Dr. Alireza Safaiyan
Occupational medicine specialist
PFT Pulmonary Function Testing
PFTs can include :
1) Simple screening spirometry
2) Formal lung volume measurement
3) Diffusing capacity for carbon monoxide
4) Arterial blood gases
5) Inhalation challenge tests
6) Exercise stress tests
Total lung capacity (TLC)
FRC is usually measured by:
1) gas dilution technique or
2) body plethysmography
Gas dilution technique
 Helium dilution
 Nitrogen-washout
techniques:
technique:
based on the inhalation of a
known concentration and volume
of an inert tracer gas, such as
helium, followed by equilibration
of 7 to 10 minutes in the closedcircuit helium dilution technique.
The final exhaled helium
concentration is diluted in
proportion to the unknown
volume of air in the patient's
chest (residual volume).
the patient breathes 100%
oxygen, and all the nitrogen in
the lungs is washed out. The
exhaled volume and the
nitrogen concentration in that
volume are measured. The
difference in nitrogen volume
at the initial concentration and
at the final exhaled
concentration allows a
calculation of intrathoracic
volume, usually FRC.
Gas dilution technique
 A limitation of this technique is that it does not
measure air in noncommunicating bullae, and
therefore it can underestimate total lung capacity,
especially in patients with severe emphysema.
Body plethysmography

principle of Boyle's
law, which states that
the volume of gas at a
constant temperature
varies inversely with
the pressure applied to
it

can measure the total
volume of air in the chest,
including gas trapped in
bullae.
can be performed quickly

DLCO Diffusing capacity of the lung for carbon monoxide
 the single-breath breath-holding





technique
a subject inhales a known volume of test
gas that usually contains 10% helium,
0.3% carbon monoxide, 21% oxygen, and
the remainder nitrogen.
holds his or her breath for 10 seconds.
exhales to wash out a conservative
overestimate of mechanical and anatomic
dead space.
an alveolar sample is collected.
DLCO is calculated from the total volume
of the lung, breath-hold time, and the
initial and final alveolar concentrations of
carbon monoxide
Hemoglobin concentration is a very
important measurement in interpreting
reductions in DLCO
Obstructive Lung Diseases
Cystic fibrosis
Emphysema
Parenchymal Lung Disease
Drug reactions (e.g., amiodarone, bleomycin)
Idiopathic
Interstitial lung disease
Lung disease caused by fibrogenic dusts (e.g., asbestosis)
Lung disease caused by biologic dusts (e.g., allergic
alveolitis)
Sarcoidosis
Pulmonary Involvement in Systemic Diseases
Dermatomyositis-polymyositis
Inflammatory bowel disease
Mixed connective tissue disease
Progressive systemic sclerosis
Rheumatoid arthritis
Systemic lupus erythematosus
Wegener's granulomatosis
Cardiovascular Diseases
Acute and recurrent pulmonary thromboembolism
Acute myocardial infarction
Fat embolization
Mitral stenosis
Primary pulmonary hypertension
Pulmonary edema
Other
Acute and chronic ethanol ingestion
Bronchiolitis obliterans with organizing pneumonia
(BOOP)
Chronic hemodialysis
Chronic renal failure
Ciagarette smoking
Cocaine freebasing
Diseases associated with anemia
Marijuana smoking
Increases In DLCO
Diseases associated with increased pulmonary blood
flow (e.g., left-to-right intracardiac shunts)
Diseases associated with polycythemia
Exercise
Pulmonary hemorrhage
Exhaled Nitric Oxide
 The measurement of exhaled nitric oxide as a
reflection of airway inflammation is gaining rapid
acceptance as a pulmonary function test
Inhalation challenge tests
(Bronchoprovocation)
 To define nonspecific airway hyperreactivity
 Methacholine and histamine are the agents most often used
with this procedure inhaled through a nebulizer, although
other agents may also be useful.
 a five-stage procedure with five different increasing
concentrations.(0.0625 – 16 mg/ml) After each stage, the
patient performs a spirometry.
 a 20% reduction in the FEV1 (PC20FEV1 ) is significant.
 In rare cases, a bronchospasm can occur with inhalation
challenge testing.
Exercise stress tests
 Exercise stress tests evaluate the effect of exercise
on lung function tests. Spirometry readings are done
after exercise and then again at rest.
 Six-minute walk test
Definition of spirometry
 A physiological test for measuring volumes inhaled or
exhaled by an individual as a function of time
 A non-invasive method of evaluation of pulmonary
function
 Not for definitive diagnosis
 Simple, cost effectiveness, accessible
 Needs patient cooperation
Indication
 Not a screening test for general population
 Diagnostic
 Monitoring
 Impairment evaluation
 Public health
Diagnostic
To evaluate symptoms
 Chest pain
 Cough
 Dyspnea
 Orthopnea
 Phlegm production
To evaluate signs
 Wheezing
 Chest deformity
 Cyanosis
 Diminished breath sounds
 Expiratory slowing
 Overinflation
 Unexplained crackles
To evaluate abnormal laboratory tests
 Abnormal chest radiographs
 Hypercapnia
 Hypoxemia
 Polycythemia
To measure the effect of disease on
pulmonary function
To screen persons at risk for pulmonary
diseases
 Smokers
 Persons in occupations with exposures to
injurious substances
Some routine physical examinations
 To assess preoperative risk
 To assess prognosis (lung transplant,
etc.)
 To assess health status before enrollment
in strenuous physical activity programs
Monitoring
To assess therapeutic interventions
 Bronchodilator therapy
 Steroid treatment for asthma, interstitial lung disease, etc.
 Management of congestive heart failure
 Other (antibiotics in cystic fibrosis, etc.)
To describe the course of diseases affecting lung function
 Pulmonary diseases
 Obstructive small airway diseases
 Interstitial lung diseases
 Cardiac diseases
 Congestive heart failure
 Neuromuscular diseases
 Guillain-Barré syndrome
 To monitor persons in occupations with exposure to injurious agents
To monitor for adverse reactions to drugs with known pulmonary toxicity
Evaluation of Disability or Impairment
To assess patients as part of a rehabilitation program
 Medical
 Industrial
 Vocational
To assess risks as part of an insurance evaluation
To assess persons for legal reasons
 Social Security or other government compensation
programs
 Personal injury lawsuits
 Other
Public Health
 Epidemiologic surveys
 Comparison of health status of populations living in
different environments
 Validation of subjective complaints in occupational or
environmental settings
 Derivation of reference equations
Indications in occupational medicine
 Primary prevention (Pre-employment)
 physical demands of a job require a certain level of
cardiopulmonary fitness, eg, heavy manual labor or
firefighting
 Respirator use can impose a significant burden on the
cardiopulmonary systems, eg, use of a self-contained
breathing apparatus, or prolonged use of certain negativepressure masks under conditions of heavy physical exertion
and/or heat stress
 Research (Respiratory hazards)
 Secondary prevention
Medical surveillance programs & periodic evaluation
OSHA :
asbestos, cadmium, coke oven emissions, or cotton dust
respirator-wearers exposed to benzene, formaldehyde
methylene chloride
Silicosis
 Tertiary prevention
 Follow-up spirometry
 Workers’ compensation setting
Contraindications
 Active hemoptysis
 Pneumothorax
 Unstable Cardiovascular status (6 w)
 Cerebral/Thoracic/Abdominal aneurysm
 Recent eye surgery
 Acute disorder that may interfere with
performance (e.g, vomiting)
 Thoracic or abdominal surgery( 3 w)
 Recent CVA or pulmonary emboli
 Respiratory distress
Confounding factors
 Common cold (previous 3 days)
 Severe respiratory infection (previous 3w)
 Smoking( 1hr)
 Heavy food (1hr)
 Bronchodilator use
Complications
 Chest pain
 Syncope, dizziness
 Increased ICP
 Paroxysmal coughing
 Nosocomial infection
 Bronchospasm
Type of spirometer
Flow-type spirometer
Volumetric spirometer
Hygiene & infection control
 Hand washing
 Gloves
 Disposable mouth piece & nose clip
 Disinfection or sterilization of reusable mouth piece
 Extra precautions for patient with known transmissible
infection
Normality and predicted equations
 lung function, such as FEV1 or FVC, are affected most
significantly by standing height, age, gender, race, and, to
a lesser extent, weight
 These reference standards are based on a cohort of normal
subjects of similar age, height, and race,
with normal being defined as persons without a history of
smoking or disease that can affect lung function.
Reference values
 Knudson (male/ female)
 National Health and Nutrition Examination Survey




(NHANES III)
ERS (ECCS)
ATS
Golshan
ITS
Spirometric values
FVC—Forced vital capacity; the total volume of air that can be exhaled during a maximal forced
expiration effort.
FEV1—Forced expiratory volume in one second; the volume of air exhaled in the first second under
force after a maximal inhalation.
FEV1/ FVC ratio—The percentage of the FVC expired in one second.
FEV6 —Forced expiratory volume in six seconds.
FEF25–75%—Forced expiratory flow over the middle one half of the FVC; the average flow from the
point at which 25 percent of the FVC has been exhaled to the point at which 75 percent of the FVC
has been exhaled.
MVV—Maximal voluntary ventilation. This measures the greatest amount of air you can breathe in and
out during one minute.
Lung volumes
ERV—Expiratory reserve volume; the maximal volume of air exhaled from end-expiration.
IRV—Inspiratory reserve volume; the maximal volume of air inhaled from end-inspiration.
RV—Residual volume; the volume of air remaining in the lungs after a maximal exhalation.
VT —Tidal volume; the volume of air inhaled or exhaled during each respiratory cycle.
Lung capacities
FRC—Functional residual capacity; the volume of air in the lungs at resting end-expiration.
IC—Inspiratory capacity; the maximal volume of air that can be inhaled from the resting expiratory
level.
TLC—Total lung capacity; the volume of air in the lungs at maximal inflation.
VC—Vital capacity; the largest volume measured on complete exhalation after full inspiration.
Spirometry steps
Equipment performance criteria
Equipment validation
Quality control
Subject maneuvers
Measurements procedures
Acceptability
Repeatability
interpretation
‫کاليبراسيون دستگاه‬
‫‪ ‬کاليبراسيون روزانه يا هر ‪ 4‬ساعت در موارد شلوغ‬
‫‪ ‬سرنگ مخصوص کاليبراسيون(‪ 1‬ليتري يا ‪ 3‬ليتري)‬
‫‪ ‬خطاي پذيرفته شده ‪ %3‬يا ‪ 90‬سي سي است(‪)3/09-2/91‬‬
Subject maneuvers

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FVC maneuver

Closed circuit

Open circuit
Well-fitting false teeth → yes or no
Sitting or standing
Nose clip
Procedure
1. Inhale compete
2. Exhale:
with minimal hesitation
“blast” not just “blow”
“keep going”
maneuver evaluation
 Start of test criteria
- Extrapolation volume (EV < 5% of FVC or 150 ml)
-Time-to-PEF < 0.120 s
 End of test criteria
- the subject cannot or should not continue
- exhalation at least 6s (in children <10 yrs: at least 3s)
- volume-time curve show no change in volume (<0.025 lit)
for at least 1s
 In obstruction or older subjects more than 6s exhalation
(till 15s)
Acceptability
 Start of test criteria
 End of test criteria
 Cough especially during first second
 Valsalva maneuver (glottis closure)
 Leak from the mouth
 Obstruction of the mouthpiece
 Extra breath during the maneuver
 At the most eight tests should be performed
Reproducibility
 At least three acceptable maneuvers
Maximum difference between the largest and next
largest FVC and FEV1 = 150ml or 5%
(If FVC <1lit, this value is 100ml)
Flow chart of criteria
Perform FVC
Acceptability criteria
3 acceptable maneuvers
Repeatability criteria
Largest FVC and largest FEV1
Maneuver with largest FVC + FEV1 for other indices
The most common technical errors
FVC
FEV1
FEV1/FVC
FEF25-75
Actual
4.0
2.4
60
2.2
Predicted
4.5
4.2
82
4.4
% Predicted
88
58
76
50
Common Restrictive and
Obstructive Lung Diseases
Common Obstructive Lung
Diseases
 Asthma
 Asthmatic bronchitis
 Chronic obstructive
bronchitis
 Chronic obstructive
pulmonary disease (includes
asthmatic bronchitis, chronic
bronchitis, emphysema, and
the overlap between them)
 Cystic fibrosis
 Emphysema
Common Restrictive Lung
Diseases
 Beryllium disease
 Congestive heart failure
 Idiopathic pulmonary fibrosis
 Infectious inflammation
(e.g., histoplasmosis,
mycobacterium infection)
 Interstitial pneumonitis
 Neuromuscular diseases
 Sarcoidosis
 Thoracic deformities