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Spirometry in Primary Care

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  1. Spirometry in Primary Care Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2010

  2. Spirometry - Introduction • Spirometry is the gold standard for COPD diagnosis • Underuse leads to inaccurate COPD diagnosis • Widespread uptake has been limited by: • Concerns over technical performance of operators • Difficulty with interpretation of results • Lack of approved local training courses • Lack of evidence showing clear benefit when spirometry is incorporated into management

  3. What is Spirometry? Spirometry is a method of assessing lung function by measuring the total volume of air the patient can expel from the lungs after a maximal inhalation.

  4. Why Perform Spirometry? • Measure airflow obstruction to help make a definitive diagnosis of COPD • Confirm presence of airway obstruction • Assess severity of airflow obstruction in COPD • Detect airflow obstruction in smokers who may have few or no symptoms • Monitor disease progression in COPD • Assess one aspect of response to therapy • Assessprognosis (FEV1) in COPD • Perform pre-operative assessment

  5. Spirometry – Additional Uses • Make a diagnosis and assess severity in a range of other respiratory conditions • Distinguish between obstruction and restriction as causes of breathlessness • Screen workforces in occupational environments • Assess fitness to dive • Perform pre-employment screening in certain professions

  6. Types of Spirometers • Bellows spirometers: Measure volume; mainly in lung function units • Electronic desk top spirometers: Measure flow and volume with real time display • Small hand-held spirometers: Inexpensive and quick to use but no print out

  7. Volume Measuring Spirometer

  8. Flow Measuring Spirometer

  9. Desktop Electronic Spirometers

  10. Small Hand-held Spirometers

  11. Standard Spirometric Indicies • FEV1 - Forced expiratory volume in one second: The volume of air expired in the first second of the blow • FVC- Forced vital capacity: The total volume of air that can be forcibly exhaled in one breath • FEV1/FVC ratio: The fraction of air exhaled in the first second relative to the total volume exhaled

  12. Additional Spirometric Indicies • VC - Vital capacity: A volume of a full breath exhaled in the patient’s own time and not forced. Often slightly greater than the FVC, particularly in COPD • FEV6 – Forced expired volume in six seconds: Often approximates the FVC. Easier to perform in older and COPD patients but role in COPD diagnosis remains under investigation • MEFR – Mid-expiratory flow rates: Derived from the mid portion of the flow volume curve but is not useful for COPD diagnosis

  13. Lung Volume Terminology Inspiratory reserve volume Inspiratory capacity Total lung capacity Tidal volume Expiratory reserve volume Vital capacity Residual volume

  14. Spirogram Patterns • Normal • Obstructive • Restrictive • Mixed Obstructive and Restrictive

  15. SpirometryPredicted Normal Values

  16. Predicted Normal Values • Age • Height • Sex • Ethnic Origin Affected by:

  17. Criteria for Normal Post-bronchodilator Spirometry • FEV1: % predicted > 80% • FVC: % predicted > 80% • FEV1/FVC: > 0.7 - 0.8, depending on age

  18. Normal Trace Showing FEV1 and FVC FVC 5 4 FEV1 = 4L FVC = 5L FEV1/FVC = 0.8 Volume, liters 3 2 1 1 2 3 4 5 6 1 Time, sec

  19. SPIROMETRY OBSTRUCTIVE DISEASE

  20. Spirometry: Obstructive Disease Normal 5 4 3 Volume, liters FEV1 = 1.8L FVC = 3.2L FEV1/FVC = 0.56 2 Obstructive 1 1 2 3 4 5 6 Time, seconds

  21. Spirometric Diagnosis of COPD • COPD is confirmed by post–bronchodilator FEV1/FVC < 0.7 • Post-bronchodilator FEV1/FVC measured 15 minutes after 400µg salbutamol or equivalent

  22. Bronchodilator Reversibility Testing • Provides the best achievable FEV1(and FVC) • Helps to differentiate COPD from asthma Must be interpreted with clinical history - neither asthma nor COPD are diagnosed on spirometry alone

  23. Bronchodilator Reversibility Testing • Can be done on first visit if no diagnosis has been made • Best done as a planned procedure: pre- and post-bronchodilator tests require a minimum of 15 minutes • Post-bronchodilator only saves time but does not help confirm if asthma is present • Short-acting bronchodilators need to be withheld for at least 4 hours prior to test

  24. Bronchodilator Reversibility Testing * Some guidelines suggest nebulised bronchodilators can be given but the doses are not standardised. “There is no consensus on the drug, dose or mode of administering a bronchodilator in the laboratory.” Ref: ATS/ERS Task Force : Interpretive strategies for Lung Function Tests ERJ 2005;26:948 **Usually 8 puffs of 20 µg

  25. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD GOLD Report (2009)

  26. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD • Preparation • Tests should be performed when patients are clinically stable and free from respiratory infection • Patients should not have taken: • inhaled short-acting bronchodilators in the previous six hours • long-acting bronchodilator in the previous 12 hours • sustained-release theophylline in the previous 24 hours

  27. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD • Spirometry • FEV1 should be measured (minimum twice, within 5% or 150mls) before a bronchodilator is given • The bronchodilator should be given by metered dose inhaler through a spacer device or by nebulizer to be certain it has been inhaled • The bronchodilator dose should be selected to be high on the dose/response curve • (…..continued)

  28. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD • Spirometry (continued) • Possible dosage protocols: • 400 µg β2-agonist, or • 80-160 µg anticholinergic, or • the two combined • FEV1 should be measured again: • 15 minutes after a short-acting bronchodilator • 45 minutes after the combination

  29. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD • Results • An increase in FEV1 that is both greater than 200 ml and 12% above the pre-bronchodilator FEV1 (baseline value) is considered significant • It is usually helpful to report the absolute change (in ml) as well as the % change from baseline to set the improvement in a clinical context

  30. SPIROMETRY RESTRICTIVE DISEASE

  31. Criteria: Restrictive Disease • FEV1:normal or mildly reduced • FVC: < 80% predicted • FEV1/FVC: > 0.7

  32. Spirometry: Restrictive Disease Normal 5 4 3 Volume, liters Restrictive FEV1 = 1.9L FVC = 2.0L FEV1/FVC = 0.95 2 1 1 2 3 4 5 6 Time, seconds

  33. Mixed Obstructive/Restrictive • FEV1: < 80% predicted • FVC: < 80% predicted • FEV1 /FVC: < 0.7

  34. Mixed Obstructive and Restrictive Normal Volume, liters FEV1 = 0.5L FVC = 1.5L FEV1/FVC = 0.30 Obstructive - Restrictive Time, seconds Restrictive and mixed obstructive-restrictive are difficult to diagnose by spirometry alone; full respiratory function tests are usually required (e.g., bodyplethysmography, etc)

  35. SPIROMETRY Flow Volume

  36. Flow Volume Curve • Standard on most desk-top spirometers • Adds more information than volume time curve • Less understood but not too difficult to interpret • Better at demonstrating mildairflow obstruction

  37. Flow Volume Curve Maximum expiratory flow (PEF) Expiratory flow rate L/sec FVC RV TLC Inspiratory flow rate L/sec Volume (L)

  38. Flow Volume Curve Patterns Obstructive and Restrictive Obstructive Severe obstructive Restrictive Expiratory flow rate Expiratory flow rate Expiratory flow rate Volume (L) Volume (L) Volume (L) Reduced peak flow, scooped out mid-curve Steeple pattern, reduced peak flow, rapid fall off Normal shape, normal peak flow, reduced volume

  39. Spirometry: Abnormal Patterns Obstructive Restrictive Mixed Volume Volume Volume Time Time Time Fast rise to plateau at reduced maximum volume Slow rise to reduced maximum volume; measure static lung volumes and full PFT’s to confirm Slow rise, reduced volume expired; prolonged time to full expiration

  40. PRACTICAL SESSION Performing Spirometry

  41. Spirometry Training • Training is essential for operators to learn correct performance and interpretation of results • Training for competent performance of spirometry requires a minimum of 3 hours • Acquiring good spirometry performance and interpretation skills requires practice, evaluation, and review • Spirometry performance (who, when and where) should be adapted to local needs and resources • Training for spirometry should be evaluated

  42. Obtaining Predicted Values • Independent of the type of spirometer • Choose values that best represent the tested population • Check for appropriateness if built into the spirometer Optimally, subjects should rest 10 minutes before performing spirometry

  43. Withholding Medications Before performing spirometry, withhold: • Short acting β2-agonists for 6 hours • Long acting β2-agonists for 12 hours • Ipratropium for 6 hours • Tiotropium for 24 hours Optimally, subjects should avoid caffeine and cigarette smoking for 30 minutesbefore performing spirometry

  44. Performing Spirometry - Preparation • Explain the purpose of the test and demonstrate the procedure • Record the patient’s age, height and gender and enter on the spirometer • Note when bronchodilator was last used • Have the patient sitting comfortably • Loosen any tight clothing • Empty the bladder beforehand if needed

  45. Performing Spirometry • Breath in until the lungs are full • Hold the breath and seal the lips tightly around a clean mouthpiece • Blast the air out as forcibly and fast as possible. Provide lots of encouragement! • Continue blowing until the lungs feel empty

  46. Performing Spirometry • Watch the patient during the blow to assure the lips are sealed around the mouthpiece • Check to determine if an adequate trace has been achieved • Repeat the procedure at least twice more until ideally 3 readings within 100ml or 5% of each other are obtained

  47. Reproducibility - Quality of Results Volume, liters Time, seconds Three times FVC within 5% or 0.15 litre (150ml)

  48. Spirometry - Possible Side Effects • Feeling light-headed • Headache • Getting red in the face • Fainting: reduced venous return or vasovagal attack (reflex) • Transient urinary incontinence Spirometry should be avoided after recent heart attack or stroke

  49. Spirometry - Quality Control • Most common cause of inconsistent readings is poor patient technique • Sub-optimal inspiration • Sub-maximal expiratory effort • Delay in forced expiration • Shortened expiratory time • Air leak around the mouthpiece • Subjects must be observed and encouraged throughout the procedure

  50. Spirometry – Common Problems • Inadequate or incomplete blow • Lack of blast effort during exhalation • Slow start to maximal effort • Lips not sealed around mouthpiece • Coughing during the blow • Extra breath during the blow • Glottic closure or obstruction of mouthpiece by tongue or teeth • Poor posture – leaning forwards