Pulmonary Function Testing

Dr. Riham Hazem Raafat
Lecturer of Pulmonary Medicine
Ain Shams University

Objectives
 Briefly review pulmonary anatomy and
physiology
 Review lung volumes and capacities
 Provide an overview of PFTs
 Discuss spirometry and review its clinical
applications

Anatomy
 Lungs comprised
of
• Airways
• Alveoli

Weibel ER: Morphometry of the Human
Lung. Berlin and New York: Springer-
Verlag, 1963
The Airways
 Conducting zone: no gas
exchange occurs
Anatomic dead space
 Transitional zone: alveoli
appear, but are not great
in number
 Respiratory zone: contain
the alveolar sacs

The Alveoli
 Approximately 300
million alveoli
 1/3 mm diameter
 Total surface area if
they were complete
spheres 85 sq. meters
(size of a tennis court)
Murray & Nadel: Textbook of Respiratory
Medicine, 3rd ed., Copyright © 2000 W. B.
Saunders Company

Pulmonary Functions
Respiration
Process by which cells utilize O2 produce Co2 &
exchange the gases with atmosphere
Normal Lung Function
The lungs maintain normal O2 & Co2 press & content
in the arterial blood in all physiological circumstances.
Constant art. blood gases is maintained by efficient
transfer of gas between alveolar air & blood passing
through the alveolar capillaries.

There are 3 components of pulmonary gas
exchange:
Ventilation: amount of air which ventilates alveoli
each min. (4 lit/min). It must be evenly distributed to
all perfused alveoli.
Perfusion: amount of blood which pass through
pulmonary cap. Per min. = 5 lit/min
Diffusion: across the alveolar cap. mem., the transfer of
gas between alveolar air & pulm cap bld being
determined by the gas tension gradients bet. them =
DLCO 20 ml/ mmHg/min.
V/ QV/ Q 4/54/5= == 0.80.8

Mechanics of Breathing
 Inspiration
• Active process
 Expiration
• Quiet breathing: passive
• Can become active

Lung Volumes
 4 Volumes
 4 Capacities
• Sum of 2 or
more lung
volumes
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Tidal Volume (TV)
 Volume of air
inspired and
expired during
normal quiet
breathing
 N – ~6-8 ml/kg.
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Inspiratory Reserve Volume (IRV)
 The maximum
amount of air
that can be
inhaled after a
normal tidal
volume
inspiration
 N- 1900 ml- 3300
ml.
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Expiratory Reserve Volume (ERV)
 Maximum
amount of air that
can be exhaled
from the resting
expiratory level
 N- 700 ml- 1000 ml.
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Residual Volume (RV)
 Volume of air
remaining in the
lungs at the end
of maximum
expiration
 N- 1700 ml- 2100
ml. (20-25ml/kg)
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Vital Capacity (VC)
 Volume of air that can
be exhaled from the
lungs after a maximum
inspiration
 FVC: when VC exhaled
forcefully
 SVC: when VC is
exhaled slowly
 VC = IRV + TV + ERV
 N- 3100 ml- 4800 ml.
(60-70ml/kg)
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Inspiratory Capacity (IC)
 Maximum amount of
air that can be
inhaled from the end
of a tidal volume
 IC = IRV + TV
 N- 2400 ml- 3800
ml.
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Functional Residual Capacity (FRC)
 Volume of air remaining
in the lungs at the end of
a TV expiration
 The elastic force of the
chest wall is exactly
balanced by the elastic
force of the lungs
 FRC = ERV + RV
 N- 2300 ml- 3300 ml.
(30-35ml/kg)
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Total Lung Capacity (TLC)
 Volume of air in the
lungs after a maximum
inspiration
 TLC = IRV + TV +
ERV + RV (VC + RV)
 N- 4000 ml- 6000 ml.
(80-100ml/kg)
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV

Pulmonary Function Tests
 Evaluates one or more major aspects of the
respiratory system:
• Lung volumes
• Airway function
• Gas exchange

• It is a valuable tool for evaluating the respiratory system,
representing an important adjunct to the patient history,
various lung imaging studies, and invasive testing such
as bronchoscopy and open-lung biopsy.
• Insight into underlying pathophysiology can often be gained
by comparing the measured values for pulmonary function
tests obtained on a patient at any particular point with
normative values derived from population studies.
The percentage of predicted normal is used to grade the
severity of the abnormality.
Definition

PFTs can include:
1) Simple screening Spirometry,
2) Formal Lung Volume measurement,
3) Diffusing Capacity for Carbon Monoxide, and
4) Arterial Blood Gases.
These studies may collectively be referred to as:
complete pulmonary function survey.

Indications
 Detect disease
 Evaluate extent and monitor course of
disease
 Evaluate treatment
 Measure effects of exposures
 Assess risk for surgical procedures

Pulmonary Function Tests
 Airway function
• Simple spirometry
• Forced vital capacity
maneuver
• Maximal voluntary
ventilation
• Maximal
inspiratory/expiratory
pressures
• Airway resistance
• Lung volumes and
ventilation
–Functional residual
capacity
–Total lung capacity,
residual volume
–Minute ventilation,
alveolar ventilation,
dead space
–Distribution of
ventilation

 Diffusing capacity
tests
 Blood gases and
gas exchange tests
• Blood gas analysis
• Pulse oximetry
• Capnography
 Cardiopulmonary
exercise tests

Categories Of PFTs:
A. Ventilatory function tests
• Airway functions:-
a. Simple Spirometry (Ventilation testing)
1. Static lung volumes  TLC, FRC, RV
2. Dynamic lung volume  FVC & MVV
b. Airway resistance (Raw) ,and compliance (C1)
• Graphic representation
• Bronchodilator response
• Bronchoprovocation testing

B. Lung Volume Tests (static lung volume tests)
C. Tests for Gas Exchange
• Diffusion Lung capacity (DLCO)
• Arterial Blood Gases
• Pulse Oximetry & Capnography
D. Simple and complex cardiopulmonary exercise
testing (6MWT, CPET)
E. Respiratory Muscle Tests (Spirometry, MIP, MEP,
MVV, Sniff Test, Mouth Pressures, Pdi, EMG, US)
F. Bed Side PFTs

Spirometry
 Measurement of the pattern of air movement
into and out of the lungs during controlled
ventilatory maneuvers.
 Often done as a maximal expiratory
maneuver.

Indications:
1. Symptoms and clinical signs
• Dyspnea with or without or wheezing
• Chest pain or orthopnea
• Cough for a longer time with or without phlegm production
• Cyanosis
• Decreased or unusual breath sounds
2. Abnormal chest x-ray (e.g. Hyperinflation)
3. Abnormal blood gases (hypoxemia, hypercapnia)
4. Abnormal laboratory findings (e.g. polycythemia)
5. Monitoring of known pulmonary diseases

6. Assessing severity or progression of disease (e.g.
asthma, COPD)
• Control of therapy, e.g. Bronchodilatator or steroids. (no therapy
without control)
• Assessing reversibility (asthma versus COPD)  > 12 % FEV1 (4
inhalations 100 mcg each of B2 ag or 40 mcg each of anticholin.)
7- Further Indications for spirometry:
• Periodic examinations in high-risk groups
• Course of FEV1 in smokers
• Risk stratification of patients for surgery
• Check-up
• Evaluating disability or impairment
• Extrapulmonary diseases with lung involvement

Diagnostic
1- To evaluate symptoms, signs or abnormal laboratory
tests
o Symptoms: dyspnea, wheezing, orthopnea, cough,
phlegm production, chest pain
o Signs: diminished breath sounds, overinflation, expiratory
slowing, cyanosis, chest deformity, unexplained crackles
o Abnormal lab: hypoxemia, hypercapnia, polycythemia,
abn CXR
2- To screen individuals at risk of having pulmonary
disease
o Smokers
o Individuals in occupations with exposures to injurious
subs.
o Some routine physical examinations

4- Assess pre-operative risk:
 Age > 70 yrs.
 Morbid obesity
 Thoracic or Cardiac surgery
 Upper abdominal surgery
 Smoking history and cough
 Any known pulmonary disease
3- Measure the effect of disease on pulmonary function
5- Assess prognosis (after ttt, lung transplant ...etc.)
6- Assess health status before beginning strenuous
physical activity

Pre-operative Risk Assessment for
Pulmonary Resection Surgery

1- To assess therapeutic intervention
o Bronchodilator therapy
o Steroid treatment for asthma, ILD, etc.
o Management of congestive heart failure
o Other (antibiotics in cystic fibrosis, etc.)
2- To describe course of diseases that affect lung function
o Pulmonary diseases (Ob Aw, ILD)
o Cardiac diseases (CHF)
o Neuromuscular diseases (Guillian-Barre Syndrome)
3- To monitor people exposed to injurious agents
4- To monitor for adverse reactions to drugs with known
pulmonary toxicity
Monitoring

Disability/impairment
evaluations
1- To assess patients as part of a rehabilitation
program (medical, industrial, vocational)
2- To assess risks as part of an insurance evaluation
3- To assess individuals for legal reasons

Public health
• Epidemiological surveys
• Derivation of reference equations
• Clinical research

Relative contraindications for
spirometry
1. Acute disorders affecting test performance (e.g. vomiting,
nausea, vertigo)
2. Hemoptysis of unknown origin (FVC maneuver may
aggravate underlying condition.)
3. Pneumothorax
4. Recent abdominal or thoracic surgery
5. Recent eye surgery (increases in intraocular pressure
during spirometry)
6. Recent myocardial infarction or unstable angina
7. Thoracic, abdominal, or cerebral aneurysms (risk of
rupture because of increased thoracic pressure)

Only Absolute Contraindication is:
Myocardial Infarction
within the Previous Month

Possible side-effects
1. Serious complications are rare: Syncope, dizziness, light-
headedness
2. Paroxysmal coughing
3. Bronchospasm (e.g. Asthma)
4. Increased intracranial pressure
5. Thoracic pain
6. Pneumothorax (very rare)
7. Nosocomial infections (very rare)

Limitations
 Test results can show abnormalities of lung function, but these
are not disease-specific.
• A reduction of vital capacity is regarded as a sign of respiratory
disease, but it cannot allow differentiation between restriction and
obstruction.
• Spirometry can detect obstructive abnormalities at relatively early
stages, but it may not be sensitive to restrictive abnormalities
before extensive damage has occurred.

Infection control and safety during
spirometry
1. Spirometers should be cleaned according to the
manufacturer´s recommendations
2. Change of mouthpiece
3. In infectious pts (e.g. MRSA, HIV, hepatitis B, TB), as well
as in patients with immunodeficiency (e.g. chemotherapy,
post-transplantation, CF) bacteria filters should always be
used.
4. A mask should be worn by the technologist when testing
subjects who have active TB or other serious diseases that
can be transmitted by coughing.
5. Proper hand washing & Gloves should be worn when
handling potentially contaminated equipment

Preparation & instructions to the
patient
1- Information about the purpose: before starting, explain to
the pt. how fast & how much he can exhale from his lungs.
2. Tell the pt. that only the maximal effort will lead to a
reliable result. This may enhance his motivation to follow
the instructions correctly.
3. Demonstrating of breathing maneuver: Possible even
without spirometer. This can save a lot of time spent on
repeated measurements.

Guidelines for Holding Medical
Drugs

Technique
 Have patient seated comfortably (upright, head
straight or slightly extended, no tight clothes)
 Open circuit technique or Closed-circuit technique
• Place nose clip on
• Have patient breathe on mouthpiece (lips tightly sealed)
• Have patient take a deep breath as fast as possible
• Blow out as hard as they can until you tell them to stop
• 3 trials done as previous (not > 6)
* Parameters measured in standing position are 2-7% increased than sitting parameters

Factors That Affect Results
 Age
 Sex
 Height
 Weight
 Race
 Disease
 Speed & Effort of the test
 Rest before test (15 mins at least)
 Max inhalation time (2-4 sec)
 Interpretation (combine parameters with graphs)

Acceptability &
Reproducibility Criteria:

Terminology & Interpretation
 Forced vital capacity (FVC):
• Total volume of air that can be
exhaled forcefully from TLC
• The majority of FVC can be
exhaled in <3 seconds in normal
people, but often is much more
prolonged in obstructive diseases
• Measured in liters (L)

• Interpretation of % predicted:
– Mild - 70-79% of predicted
– Moderate - 60-69% of predicted
– Moderately severe - 50-59%
– Severe - 35-49% of predicted
– Very severe - Less than 35% of predicted

• Forced expiratory volume in
1 second: (FEV1)
– Volume of air forcefully expired
from full inflation (TLC) in the
first second
– Measured in liters (L)
– Normal people can exhale more
than 75-80% of their FVC in the
first second; thus the FEV1/FVC
can be utilized to characterize
lung disease

– Mild - 70-79% of predicted
– Moderate - 60-69% of predicted
– Moderately severe - 50-59%
– Severe - 35-49% of predicted
– Very severe - Less than 35% of predicted
FVC

*N.B. FEV1 begins to decrease after age 20.
• The annual decline is small at first but accelerates with aging. The
forced vital capacity (FVC) decreases as well, by about 14 to 30
mL/yr in men and 15 to 24 mL/yr in women.
• Until age 40, decreases in FEV1 and FVC are thought to result
from changes in body weight and strength rather than from loss of
tissue.
• After age 40, decreases in FEV1 and FVC are due to aging itself
and superimposed cumulative effects of inflammatory injury from
respiratory illness, smoking, and exposure to oxidant injuries or
environmental toxins.
• For example, cigarette smoking repeatedly induces inflammatory
mediators, humoral protection (elastase and antielastase, oxidant
and antioxidant), neutrophil recruitment, and tissue repair,
culminating in inflammatory lung destruction and airway obstruction

. FEV1% = FEV1/VC X100
- This parameter is also known as the Tiffeneau
index, named after the french physician that
discovered the FEV1/VC ratio.
- Nowadays FEV1/FVC X100 is also accepted as
FEV1% (FEV1/FVC ratio)

. Peak Expiratory Flow: (PEF)
• PEF is attained within the first 150 milliseconds of the
test. The Peak Flow is a measure for the air expired
from the large upper airways (trachea-bronchi).

• Forced expiratory flow 25-
75% (FEF25-75)
– Mean forced expiratory flow
during middle half of FVC
– Measured in L/sec
– May reflect effort independent
expiration and the status of the
small airways
– Depends heavily on FVC
– Early termination artificially
increases it.

– >60% Normal
– 40-60% Mild obstruction
– 20-40% Moderate obstruction
– <10% Severe obstruction

• MVV
• It's the maximum volume of
air which can be respired in
1min. By deepest and fastest
breathing (test of entire
respiratory system).
• MVV = FEV1 x 35
• Reflects the status of the
respiratory muscles,
compliance of the thorax-
lung complex, and airway
resistance
• N- 150-175 L/min

Normal Values of PFT
 BMI  21- 25 kg/m2
 FEV1  N: 80% to 120%
 FVC  N: 80% to 120%
 FEV1 /FVC  N: >70%, within 5% of the predicted ratio
 FEF25-75%  N: >60-125%.
 PEFR  N: 80-100%.
 TLC  N: 80% to 120%
 FRC  N: 80% to 120%
 RV  N: 65% to 135%
 RV/TLC  N: 25-35%
 FRC/TLC  N: 50%
 DLCO  (N 15-32 ml/min/mmHg) >80% to < 120%
 KCo Krogh coefficient = DLCO/VA Diffusing capacity for carbon monoxide per
unit of alveolar volume

* N.B: The lower limit of normal is defined as the result
of the mean predicted value (based on the patient's
sex, age, and height) minus 1.64 times, the standard
error of the estimate from the population study on
which the reference equation is based.

Flow-Volume Loop
 Illustrates maximum expiratory
and inspiratory flow-volume
curves
 Normally:
FEF50 / FIF50 = 0.8
• Steep exp. Curve 1st
(max
effort) then linear drop
(dynamic compression of AWs)

• It's a curve representing the relation between flow rates
and volume during VC divided into maximum expiratory
(from TLC to RV, not effort dependant) and inspiratory
(from RV to TLC, effort dependant) flow volume curves.
• Measured by: patient must breathe several breaths in
tidal breathing  maximum inspiration to TLC 
maximum expiration to RV  maximum inspiration again.

Significance of Flow Volume Loop
1- Obtain data:
o FVC (from TLC to RV),
o PEFR (from zero line to maximum expiratory deflection on flow
axis),
o PIFR (-ve deflection),
o Timed FEV (if timing or computer are available)
o Maximal Flow Rates at any % volume of air.
2- Differentiate between obstructive (volume dependant airway
narrowing) & restrictive (pressure dependant airway collapse)
lesions.
3- Localizes site of obstruction
4- Detection of small airway obstruction
5- Detect poor effort and test mistakes

Detecting poor effort & Mistakes in
performing the test

Inconsistent and Consistent Curves

Significance:
A) Assessing whether the end-of-test criteria have been met,
whereas the flow-volume loop is most valuable in
evaluating the start-of-test criteria.
B) The zero time point on the volume-time tracing has been
carefully defined and extrapolated to provide a uniform
start point for measurement. It corrects for a possible
delayed start that may not actually reflect airflow
Volume-Time Tracing

Inconsistent & Consistent curves

Obstructive Disorders
 Characterized by a limitation of
expiratory airflow
• Examples: asthma, COPD
 Decreased: FEV1, FEF25-75,
FEV1/FVC ratio (<0.7)
 Increased or Normal: TLC

 Slow rise in upstroke
 May not reach plateau
* N.B: Severe obstruction FVC <
IVC No error! The open loop is
caused by airway closure at the
end of the forced expiration.
This phenomenon disappears in
part during slow exhalation


Restrictive Lung Disease
 Characterized by diminished lung
volume due to:
• change in alteration in lung
parenchyma (interstitial lung
disease)
• disease of pleura, chest wall (e.g.
scoliosis), or neuromuscular
apparatus (e.g. muscular
dystrophy)
 Decreased TLC, FVC
 Normal or increased: FEV1/FVC ratio

 Rapid upstroke as in
normal spirometry
 Plateau volume is low

Large Airway Obstruction
 Characterized by a
truncated inspiratory
or expiratory loop

Fixed Upper Airway Obstruction
 Post-intubation stenosis
 Large goiters compressing trachea
 Endotracheal neoplasms
 Stenosis of both main bronchi
 Obstruction of internal airway

Variable Extrathoracic Obstruction
 Bilateral or unilateral
vocal cord palsy
 Adhesions of vocal cord
 Vocal cord constriction
 Obstructive sleep
apnea
 Burns

Variable Intrathoracic Obstruction
 Obstruction of lower
trachea
 Obstruction of main
bronchi

*EMPEY Index:
It’s the ratio of FEV1 to PEF
Indicator for large airway obstruction
Significant value: greater than 8
The higher the index the more severe the obstruction
Used as a clinical screen in the absence of F-V Loop
for presence of UAO

Specific Situations
 Assessment of reversibility of airway obstruction
 Assessment of small airway affection
 Assessment of diaphragmatic strength by performing
upright and supine spirometry  reduction of FVC > 90%
of the upright FVC suggests weakness or paralysis (pitfall:
if pt’s BMI > 45)
 Pre-operative assessment: Postoperative FEV1 =
Preoperative FEV1 X Q% of the remaining lung.

Lung Volumes
 Measured through various methods
• Dilutional: helium, 100% oxygen
• Body plethysmography
• Nitrogen washout

Static Lung Volumes
 Total lung capacity (TLC)
• Total volume of air in the lungs at the end of an maximal
inspiration
 Residual volume (RV)
• Volume of air remaining in the lungs at the end of a
maximal expiration
 Functional residual volume (FRC)
• Volume of air remaining in the lungs at the end of tidal
expiration

Changes in Lung Volumes in Various
Disease States

Causes of Abnormal Lung
Volumes
 Reduced TLC
• Restrictive defect (intrapulmonary or extrapulmonary)
 Raised TLC
• COPD esp. emphysema
• Transiently during/recovering from asthma exacerbation
 Increased RV
• Airways disease (air-trapping)
• Respiratory muscle weakness (extrapulmonary)

 Raised FRC
• COPD incl. emphysema
 Reduced FRC
• Fibrotic lung disease (intrapulmonary)
• Obesity (extrapulmonary)

DLCo
- Defined as the rate at which gas enters into blood.
A) High affinity for Hb which is approx. 200 times that of O2 , so does not
rapidly build up in plasma
B) Under N condition it has low blood conc ≈ 0
C) Therefore, pulm conc.≈0
- Pt inspires a dilute mixture of CO and hold the breath for 10 secs.
 CO taken up is determined by infrared analysis:
DLCO = CO ml/min/mmhg
PACO – PcCO
N range 20- 30 ml/min./mmhg  80-120% of predicted

 TLCO = transfer factor for the lung for carbon monoxide i.e.
Total diffusing capacity for the lung
• Same as DLCO
 KCO = transfer coefficient i.e. Diffusing capacity of the lung
per unit volume, standardised for alveolar volume (VA)
 VA = Lung volume in which carbon monoxide diffuses into
during a single breath-hold technique
TLCO = KCO x VA

Diffusion is limited by:
• Surface area in which diffusion occurs,
• Capillary blood volume,
• Hemoglobin concentration, and
• Properties of the lung parenchyma that separate the
alveolar gas from the red blood cell with the capillary
(alveolar-capillary membrane thickness and/or the
presence of excess fluid in the alveoli)

Interpreting DLCo
Degree of severity DL,CO % predDegree of severity DL,CO % pred
 Mild >60% -80%>
 Moderate 40–60%
 Severe <40

Abnormal Diffusion Capacity
 Low TLC: Low TLCO and Low/Normal KCO =
Intrapulmonary Restrictive Defect
• Interstitial lung diseases e.g. Idiopathic pulmonary fibrosis,
sarcoidosis, CTD, HP
• Cardiac e.g. Pulmonary oedema
• Pulmonary vascular disease e.g. Pulmonary HTN (may
have normal TLCO)
 High TLC: Low TLCO + KCO
• emphysema (in the context of obstruction)

• Low TLCO but high KCO =
Extrapulmonary Restrictive Defect
– Obesity
– Respiratory muscle weakness (neuromusclar)
– Pleural disease e.g. effusion, encasement
– Skeletal e.g. Ankolysing spond., thoracoplasty, severe
kyphoscoliosis
– Severe dermatological disease e.g. Scleroderma
AND Post pneumonectomy

• Normal/raised TLCO + raised KCO
– Asthma
– Pulmonary haemorrhage e.g. vasculitis
– Supine position
– Exercise
– Obesity
– L-R shunt
– Polycythemia
– Mild Congestive HF

FEV1/VC
VC VC
Spirometry
Normal
DLCO
Normal PV
Disorder
TLC TLC
Restriction Obstruction Obstructive &
Restrictive Defects
DLCO
Chest wall or
Neuromuscular
Disorders
ILD or
Pneumonitis
DLCO DLCO
Asthma or
Chronic
Bronchitis
Emphysema Chest wall,
Neuromuscular
Disorders,
Asthma, or
Chronic
Bronchitis
ILD,
Pneumonitis,
or
Emphysema
Normal
or high Low Low Low Low
Normal
Lo
w
Low
Normal or high
Low
LowNormal
or high
Normal Low
Normal
Normal
or high
Normal
or high
Normal
or high
FEV1/VC
VC VC
Spirometry
Normal
DLCO
Normal PV
Disorder
TLC TLC
Restriction Obstruction Obstructive &
Restrictive Defects
DLCO
Chest wall or
Neuromuscular
Disorders
ILD or
Pneumonitis
DLCO DLCO
Asthma or
Chronic
Bronchitis
Emphysema Chest wall,
Neuromuscular
Disorders,
Asthma, or
Chronic
Bronchitis
ILD,
Pneumonitis,
or
Emphysema
Normal
or high Low Low Low Low
Normal
Lo
w
Low
Normal or high
Low
LowNormal
or high
Normal Low
Normal
Normal
or high
Normal
or high
Normal
or high

FEV1 VC Ratio TLC TLCO KCO
Asthma
(can be normal)
↓ ↓ ↔/
↓
↓ ↑ ↔/ ↑ ↑
COPD
(Emphysema)
↓ ↓ ↓ ↓ ↑ ↓ ↓ ↓ ↓
Intrapulmonary
Restrictive
Disease
↓ ↓↓ ↔/ ↑ ↓ ↓ ↓ ↓/ ↔
Extrapulmonary
Restrictive
Disease
↓ ↓↓ ↔/ ↑ ↓ ↓ ↑

Mixed Mainly Restrictive
(Diaphragmatic W
eakness)

Case 6:
 A 51-year-old woman
presents for evaluation
of shortness of breath,
cough, and wheezing,
especially in the
summer. Her
symptoms are relieved
with albuterol,
salmeterol, and
fluticasone inhalers.
She does not smoke.
Her spirometry values
shows.

Case 7:
 A 68-year-old woman
presents for evaluation of
shortness of breath without
cough or wheezing. She has
RA (for which she takes
prednisone and
methotrexate) and
hypertension (for which she
takes metoprolol and
hydrochlorothiazide).
 Her O2sat is 94% by pulse
oximetry while breathing
room air.
 Her Hg conc. is 12.3 g/dL.

Case 8:
 60 year old man with a 60 pack/year smoking history
and dyspnea on exertion. An arterial blood gas
demonstrates PaO2 = 56 and PaCO2 = 44.

Case 9:
 50 year old man with a 65 pack/year smoking
history and cough. His chest x-ray shows a diffuse
reticulonodular pattern.

Case 10:
36 year old man with muscular dystrophy. He is
presently wheelchair bound and an ABG demonstrates
a PaO2 = 60 and PaCO2 = 52.

Impulse Oscillometry
Methods of measurement of airway resistanceMethods of measurement of airway resistance
 Occlusion technique
 Impulse oscillometry
 Bodyplethysmography

Advantages of IOS
 Very simple to perform
 No special breathing necessary
 Minimal (no) co-operation
 Use with small children (down to 2 years)
 No forced manoeuvre necessary
 No box necessary
 Peripheral and Central Resistance separated
 Reversibility Test (decrease R > 20-25%)

Impulse Penetration
Slow Impulses 5Hz Fast Impulses 20 Hz
Resistance (R) = pressure/flow

Lung Reactance (X)
 Reactance is how the alveoli, diaphragm,
chest wall, all react to the pressure wave.
 Low reactance means there is little stretch and
recoil of the lungs

Interpretation of IOS
 R5 total airway resistance normal if
Lower than 150% of R5 predicted
 R20 proximal airway resistance normal if
Lower than 150% of R20 predicted
 X5 Distal capacitive reactance normal if
Higher than X5 predicted – 0.2 kps/l/s

Normal R & X
Peripheral AW
Obstruction
Central AW
Obstruction

Normal R & X
Restrictive Lung
Disease
Central AW
Obstruction

Tests For Cardio-Pulmonary
Interactions
 Reflects gas exchange, ventilation, tissue O2, CO2.
 QUALITATIVE-
History, examination, ABG, Stair climbing test
 QUANTITATIVE- 6 minute walk test, CPET

1) Stair Climbing Test
• If able to climb 3 flights of stairs without stopping/dyspnoea -
↓ed morbidity & mortality
• If not able to climb 2 flights – high risk
2) 6MWT or CPET:
- Gold standard
- C.P. reserve is measured by estimating max. O2 uptake
during exercise
- Modified if pt. can’t walk – bicycle/ arm exercises
- If pt. is able to walk for >2000 feet during 6 min
- VO2 max > 15 ml/kg/min
- If 1080 feet in 6 mins : VO2 of 12ml/kg/min
- Simultaneously oximetry is done & if Spo2 falls >4%- high
risk

Indications of Exercise Testing
A) Evaluate exercise intolerance or level of fitness
B) Document or diagnose exercise limitation as a result of fatigue,
dyspnea, or pain
1. Cardiovascular diseases
a. Myocardial ischemia or dyskinesia
b. Cardiomyopathy
c. Congestive heart failure
d. Peripheral vascular disease
e. Selection for heart transplantation
2. Pulmonary diseases
a. Airway obstruction (including cystic fibrosis) or hyperreactivity
b. Interstitial lung disease
c. Pulmonary vascular disease
3. Mixed cardiovascular and pulmonary etiologies
4. Unexplained dyspnea
C) Exercise evaluation for cardiac or pulmonary rehabilitation
1. Exercise desaturation/hypoxemia
2. Oxygen prescription
D) Assess preoperative risk, particularly lung resection or reduction
E) Assess disability, particularly related to occupational lung disease
F) Evaluate therapeutic interventions

Bed Side PFTs
1) Sabrasez breath holding test:
Ask the patient to take a full but not too deep breath &
hold it as long as possible.
- >25 SEC.- NORMAL Cardiopulmonary Reserve (CPR)
- 15-25 SEC- LIMITED CPR
- <15 SEC- VERY POOR CPR (Contraindication for elective
surgery)
25- 30 SEC - 3500 ml VC (normal-3100-4800ml)
20 – 25 SEC - 3000 ml VC
15 - 20 SEC - 2500 ml VC
10 - 15 SEC - 2000 ml VC
5 - 10 SEC - 1500 ml VC

2) Single breath count:
After deep breath, hold it and start counting till the next
breath.
Indicates vital capacity
N- 30-40 COUNT

3) Schneider’s Match Blowing Test:
(Measures Maximum Breathing Capacity)
Ask the patient to blow a match stick from a distance of 6”
(15 cms) with-
 Mouth wide open
 Chin rested/supported
 No purse lipping
 No head movement
 No air movement in the room
 Mouth and match at the same level

• Can not blow out a match
– MBC < 60 L/min
– FEV1 < 1.6L
• Able to blow out a match
– MBC > 60 L/min
– FEV1 > 1.6L
• MODIFIED MATCH TEST:
DISTANCE MBC (N-150-175 L/min)
9” >150 L/MIN.
6” >60 L/MIN.
3” > 40 L/MIN.

4) Cough Test: DEEP BREATH F/BY COUGH
 Ability to Cough
 Strength
 Effectiveness
-VC ~ 3 TIMES TV FOR EFFECTIVE COUGH.
A wet productive cough / self propagated paraoxysms of
coughing – patient susceptible for pulmonary Complication.
5) Wheeze Test:
Patient asked to take 5 deep breaths, then auscultated
between shoulder blades to check presence or absence of
wheeze.

6) Forced Expiratory Time:
After deep breath, exhale maximally and forcefully &
keep stethoscope over trachea & listen.
N FET – 3-5 SECS.
OBS.LUNG DIS. - > 6 SEC
RES. LUNG DIS.- < 3 SEC
7) Debono’s Whistle Blowing Test: MEASURES PEFR.
Pt blows down a wide bore tube at the end of which is a
whistle, on the side is a hole with adjustable knob.
As subject blows → whistle blows, leak hole is gradually
increased till the intensity of whistle disappears. At the last
position at which the whistle can be blown , the PEFR can
be read off the scale.

8) Wright Respirometer:
measures TV, MV
• Simple and rapid
• Can be connected to endotracheal tube
or face mask
• Prior explanation to patients needed.
• Ideally done in sitting position
• MV- instrument records for 1 min and reads directly.
• TV-calculated by dividing MV by counting Respiratory
Rate.
9) Pulse Oximetry
10) ABG.

 https://quizlet.com/8265409/pulmonary-
function-tests-spirometry-flash-cards/

Pulmonary Function Testing

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