Mohammad Tohidi M.D. Professor of Internal Medicine Department of Pulmonary Medicine Ghaem Hospital MUMS Mashhad

2. Mohammad Tohidi M.D. Professor of Internal Medicine Department of Pulmonary Medicine Ghaem Hospital MUMS Mashhad IRAN

3. PFTs

4. Objectives • Identify the components of PFTs • Describe the indications • Develop a stepwise approach to interpretation • Recognize common patterns • Apply this information to patient care

5. Pulmonary function tests (PFTs) • Pulmonary function testing is a valuable tool for evaluating the respiratory system • comparing the measured values for pulmonary function tests obtained on a patient at any particular point with normal values derived from population studies. • The percentage of predicted normalis used to grade the severity of the abnormality.

6. Pulmonary Function Tests • Evaluates 1 or more major aspects of the respiratory system

7. PFTs • Four lung components include : The airways (large and small), Lung parenchyma (alveoli, interstitium), Pulmonary vasculature, and The bellows-pump mechanism

8. PFTs • PFTs can include: simple screening spirometry, Flow Volume Loop Formal lung volume measurement, Bronchoprovocation testing Diffusing capacity for carbon monoxide, and Arterial blood gases. Measurement of maximal respiratory pressures • These studies may collectively be referred to as a complete pulmonary function survey.

10. 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

11. 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

12. Spirometry • Simple, office-based • Measures flow, volumes • Volume vs. Time • Can determine: - Forced expiratory volume in one second (FEV1) - Forced vital capacity (FVC) - FEV1/FVC - Forced expiratory flow 25%-75% (FEF25-75)

13. Spirometry the most readily available most useful pulmonary function test It takes ten to 15 minutes carries no risk

14. Spirometry • Spirometry is the most commonly used lung function screening study. • should be the clinician's first option • other studies being reserved for specific indications • easily performed • in the ambulatory setting, physician's office, emergency department, or inpatient setting.

16. Patient care/preparations • Two choices are available with respect to bronchodilator and medication use prior to testing. Patients may withhold oral and inhaled bronchodilators to establish baseline lung function and evaluate maximum bronchodilator response, or they may continue taking medication as prescribed. If medications are withheld, a risk of exacerbation of bronchial spasm exists.

17. Spirometry • The slow vital capacity (SVC) can also be measured with spirometers collect data for at least 30 seconds when airways obstruction is present, the forced vital capacity (FVC) is reduced and slow vital capacity (SVC) may be normal

18. Spirometry • When the slow or forced vital capacity is within the normal range: No significant restrictive disorder . No need to measure static lung volumes (residual volume and total lung capacity).

19. Indications — Diagnosis • Evaluation of signs and symptoms - SOB, exertional dyspnea, chronic cough • Screening at-risk populations • Monitoring pulmonary drug toxicity • Abnormal study - CXR, EKG, ABG, hemoglobin • Preoperative assessment

20. Indications — Diagnosis • Evaluation of signs and symptoms - SOB, exertional dyspnea, chronic cough • Screening at-risk populations • Monitoring pulmonary drug toxicity • Abnormal study - CXR, EKG, ABG, hemoglobin • Preoperative assessment Smokers > 45yo (former & current)

21. Indications — Diagnosis • Evaluation of signs and symptoms - SOB, exertional dyspnea, chronic cough • Screening at-risk populations • Evaluation of occupational symptoms • Monitoring pulmonary drug toxicity • Abnormal study - CXR, EKG, ABG, hemoglobin • Preoperative assessment

22. Indications — Prognostic • Assess severity • Follow response to therapy • Determine further treatment goals • Referral for surgery • Disability

23. Contraindications for spirometry • Relative contraindications for spirometry include hemoptysis of unknown origin, pneumothorax, unstable angina pectoris, recent myocardial infarction, thoracic aneurysms, abdominal aneurysms, cerebral aneurysms, recent eye surgery (increased intraocular pressure during forced expiration), recent abdominal or thoracic surgical procedures, and patients with a history of syncope associated with forced exhalation

24. Spirometry • Spirometry requires a voluntary maneuver in which a seated patient inhales maximally from tidal respiration to total lung capacity and then rapidly exhales to the fullest extent until no further volume is exhaled at residual volume

25. Spirometry • The maneuver may be performed in a forceful manner to generate a forced vital capacity (FVC) or in a more relaxed manner to generate a slow vital capacity (SVC).

26. In normal persons, the inspiratory vital capacity, the expiratory SVC, and expiratory FVC are essentially equal. However, in patients with obstructive airways disease, the expiratory SVC is generally higher than the FVC.

27. Interpretation of spirometry results(1) • should begin with an assessment of test quality. to inspect the graphic data (the volume-time curve and the flow-volume loop)

28. Interpretation of spirometry results(2) • to ascertain whether the study meets certain well-defined acceptability and reproducibility standards

29. acceptable spirometry (ATS) • 1) minimal hesitation at the start of the forced expiration (extrapolated volume (EV) <5% of the FVC or 0.15 L, whichever is larger • Time to PEF is <120 ms (optional until further information is available) (2) no cough in the first second of forced exhalation, • 3) meets 1 of 3 criteria that define a valid end-of-test

30. Valid end-of-test • (a) smooth curvilinear rise of the volume-time tracing to a plateau of at least 1-second duration; (b) if a test fails to exhibit an expiratory plateau, a forced expiratory time (FET) of 15 seconds; or (c) when the patient cannot or should not continue forced exhalation for valid medical reasons.

31. If both of these criteria are not met, continue testing until: Both of the criteria are met with analysis of additional acceptable spirograms or • A total of eight tests have been performed or • Save a minimum of three best maneuvers

32. Acceptability Criteria • Good start of test • No coughing • No variable flow • No early termination • Reproducibility

33. The volume-time tracing • The volume-time tracing is most useful in assessing whether the end-of-test criteria have been met

34. Spirometry

35. Flow-volume loop • the flow-volume loop is most valuable in evaluating the start-of-test criteria.

36. Flow-Volume Loop Ruppel GL. Manual of Pulmonary Function Testing, 8th ed., Mosby 2003

37. Repeatability Criteria • After three acceptable spirograms have been obtained, apply the following tests. Are the two largest FVCs within 0.2 L of each other? • Are the two largest FEV1s within 0.2 L of each other? • If both of these criteria are met, the test session may be concluded

38. Well trained technician

39. Lung Volumes

40. 4 Volumes 4 Capacities Sum of 2 or more lung volumes Lung Volumes IRV IC VC TLC TV ERV FRC RV RV

41. Spirometry

42. Lung Factors Affecting Spirometry • Mechanical properties • Resistive elements

43. Mechanical Properties • Compliance • Describes the stiffness of the lungs • Change in volume over the change in pressure • Elastic recoil • The tendency of the lung to return to it’s resting state • A lung that is fully stretched has more elastic recoil and thus larger maximal flows

44. Resistive Properties • Determined by airway caliber • Affected by • Lung volume • Bronchial smooth muscles • Airway collapsibility

45. Factors That Affect Lung Volumes • Age • Sex • Height • Weight • Race • Disease

46. Technique • Have patient seated comfortably • Closed-circuit technique • Place nose clip on • Have patient breathe on mouthpiece • Have patient take a deep breath as fast as possible • Blow out as hard as they can until you tell them to stop

47. 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)

48. FVC • Interpretation of % predicted: • 80-120% Normal • 70-79% Mild reduction • 50%-69% Moderate reduction • <50% Severe reduction FVC

49. 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

50. FEV1 • Interpretation of % predicted: • >75% Normal • 60%-75% Mild obstruction • 50-59% Moderate obstruction • <49% Severe obstruction FEV1 FVC