Basics of Pulmonary Function test

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Spirometry
Shams Ali Shah Respiratory Technician PSCCQ
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Spirometry

• is the measurement of air flow into and out of
  the lungs

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Purpose

• How much of air volume can be moved in and out of
  the lungs (static lung volumes)
• How fast the air in the lungs can be moved in and
  out (dynamic volumes)
• How stiff are the lungs and chest wall
• (compliance )
• The gas diffusion (transfer factor )
• How the lungs respond to chest physical therapy
  procedures .

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Description

• The nose is pinched off as the during breathing
  through a mouthpiece attached to the spirometer.
  The patient is instructed on how to breathe
  during the procedure.
• Three breathing maneuvers are practiced before
  recording the procedure, and the highest of three
  trials is used for evaluation of breathing.
• This procedure measures air flow by electronic or
  mechanical displacement principles, and uses a
  microprocessor and recorder to calculate and plot
  air flow.

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Factors which have an impact on the PFT

• GENDER
• AGE
• BODY WEIGHTSIZE
• RACE
• OTHERS

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Measurements

• Height - Tall people have larger lungs
• Age - Respiratory function declines with age
• Sex - Lung volumes smaller in females
• Race - Studies show Blacks and Asians have
  smaller lung volumes (-12)
• Posture - Little difference between sitting and
  standing reduced in supine position

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Measurements
TV Tidal Volume
VC Vital Capacity
FEV1 Forced expired volume in 1 second
FVC Forced vital capacity
FEV1 /FVC Ratio Ratio of the above
PEFR Peak expiratory flow rate
FEF 25-75 Forced expiratory flow between 25-75 of the vital capacity
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Lung Volumes

• 4 Volumes
• 4 Capacities
• Sum of 2 or more lung volumes

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV
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Tidal Volume (TV)

• Volume of air inspired and expired during
  normal quiet breathing

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV
Tidal volume (T.V) is the volume of air moved
with each breath during normal breathing.
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Inspiratory Reserve Volume (IRV)

• The maximum amount of air that can be
  inhaled after a normal tidal volume inspiration

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV
Inspiratory reserve volume (IRV) is the
maximal volume of air that can be inhaled at the
end of a quiet inhalation.
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Inspiratory Capacity (IC)

• Maximum amount of air that can be inhaled from
  the end of a tidal volume
• IC IRV TV

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV
Inspiratory capacity (IC) is the volume of air
that can be inspired from normal expiration ( TV
IRV).
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Expiratory Reserve Volume (ERV)

• Maximum amount of air that can
  be exhaled from the resting
  expiratory level.

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV
Expiratory reserve volume (ERV) is the
maximal volume of air that can be exhaled at the
end of quiet exhalation.
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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

IRV
IC
VC
TLC
TV
FRC
ERV
RV
RV

• Vital capacity (VC) is the maximal volume of
  air that can be exhaled after a maximal
  inhalation.

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Vital capacity (VC)

• This is the amount of air (in liters) moved out
  of the lung during normal breathing. The patient
  is instructed to breathe in and out normally to
  attain full expiration. Vital capacity is usually
  about 80 of the total lung capacity. Because of
  the elastic nature of the lungs and surrounding
  thorax, a small volume of air will remain in the
  lungs after full exhalation. This volume is
  called the residual volume (RV).

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Residual Volume (RV)

• Volume of air remaining in
  the lungs at the end
  of maximum expiration

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV
Residual volume (RV) is the volume of air
remaining in the lungs after a maximal
exhalation.
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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

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV

• Functional residual capacity (FRC) is the
  volume of air in the lungs at the end of a
  quiet exhalation.

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Total Lung Capacity (TLC)

• Volume of air in the lungs after a maximum
  inspiration .
• TLC IRV TV ERV RV

IRV
IC
VC
TLC
TV
ERV
FRC
RV
RV

• Total lung capacity (TLC) is the volume of
  air in the lungs at the end of a
  maximal inspiration.
• 
  

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Values of Spirometry (Average )
Female Male Spirometry
500 ml 600 ml TV
1.9L 3 L IRV
800 ml 1.2L ERV
1000 ml 1.2L RV
3.2L 4.8L FVC
2.4L 3.6L IC
1.8L 2.4L FRC

Reference 1. MILLER A , PFT in
Occupational disease 1996 2. Wasserman K
at.al(1999)principle of exercise
testing 3. McARDLE W.D et al(2000)Essential for
exercise Physiology)
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Measurements

• Bronchodilator reversibility testing
• Beta-agonist
• Short-acting wait 20 minutes before retesting
• Long-acting wait 2 hours before retesting
• Do not take bronchodilator the day of testing
• Measured reversibility will be limited if the
  patient is bronchodilator for the pretest.

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Precautions

• hemoptysis (spitting up blood from the lungs or
  bronchial tubes)
• pneumothorax (free air or gas in the pleural
  cavity)
• recent heart attack
• unstable angina
• aneurysm (cranial, thoracic, or abdominal)
• thrombotic condition (such as clotting within a
  blood vessel)
• recent thoracic or abdominal surgery
• nausea or vomiting

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(Forced vital capacity (FVC

• After breathing out normally to full expiration,
  the patient is instructed to breathe in with a
  maximal effort and then exhale as forcefully and
  rapidly as possible. The FVC is the volume of air
  that is expelled into the spirometer following a
  maximum inhalation effort.

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Forced expiratory volume (FEV

• At the start of the FVC maneuver, the spirometer
  measures the volume of air delivered through the
  mouthpiece at timed intervals of 0.5, 1.0, 2.0,
  and 3.0 seconds. The sum of these measurements
  normally constitutes about 97 of the FVC
  measurement. The most commonly used FEV
  measurement is FEV-1, which is the volume of air
  exhaled into the mouthpiece in one second. The
  FEV-1 should be at least 70 of the FVC.

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Forced expiratory flow 2575 (FEF 2575).

• This is a calculation of the average flow rate
  over the center portion of the forced expiratory
  volume recording.
• It is determined from the time in seconds at
  which 25 and 75 of the vital capacity is
  reached.
• The volume of air exhaled in liters per second
  between these two times is the FEF 2575. This
  value reflects the status of the medium and small
  sized airways.

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Maximal voluntary ventilation (MVV).

• This maneuver involves the patient breathing as
  deeply and as rapidly as possible for 15 seconds.
  The average air flow (liters per second)
  indicates the strength and endurance of the
  respiratory muscles.

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• Normal values for FVC, FEV, FEF, and MVV are
  dependent on the patient's age, gender, and
  height.

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Preparation

• The patient's age, gender, and race are recorded,
  and height and weight are measured before the
  procedure begins.
• The patient should not have eaten heavily within
  three hours of the test. He or she should be
  instructed to wear loose-fitting clothing over
  the chest and abdominal area.
• The respiratory therapist or other testing
  personnel should explain and demonstrate the
  breathing maneuvers to the patient.
• The patient should practice breathing into the
  mouthpiece until he or she is able to duplicate
  the maneuvers successfully on two consecutive
  attempts

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Technique

• Forced expiratory maneuver
• Coach patient to get a maximal effort
• Six seconds of effort required though most of air
  pushed out in the first second
• Pace of expired air is most important variable
  therefore it should be released with explosive
  force

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Normal results

• FEV-0.550-60 of FVC
• FEV-175-85 of FVC
• FEV-295 of FVC
• FEV-397 of FVC

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Quality Spirometry

• Know technique
• Have staff coach the patient
• Do sufficient numbers of tests
• Maintain and calibrate the equipment
• Understand interpretative algorithms

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None of the following should occur

• Unsatisfactory start, with excessive hesitation
  or false start
• Air leak
• Coughing during the first second
• Early termination of forced expiration
• Glottis closure
• Obstructed mouthpiece
• Tongue
• False teeth
• Chewing gum

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Barriers

• Inaccessibility of Equipment
• Concern patient effort and cooperation are
  insufficient
• Difficulty remembering interpretive algorithm
• Frustration by ambiguous results
• Difficulty working 30-minute spirometry into
  office flow
• Central location for spirometry versus going room
  to room
• Lack of staff training
• Poor integration with electronic health record
• Lack of adequate reimbursement

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Case Study 1

• A 53-year-old white male presents for annual
  visit. Although he quit 10 years ago he is a
  previous cigarette smoker with a 20 pack-year
  history. During the past 12 months, he has had 3
  episodes of bronchitis. His history of tobacco
  use and recent episodes of acute bronchitis lead
  you to perform spirometry.

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Results
Spirometry Pre-Bronchodilator Pre-Bronchodilator Pre-Bronchodilator Post-Bronchodilator Post-Bronchodilator Post-Bronchodilator
Spirometry Predicted Measured Measured change
FVC 4.65 4.65 100 4.95 106 6
FEV1 3.75 3.13 83 3.34 89 6
FEV1/FVC 80 67 -13 67 -13 0
PEF 511 462 90 522 102 12
FEF 25 7.86 5.7 73 6.00 76 5
FEF 50 4.46 2.3 52 2.10 47 -9
FEF 75 1.75 .5 29 0.60 35 18
FEF 25-75 3.76 1.77 47 1.78 47 0
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Results
Pre-Bronchodilator Pre-Bronchodilator Post-Bronchodilator Post-Bronchodilator
Predicted Measured Measured change
FVC 4.65 4.65 100 4.95 106 6
FEV1 3.75 3.13 83 3.34 89 6
FEV1/FVC 80 67 -13 67 -13 0
Is there obstruction? FEV1/FVC 67 of
predicted therefore, obstruction present Is
there restriction? FVC 100 of predicted
therefore, no restriction present
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Results
Pre-Bronchodilator Pre-Bronchodilator Post-Bronchodilator Post-Bronchodilator
Predicted Measured Measured change
FVC 4.65 4.65 100 4.95 106 6
FEV1 3.75 3.13 83 3.34 89 6
FEV1/FVC 80 67 -13 67 -13 0
What is the severity of obstruction? FEV1 is
83 of predicted therefore, the obstruction is
mild Is the obstruction reversible (is
reversibility present)? FEV1 increases from 83
to 89 (6 increase) and increases from 3,130 cc
to 3,340 cc (increase of 210 cc) Interpretation
Mild Obstruction with minimal reversibility
Mild COPD
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Diagnostic Flow Diagram for Obstruction
Is FEV1 / FVC Ratio Low? (lt70)
Yes
Obstructive Defect
Is FVC Low? (lt80 pred)
No
Yes
Combined Obstruction Restriction /or
Hyperinflation
Pure Obstruction
Reversible Obstruction with ß-agonist
Improved FVC with ß-agonist
No
Yes
No
Yes
Further Testing with Full PFTs
Suspect Asthma
Suspect COPD
Adapted from Lowry.
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Case Study 2

• A 33 year old female presents to the office
  complaining of dyspnea and cough for the past 2
  days. Her cough is productive of a white mucous.
  
• Her past medical history is significant for
  asthma since childhood, obesity, gastroesophageal
  reflux disease (GERD), and an occasional migraine
  headache. She is a nonsmoker and has no known
  allergies.

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Case Study 2 (cont)

• Her current medications include the following
• Albuterol 2 puffs po qid prn wheezing, cough, or
  dyspnea
• Fluticasone 110 micrograms 2 puffs po bid
• Ranitidine 150 mg po bid
• Her father recently died secondary to advanced
  COPD.
• Due to her symptoms, you order spirometry.

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Results
Spirometry Pre-Bronchodilator Pre-Bronchodilator Pre-Bronchodilator Post-Bronchodilator Post-Bronchodilator Post-Bronchodilator
Predicted Measured Measured change
FVC 3.78 1.92 51 2.7 71 34
FEV1 3.24 1.11 34 1.61 50 36
FEV1/ FVC 86 58 -28 60 -26 3
Obstruction? FEV1/FVC 60 therefore,
obstruction present Restriction? FVC 51 of
predicted therefore, restriction present
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Results
Spirometry Pre-Bronchodilator Pre-Bronchodilator Pre-Bronchodilator Post-Bronchodilator Post-Bronchodilator Post-Bronchodilator
Predicted Measured Measured change
FVC 3.78 1.92 51 2.7 71 34
FEV1 3.24 1.11 34 1.61 50 36
FEV1/ FVC 86 58 -28 60 -26 3
What is the severity of obstruction? 60
therefore, moderate obstruction Is the
obstruction reversible (is reversibility
present)? FEV1 increases from 34 to 50 (16
increase) and increases by 500 cc What is the
severity of restriction? 71 of predicted
therefore, mild restriction Interpretation
Moderate obstruction with reversibility (Moderate
obstruction)
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Diagnostic Flow Diagram for Restriction
Is FEV1 / FVC Ratio Low? (lt70)
No
Is FVC Low?(lt80 pred)
No
Yes
Restrictive Defect
Normal Spirometry
Further Testing with Full PFTs consider
referral if moderate to severe
Adapted from Lowry, 1998
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References
Blonshine, S. and J.B. Fink. "Spirometry Asthma
and COPD Guidelines Creating Opportunities for
RTs." AARC Times (January 2000)
43-7. organizations National Lung Health
Education Program (NLHEP). 1850 High Street,
Denver, CO 80218. lthttp//www.nlhep.orggt.
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SHUKRANSHAMS ALI SHAH RT PSCCQ