Title: Spirometry and Peak Expiratory Flow : The key measurement of lung function
1 Spirometry and Peak Expiratory Flow The key measurement of lung function
Anakapong Phunmanee M.D.
Division of Pulmonary Medicine
Department of Medicine Khon Kaen University
2 Basic concepts Back to the TOP 3 (No Transcript) 4 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)
5 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)
6 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)
7 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)
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
Back to the TOP 9 Contraindication for Spirometry
Cardiovascular instability eq. Severe hypertension hypotension recent MI pulmonary embolism
Recent surgery eq. Eye surgery abdominal surgery
Active respiratory infection eq. Active TB
Severe nausea vomiting
Spirometry is very safe rarely seen
Increase intracranial pressure
Dizziness vertigo syncope
11 Spirometry Back to the TOP 12 Spirometry (closed technique)
13 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)
14 Spirometry 15 Assess technique quality Back to the TOP 16 (No Transcript) 17 (No Transcript) 18 (No Transcript) 19 (No Transcript) 20 (No Transcript) 21 (No Transcript) 22 Unacceptable Curve 23 Unacceptable Curve 24 Unacceptable Curve 25 Unacceptable Curve 26 Unacceptable Curve 27 Reproducibility Criteria
Two largest FVC from acceptable maneuver not vary gt 200 ml
Two largest FEV1 from acceptable maneuver not vary gt 200 ml
28 Spirometry volume verification
3 L calibration syringe
Acceptable range 2.91-3.09 L(3)
29 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. 30 Program to interpret spirometry 31 Peak Flow Back to the TOP 32 Peak Flow measurement
Minimum of 3 acceptable blows
Standing position is preferred
Nose clip not necessary
Blow duration 1 to 2 seconds
33 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)
Lowest in the morning
Highest at night
Careful instruction is required
35 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)
36 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 GO TOP Definite Dx TLC 37 spirometry 38 Flow volume curve 39 Flow volume loop of obstructive Airway diseases Severe Mild 40 Spirometry Back to the TOP 41 Male 55 years COPD
FEF25-75 33 predicted.
There was no reversal of obstruction after administration of an inhaled bronchodilator.
42 Male 38 years Bronchiectasis Reversible airway obstruction 43 Male 52 years SCC Restrictive lung disease 44 UAO 45 Fixed airway obstruction 46 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 47 Male 55 years Dyspnea 6 months Irreversible airway obstruction 48 Male 67 years Dyspnea 5 months Irreversible airway obstruction
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