Pulmonary function tests are used to evaluate respiratory status, quantify pulmonary disability, and manage patients with known pulmonary disease. Acceptable tests require adequate equipment, lack of artifacts, satisfactory start and exhalation, and reproducibility between tests. Obstructive lung disease is identified by reduced FEV1/FVC ratio below normal limits, while restrictive lung disease shows reduced FEV1 and FVC proportionately with normal FEV1/FVC ratio. Upper airway obstruction can be extra-thoracic or intra-thoracic.

1. INTERPRETATION OF PULMONARY FUNCTION TESTS A.A. Eldawlatly [email_address]

2. INDICATIONS Is a basic tool to evaluate the patient respiratory status. It is often the first diagnostic test employed in the work up. Used for preoperative evaluation. Used for managing patients with known pulmonary disease. Used to quantify pulmonary disability.

3. Requirement for Good PFTs Adequate equipment Reproducible performance

4. AMERICAN THORACIC SOCIETY (ATS) GUIDELINES FOR ACCEPTABILITY & REPRODUCIBILITY Criteria for acceptability Lack of artifacts Satisfactory start without hesitation Satisfactory exhalation with 6 sec of smooth continuous exhalation Criteria for reproducibility Largest FVC within 0.2L of next largest FVC Largest FEV1 within 0.2L of next largest FEV1 If the two above not met, additional spirogram should be obtained

5. Variable effort, cough, early glottic closure can be seen on the graph but not at the values of the FEV1 and FVC

6. INTERPRETING SPIROMETRY Normal flow/volume Normal volume/time Acceptability

7. OBSTRUCTIVE LUNG DISEASE FEV1 reduced more than FVC with FEV1/FVC ratio <70-80%. FEV1 >80% Normal 60-80% mild obstruction 50-65% moderate obstruction <50% severe obstruction

8. Example of spirometry with mild obstruction Variable Means Predicted %Pred FVC 2.63 3.11 84 FEV1 1.58 2.28 69 FEV1/FVC 60 73 - FEF25-75% 0.59 3.56 23 PEF 4.9 5.78 85

10. RESTRICTIVE LUNG DISEASE Both FEV1&FVC reduced proportionately FEV1/FVC normal or elevated Example: Variable Means Predicted %Pred FVC 0.96 2.75 35 FEV1 0.94 1.90 49 FEV1/FVC 98 69 - FEF25-75% 2.25 2.11 107 PEF 2.98 5.40 55

12. UPPER AIRWAY OBSTRUCTION (UAO) Types Variable extra thoracic obstruction ( VEO ): inspiratory stridor, vocal cord paralysis, tracheomalacia. Variable intra thoracic obstruction ( VIO ): expiratory stridor, tracheomalacia, neoplasm Mixed : tracheal stenosis, foreign body or neoplasm

15. Mediastinal mass

16. Lack artifacts, start without hesitation, exhalation for 6 s

17. Examples

23. Example 1 Variable means predicted %pred FVC 2.62 2.82 93 FEV1 1.45 1.98 73 FEV1/FVC 55 70 FEF25-75% 0.43 2.20 20 PEF 4.50 5.48 82

24. Example 2 Variable Means Predicted %pred FVC 2.20 2.58 85 FEV1 1.79 1.85 97 FEV1/FVC 81 72 FEF25-75% 1.82 2.23 82 PEF 5.67 5.20 109

25. Example 3 Variable Means Predicted %pred FVC 5.08 4.94 103 FEV1 2.66 3.58 74 FEV1/FVC 52 72 FEF25-75% 1.40 3.47 40 PEF 6.49 9.10 71

26. Example 4 Variable Means Predicted %pred FVC 1.85 4.60 40 FEV1 0.92 3.33 28 FEV1/FVC 50 72 FEF25-75% 0.28 3.28 9 PEF 3.82 8.55 45

27. Example 5 Variable Means Predicted %pred FVC 2.78 2.75 101 FEV1 1.90 1.90 100 FEV1/FVC 69 69 FEF25-75% 0.95 2.35 40 PEF 4.82 5.45 88

28. Example 6 Variable Means Predicted %pred FVC 2.78 2.75 101 FEV1 1.90 1.90 100 FEV1/FVC 69 69 FEF25-75% 0.95 2.35 40 PEF 4.82 5.45 88

29. Example 7 Variable Means Predicted %pred FVC 3.66 4.39 83 FEV1 1.03 2.87 36 FEV1/FVC 28 65 FEF25-75% 0.33 2.48 13 PEF 4.29 8.33 52

30. Example 8 Variable Means Predicted %pr FVC 3.66 3.54 103 FEV1 2.30 2.77 83 FEV1/FVC 63 78 FEF25-75% 2.15 4.20 51 PEF 2.39 6.25 38

31. Example 9 Variable Means Predicted %pred FVC 3.66 3.54 103 FEV1 2.30 2.77 83 FEV1/FVC 63 78 FEF25-75% 2.15 4.20 51 PEF 2.39 6.25 38

32. Example 10 Variable Means Predicted %pred FVC 4.09 4.25 96 FEV1 1.95 2.88 68 FEV1/FVC 48 68 FEF25-75% 0.48 2.65 18 PEF 6.27 8.06 78

33. Example 11 Variable Means Predicted %pred FVC 1.40 2.48 56 FEV1 0.85 1.75 49 FEV1/FVC 61 74 FEF25-75% 0.37 2.11 18 PEF 1.30 5.10 25

34. Example 12 Variable Means predicted %pred FVC 3.02 3.41 88 FEV1 1.23 2.53 49 FEV1/FVC 41 74 FEF25-75% 0.41 2.77 15 PEF 3.95 6.10 65

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