Clinical Application of
Pulmonary Function Tests
Sevda Özdoğan MD, Prof.
Chest Diseases
Pulmonary Function Tests
• Spirometry (SVC)
A physiological test that
• Flow Volume Curve
measures how an individual
inhales or exales volumes of air
• MVV
as a function of time
a) Volume
• Diffusion test
b) Flow
• Reversibility and Provocation tests
• Exercise tests
– 6 minutes walking test
– Cardiopulmonary exercise tests
İndications for PFT
• Diagnostic
– To evaluate dispnea!!
– To assess the etiology of dyspnea
(cardiac/pulmonary)
– To measure the effect of the disease on
pulmonary function
– To assess any airway obstruction, the severity
of the obstruction and response to
bronchodilators
– To assess prognosis
–
–
–
–
–
To assess preoperative risk
To assess etiology of chronic cough
To assess respiratory muscle strenght
To measure gas diffusion
To monitor for adverse reactions to drugs
with known pulmonary toxicity
– Disability/impairment evaluations
– Epidemiological or clinical survey
Definitions
• Static Lung Volumes:
– Tidal Volume (TV): The volume of gas inhaled and
exhaled during a respiratory cycle (resting)
– Expiratory Reserve Volume (ERV): Maximum volume
of gas that can be exhaled from the end expiratory
level during tidal breathing
– Inspiratory Reserve Volume (IRV): Maximum volume
of gas that can be inhaled from the end inspiratory
level during tidal breathing
– Total Lung Capacity (TLC): The volume of gas in
lungs after maximal inspiration (Sum of all
compartments)
– Vital capacity (VC): Maximal volume of air
exhaled from a position of full inspiration
– Residuel Volume (RV): The volume of gas
remains in the lung after maximal exhalation
– Functional Residuel Capacity (FRC): The
volume of gas present in the lung at end
expiration during tidal breathing
• Static lung volumes can be measured by:
– Spirometry (SVC maneuver)
– Body pletismography
PxV=k
– Washout Techniques
• Nitrogen Washout:
Based on washing out the N2 from the
lungs when the patient breathes 100% O2
– Multipl breath
Body pletismography
•Helium dilution:
Based on the
equlibration of gas in
the
lung with a
known
Volume of gas
containing
helium
Slow vital capacity
• After 2-3 normal breathing (TV)
• Make a slow maksimum inspiration (TLC)
• Then make a slow maksimum expiration
(VC)
• Static Lung volumes are decreased in
– Restrictive lung diseases
– Atelectasis
– Lobectomy, pneumonectomy
– Chest wall deformities
– Diaphragmatic paralysis
– Neurologic pathologies
– Hiatus hernia
(Normal values are calculated according to the patients
age, height, weight)
• Dynamic Lung Volumes (Flow volume
Curve)
– Forced Vital Capacity (FVC): is the maximal
volume of air exhaled with maximaly forced
effort from a maximal inspiration.
– Forced Expiratory Volume 1 (FEV1): the
maximal volume of air exhaled in the first
second of forced expiration from a position of
full inspiration
• Peak expiratory flow (PEF): The maximum
flow rate reached during a forced
expiration
• FEF 25-75%: Average
expiratory flow over
the middle half of FVC
(MMEF)
Decreases in small airway obstructions
• Maximum Voluntary Ventilation (MVV):
A dynamic test in which the patient
breaths rapidly and deeply for 10-15
seconds. The total volume (inhaled and
exhaled) is calculated and expressed as
L/min)
Decreases in obstructive and restrictive diseases as well as
neuromuscular diseases
• Dynamic lung volumes and flow rates are
decreased in:
– Obstructive lung diseases (COPD, Asthma)
• İnpiratory parameters are also important
especially in upper airway pathologies
– MIF; IC; FIV1
FEV1
Obstructive
Restrictive
FVC
FEV1/F
VC
FEF2575
N or
N or
N
N
FEV1/FVC
Yes
No
FVC
FVC
Yes
Combined
Further
examination
No
Obstructive
Yes
Restrictive
Reversibility?
Yes
Asthma
No
COPD
No
Normal
Staging in pulmonary function
abnormalities
%
FVC
Normal >80
Mild
FEV 1
80
FEV1/F DLCO
VC
75
80
=79-60 79-60
74-60
79-60
Medium =59-51 59-51
59-41
59-41
Severe <50
40
40
40
Reversibility
• Assessment of postbronchodilator
response in obstructive pathologies
• Spirometry is repeated 15-20 minutes after
the administration of an inhaled short
acting bronchodilator. An 12-15% increase
in FEV1 or an absolute value of 200 ml
increase represents a significant positive
reversibility test.
Bronchoprovocation test
(Challenge)
• Performed in patients who have suspected
reactive airway disease with normal
spirometry.
• Can be performed by
–
–
–
–
Methacoline
Most frequently
Histamine
Cold air inhalation?
Exercise
• Methacoline responsiveness:
• Starting with a single inhalation at a very
low concentration, patients are tested each
time after progresively increasing inhaled
doses until
– Either a predetermined maximum dose (16
mg/ml) has been achieved
– Or FEV1 has been observed to fall by 20%
CO Diffusion test
• The capacity of the lung to exchange gas
across the alveolocapillary interface is
determined by DLCO
• This process is a passive diffusion and is a
function of
– Pressure difference
– Surface area
– Resistive properties of the membrane
• CO gas is used as the test gas because of
its high affinity to hb
Single breath method
Staging in pulmonary function
abnormalities
%
FVC
Normal >80
Mild
FEV 1
80
FEV1/F DLCO
VC
75
80
=79-60 79-60
74-60
79-60
Medium =59-51 59-51
59-41
59-41
Severe <50
40
40
40
Cardiopulmonary Exercise Testing
• To assess a patients exercise capacity
objectively
• To observe the response of the
components of oxygen delivery system to
this stress
• To determine the factors that limit exercise
capacity or cause exertional dyspnea
• Performed on
– Treadmill with increasing speeds and slope
– Bicycle pedaled at a constant rate with a
variable resistance
• Load is increased in a continious ramp or
at intervals
• ECG, Pulse oxymeter, respiratory rate, Vt,
minute ventilation and blood gases are
monitored
Parameters measured
• Oxygen consumption (VO2max)
• Heart rate
• Oxygen pulse
• Blood pressure
• Ventilation (VEmax)
• Anaerobic treshold
• Arterial blood gases
End