Transcript Spirometry and Related Tests

Spirometry and Related Tests
RET 2414
Pulmonary Function Testing
Module 2.0
SPIROMETRY AND RELATED TESTS

Learning Objectives



Determine whether spirometry is
acceptable and reproducible
Identify airway obstruction using forced
vital capacity (FVC) and forced expiratory
volume (FEV1)
Differentiate between obstruction and
restriction as causes of reduced vital
capacity
SPIROMETRY AND RELATED TESTS

Learning Objectives



Distinguish between large and small
airway obstruction by evaluating flowvolume curves
Determine whether there is a significant
response to bronchodilators
Select the appropriate FVC and FEV1 for
reporting from series of spirometry
maneuvers
Predicted Values

Laboratory Normal Ranges

Laboratory tests performed on a large
number of normal population will show
a range of results
Predicted Values

Laboratory Normal Ranges
Predicted Values

Laboratory Normal Ranges

Most clinical laboratories consider
two standard deviations from the
mean as the normal range since it
includes 95% of the normal
population.
PFT Reports
o
When performing PFT’s three values
are reported:
o
Actual – what the patient performed
o
Predicted – what the patient should
have performed based on Age, Height,
Sex, Weight, and Ethnicity
o
% Predicted – a comparison of the
actual value to the predicted value
PFT Reports

Example
VC
Actual
Predicted
%Predicted
4.0
5.0
80%
SPIROMETRY

Vital Capacity
The vital capacity (VC) is the volume
of gas measured from a slow,
complete expiration after a maximal
inspiration, without a forced effort.
SPIROMETRY

Vital Capacity
SPIROMETRY

Vital Capacity

Valid VC measurements important
 IC and ERV used to calculate
RV and TLC
 Example:


RV = FRC - ERV
TLC = IC + FRC
SPIROMETRY

VC: Criteria for Acceptability
1.
End-expiratory volume varies by less than
100 ml for three preceding breaths
2.
Volume plateau observed at maximal
inspiration and expiration
SPIROMETRY

VC: Criteria for Acceptability
3.
Three acceptable VC maneuvers should be
obtained; volume within 150 ml.
4.
VC should be within 150 ml of FVC value
SPIROMETRY

VC: Selection Criteria
The largest value from at least 3 acceptable
maneuvers should be reported
SPIROMETRY

VC: Significance/Pathophysiology

Decreased VC
 Loss of distensible lung tissue








Lung CA
Pulmonary edema
Pneumonia
Pulmonary vascular congestion
Surgical removal of lung tissue
Tissue loss
Space-occupying lesions
Changes in lung tissue
SPIROMETRY

VC: Significance/Pathophysiology

Decreased VC






Obstructive lung disease
Respiratory depression or
neuromuscular disease
Pleural effusion
Pneumothorax
Hiatal hernia
Enlarged heart
SPIROMETRY

VC: Significance/Pathophysiology

Decreased VC
 Limited movement of diaphragm




Pregnancy
Abdominal fluids
Tumors
Limitation of chest wall movement



Scleraderma
Kyphoscoliosis
Pain
SPIROMETRY

VC: Significance/Pathophysiology

If the VC is less than 80% of
predicted: FVC can reveal if caused by
obstruction
SPIROMETRY

VC: Significance/Pathophysiology

If the VC is less than 80% of
predicted: Lung volume testing can
reveal if caused by restriction
SPIROMETRY

Forced Vital Capacity (FVC)
The maximum volume of gas that
can be expired when the patient
exhales as forcefully and rapidly as
possible after maximal inspiration
(sitting or standing)
SPIROMETRY

FVC (should be within 150 ml of VC)
SPIROMETRY

FVC: Criteria for Acceptability
1.
Maximal effort; no cough or glottic closure
during the first second; no leaks or obstruction
of the mouthpiece.
2.
Good start-of-test; back extrapolated volume
<5% of FVC or 150 ml, whichever is greater
SPIROMETRY

3.
FVC: Criteria for Acceptability
Tracing shows 6 seconds of exhalation or an
obvious plateau (<0.025L for ≥1s); no early
termination or cutoff; or subject cannot or
should not continue to exhale
SPIROMETRY

4.
FVC: Criteria for Acceptability
Three acceptable spirograms obtained; two
largest FVC values within 150 ml; two largest
FEV1 values within 150 ml
SPIROMETRY

FVC: Selection Criteria
The largest FVC and largest FEV1 (BTPS)
should be reported, even if they do not
come from the same curve
SPIROMETRY

FVC: When to call it quits !!!
If reproducible values cannot be
obtained after eight attempts, testing
may be discontinued
SPIROMETRY

FVC: Significance and Pathophysiology


FVC equals VC in healthy individuals
FVC is often lower in patients with
obstructive disease
SPIROMETRY

FVC: Significance and Pathophysiology

FVC can be reduced by:






Mucus plugging
Bronchiolar narrowing
Chronic or acute asthma
Bronchiectasis
Cystic fibrosis
Trachea or mainstem bronchi obstruction
SPIROMETRY

FVC: Significance and Pathophysiology


Healthy adults can exhale their FVC
within 4 – 6 seconds
Patients with severe obstruction (e.g.,
emphysema) may require 20 seconds,
however, exhalation times >15
seconds will rarely change clinical
decisions
SPIROMETRY

FVC: Significance and Pathophysiology

FVC is also decreased in restrictive
lung disease

Pulmonary fibrosis


Congestion of pulmonary blood flow


dusts/toxins/drugs/radiation
pneumonia/pulmonary hypertension/PE
Space occupying lesions

tumors/pleural effusion
SPIROMETRY

FVC: Significance and Pathophysiology

FVC is also decreased in restrictive
lung disease

Neuromuscular disorders, e.g,


Chest deformities, e.g,


myasthenia gravis, Guillain-Barre
scoliosis/kyphoscoliosis
Obesity or pregnancy
SPIROMETRY

Forced Expiratory Volume (FEV1)
The volume expired over the first
second of an FVC maneuver
SPIROMETRY

Forced Expiratory Volume (FEV1)

May be reduced in obstructive or
restrictive patterns, or poor patient
effort
SPIROMETRY

Forced Expiratory Volume (FEV1)

In obstructive disease, FEV1 may be
decreased because of:

Airway narrowing during forced expiration





emphysema
Mucus secretions
Bronchospasm
Inflammation (asthma/bronchitis)
Large airway obstruction

tumors/foreign bodies
SPIROMETRY

Forced Expiratory Volume (FEV1)

The ability to work or function in
daily life is related to the FEV1 and
FVC

Patients with markedly reduced FEV1
values are more likely to die from COPD or
lung cancer
SPIROMETRY

Forced Expiratory Volume (FEV1)

FEV1 may be reduced in restrictive
lung processes




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Fibrosis
Edema
Space-occupying lesions
Neuromuscular diseases
Obesity
Chest wall deformity
SPIROMETRY

Forced Expiratory Volume (FEV1)

FEV1 is the most widely used
spirometric parameter, particularly
for assessment of airway
obstruction
SPIROMETRY

Forced Expiratory Volume (FEV1)

FEV1 is used in conjunction with
FVC for:




Simple screening
Response to bronchodilator therapy
Response to bronchoprovocation
Detection of exercise-induced
bronchospasm
SPIROMETRY

Forced Expiratory Volume Ratio (FEVT%)

FEVT% = FEVT/FVC x 100

Useful in distinguishing between
obstructive and restrictive causes of
reduced FEV1 values
SPIROMETRY

Forced Expiratory Volume Ratio (FEVT%)


Normal FEVT% Ratios for Health Adults

FEV 0.5% = 50%-60%

FEV 1%
= 75%-85%

FEV 2%
= 90%-95%

FEV 3%
= 95%-98%

FEV 6%
= 98%-100%
Patients with obstructive disease have
reduced FEVT% for each interval
SPIROMETRY

Forced Expiratory Volume Ratio (FEVT%)

A decrease FEV1/FVC ratio is the
“hallmark” of obstructive disease
 FEV1/FVC
<75%
SPIROMETRY

Forced Expiratory Volume Ratio (FEVT%)

Patients with restrictive disease often have
normal or increased FEVT% values


FEV1 and FVC are usually reduced in equal
proportions
The presence of a restrictive disorder may
by suggested by a reduced FVC and a
normal or increased FEV1/FVC ration
SPIROMETRY

Forced Expiratory Flow 25% - 75%
(maximum mid-expiratory flow)

FEF 25%-75% is measured from a
segment of the FVC that includes flow
from medium and small airways

Normal values: 4 – 5 L/sec
SPIROMETRY

Forced Expiratory Flow 25% - 75%
In the presence of a borderline
value for FEV1/FVC, a low FEF
25%-75% may help confirm
airway obstruction
SPIROMETRY

Flow – Volume Curve

AKA: Flow–Volume Loop (FVL)
The maximum expiratory flowvolume (MEFV) curve shows flow
as the patient exhales from
maximal inspiration (TLC) to
maximal expiration (RV)

FVC followed by FIVC
SPIROMETRY

FVL


FEF 25% or Vmax 75
X axis: Volume
Y axis: Flow

PEF (Peak Expiratory Flow)

PIF (Peak Inspiratory Flow)
.

Vmax 75 or FEF 25%
FVC Remaining or Percentage FVC exhaled
.

Vmax 50 or FEF 50%
.

Vmax 25 or FEF 75%
FEF 75% or Vmax 25%
SPIROMETRY
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FVL

FEVT and FEF% can be read from
the timing marks (ticks) on the FVL
SPIROMETRY

FVL

Significant decreases in flow or volume
are easily detected from a single graphic
display
SPIROMETRY

FVL: Severe Obstruction
SPIROMETRY

FVL: Bronchodilation
SPIROMETRY

Peak Expiratory Flow (PEF)

The maximum flow obtained
during a FVC maneuver
Measured from a FVL
 In laboratory, must perform a
minimum of 3 PEF maneuvers
 Largest 2 of 3 must be within 0.67
L/S (40 L/min)
 Primarily measures large airway
function
 Many portable devices available

SPIROMETRY

Peak Expiratory Flow (PEF)

When used to monitor asthmatics



Establish best PEF over a 2-3 week
period
Should be measured twice daily
(morning and evening)
Daily measurements are compared to
personal best
SPIROMETRY

Peak Expiratory Flow (PEF)

The National Asthma Education Program
suggests a zone system



Green: 80%-100% of personal best
 Routine treatment can be continued; consider
reducing medications
Yellow: 50%-80% of personal best
 Acute exacerbation may be present
 Temporary increase in medication may be
needed
 Maintenance therapy may need increases
Red: Less than 50% of personal best
 Bronchodilators should be taken immediately;
begin oral steroids; clinician should be
notified if PEF fails to return to yellow or
green within 2 – 4 hours
SPIROMETRY

Peak Expiratory Flow (PEF)



PEF is a recognized means of
monitoring asthma
Provides serial measurements
of PEF as a guide to treatment
ATS Recommended Ranges
 60-400 L/min (children)
 100-850 L/min (adults)
SPIROMETRY

Maximum Voluntary Ventilation
(MVV)
The volume of air exhaled in a
specific interval during rapid, forced
breathing
SPIROMETRY

MVV



Rapid, deep breathing
VT ~50% of VC
For 12-15 seconds
SPIROMETRY

MVV

Tests overall function of
respiratory system

Airway resistance

Respiratory muscles

Compliance of lungs/chest wall

Ventilatory control mechanisms
SPIROMETRY

MVV




At least 2 acceptable maneuvers should be
performed
Two largest should be within 10% of each
other
Volumes extrapolated out to 60 seconds
and corrected to BTPS
MVV is approximately equal to 35 time the
FEV1
SPIROMETRY

MVV

Selection Criteria

The highest MVV (L/min, BTPS) and MVV
rate (breaths / min) should be reported
SPIROMETRY

MVV
Decreased in:



Patients with moderate to severe
obstructive lung disease
Patients who are weak or have decreased
endurance
Patients with neurological deficits
SPIROMETRY

MVV
Decreased in:


Patients with paralysis or nerve damage
A markedly reduced MVV correlates with
postoperative risk for patients having
abdominal or thoracic surgery
SPIROMETRY

Before/After Bronchodilator

Spirometry is performed before
and after bronchodilator
administration to determine the
reversibility of airway obstruction
SPIROMETRY

Before/After Bronchodilator


An FEV1% less than predicted is a
good indication for bronchodilator
study
In most patients, an FEV1% less
than 70% indicates obstruction
SPIROMETRY

Before/After Bronchodilator


Any pulmonary function parameter
may be measured before and after
bronchodilator therapy
FEV1 and specific airway
conductance (SGaw) are usually
evaluated
SPIROMETRY

Before/After Bronchodilator

Lung volumes should be recorded
before bronchodilator
administration

Lung volumes and DLco may also
respond to bronchodilator therapy
SPIROMETRY

Before/After Bronchodilator

Routine bronchodilator therapy should be
withheld prior to spirometry










Ruppel 9th edition, pg. 66: Table 2-2
Short-acting β-agonists
Short-acting anticholinergic
Long-acting β-agonists
Long-acting anticholinergic
Methylxanthines (theophyllines)
Slow release methylxanthines
Cromolyn sodium
Leukotriene modifiers
Inhaled steroids
4 hours
4 hours
12 hours
24 hours
12 hours
24 hours
8-12 hours
24 hours
Maintain dosage
SPIROMETRY

Before/After Bronchodilator


Minimum of 10 minutes, up to 15
minutes, between administration
and repeat testing is recommended
(30 minutes for short-acting
anticholinergic agents)
FEV1, FVC, FEF25%-75%, PEF,
SGaw are commonly made before
and after bronchodilator
administration
SPIROMETRY

Before/After Bronchodilator

Percentage of change is calculated
%Change = Postdrug – Predrug X 100
Predrug
SPIROMETRY

Before/After Bronchodilator



FEV1 is the most commonly used
test for quantifying bronchodilator
response
FEV1% should not be used to judge
bronchodilation response
SGaw may show a marked increase
after bronchodilator therapy
SPIROMETRY

Before/After Bronchodilator
Significance and Pathophysiology

Considered significant if:

FEV1 or FVC increase ≥12% and ≥200 ml

SGaw increases 30% - 40%
SPIROMETRY

Before/After Bronchodilator
Significance and Pathophysiology

Diseases involving the bronchial
(and bronchiolar) smooth muscle
usually improve most from “before”
to “after”

Increase >50% in FEV1 may occur in
patients with asthma
SPIROMETRY

Before/After Bronchodilator
Significance and Pathophysiology

Patients with chronic obstructive
diseases may show little
improvement in flows



Inadequate drug deposition (poor
inspiratory effort)
Patient may respond to different drug
Paradoxical response <8% or 150 ml not
significant
SPIROMETRY

Maximal Inspiratory Pressure (MIP)

The lowest pressure developed
during a forceful inspiration against
an occluded airway

Primarily measures inspiratory muscle
strength
SPIROMETRY

MIP



Usually measured at maximal
expiration (residual volume)
Can be measured at FRC
Recorded as a negative number in
cm H20 or mm Hg, e.g. (-60 cm H2O)
SPIROMETRY

MIP
SPIROMETRY

MIP
Significance and Pathophysiology


Healthy adults > -60 cm H2O
Decreased in patients with:



Neuromuscular disease
Diseases involving the diaphragm,
intercostal, or accessory muscles
Hyperinflation (emphysema)
SPIROMETRY

MIP
Significance and Pathophysiology


Sometimes used to measure
response to respiratory muscle
training
Often used in the assessment of
respiratory muscle function in
patients who need ventilatory
support
SPIROMETRY

Maximal Expiratory Pressure (MEP)

The highest pressure developed
during a forceful exhalation against
an occluded airway

Dependent upon function of the
abdominal muscles, accessory muscles
of expiration, and elastic recoil of lung
and thorax
SPIROMETRY

MEP



Usually measured at maximal
inspiration (total lung capacity)
Can be measured at FRC
Recorded as a positive number in
cm H20 or mm Hg
SPIROMETRY

MIP and MEP
SPIROMETRY

MEP
Significance and Pathophysiology


Healthy adults >80 to 100 cm H2O
Decreased in:

Neuromuscular disorders

High cervical spine fractures

Damage to nerves controlling
abdominal and accessory muscles of
inspiration
SPIROMETRY

MEP
Significance and Pathophysiology

A low MEP is associated with
inability to cough

May complicate chronic bronchitis, cystic
fibrosis, and other diseases that result in
excessive mucus production
SPIROMETRY

Airway Resistance (Raw)



The drive pressure required to
create a flow of air through a
subject’s airway
Recorded in cm H2O/L/sec
When related to lung volume at the
time of measurement it is known as
specific airway resistance (SRaw)
SPIROMETRY

Raw

Measured in a
plethysmograph
as the patient
breathes
through a
pneumotachometer
SPIROMETRY

Raw

Criteria of Acceptability
 Mean of three or more acceptable
efforts should be reported;
individual values should be within
10% of mean
SPIROMETRY

Airway Resistance (Raw)
Normal Adult Values
Raw
0.6 – 2.4 cm H2O/L/sec
SRaw 0.190 – 0.667 cm H2O/L/sec/L
SPIROMETRY

Airway Resistance (Raw)

May be increased in:





Bronchospasm
Inflammation
Mucus secretion
Airway collapse
Lesions obstructing the larger airways

Tumors, traumatic injuries, foreign bodies
SPIROMETRY

Raw
Significance and Pathology



Increased in acute asthmatic episodes
Increased in advanced emphysema because of
airway narrowing and collapse
Other obstructive disease, e.g., bronchitis may
cause increase in Raw proportionate to the
degree of obstruction in medium and small
airways
SPIROMETRY

Airway Conductance (Gaw)

A measure of flow that is generated
from the available drive pressure

Recorded in L/sec/cm H2O

Gaw is the inverse of Raw

When related to lung volume at the
time of measurement it is known as
specific airway conductance (SGaw)
SPIROMETRY

Gaw

Measured in a
plethysmograph
as the patient
breathes
through a
pneumotachometer
SPIROMETRY

Gaw

Criteria of Acceptability
 Mean of three or more acceptable
efforts should be reported;
individual values should be within
10% of mean
SPIROMETRY

Airway Conductance (Gaw)
Normal Adult Values
Gaw
0.42 – 1.67 L/sec/cmH2O
SGaw 0.15 – 0.20 L/sec/cm H2O/L
SPIROMETRY

Airway Conductance (Gaw)
Significance and Pathology
 SGaw
Values <0.15 – 0.20
L/sec/cm H2O/L are consistent
with airway obstruction
Quiz Practice
Most clinical laboratories consider
two standard deviations from the
mean as the normal range when
determining predicted values since it
includes 95% of the normal
population.
a.
b.
c.
d.
False
Only for those individuals with lung
disease
This applies only to cigarette smokers
True
Quiz Practice
Vital capacity is defined as which of
the following?
a.
b.
c.
d.
The volume of gas measured from a slow,
complete exhalation after a maximal
inspiration, without a forced effort
The volume of gas measured from a rapid,
complete exhalation after a rapid maximal
inspiration
The volume of gas measured after 3 seconds of
a slow, complete exhalation
The total volume of gas within the lungs after a
maximal inhalation
Quiz Practice
Which of the following statements are
true regarding the acceptability criteria
for vital capacity measurement?
I.
II.
III.
IV.
a.
b.
c.
d.
End-expiratory volume varies by less than 100
ml for three preceding breaths
Volume plateau observed at maximal inspiration
and expiration
Three acceptable vital capacity maneuvers
should be obtained; volume within 150 ml
Vital capacity should be within 150 ml of forced
vital capacity in healthy individuals
I, II, and IV
II, III, and IV
III and IV
I, II, III, IV
Quiz Practice
Which of the following best
describes the Forced Vital Capacity
(FVC) maneuver?
a.
b.
c.
d.
The volume of gas measured from a slow,
complete exhalation after a maximal
inspiration, without a forced effort
The volume of gas measured from a slow,
complete exhalation after a rapid maximal
inspiration
The volume of gas measured after 3 seconds
of a rapid, complete exhalation
The maximum volume of gas that can be
expired when the patient exhales as forcefully
and rapidly as possible after maximal
inspiration
Quiz Practice
All of the following are true
regarding the acceptability
criteria of an FVC maneuver
EXCEPT?
a.
b.
c.
d.
Maximal effort, no cough or glottic
closure during the first second; no leaks
of obstruction of the mouthpiece
Good start of test; back extrapolated
volume less than 5% of the FVC or 150 ml
Tracing shows a minimum of 3 seconds of
exhalation
Three acceptable spirograms obtained;
two largest FVC values within 150 ml; two
largest FEV1 values within 150 ml
Quiz Practice
The FEV1 is the expired volume of
the first second of the FVC
maneuver.
a.
b.
c.
d.
True
False
Only when done slowly
Only when divided by the FVC
Quiz Practice
Which of following statements is
true regarding FEV1?
a.
b.
c.
d.
FEV1 may be larger than the FVC
FEV1 is always 75% of FVC
May be reduced in obstructive and
restrictive lung disease
Is only reduced in restrictive disease
Quiz Practice
The FEV1% is useful in
distinguishing between obstructive
and restrictive causes of reduced
FEV1 values
a.
b.
c.
d.
True
False
Only helps to distinguish obstructive
lung disease
Only helps to distinguish restrictive
lung disease
Quiz Practice
Which statements are true
regarding the FEV 1%, also known
as the FEV1/FVC?
I.
II.
III.
IV.
a.
b.
c.
d.
A decreased FEV1/FVC is the hallmark of
obstructive disease
Patients with restrictive lung disease often
have normal or increased FEV1/FVC ratios
The presence of a restrictive disorder may
be suggested by a reduced FVC and a
normal or increased FEV1/FVC ratio
A normal FEV1/FVC ratio is between 75%
- 85%
I and II
I, II and III
II, III and IV
I, II, III and IV
Quiz Practice
What test is
represented by the
graph to the right?
a.
b.
c.
d.
Forced Vital Capacity
Flow-Volume Loop
Slow Vital Capacity
Total Lung Capacity
Maneuver
Quiz Practice
What type of pulmonary disorder is
represented by the graph below?
a.
b.
c.
d.
Obstructive lung disease
Restrictive lung disease
Upper airway obstruction
Normal lung function
(The dotted lines represent the predicted values)
Quiz Practice
Which is true regarding Peak
Expiratory Flow (PEF)?
I.
II.
III.
IV.
a.
b.
c.
d.
Primarily measures large airway function
Is a recognized means of monitoring
asthma
Serial measurements of PEF are used a
guide to treat asthma
When less than 50% of personal best, it is
an indication that immediate treatment is
required
I only
II and III
II, III, and IV
I, II, III, and IV
Quiz Practice
MVV is decreased in patients with
which of the following disorders?
I.
II.
III.
IV.
a.
b.
c.
d.
Moderate to severe obstructive lung
disease
Weak or with decrease endurance
Neurological defects
Paralysis or nerve damage
I and IV
II and III
III and IV
I, II, III, and IV
Quiz Practice
Spirometry before and after
bronchodilator therapy is used to
determine which of the following?
a.
b.
c.
d.
Reversibility of airway obstruction
The severity of restrictive disorders
The rate at which CO diffuses through the lung
into the blood
If the patient has exercised induced asthma
Quiz Practice
What is the minimum amount of
time between administration of
bronchodilator therapy and repeat
pulmonary function testing?
a.
b.
c.
d.
5 minutes
10 minutes
30 minutes
60 minute
Quiz Practice
Bronchodilation is considered
significant when which of the
following occurs?
a.
b.
c.
d.
FEV1/FVC increases by 12%
SGaw increases by 12%
FVC and/or FEV1 increases by 12% and 150 ml
DLco increases by 12%
Quiz Practice
Which of the following is true
regarding Maximal Inspiratory
Pressure (MIP)?
I.
II.
III.
IV.
a.
b.
c.
d.
Primarily measures inspiratory muscle
strength
Measures airway resistance during
inspiration
Is decreased in patients with neurological
disease
Often used in the assessment of
respiratory muscle function in patients
who need ventilatory support
I, II, and III
I, III, and IV
II and III
II, III, and IV
Quiz Practice
Airway resistance (Raw) is the
drive pressure required to create a
flow of air through a subject’s
airway.
a.
b.
c.
d.
True
False
Only in patients with COPD
Only in patients with restrictive
disorders
Quiz Practice
Airway resistance may be
increased in which of the following
patients?
I.
II.
III.
IV.
a.
b.
c.
d.
Purely restrictive lung disorders
Acute asthmatic episodes
Mucus secretion
Lung compliance changes
I only
I and IV
II and III
I, II, III, and IV
Quiz Practice
Airway Conductance (Gaw) is a
measure of flow that is generated
from the available drive pressure.
a.
b.
c.
d.
True
False
Only in patients with COPD
Only in patients with restrictive
disorders
Quiz Practice
A patient’s pulmonary function
tests reveal the following:
Actual
4.01 L
2.58 L

FVC
FEV1

FEV1% 51

Predicted
4.97 L
3.67 L
>75
Select the correct interpretation
a.
b.
c.
d.
Restrictive pattern
Obstructive pattern
Inconclusive
Normal
%Predicted
81
56
_
Quiz Practice
A patient’s pulmonary function tests reveal
the following:
FVC
FEV1
FEV1%
Actual
3.75 L
2.80 L
75
Predicted
4.97 L
3.67 L
>/=75
Select the correct interpretation
a.
Restrictive pattern
b.
Obstructive pattern
c.
Inconclusive
d.
Normal
%Predicted
75
76
_