Spirometry

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it describes simply how to do & interpret a spirometric test with examples

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Spirometry

  1. 1. Dr. Maha Yousif Assist. Lecturer of Chest Diseases Minufiya University, Egypt E-mail: drmahayousif@gmail.com Oct. 2008 Basics of spirometry
  2. 3. Contraindications to spirometry <ul><li>No absolute contraindications. </li></ul><ul><li>FVC manoeuvre raise intra-cranial, intra-thoracic and intra-abdominal pressures so, Relative contraindications may be: </li></ul><ul><li>◆ Recent eye, thoracic or abdominal surgery </li></ul><ul><li>◆ Recent myocardial infarction, uncontrolled hypertension or pulmonary embolism </li></ul><ul><li>◆ Recent cerebrovascular haemorrhage or known cerebral or </li></ul><ul><li>abdominal aneurysm </li></ul><ul><li>◆ Pneumothorax </li></ul><ul><li>◆ Haemoptysis of unknown origin (FVC maneuver may aggravate underlying condition.) </li></ul><ul><li>◆ Acute disorders affecting test performance (e.g. vomiting, nausea, vertigo) </li></ul>
  3. 4. Patient preparation <ul><li>Before the test </li></ul><ul><li>◘ Avoid: </li></ul><ul><li>Acohol 4h </li></ul><ul><li>Large meal 2h </li></ul><ul><li>Smoking 1h </li></ul><ul><li>Vigorous exercise 30min </li></ul><ul><li>◘ Wear loose , comfortable clothing. </li></ul><ul><li>◘ relaxed, and have time to visit the toilet. </li></ul>
  4. 5. <ul><li>For bronchodilator reversibility testing withhold bronchodilators prior to the test: </li></ul><ul><li>◘ Short-acting inhaled β2 agonists for 2–4h. </li></ul><ul><li>◘ Short-acting inhaled anticholinergics for 4–6 h. </li></ul><ul><li>◘ Long-acting inhaled or oral β2 agonists for 12–24 h </li></ul><ul><li>◘ Long-acting inhaled anticholinergics for 24–36 h. </li></ul><ul><li>◘ Theophyllines for 12 h. </li></ul><ul><li>◘ Sustained release theophyllines for 24 h. </li></ul>
  5. 6. Calibration <ul><li>To ensure accurate recording of the tested lung volumes. </li></ul><ul><li>Daily routine. </li></ul><ul><li>A spirometer that is transported from one location to another and exposed to changes in temperature should be re-calibration before use. </li></ul>
  6. 7. Performing the test <ul><li>Explain the procedure. </li></ul><ul><li>Check any contraindications,complied instructions as withholding bronchodilators, not smoking,…… </li></ul><ul><li>Accurately measure height, standing (without shoes) </li></ul><ul><li>If patients are unable to stand, or have a severe spinal deformity such as a scoliosis, height can be estimated by measuring arm span. </li></ul><ul><li>Enter the patient data to the software. </li></ul><ul><li>N.B: </li></ul><ul><li>False teeth, unless they are very ill-fitting and loose, should be left in. </li></ul><ul><li>Record any deviations from the ideal so that subsequent tests can be carried out under the same conditions </li></ul>
  7. 8. Correct position of head and body <ul><li>Seating Position: (The standing position is not advised), The test position should be noted on the report. </li></ul><ul><li>Upright position: </li></ul><ul><li>Position of the head : upright or slightly leaned back. (If the neck is flexed forward the upper airways are narrowing. </li></ul><ul><li>No leaning forward during the test. </li></ul>
  8. 9. Slow expiratory vital capacity( SVC,EVC). <ul><li>Should be tested before any forced maneuvres </li></ul><ul><li>SVC Maneuvre </li></ul><ul><li>1) Breath normally (Facultative) </li></ul><ul><li>2) Execute a maximal slow inspiration </li></ul><ul><li>3) Execute a maximal slow expiration </li></ul><ul><li>4) Breath at rest </li></ul><ul><li>Wait a minute or so before attempting another recording </li></ul>
  9. 10. Slow Vital Capacity (SVC) <ul><li>Main parameters measured are: </li></ul><ul><li>EVC: Slow expiratory vital capacity( SVC). </li></ul><ul><li>IVC : Inspiratory Vital cpacity </li></ul><ul><li>ERV: Expiratory reserve volume </li></ul><ul><li>IRV: Inspiratory reserve volume </li></ul><ul><li>Others are: </li></ul><ul><li>VE: Expired Volume per minute </li></ul><ul><li>Vt : Tidal Volume </li></ul><ul><li>Rf: Respiratory Frequency </li></ul><ul><li>Ttot: Duration of a complete respiratory cycle </li></ul><ul><li>Ti/Ttot, Vt/Ti </li></ul>
  10. 11. Forced Vital Capacity <ul><li>FVC Manoeuvre </li></ul><ul><li>1) Breath normally (Facultative) </li></ul><ul><li>2) Execute a Forced Maximal inspiration </li></ul><ul><li>3) Execute a Forced maximal expiration </li></ul><ul><li>4) Execute a maximal inspiration (Facultative) </li></ul><ul><li>5) Breath at rest </li></ul><ul><li>Wait at least 1 minute before attempting another recording </li></ul><ul><li>N.B </li></ul><ul><li>Normally, the SVC and FVC are nearly equal. But in airway obstruction SVC > FVC. </li></ul>
  11. 12. Forced Vital Capacity <ul><li>The Main Measured Parameters are: </li></ul><ul><li>FVC Forced Expiratory Vital Capacity. </li></ul><ul><li>FEV1 Forced Expired Volume after one second. </li></ul><ul><li>FEV1/FVC% Percentage of FEV1 against the FVC. </li></ul><ul><li>PEF Expiratory Peak flow. </li></ul><ul><li>MEF 25-75% (FEF 25-75% )Mean Forced expiratory flow. </li></ul><ul><li>The representative graphs are: </li></ul><ul><li>The flow-volume curve (loop). </li></ul><ul><li>The volume-time curve. </li></ul>
  12. 13. Flow / volume curve Volume / time curve
  13. 14. The volume/time curve <ul><li>A normal volume/time curve has a typical shape. There is a rapid rise to the trace as three-quarters of the air is expired in the first second </li></ul><ul><li>The trace plateaus between 4 and 6 seconds </li></ul>
  14. 15. <ul><li>A normal flow/volume curve has a typical shape </li></ul><ul><li>◘ Rises almost vertically to PEF </li></ul><ul><li>◘ The trace merges smoothly with the horizontal axis of the graph at FVC </li></ul>The flow/volume curve
  15. 16. Mid-expiratory flow rates (MEF25, MEF50, MEF75) <ul><li>MEF25: ‘The maximum flow achievable when 75% of the FVC has been expired’ (when 25% of the FVC remains in the lungs). </li></ul><ul><li>MEF75: refers to the maximum flow achievable when 75% of the FVC remains in the lungs and the MEF50 is the maximum flow rate achievable when the lungs are half-empty </li></ul><ul><li>a sign of early airflow obstruction ( small airway disease ). </li></ul><ul><li>Some spirometers use the equivalent of MEF: the forced expiratory flow (FEF25, FEF50 and FEF75). </li></ul>
  16. 17. <ul><li>Peak expiratory flow: the highest flow achieved from a maximal forced expiratory manoeuvre started without hesitation from a position of maximal lung inflation’ </li></ul><ul><li>occurs very early in a forced expiration – within the first tenth of a second </li></ul><ul><li>airflow from the larger airways </li></ul>
  17. 18. Common errors Coughing
  18. 19. <ul><li>Failure to expire to FVC: </li></ul><ul><li>The volume/time trace will fail to plateau </li></ul><ul><li>The flow/volume trace will not merge with the horizontal axis and will ‘drop off’ </li></ul>
  19. 20. <ul><li>Slow start to the forced expiratory manoeuvre: </li></ul><ul><li>Will give an ‘S’ shape to the start of the volume/time trace, The flow/volume trace will have a sloping, rather than vertical start </li></ul>
  20. 21. <ul><li>Air leak: </li></ul><ul><li>The volume/time trace will ‘dip’ downwards, rather than rise steadily to a plateau </li></ul>
  21. 23. Technical acceptability <ul><li>Maximum effort for the forced manoeuvre </li></ul><ul><li>Immediate exhalation from the position of maximal inspiration </li></ul><ul><li>No coughing </li></ul><ul><li>Complete exhalation. </li></ul><ul><li>Traces are smooth and free of irregularity </li></ul><ul><li>The volume/time trace should plateau for at least 1 second and there should not be an ‘S’ shape to the beginning of the trace </li></ul>
  22. 24. <ul><li>The flow/volume trace should rise almost vertically to a peak and the trace should merge smoothly with the horizontal axis at the end of the blow </li></ul><ul><li>At least three technically acceptable manoeuvres should be obtained, ideally with less than 0.2 L (5%) variability for FEV1 (and FVC) between the highest and second highest result. Quote the largest value. </li></ul><ul><li>If the difference is > 5% this means Sub-maximal effort. (repeat the test) </li></ul><ul><li>Reductions in PEF and FEV1 have been shown when inspiration is slow and/or there is a 4–6 s pause at total lung capacity (TLC) before beginning exhalation </li></ul>
  23. 26. Spirometry interpretation <ul><li>Spirometry parameters are considered to be within the normal range if: </li></ul><ul><li>The FEV1, FVC and VC are between 80% and 120% of the reference value for someone of that age, gender, height and ethnic group </li></ul><ul><li>The FEV1/FVC is about 75% (0.75) or over 80% of the reference value for someone of that age, gender, height and ethnic group </li></ul>
  24. 27. Obstructive abnormality <ul><li>Spirometry parameters compatible with airflow obstruction are: </li></ul><ul><li>◘ A reduced FEV1/FVC, or FEV1/VC. Values of less than 70% and/or less than 80% of the reference value </li></ul><ul><li>◘ An FEV1 of less than 80% of the reference value </li></ul><ul><li>N.B: When the slow vital capacity is higher than the FVC, the FEV1/VC should be calculated </li></ul><ul><li>◘ Once the diagnosis of obstructive abnormality is made, comment on: </li></ul><ul><li>Severity of obstruction. </li></ul><ul><li>Reversibility of obstruction </li></ul>
  25. 28. Severity of obstruction <ul><li>The severity of reductions in the FEV1% pred can be characterized by the following scheme: </li></ul>
  26. 29. Reversibility test <ul><li>Response to β agonist is assessed after 10-15 min after inhalation of (100 mcg each, 400 mcg total dose) albuterol administered through a valved spacer device. When concern about tremor or heart rate exists, lower doses may be used. Response to an anticholinergic drug may be assessed 30 minutes after 4 inhalations (40 mcg each, 160 mcg total dose) of ipratropium bromide. </li></ul>
  27. 30. Reversibility test <ul><li>FVC before and after bronchodilator </li></ul>
  28. 31. Restrictive abnormality <ul><li>Spirometry parameters compatible with a restrictive abnormality are: </li></ul><ul><li>◘ An FEV1, FVC and VC reduced to less than 80% of their reference value </li></ul><ul><li>◘ A normal or high FEV1/FVC, or FEV1/VC (about 75%). The FEV1/FVC will be over 80% of the reference value </li></ul><ul><li>◘ The severity of restriction is based on the degree of reduction in FVC % Pred.the same classification as obstructive abnormality. </li></ul>
  29. 32. Mixed abnormality <ul><li>Reduced FVC & a low FEV1/FVC% ratio. </li></ul><ul><li>Means: a combination of both obstruction and restriction, or airflow obstruction with gas trapping. It is necessary to measure the patient's total lung capacity to distinguish between these two possibilities. </li></ul>
  30. 36. <ul><li>Examples of lesions of the major airway detected with the flow-volume loop </li></ul><ul><li>Variable extrathoracic lesions   ◘ Vocal cord paralysis </li></ul><ul><li>  ◘ Subglottic stenosis   ◘  Hypopharyngeal or tracheal tumour </li></ul><ul><li>   ◘ Goiter </li></ul><ul><li>Variable intrathoracic lesions    ◘ Tumor of lower trachea (below sternal notch)     ◘ Tracheomalacia     ◘ Strictures     ◘ Wegener's granulomatosis or relapsing polychondritis </li></ul><ul><li>Fixed lesions    ◘ Fixed neoplasm in central airway (at any level)     ◘ Vocal cord paralysis with fixed stenosis     ◘ Fibrotic stricture </li></ul>
  31. 37. Maximum Voluntary Ventilation (MVV) <ul><li>Normally, the MVV is approximately = FEV1×40. If the FEV1 is 3.0 L, the MVV should be approximately 120 L/min. </li></ul><ul><li>MVV/(40×FEV1)< 0.80 indicates that the MVV is low relative to the FEV1, means: </li></ul><ul><li>◘ a major airway obstruction </li></ul><ul><li>◘ neuromuscular diseases (amyotrophic lateral sclerosis, myasthenia gravis, polymyositis). </li></ul><ul><li>◘ Poor patient performance due to weakness, lack of coordination, </li></ul><ul><li>◘ the subject is massively obese? The MVV tends to decrease before the FEV1 does. </li></ul>
  32. 38. Maximum Voluntary Ventilation (MVV) <ul><li>MVV Manoeuvre </li></ul><ul><li>Breath in and out deeply and rapidly for 12 second. </li></ul>
  33. 39. Obstructive abnormality: very severe, Restrictive abnormality: moderate (mixed).
  34. 40. Obstructive abnormality: very severe, Restrictive abnormality: severe (mixed).
  35. 41. Obstructive abnormality: severe, Restrictive abnormality: mild (mixed).
  36. 42. Moderate restrictive abnormality
  37. 43. Normal spirometry
  38. 44. Mild restrictive abnormality
  39. 45. Restrictive abnormality: moderatey severe
  40. 46. Obstructive abnormality: moderately severe.
  41. 47. The End

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