Spirometry and Peak Expiratory Flow : The key measurement of lung function

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Spirometry and Peak Expiratory Flow The key
measurement of lung function

• Anakapong Phunmanee M.D.
• Associated Professor
• Division of Pulmonary Medicine
• Department of Medicine Khon Kaen University

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Basic concepts
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A Glossary of Spirometry Terminology

• FVC- forced vital capacity the total amount of
  air that can be blown out after inhaling as
  deeply as possible and then blowing out as hard
  and forcefully and long as possible. (unit is in
  liters)

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A Glossary of Spirometry Terminology

• FEV1- forced expiratory volume in one second the
  amount of air that is blown out in the first
  second of the forced vital capacity manuever.
  (unit is in liters)

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A Glossary of Spirometry Terminology

• FEFmax- forced expiratory flow maximum (also
  know as PEF peak expiratory flow or PEFR peak
  expiratory flow rate) the fastest flow that can
  be forcefully blown out. (unit is in
  liters/second although home peak flow meters
  measure this in liters/minute)

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A Glossary of Spirometry Terminology

• FEF25-75- forced expiratory flow between 25 and
  75 of the vital capacity (also known as MMEF
  maximum mid-expiratory flow) the fastest flow
  that can be forcefully blown out within the
  middle half of the forced vital capacity
  manuever. (unit is in liters/second)

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Indications

• Detect the presence or absence of lung
  dysfunction suggested by clinicals and/or
  laboratory tests
• Quantify severity of know lung disease
• Assess the change in lung function over the time
  or F/U after Tx
• Assess the potential effects or response to env.
  or occup. Exposure
• Assess the risk for surgery
• Assess impairment and/or disability

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Contraindication for Spirometry

• Hemoptysis
• Pneumothorax
• Cardiovascular instability eq. Severe
  hypertension hypotension recent MI pulmonary
  embolism
• Vascular aneurysm
• Recent surgery eq. Eye surgery abdominal surgery
• Active respiratory infection eq. Active TB
• Pregnancy (relatively)
• Severe nausea vomiting

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Complications

• Spirometry is very safe rarely seen
• Increase intracranial pressure
• Dizziness vertigo syncope
• Cough
• Bronchospasm
• Chest pain
• Pneumothorax
• Respiratory infection

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Spirometry
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Spirometry (closed technique)

• mouth piece
• 2-3 TLC
• RV
• FV
• 3
• acceptability
  reproducibility

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The use of noseclips during spirometry maneuvers

• The 1994 American Thoracic Society statement
  on standardization of spirometry encourages the
  use of noseclips.
• Noseclips should be used during the
  performance of spirometry maneuvers.
• (Am j Respir Crit Care Med Vol 152. pp 1107-1136)

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Spirometry
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Assess technique quality
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Unacceptable Curve
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Unacceptable Curve
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Unacceptable Curve
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Unacceptable Curve
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Unacceptable Curve
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Reproducibility Criteria

• Two largest FVC from acceptable maneuver not vary
  gt 200 ml
• Two largest FEV1 from acceptable maneuver not
  vary gt 200 ml

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Spirometry volume verification

• Calibration daily
• 3 L calibration syringe
• Acceptable range 2.91-3.09 L(3)

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The ability to use a program to interpret
spirometry is negated when the spirometry is
suboptimal. The conclusion could mislead. Poor
quality spirometry can however frequently
provide useful information. It should be
evaluated by a person with considerable expertise
in interpretation of pulmonary function tests.
The test may need to be reattempted.
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Program to interpret spirometry
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Peak Flow
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Peak Flow measurement

• Minimum of 3 acceptable blows
• Standing position is preferred
• Nose clip not necessary
• No cough
• Blow duration 1 to 2 seconds

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Spirometry vs Peak Flow

• Spirometry more sensitive in assessing
  progression in patient who severe compromise lung
  function (PF relatively well preserved in such
  Pt.)
• May underestimate airflow obstruction in
  children( can normal as obstruction worsen)
  ideally comparing to previous best (Brand PLet
  al.Thorax 199954103-7)

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PEF

• Lowest in the morning
• Highest at night
• Careful instruction is required
• Effort dependent

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PEF variability

• Method 1 difference between prebronchodilator
  morning and postbronchodilator evening
• Method 2 minimum morning prebronchodilator PEF
  over 1 weekexpressed as a percent of recent
  best(MinMax)

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Spirometry interpretation
FEV1/FVC
Normal or Increase
Low
Obstruction
Mixed FVC
FVC
Low
Normal
Inhaled B2 reverse
FEF25-75
Mixed
Restriction
Yes
No
Normal
Low
Small airway disease
Normal spirometry
Reversible airway obstruction
Irreversible airway obstruction
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Definite Dx TLC
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spirometry
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Flow volume curve
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Flow volume loop of obstructive Airway diseases
Severe
Mild
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Spirometry
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Male 55 years COPD

• FEV1/FVC 68
• FEF25-75 33 predicted.
• There was no reversal of obstruction after
  administration of an inhaled bronchodilator.

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Male 38 years Bronchiectasis
Reversible airway obstruction
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Male 52 years SCC
Restrictive lung disease
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UAO
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Fixed airway obstruction
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Male 42 years Dyspnea 2 months

• FEV1/FVC 87.6 (115pred)
• FEV1 3.11 L(84pred)
• FVC 3.55 L(76pred)

1. Leak FVC 2. Not fully inspired
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Male 55 years Dyspnea 6 months
Irreversible airway obstruction
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Male 67 years Dyspnea 5 months
Irreversible airway obstruction