not))
 Detailed composite: CPET
PFT Indications




Diagnostic
g
 Respiratory symptoms
 Screening highhigh-risk patients?
 Lung
L
resection
ti surgery
 Lung transplantation evaluation
Monitoring
 Response to therapy
 Natural history
 Occupational, Drug exposures
Disability Assessment
Epidemiologic Surveys/Research
PFT CONTRAindications(?)
 Active
pulmonary TB
 Recent pneumothorax?
 Recent
R
t MI
MI, Unstable
U t bl angina?
i ?
 Recent chest, abdominal, eye surgery?
 Bronchodilator
contraindications if doing
post--bronchodilator
post
Spirometry
Spirometry--Equipment
Spirometry

Volume measurements


Fl
Flow
measurements
t



Measure volumes of at least 7 L with error of no
more than 3% or 50 mL, whichever is greater, with
flows of 00-12 Lps
Measure flows of between -12 Lps and +12 Lps
with error of no more than ±5%,, or 200 mL,,
whichever is greater
Appropriate scaling
Equipment quality control
Spirometry--Performance
Spirometry
Three phases of spirometry:
Deep



breath in
Critical to FEV1 and FVC
Easy to “fake
fake””
Coaching
g critical
BLAST!!!

Critical to FEV1
Keep

going…
Critical to FVC
Spirometry--Performance
Spirometry
BEV <5% of FVC and <150mL
Spirometry--Performance
Spirometry





Patient should be seated vs. standing?
Nose clip is recommended
Start of test
 Full inspiration with good expiratory effort
 Extrapolated volume does not exceed 5% of FVC
or 150 mL, whichever is greater
End of test
 Obvious plateau in volumevolume-time curve of at least 2
seconds
 Minimum exhalation time of 6 seconds,
, but up
p to
15 seconds
Number of maneuvers
 Minimum of 3 and maximum of 8
Spirometry--Performance
Spirometry
Common “Acceptability
Acceptability”” Issues
Cough
Early stop
G t!
Great!
Poor effort
Hesitant
Start
Spirometry--Performance
Spirometry

Largest and second largest FVC should
differ by no more 150 mL

Largest and second largest FEV1 should
differ
diff by
b no more than
th 150 mL
L
Spirometry--Performance
Spirometry
Spirometry--Performance
Spirometry
Spirometry--Interpretation
Spirometry
Trial 1
Trial2
Trial 3
FEV1 (L)
1.20
1.40
1.38
FVC (L)
2.70
2.67
2.71
FEV1/FVC
44%
52%
51%
FEV1+FVC (L)
3.90
4.07
4.09
Acceptability criteria
Yes
Yes
Yes
The final report should be:
FVC
Ratio
FEV1
a)
1.40
2.67
52%
b)
1.38
2.71
51%
c)
1.40
2.71
52%
d)
1.33
2.69
51%
e))
“Test
T t does
d
nott meett ATS criteria—
criteria
it i —repeatt if clinically
li i ll iindicated”
indicated
di t d”
d”

All of the following are included in spirometric
prediction equations EXCEPT:
a)) Age
g
b) Gender
c) Height
d) Weight
e) Ethnicity
Estimates of between subject variability
FACTOR
Age
Sex
Height
Ethnicity
Technical
Unexplained
p
PROPORTION
0.30
0.08
0 08
0.20
0.10
0.03
0.29
Spirometry--Interpretation
Spirometry
 Useful



FEV1
FVC
FEV1/FVC (calculated)
( l l t d)
 Not



useful
PEFR
MEFR, MMF
FEF75, FEF50, FEF25
Spirometry--Interpretation
Spirometry
 Useful



FEV1
FVC
FEV1/FVC (calculated)
( l l t d)
 Not



useful
PEFR
MEFR, MMF
FEF75, FEF50, FEF25
Spirometry--Interpretation
Spirometry
Obstructive
FEV1
Obstructive
Restrictive
Restrictive
FVC
FEV1/FVC
Spirometry--Interpretation
Spirometry

Obstructive

Definite
• FEV1/FVC < LLN (GOLD states anything < 0.70)
• FEV1 < predicted
Example:
85 y/o
Male
Caucasian
Predicted FEV1/FVC:
88.1 + (85 * -0.2066)
=70.5%
LLN FEV1/FVC:
78.4 + (85*(85*-0.2066)
=60.4%
70.5
Example:
85 y/o
Male
Caucasian
Predicted FEV1/FVC:
88.1 + (85 * -0.2066)
=70.5%
60.4
LLN FEV1/FVC:
78.4 + (85*(85*-0.2066)
=60.4%
84.5
Example:
35 y/o
Female
Mexican--American
Mexican
Predicted FEV1/FVC:
=84.5%
75.2
LLN FEV1/FVC:
=75.2%
Spirometry--Interpretation
Spirometry

Obstructive

Definite
• FEV1/FVC < LLN (GOLD states anything < 0.70)
• FEV1 < predicted

Probable
• FEV1/FVC < predicted
• FEV1 < LLN

Severityy
•
•
•
•
Mild (FEV1 ≥ 80% predicted)
Moderate (FEV1 ≥ 50% and < 80% predicted)
Severe (FEV1 ≥ 30% and < 50% predicted)
Very severe (FEV1 < 30% predicted)
Spirometry--Interpretation
Spirometry

Restrictive

High probability (TLC for “Definite
Definite””)
• FVC < LLN
• FEV1/FVC > ULN

Moderate probability
• FVC < LLN
• FEV1FVC > predicted

Severity
•
•
•
•
Mild (FVC ≥ 80% predicted)
Moderate (FVC ≥ 50% and < 80% predicted)
Severe (FVC ≥ 30% and < 50% predicted)
Very severe (FVC < 30% predicted)
Health Status and FEV1
Poor Health 100
80
SGRQ
score
r = - 0.23
0 23
p < 0.0001
60
40
20
Good Health
Upper limit
of normal
0
10
20
30
40
50
60
70
80
90
FEV1 (% predicted)
Jones Thorax 2001; 56: 880
Bronchodilator Testing
Patients with “irreversible disease”
disease” by ATS criteria
Irreversible
660
Reversible
385
287
213
74
275
98
48
Visit 1
58%
irreversible
154
121
50
75
46
51
103
Calverley, PMA (ISOLDE Trial). Thorax 2003;58:659
Visit 2
62%
i
irreversible
ibl
Visit 3
59%
irreversible
Upper Airway Obstruction
Fixed upper airway
Variable extra-thoracic
Variable intra-thoracic
Quiz:
The most common cause of a low FVC is: ____________.
Lung Volumes
Lung Volumes

Helium dilution

Nitrogen washout
Less accurate in obstructive lung diseases—
diseases—due
to air (gas) trapping

Plethysmography
Lung Volumes
Vital
capacity
Functional
residual
capacity
Residual
volume
Normal
Obstructive Restrictive
Lung Volumes
Restrictive Lung Disease:
P leural
A lveolar
l
l
I interstitial
N euromuscular (increased RV/TLC *boards alert!)
T horacic
Mixed ObstructiveObstructive-Restrictive (FEV1/FVC and TLC <LLN):
Sarcoidosis
Pulmonary Langerhans Cell Histiocytosis
(Histocytosis X / Eosinophilic granuloma)
Lymphangioleiomyomatosis
y p
g
y
(LAM)
(
)
Hypersensitivity Pneumonitis
(Silicosis, Berylliosis,
Berylliosis, Others)
Diffusing Capacity
Diffusing Capacity
Sensitive or Specific?
C
Causes
off decreased
d
d DLCO:
CO
Anemia
Emphysema
p y
ILD
Pulmonary edema
Pulmonary vascular disease
Causes of increased DLCO:
Ob it
Obesity
Asthma
LR shunt
Alveolar hemorrhage
Methacholine Challenge






Measures decrease in FEV1 in response to escalating
doses of inhaled methacholine
T ti procedure
Testing
d
is
i complex
l
Most patients with clinical diagnosis of asthma will have
positive test
Excellent sensitivity but many false positives (CHF,
COPD, allergic rhinitis)
May have useful applications,
applications such as occupational
screening
Clinical applications are not well established (ATS
St t
Statement)
t)
Methacholine Challenge
Categorization of bronchial responsiveness
PC20 (mg/ml)
Interpretation
16
Normal
4-16
Borderline BHR
1-4
Mild BHR
<1
Moderate
M d t to
t severe BHR
Methacholine Challenge
Summary






PFT standards are p
published ((for PFT lab directors))
Spirometry most useful PFT
Prediction equations have significant limitations
Lung volumes if distinguishing obstruction from
restriction clinically important
Caution when interpreting “reversible airflow obstruction”
obstruction”
or “bronchial hyperhyper-reactivity”
reactivity”.
Boards: back
back--extrapolated
p
volumes,, flowflow-volume loops,
p ,
mixed obstructiveobstructive-restrictive diseases, causes of
increased RV/TLC, causes of increased/decreased
DLCO.
DLCO
Interpretation of Pulmonary
Function Tests
Ken Kunisaki, MD
kunis001@umn.edu