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Spirometry: Objective Testing for Assessing Impairment

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Title: Spirometry: Objective Testing for Assessing Impairment


1
SpirometryObjective Testing forAssessing
Impairment
  • Mary Bouthiette RN, AE-C
  • Dartmouth Hitchcock Manchester
  • January 2009

2
What is Spirometry?
  • Spirometry is a pulmonary function test that
    measures the volume of air an individual inhales
    or exhales as a function of time.
  • Flow, or the rate at which volume is changing
    as a function of time, can also be measured with
    spirometry.

3
Spirometry
  • A crucial tool for the assessment of the
    impairment domain of asthma control
  • Reported patient symptoms alone may not
    necessarily reflect objective pulmonary function
  • Although a normal reading does not exclude
    asthma, spirometry provides an objective measure
    of airflow obstruction

4
Spirometry Suitable for Primary Care
  • Inexpensive and user-friendly spirometers are now
    readily available for office use
  • Modern office spirometers are portable, process
    numeric results automatically and print out a
    report
  • Spirometry ideally should take place before the
    clinician examines the patient so that results
    are available at the point of diagnosis

5
Indications for Spirometry
  • Diagnostic
  • Evaluation of symptoms, signs, or abnormal lab
    tests
  • Measure the effect of disease on pulmonary
    function
  • Screen at risk individuals
  • Assess preoperative risk
  • Assess prognosis
  • Assess health status prior to initiation of
    activity

6
Indications for Spirometry (cont.)
  • Monitoring
  • Assess therapeutic interventions
  • Describe the course of diseases affecting the
    lungs
  • Monitor for effects of occupational exposure
  • Monitor for adverse reactions to drugs with known
    pulmonary toxicity

7
Indications for Spirometry (cont.)
  • Disability/Impairment evaluations
  • Assess patients as part of a rehabilitation
    program
  • Assess risks as a part of insurance evaluation
  • Assess for legal reasons

8
Indications for Spirometry (cont.)
  • Public health
  • Epidemiologic surveys such as validation of
    subjective complaints in occupational/environmenta
    l settings

9
  • Objective Measures
  • Objective assessments of pulmonary function are
    necessary for the diagnosis of asthma because
  • Medical history and physical examination alone
    are not reliable means of excluding other
    diagnoses or of characterizing the status of lung
    impairment in the clinicians office.

10
Importance of Spirometry
  • Provides objective measure of lung function
  • Establishes airflow obstruction and reversibility
  • Assists in asthma diagnosis and treatment
  • Assists in asthma severity

11
SpirometryWhen?
  • Initial assessment and diagnosis
  • Improvement in symptoms and peak flows following
    asthma treatment
  • At least once per year

12
Spirometry Components
  • Forced Vital Capacity (FVC) - the maximal volume
    of air forcibly exhaled from the point of maximal
    inhalation
  • Forced Expiratory volume in 1 second (FEV 1) -
    the volume of air exhaled during the first second
    of the FVC
  • FEV1/FVC - ratio of FEV1 to FVC, expressed as a
    percentage
  • Peak Expiratory Flow Rate (PEFR) is the maximum
    air flow (rate) during forced exhalation

13
Spirometry Results
  • Airflow obstruction is indicated by reduced FEV1
    and FEV1 /FVC values relative to reference or
    predicted values
  • The predicted values for FVC and FEV1 for a
    patient depend on the individuals age, gender,
    height, and race
  • The numbers are presented as percentages of the
    average expected in someone of the same age,
    height, sex, and race. This is called percent
    predicted.

14
Objective Measures Spirometry
  • Is airflow obstruction present and is it at least
    partially reversible?
  • Use spirometry to establish airflow obstruction
  • FEV1 lt 80 predicted
  • FEV1/FVC below the lower limit of normal, as
    compared to the individuals own predicted value
  • Use spirometry to establish reversibility
  • FEV1 increases gt12 and at least 200 ml. after
    using a short-acting inhaled beta2-agonist
  • A 2- to 3-week trial of oral corticosteroid
    therapy may be required to demonstrate
    reversibility

15
Flow Volume Loop
  • A normal flow volume loop has a rapid peak
    expiratory flow rate with a gradual decline in
    flow back to zero.

16
  • Obstructive lung disease changes the appearance
    of the flow volume curve
  • As with a normal curve, there is a rapid peak
    expiratory flow, but the curve descends more
    quickly than normal and takes on a concave shape

17
Example of Spirometry results demonstrating
obstruction
18
(No Transcript)
19
Flow volume loop
Volume (L)
20
Reliability of Spirometry
  • Spirometry is an effort-dependent maneuver that
    requires understanding, coordination, and
    cooperation by the patient-subject, who must be
    carefully instructed
  • Technicians must be trained and must maintain a
    high level of proficiency to assure optimal
    results
  • Spirometry should be performed using equipment
    and techniques that meet standards developed by
    the American Thoracic Society

21
Reliability of Spirometry
  • Criteria for acceptability include
  • lack of artifact induced by coughing, glottic
    closure, or equipment problems (primarily leak).
  • satisfactory start to the test without
    hesitation.
  • satisfactory exhalation with six seconds of
    smooth continuous exhalation, or a reasonable
    duration of exhalation with a plateau.

22
Unacceptable Efforts
Cough
Variable Effort
23
Reliability of Spirometry
  • Correct technique, calibration methods, and
    maintenance of equipment are necessary to achieve
    consistently accurate test results
  • Maximal patient effort in performing the test is
    required to avoid important errors in diagnosis
    and management
  • Spirometry is generally valuable in children over
    age 4 however, some children cannot conduct the
    maneuver adequately until after age 7

24
The Expert Panel recommends that spirometry tests
be done
  • at the time of the initial assessment
  • after treatment is initiated and symptoms and
    peak flow have stabilized to document attainment
    of (near) normal airway function
  • at least every 1 to 2 years to assess the
    maintenance of airway function
  • Ref Expert Panel NAEPP Guidelines

25
Spirometry May be Done More Frequently
  • Depending on clinical severity, Spirometry is
    also useful
  • As a periodic check on the accuracy of the peak
    flow meter
  • When more precision is desired
  • Evaluating response to therapy
  • When Peak Flow results are unreliable

26
References
  • Clinical Guidelines for the Diagnosis, Evaluation
    and Management of Adults and Children with
    Asthma-2007
  • NAEPP Expert Panel Report-Update on Selected
    Topics 2007
  • National Heart Lung and Blood Institute
  • United States Environmental Protection Agency
  • Asthma and Allergy Foundation of America
  • Acknowledgements
  • Mary Bouthiette, RN, AE-C
  • Asthma Educator and Consultant
  • Lynn Feenan, RN, MSN, AE-C
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