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Use and Interpretation of Pulmonary Function Testing

Use and Interpretation of PFTs. Types of pulmonary function testingIndications for pulmonary function testingSpirometryVolumes and CapacitiesInterpretation: Values and CurvesPatterns of diseaseCases. Types of Pulmonary Function Testing. . Tests of Pulmonary Function. Spirometry (PFTs): forced

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Use and Interpretation of Pulmonary Function Testing

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    1. Use and Interpretation of Pulmonary Function Testing Jessica E. Pittman, MD, MPH Fellow, Pediatric Pulmonology jessica_pittman@med.unc.edu

    2. Use and Interpretation of PFTs Types of pulmonary function testing Indications for pulmonary function testing Spirometry Volumes and Capacities Interpretation: Values and Curves Patterns of disease Cases

    3. Types of Pulmonary Function Testing

    4. Tests of Pulmonary Function Spirometry (PFTs): forced exhalation Plethysmography lung volumes Diffusion Testing (DLCO) Exercise testing (using spirometry) Infant Pulmonary Function Testing (iPFTs) lung volumes & forced exhalation Impedance Oscillometry (IOS) airway resistance & compliance Multiple Breath Washout (MBW/LCI) ventilation inhomogeneity (marker of obstruction) Ventilation-Perfusion Scans (VQ)

    5. Indications for Pulmonary Function Testing

    6. Indications for Pulmonary Function Testingand (perhaps) to refer Asthma Change in asthma Sx Persistent cough Persistent wheeze Stridor/noisy breathing Shortness of Breath Recurrent infections Oxygen requirement Rheumatologic conditions Sickle Cell Disease Chemotherapy Scoliosis

    7. Spirometry (PFTs)

    10. Spirometric Measures FVC: forced vital capacity volume of a forced exhalation (big breath) FEV1: forced expiratory volume in 1 sec sensitive for airway obstruction mainly measuring flow from medium & large airways FEV0.5: equivalent in infant/preschool PFTs FEF25-75: forced expiratory flow between 25% and 75% of FVC flow occurring later in the exhalation thought to represent small & medium airways sensitive for obstruction, also most variable FEV1/FVC: ratio may be more sensitive for obstructive disease must ensure adequacy of maneuver (forced exhalation, peak flow) PEF: peak expiratory flow

    11. Spirometric Measures: Flow-Volume Loop

    12. Spirometry: Percent Predicted Absolute values can be compared for one subject at different times Percent predicted values allow comparison to population norms based on: Sex Age Height Race** - typically Black, White, Hispanic; everything else refers back to White values Weight Percent predicted also can be compared for one subject over time, allows for growth

    13. Spirometry: Whats normal (FEV1)? Normal: = 80% predicted Mild Obstruction: 60 79% predicted Moderate Obstruction: 40 59% predicted Severe Obstruction: < 40% predicted important to look at individual trends: patients can drop lung function & remain in normal values

    14. What constitutes a change? FEV1: >10% change FEF25-75: >20-25% change

    15. Look at the curve!!!

    16. Spirometry: Curves

    17. Not all curves are created equal

    18. Patterns of disease OBSTRUCTIVE FVC normal FEV1 decreased FEV1/FVC decreased FEF25-75 decreased PEF decreased RESTRICTIVE** FVC decreased FEV1 normal or decreased FEV1/FVC normal or increased FEF25-75 normal or decreased PEF variable

    19. Quick Review

    20. Normal Spirometry

    21. Obstructive Disease

    22. Restrictive Disease (suggestive)

    23. Cases

    24. Differential Diagnosis:

    25. Case #1: 7 year old male w recurrent wheeze x 1 year HPI: began w/ URI, mainly whz w URIs, ?worse w exertion. No change w abx. PMH: no asthma/whz. RSV at 4 mo (no hosp). Mild eczema ROS: occ. dry cough, no rhinorrhea, no watery or itchy eyes. Fam Hx: 2 healthy sibs, father w mild asthma Soc Hx: 2nd grade; no smokers, 2 dogs PE: RR 25, 98% on RA. Lungs CTAB.

    26. Whats your differential?

    27. Case #1: Initial spirometry

    28. Case #1: Post-albuterol spirometry

    29. Whats your diagnosis?

    30. Case #1: Dx & Management PFT Interpretation: mild obstructive disease w significant bronchodilator response Dx: Mild intermittent asthma URI & possible exercise trigger Management: Inhaled corticosteroid, bronchodilator prn, both with spacer

    31. Case #2: 6 year old male w harsh cough x 4 months. HPI: started w URI Sx, but continued s/p URI. No PM cough. No wheeze. No shortness of breath. Occ c/o abd pain & central chest pain. PMH: h/o GERD as infant. Multiple croup episodes. No asthma. ROS: no allergy Sx. Fam Hx: no asthma, allergies, eczema. Soc Hx: started kindergarten, no smokers PE: RR 22, 100% on RA. Lungs CTAB. Occ. harsh, dry, singular cough w preceding deep inhalation

    32. Whats your differential?

    33. Case #2: Initial spirometry

    34. Case #2: Post-albuterol spirometry

    35. Whats your diagnosis?

    36. Case #2: Dx & Management PFT Interpretation: normal spirometry w significant decline in function s/p bronchodilator Dx: tracheomalacia w mechanical tracheitis Management: techniques for tracheitis, no other management necessary

    37. Case #3: 10 year old female w cough x 6 months HPI: cough worse w cold air, exertion, URIs. Presenting w URI Sx, hypoxia. No fevers. Some chest pain/tightness. PMH: no whz/asthma. No allergies/eczema. + occasional nausea, pain/burning after eating. ROS: no whz, no allergy Sx. Fam Hx: no asthma/allergies. Soc Hx: lives w parents, 2 uncles, 12 other children, 3 dogs, no smokers. 4th grade. PE: RR 40, sats 89% RA. Lungs slightly dim BS, no whz.

    38. Whats your differential?

    39. Case #3: Initial spirometry

    40. Case #3: Post-albuterol spirometry

    41. Whats your diagnosis?

    42. Case #3: Dx & Management PFT Interpretation: mild-mod obstructive disease w significant bronchodilator response Dx: Moderate-Severe persistent asthma Exercise, weather, URI trigger likely GERD aggravating factor Management: Inhaled corticosteroid daily, bronchodilator prn, with spacer. May need bronchodilator prior to exercise. PPI for GERD.

    43. Case #4: 8 yo M w chronic cough x3 yrs, recurrent PNA. HPI: cough x4yrs, progressively worse. Occ. productive. Occ. whz. + abx response, ?albuterol response. PMH: PNA x3, sinusitis x1. Pancreatitis x1 ROS: intermittent nasal congestion. no allergy sx. No GI Sx. Fam Hx: 2 sibs, both w asthma. Soc Hx: 2nd grade, no smokers, 2 cats. PE: RR 30, sats 97% RA. occ coarse BS, no whz

    44. Whats your differential?

    45. Case #4: Spirometry

    46. Whats your diagnosis?

    47. Case #4: Dx & Management PFT Interpretation: Moderate to severe obstructive disease, suggestive of mild restrictive disease (mixed). Dx: Cystic fibrosis, pancreatic sufficient (dx by sweat chloride, genotyping) Management: admit for IV abx. Daily chest PT, 7% hypertonic saline neb bid, albuterol bid.

    48. Case #5: 15 y.o. F w shortness of breath w sprinting x 6 months HPI: SOB started w high school track season. Difficult to move air. No whz or cough. No chest pain. No Sx when not running. Worse w albuterol PMH: no asthma, allergies, eczema. ROS: no recent illnesses. no abd pain, nausea, heartburn, nighttime cough. Fam Hx: no asthma Soc Hx: 10th grade, A student PE: RR 18, 99% on RA, lungs CTAB.

    49. Whats your differential?

    50. Case #5: Spirometry

    51. Whats your diagnosis?

    52. Case #5: Dx & Management PFT interpretation: normal spirometry values, but with flattening of F/V loop suggestive of fixed obstruction Dx: tracheomalacia (by bronchoscopy) Management: no intervention

    53. Case #6: 4 year old female w cough x 3 months HPI: began w URI, wet cough, worse at night. Partially responded to 2 courses abx. No whz. No fevers. No SOB. PMH: Mild seasonal allergies (rhinorrhea). no whz, asthma, eczema. ROS: nasal congestion, occ rhinorrhea. no eye Sx. No GI Sx. Fam Hx: maternal aunt w asthma Soc Hx: both parents smoke at home. Day care. PE: RR 25, 98% on RA. Lungs CTAB. Thick yellow mucus in nose.

    54. Whats your differential?

    55. Case #6: Spirometry

    56. Whats your diagnosis?

    57. Case #6: Dx & Management PFT Interpretation: normal spirometry Dx: Sinus infection (by X-ray) Management: 3 wks augmentin, consider allergy medication if Sx recur.

    58. Case #7: 10 yr old F w asthma HPI: Asthma stable for years. Today is a good day. Frequent, daily cough/wheeze (during the day and o/n). ER visits q 1-2 months. No hospitalizations. PMH: Diagnosed w asthma in infancy. Mild seasonal allergies (rhinorrhea). ROS: occasional rhinorrhea. frequent cough/wheeze. some abdominal pain after eating. Fam Hx: mom w/ asthma Soc Hx: no smokers at home. In school, but unable to participate in sports. PE: RR 22, 97% on RA. Lungs CTAB, but with diminished breath sounds bilaterally.

    59. Whats your differential?

    60. Case #7: Spirometry

    61. Case #7: Spirometry post-albuterol

    62. Whats your differential?

    63. Case #7: Dx & Management PFT Interpretation: severe obstructive disease with significant bronchodilator response (though still mild-moderate obstructive disease). Dx: severe asthma, possibly aggravated by allergies, GERD Management: prolonged steroid burst, azithromycin (possible bronchitis), increased ICS dosing, zyrtec, PPI, follow-up in 2 weeks.

    64. Remember Look at the numbers and the curve Look at the effort & reproducibility Treat the patient, not just the numbers If what youre doing isnt working change your thinking change your management ask for help! (refer, get PFTs, get CXR)

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