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Pft lecture for residents mine
- 1. Pulmonary Function Testing CraigS. Glazer, MD, MSPH Pulmonary and Critical Care
- 2. What Are PFTs? •Series of maneuvers designed to measure lung size and function • Elements of the test: – Spirometry – dynamic flows and volumes – Static lung volumes – Gas transfer
- 3. Uses of PFTs •Diagnosis – Patterns of abnormalities • Obstruction – COPD, asthma, bronchiectasis, bronchiolitis • Restriction – ILD, pleural disease, neuromuscular disease, thoracic cage abnormalities – Identify subtle physiologic abnormalities • Isolated low DLCO – pulmonary hypertension, emphysema, early ILD • Prognosis – Measure of disease severity – COPD – Assess risk – neuromuscular disease • Assess treatment response
- 4. What does thetest measure? • Flow and volume during maximal inspiration and forced expiration - spirometry • Total lung volumes • Surface area of gas exchange • Respiratory muscle function • Cardiopulmonary function during exercise
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- 6. Definition of volumes time volume Tidalvolume Vital capacity (VC)
- 7. Definition of volumes time volumeTotal lung capacity (TLC) Reserve volume (RV)
- 8. Pulmonary Function Testing: Spirometry •Simplest measurement: – Measure how fast/how long you can blow • Maneuver: – Deep breath (to TLC) – Forced exhalation (to RV) – Measure volume and time – Calculate flow TLC RV
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- 10. A given patient cannever get out of the envelope of the flow-volume loop •WHY? Dynamic airway collapse Pulmonary Function Testing: Spirometry TLC RV
- 11. Dynamic ventilatory mechanics: dynamicairway compression Alveolus Palv= 0 outside PB= 0 End-expiration: (No air flow) Negative pleural pressure (- 5 cmH2O)
- 12. Dynamic ventilatory mechanics: dynamicairway compression Alveolus Palv= - 3 cmH2O Pleural pressure more negative (- 8 cmH2O) Inspiration: outside PB= 0
- 13. Dynamic ventilatory mechanics: dynamicairway compression Alveolus Palv= - 3 cmH2O Inspiration: Air flow down pressure gradient outside PB= 0 Pleural pressure more negative (- 8 cmH2O)
- 14. Dynamic ventilatory mechanics: dynamicairway compression Alveolus Palv= +30 cmH2O Forced expiration: outside PB= 0 Positive pleural pressure (+ 25 cmH2O)
- 15. Dynamic ventilatory mechanics: dynamicairway compression Alveolus Palv= +30 cmH2O Forced expiration: Air flow down pressure gradient outside PB= 0 Positive pleural pressure (+ 25 cmH2O)
- 16. Dynamic ventilatory mechanics: dynamicairway compression Alveolus Palv= +30 cmH2O Forced expiration: 30 29 28 27 26 ... outside PB= 0 Positive pleural pressure (+ 25 cmH2O)
- 17. Dynamic ventilatory mechanics: dynamicairway compression Forced expiration: 30 29 28 27 26 … 25 outside PB= 0 Positive pleural pressure (+ 25 cmH2O) Alveolus Palv= +30 cmH2O
- 18. Dynamic ventilatory mechanics: dynamicairway compression Forced expiration: Equal pressure point Closing volume
- 19. Dynamic ventilatory mechanics: dynamicairway compression • Distal movement of equal pressure point exaggerated with: – Increased airway resistance • Asthma, etc. – Reduced lung elastic recoil • Emphysema • Aging
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- 21. Spirometry Interpretation: Step1 Is the test of adequate quality? 1. Reproducibilty Criteria 2. Acceptability Criteria
- 22. Spirometry Interpretation: Acceptability Criteria •Flow Volume Loop – Good Start – No artifacts • Volume Time Curve – 6 seconds exhalation • Or plateau TLC RV
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- 24. Algorithm for Spirometry Interpretation 1.Assess test quality 2. Is there obstruction? 1. Is there a bronchodilator response? 3. Is there evidence for restriction?
- 25. Algorithm for SpirometryInterpretation FEV1/FVC ratio < lower limits of normal (LLN)? Obstruction Yes Bronchodilator response? Obstruction No response to BD No Obstruction With significant response to BD Yes Adapted from www.clevelandclinicmeded.com/diseasemanagement/pulmonary/pft/pft.htm Grade severity by the FEV1
- 26. What is theLower Limit of Normal? 5% 1.645 SD
- 27. Algorithm for SpirometryInterpretation FEV1/FVC ratio < lower limits of normal (LLN)? Obstruction Yes Bronchodilator response? Obstruction No response to BD No Obstruction With significant response to BD Yes Adapted from www.clevelandclinicmeded.com/diseasemanagement/pulmonary/pft/pft.htm Grade severity by the FEV1 No
- 28. Algorithm for SpirometryInterpretation FEV1/FVC ratio < lower limits of normal (LLN)? Normal No Suggests Restriction Ye s Adapted from www.clevelandclinicmeded.com/diseasemanagement/pulmonary/pft/pft.htm Is FVC < LLN? No
- 29. Algorithm for SpirometryInterpretation FEV1/FVC ratio < lower limits of normal (LLN)? Possible Mixed Process Yes Obstruction Yes Bronchodilator response? Obstruction No response to BD No Obstruction With significant response to BD Yes Is FVC < LLN? Isolated Obstruction No
- 30. Severity of impairmentas determined by spirometry: Normal > LLN Mild 70-80% predicted Moderate 60-69% Moderate-Severe 50-59% Severe 34-49% Very Severe < 34%
- 31. Case #1 • Obstructiveor Restrictive Process? Obstructive • What is the severity? – moderate • 45 y/o man complaining of cough and dyspnea for months. Smoked 10 pack- yrs
- 32. Case #1 Spirometry •Bronchodilator response: – Spirometry repeated after inhaled beta-agonists – “Significant” with a 12% and a 200ml improvement in FEV-1 or FVC BD response = obstructive defect but doesn’t equal asthma No response does not mean adequate Rx
- 33. Case #1 Spirometrywith BD challenge Pre-BD % Pred Post- BD % Pred % Chang e FEV1 1.33 60% 1.89 80% 42% FVC 2.61 95% 2.97 108% 14% FEV1 /FVC 50% 64%
- 34. Case #2 • 64y/o man referred for shortness of breath on exertion Suggests restrictive process - good start - smooth contour - effort/reproducibility
- 35. Spirometry interpretation • Obstruction: –Diagnosis: FEV1/FVC < LLN – Severity: degree of reduction in FEV1 • Restriction: – Defined as TLC <80% – “can be inferred” if • FEV1/FVC normal or increased and • FVC < LLN If FEV1/FVC is reduced, can’t diagnose restriction based on FVC
- 37. Static lung volumes TLC VC RV TV TLC VC RV TV TLCVC RV TV Normal ObstructiveRestrictive
- 38. How to measurestatic lung volumes • Gas dilution techniques: Introduce known amount of a gas TLC VC RV
- 39. Static lung volumes •Gas dilution techniques: Give it time to diffuse throughout the lung TLC VC RV
- 40. Static lung volumes •Gas dilution techniques: Measure concentration of the gas in the exhaled sample TLC VC RV
- 41. Static lung volumes •Gas dilution techniques: – Easy to do – Extra equipment cheap – Only measures volume of areas in free communication with the mouth TLC VC RVbulla
- 42. Static lung volumes •Body plethysmography Patient makes panting movements against a closed mouth shutter
- 43. Static lung volumes •Body plethysmography Measure pressure at the mouth and in the box Use Boyle’s law to calculate the intra-thoracic volume
- 44. Case #2 • 64y/o man referred for shortness of breath on exertion Restrictive process
- 45. CO RBC Capillary CO CO +Hb Hb.CO Alveolus Measuring gas transfer
- 46. CO RBC Capillary CO CO +Hb Hb.CO Alveolus Amount of CO taken up is proportional to surface area available for gas exchange
- 47. Gas transfer alveolus capillary CO Introduce known (andsmall) amount of carbon monoxide • Concept: – measuring the area available for gas exchange
- 48. Gas transfer alveolus capillary CO Introduce known (andsmall) amount of carbon monoxide Most will get into blood and bind Hb
- 49. Gas transfer Introduce known (andsmall) amount of carbon monoxide Most will get into Blood and bind Hb Measure amount of exhaled CO alveolus CO capillary
- 50. Gas transfer • ReducedDLCO • Increased DLCO
- 51. Gas transfer • ReducedDLCO – Fewer alveoli • • – Fewer working alveoli • • – Not enough blood • • • Increased DLCO
- 52. Gas transfer • ReducedDLCO – Fewer alveoli • Lobectomy • Pleural effusion – Fewer working alveoli • Emphysema • IPF – Not enough blood • Anemia • Vasculitis • Pulmonary Hypertension • Increased DLCO
- 53. Gas transfer • ReducedDLCO – Fewer alveoli • Lobectomy • Pleural effusion – Fewer working alveoli • Emphysema • IPF – Not enough blood • Anemia • Vasculitis • Pulmonary Hypertension • Increased DLCO – Too much blood – Faster transit of blood
- 54. Gas transfer • ReducedDLCO – Fewer alveoli • Lobectomy • Pleural effusion – Fewer working alveoli • Emphysema • IPF – Not enough blood • Anemia • Vasculitis • Pulmonary Hypertension • Increased DLCO – Too much blood • Polycythemia • Alveolar hemorrhage – Faster transit of blood • High cardiac output • L -> R shunt
- 55. Case #3 • 62y/o woman referred for shortness of breath Obstructive Defect - very severe ???? - good start - smooth contour - effort/reproducibility
- 56. Case #3 • 62y/o woman referred for shortness of breath Severe obstruction Hyperexpansion and air-trapping Moderately reduced DLCO - good start - smooth contour - effort/reproducibility
- 57. Case #4 • 53y/o woman with chest tightness • FVC 5.08 103%pred FEV-1 2.66 74%pred FEV-1/FVC 52% 72% Uninterpretable study 0 1 2 3 4 5 6 7 time
- 58. Case #5: • 32y/o LVN with poorly-controlled asthma on chronic steroids. • Admitted to Zale-Lipshy University Hospital with a diagnosis of status asthmaticus. • Physical exam: Retractions, audible wheezing, and respiratory distress.
- 61. “Asthma attack” Noattack
- 62. Vocal Cord Dysfunction: •Mimicker of asthma • Predominantly seen in women • Conversion disorder – History of physical or sexual abuse – Pre-existing psychiatric illness • Diagnosis: – Flow-volume loops – Direct laryngoscopy • Treatment: – Heli-Ox – Speech therapy and psychotherapy – ?Self-hypnosis and bio-feedback self-regulation training
- 63. Vocal Cord Paralysis •Most common cause of extra-thoracic airflow obstruction • Due to trauma or a laryngeal or intrathoracic tumor • Speech might be preserved • Acute treatment with Heli- Ox or emergency tracheostomy
- 64. Diseases of thelarynx and trachea: The Flow-Volume loop St. John RC. Journal of General Internal Medicine 1993; 8:564-572 and Cherniack RM. Pulmonary Function Testing 1992, 209-230.
- 65. Case #6 • 38y/o man with a “wheeze” FVC 3.66 103%pred FEV-1 2.30 83%pred FEV-1/FVC 63% 78% Fixed large airway obstruction
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