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Pulmonary Function Test

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  • 1. What exactly are PFTs?• The term encompasses a wide variety of objective methods to assess lung function. (Remember that the primary function is gas exchange).• Examples include: – Spirometry – Pulse oximetry – Blood gases – Lung volumes by helium dilution or body plethysmography – Exercise tests – Diffusing capacity – Bronchial challenge testing
  • 2. Spirometry• Measurement of the pattern of air movement into and out of the lungs during controlled ventilatory maneuvers.• Often done as a maximal expiratory maneuver
  • 3. Importance• Patients and physicians have inaccurate perceptions of severity of airflow obstruction and/or severity of lung disease by physical exam• Provides objective evidence in identifying patterns of disease
  • 4. Silhouette of Hutchinson Performing Spirometry From Chest, 2002
  • 5. Indications• Detect disease• Evaluate extent and monitor course of disease• Evaluate treatment• Measure effects of exposures• Assess risk for surgical procedures
  • 6. contraindications• Chest or abdominal pain of any cause• Oral or facial pain exacerbated by mouthpiece• Stress incontinence• Dementia or confused state• Within one month of Myocardial Infarction
  • 7. To be avoided• Smoking- 1 hour• Alcohol- 4 hour• Vigorous exercise -30 minutes• Large meal – 2 hour• Wearing tight clothes
  • 8. 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
  • 9. Volume Measuring Spirometer
  • 10. Flow Measuring Spirometer
  • 11. Desktop Electronic Spirometers
  • 12. Small Hand-held Spirometers
  • 13. The Airways • Conducting zone: no gas exchange occurs – Anatomic dead space • Transitional zone: alveoli appear, but are not great in number • Respiratory zone: contain the alveolar sacsWeibel ER: Morphometry of the HumanLung. Berlin and New York: Springer-Verlag, 1963
  • 14. FromNetterAtlas ofHumanAnatomy,1989
  • 15. Lung Volumes • 4 Volumes • 4 CapacitiesIRV – Sum of 2 or IC more lung VCTV volumes TLCERV FRC RV RV
  • 16. Tidal Volume (TV) • Volume of air inspired and expired during IRV normal quiet IC VC breathing TV TLC ERV FRC RV RV
  • 17. Inspiratory Reserve Volume (IRV) • The maximum amount of air that can be IRV inhaled after a IC VC normal tidal TV TLC volume inspiration ERV FRC RV RV
  • 18. Expiratory Reserve Volume (ERV) • Maximum amount of air that can be IRV exhaled from IC VC the resting TV TLC expiratory level ERV FRC RV RV
  • 19. Residual Volume (RV) • Volume of air remaining in the lungs at the end IRV of maximum IC VC expiration TV TLC ERV FRC RV RV
  • 20. Vital Capacity (VC) • Volume of air that can be exhaled from the lungs IRV after a maximum IC inspiration VC TV • FVC: when VC TLC exhaled forcefully ERV • SVC: when VC is FRC exhaled slowly RV RV • VC = IRV + TV + ERV
  • 21. Predicted Normal ValuesAffected by: Age Height Sex Ethnic Origin
  • 22. Terminology • Forced vital capacity (FVC): – Total volume of air that can be exhaled forcefully from TLC – The majority of FVC can be exhaled in <3 seconds in normal people, but often is much more prolonged in obstructive diseases – Measured in liters (L)
  • 23. FVC• Interpretation of % predicted: – 80-120% Normal – 70-79% Mild reduction – 50%-69% Moderate reduction – <50% Severe reduction FVC
  • 24. Terminology • Forced expiratory volume in 1 second: (FEV1) – Volume of air forcefully expired from full inflation (TLC) in the first second – Measured in liters (L) – Normal people can exhale more than 75-80% of their FVC in the first second; thus the FEV1/FVC can be utilized to characterize lung disease
  • 25. FEV1• Interpretation of % predicted: – >75% Normal – 60%-75% Mild obstruction – 50-59% Moderate obstruction – <49% Severe obstruction FEV1 FVC
  • 26. Terminology • Forced expiratory flow 25- 75% (FEF25-75) – Mean forced expiratory flow during middle half of FVC – Measured in L/sec – May reflect effort independent expiration and the status of the small airways – Highly variable – Depends heavily on FVC
  • 27. FEF25-75• Interpretation of % predicted: – >60% Normal – 40-60% Mild obstruction – 20-40% Moderate obstruction – <10% Severe obstruction
  • 28. 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
  • 29. Criteria for Normal Post-bronchodilator Spirometry• FEV1: % predicted > 80%• FVC: % predicted > 80%• FEV1/FVC: > 0.7
  • 30. Spirometry Interpretation: Obstructive vs. Restrictive Defect• Obstructive Disorders • Restrictive Disorders – FVC nl or↓ – FVC ↓ – FEV1 ↓ – FEV1 ↓ – FEF25-75% ↓ – FEF 25-75% nl to ↓ – FEV1/FVC ↓ – FEV1/FVC N↑ – TLC nl or ↑ – TLC ↓
  • 31. SPIROMETRYFlow Volume
  • 32. 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 mild airflow obstruction
  • 33. Flow Volume Curve Maximum expiratory flow (PEF)Expiratoryflow rateL/sec FVC RV TLCInspiratory flow rate L/sec Volume (L)
  • 34. Flow-Volume Loop • Illustrates maximum expiratory and inspiratory flow- volume curves • Useful to help characterize disease states (e.g. obstructive vs. restrictive)Ruppel GL. Manual of Pulmonary Function Testing, 8thed., Mosby 2003
  • 35. Normal Trace Showing FEV1 and FVC 5 FVCVolume, liters 4 FEV1 = 4L 3 FVC = 5L 2 FEV1/FVC = 0.8 1 1 2 3 4 5 6 Time, seconds
  • 36. Reproducibility - Quality of Results Volume, liters Time, secondsThree times FVC within 5% or 0.1 litre (100 ml)
  • 37. Spirogram Patterns• Normal• Obstructive• Restrictive• Mixed Obstructive and Restrictive
  • 38. SPIROMETRYOBSTRUCTIVE DISEASE
  • 39. Spirometry: Obstructive Disease 5 4Volume, liters Normal 3 FEV1 = 1.8L 2 FVC = 3.2L Obstructive 1 FEV1/FVC = 0.56 1 2 3 4 5 6 Time, seconds
  • 40. Flow Volume Curve Patterns Obstructive and Restrictive Obstructive Severe obstructive Restrictive Expiratory flow rate Expiratory flow rateExpiratory flow rate Volume (L) Volume (L) Volume (L) Reduced peak flow, Steeple pattern, Normal shape, scooped out mid- reduced peak flow, normal peak flow, curve rapid fall off reduced volume
  • 41. 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
  • 42. Bronchodilator Reversibility Testing in COPDSpirometry•FEV1 should be measured (minimum twice,within 5%) before a bronchodilator is given•The bronchodilator should be given bymetered dose inhaler through a spacer deviceor by nebulizer to be certain it has beeninhaled•The bronchodilator dose should be selected tobe high on the dose/response curve
  • 43. Bronchodilator Reversibility Testing in COPD•An increase in FEV1 that is both greaterthan 200 ml and 12% above the pre-bronchodilator FEV1 (baseline value) isconsidered significant•It is usually helpful to report the absolutechange (in ml) as well as the % change frombaseline to set the improvement in a clinicalcontext
  • 44. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD GOLDReport (2006)
  • 45. SPIROMETRYRESTRICTIVE DISEASE
  • 46. Spirometry: Restrictive Disease 5 NormalVolume, liters 4 3 Restrictive FEV1 = 1.9L 2 FVC = 2.0L 1 FEV1/FVC = 0.95 1 2 3 4 5 6 Time, seconds
  • 47. Flow Volume Curve Patterns Obstructive and Restrictive Obstructive Severe obstructive Restrictive Expiratory flow rate Expiratory flow rateExpiratory flow rate Volume (L) Volume (L) Volume (L) Reduced peak flow, Steeple pattern, Normal shape, scooped out mid- reduced peak flow, normal peak flow, curve rapid fall off reduced volume
  • 48. Mixed Obstructive and Restrictive Normal Volume, liters FEV1 = 0.5L Obstructive - Restrictive FVC = 1.5L FEV1/FVC = 0.30 Time, secondsRestrictive and mixed obstructive-restrictive are difficult to diagnose by spirometry alone; full respiratory function tests are usually required (e.g., body plethysmography, etc)
  • 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. TroubleshootingExamples - Unacceptable Traces
  • 51. Unacceptable Trace - Poor Effort Volume, liters Normal Variable expiratory effort Inadequate sustaining of effort May be accompanied by a slow start Time, seconds
  • 52. Unacceptable Trace – Stop Early Normal Volume, liters Time, seconds
  • 53. Unacceptable Trace – Slow Start Normal Volume, liters Time, seconds
  • 54. Unacceptable Trace - Coughing NormalVolume, liters Time, seconds
  • 55. Unacceptable Trace – Extra Breath Normal Volume, liters Time, seconds
  • 56. EXAMPLE 1TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 4.0 L 3.2 3.2FVC%(O/P) 80% 80%FEV1 3.7L 2.9 2.9 +0%- 0mlFEV1%(O/P) 78% 78%FEV1/FVC% 90% 90%PEF 3.51L/S 4.22L/S
  • 57. EXAMPLE -2TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 2.8L 0.6FVC%(O/P) 22%FEV1 2.75L 0.5FEV1%(O/P) 18.18%FEV1/FVC% 84%PEF 5.3L/S 1.6
  • 58. EXAMPLE 2 contTEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 2.8L 0.6 1.6LFVC%(O/P) 22% 57%FEV1 2.75L 0.5 1.0L +100%-500mlFEV1%(O/P) 18.18% 36.3%FEV1/FVC% 84% 63%PEF 5.3L/S 1.6 4.8
  • 59. EXAMPLE 3TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 2.60L 1.60 1.63FVC%(O/P) 62% 63%FEV1 2.17L 1.32 1.34 1.5%-20mlFEV1%(O/P) 61% 62%FEV1/FVC% 83% 82%PEF 5.85L/S 5.34 4.56
  • 60. EXAMPLE 4TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 2.3L 1.8 1.8FVC%(O/P) 78% 78%FEV1 1.95L 0.75 0.75 +0-0mlFEV1%(O/P) 38% 38%FEV1/FVC% 41% 41%PEF 3.10L/s 1.30L/S 1.34L/S
  • 61. EXAMPLE 5TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 3.22L 1.69 1.82FVC%(O/P) 52% 56%FEV1 2.50L 1.15 1.19 +3%FEV1%(O/P) 46% 48%FEV1/FVC% 68% 66%PEF 7.17L/S 4.48 4.41
  • 62. EXAMPLE 6TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 2.75L 1.1 1.5FVC%(O/P) 40% 54%FEV1 2L 0.9 1.0 +11%-100mlFEV1%(O/P) 31% 46%FEV1/FVC% 81% 66%PEF 3.7L/s 1.00L/s 3.20L/s
  • 63. EXAMPLE 7TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 3.2L 1.54 2.3FVC%(O/P) 48% 71%FEV1 2.75L 0.95 1.94 +104%- 990mlFEV1%(O/P) 34.5% 72%FEV1/FVC% 61% 69%PEF 4.50L/s 3L/s 3.70L/s
  • 64. EXAMPLE 8TEST PREDICTE BROCHODILATOR CHANGE D BEFORE AFTERFVC 3.2 L 2.55 2.75FVC%(O/P) 79% 86%FEV1 2.75L 1.95 2.3 +18%- 350mlFEV1%(O/P) 70% 84%FEV1/FVC% 76% 83%PEF 4.5L/s 4.00L/s 4.40L/s
  • 65. gowri