1. Pulmonary Function Tests
Dr Tasaduk Khan. MD. FRCP(UK). FCCP(USA)
Consultant Internist & Pulmonologist.
Security Forces Hospital,
Riyadh.
9/16/2018

2. Pulmonary Function Testing
Uses a variety of maneuvers to measure and record the properties of four(4) lung components.
1) Airways( large & small)
2) Lung parenchyma( alveoli, interstitium)
3) Pulmonary vasculature.
4) Bellows- pump mechanism.
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3. Basic concepts of normal pulmonary physiology that are involved in pulmonary function testing include.
1) Mechanics( air flows and lung volumes)
2) V/Q interrelationship.
3) Diffusion & gas exchange.
4) Respiratory muscle or bellows strength.
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4. Types of PFT Peak flow meter 2. Spirometry
3. Measurement of lung volumes-Plethismography
4. Gas transfer factor
5. Exercise test- 6 min walk test, ergometer test
6. ABG
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5. PFT Indications
Evaluation of symptoms such as chronic persistent cough, wheezing, dyspnea, and exertional cough or chest pain.
Objective assessment of bronchodilator therapy.
Assessing the presence of disease in a patient with known risk factors, such as smoking.
Evaluation of effects of exposure to dusts or chemicals at work.
Risk evaluation of patients prior to thoracic or upper abdominal surgery.
Objective assessment of impairment or disability.
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6. 3. Measurement of lung volumes-Plethismography 4. Gas transfer factor
Peak flow meter
2. Spirometry
3. Measurement of lung volumes-Plethismography
4. Gas transfer factor
5. Exercise test- walk test, ergometer test
6. ABG
9/16/2018

7. PEFR
The peak expiratory flow rate (PEFR, also known as peak flow) is the maximal rate that a person can exhale during a short maximal expiratory effort after a full inspiration.
Monitoring the PEFR is useful for detecting changes or trends in a patient’s asthma control.
An individual patient's normal PEFR range is defined as 80 and 100 percent of their personal best.
The personal best is generally the highest PEFR achieved during 2 wks post-treatment monitoring period.
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8. Peak Flow Meter Cheapest and easy 2. Home management of asthma
3. In absence of spirometer, establish, assess and monitor Bronchial asthma
4. PEF variability= (Max PEFR-Min PEFR)x100/Max PEFR; >20% is suggestive of Bronchial Asthma
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12. Types of PFT Peak flow meter 2. Spirometry
3. Measurement of lung volumes-Plethismography
4. Gas transfer factor
5. Exercise test- 6 min walk test, ergometer test
6. ABG
9/16/2018

13. Spirometry
Spirometry, in which a maximal inhalation is followed by a rapid and forceful complete exhalation into a spirometer, includes measurement of FEV1 and FVC. Spirometry is used to measure forced expiratory flow rates and volumes.
The results of spirometry can be used to determine the following:
Determine whether baseline airflow limitation (obstruction) is present (reduced FEV1/FVC ratio)
Assess the reversibility of the obstructive abnormality Characterize the severity of airflow limitation
For patients with normal airflow (normal FEV1/FVC ratio), identify a restrictive pattern as an alternate explanation for dyspnea (eg, FVC <80 percent predicted)
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14. Spirometry - Forced expiratory volume in one second (FEV1)
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)

16. 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

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

18. 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)

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

20. 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

21. FEF25-75 Interpretation of % predicted: >60% Normal
40-60% Mild obstruction
20-40% Moderate obstruction
<10% Severe obstruction

22. Flow Volume Curve
Illustrates maximum expiratory and inspiratory flow-volume curves
Useful to help characterize disease states (e.g. obstructive vs. restrictive)
Maximum expiratory flow (PEF)
Expiratory flow rate
L/sec
FVC RV
TLC
Inspiratory flow rate
L/sec
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Volume (L)

23. Categories of Disease
Obstructive
Restrictive
Mixed

24. Obstructive Disorders
Characterized by a limitation of expiratory airflow
Examples: asthma, COPD
Decreased: FEV1, FEF25-75, FEV1/FVC ratio (<0.8)
Increased or Normal: TLC

25. Spirometry in Obstructive Disease
Slow rise in upstroke
May not reach plateau

26. Restrictive Lung Disease
Characterized by diminished lung volume due to:
change in alteration in lung parenchyma (interstitial lung disease)
disease of pleura, chest wall (e.g. scoliosis), or neuromuscular apparatus (e.g. muscular dystrophy)
Decreased TLC, FVC
Normal or increased: FEV1/FVC ratio

27. Restrictive Disease Rapid upstroke as in normal spirometry
Plateau volume is low

28. Large Airway Obstruction
Characterized by a truncated inspiratory or expiratory loop

29. Normal Spirometry
Image source:

30. Obstructive Pattern Decreased FEV1 Decreased FVC Decreased FEV1/FVC
- <70% predicted
FEV1 used to follow severity in COPD
Image source:
FEV1 is decreased out of proportion to FVC, which causes the ratio to decrease as well.

31. Obstructive Lung Disease — Differential Diagnosis
Asthma
COPD
- chronic bronchitis
- emphysema
Bronchiectasis
Bronchiolitis
Upper airway obstruction
This is not a complete list, just some of the most common diseases that should be on your differential for obstructive lung disease.

32. Restrictive Pattern Decreased FEV1 Decreased FVC
FEV1/FVC normal or increased
Image source:
FEV1 decreases in proportion to decrease in FVC, so ratio remains normal or even slightly increased

33. Restrictive Lung Disease —Differential Diagnosis
Pleural
Parenchymal
Chest wall
Neuromuscular
Restrictive lung disease is made up of intrinsic lung disease (causes inflammation and scarring (interstitial lung diseases) or fill the airspaces w/ debris, inflammation (exudate); extrinsic causes are chest wall or pleural diseases that mechanically compress the lung and prevent expansion. Neuromuscular causes decreases ability of respiratory muscles to inflate and deflate the lungs.

34. Flow Volume Curve Patterns Obstructive and Restrictive
Severe obstructive
Restrictive
Expiratory flow rate
Expiratory flow rate
Expiratory flow rate
Volume (L)
Volume (L)
Volume (L)
Reduced peak flow, scooped out mid-curve
Steeple pattern, reduced peak flow, rapid fall off
Normal shape, normal peak flow, reduced volume
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35. 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
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36. Bronchodilator Reversibility Testing in COPD
Spirometry (continued)
Possible dosage protocols:
400 µg β2-agonist, or
µg anticholinergic, or
the two combined
FEV1 should be measured again:
10-15 minutes after a short-acting b2-agonist
30-45 minutes after the combination
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37. Bronchodilator Reversibility Testing
An increase in FEV1 that is both greater than 200 ml and 12% above the pre-bronchodilator FEV1 (baseline value) is considered positive response.
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38. Bronchoprovocation Test-Indications
Diagnosis of asthma: typical symptoms but normal spirometry and no response to BD; atypical symptoms eg nocturnal awakening, cough; evaluate occupational asthma, reactive airways dysfunction syndrome, or irritant-induced asthma; screening test for asthma, such as scuba divers, military personnel.
Assesssment of asthma therapy.
Identification of specific asthma triggers 
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39. Methacholine challenge test
Generally, a methacholine PC20 of 8 mg/mL (<4 mg/mL, for SGaw) or less is considered a positive test. A PC20 greater than 16 mg/mL is considered a negative test.
Positive test indicates AHR, which is present mostly in Asthma.
False positive MCT can occur in allergic rhinitis, cystic fibrosis, heart failure, COPD, and bronchitis.
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40. Examples - Unacceptable Traces
Troubleshooting
Examples - Unacceptable Traces

41. Unacceptable Trace – Slow Start
Normal
Volume, liters
Time, seconds
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42. Unacceptable Trace - Coughing
Normal
Volume, liters
Time, seconds
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43. Unacceptable Trace – Extra Breath
Normal
Volume, liters
Time, seconds
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44. 9/16/2018

45. Lung function Tests Peak flow meter 2. Spirometry
3. Measurement of lung volumes-Plethismography
4. Gas transfer factor
5. Exercise test- walk test, ergometer test
6. ABG
9/16/2018

46. Lung Volumes 4 Volumes 4 Capacities Sum of 2 or more lung volumes IRVIC VC
TLC TV
ERV
FRC RV RV

47. Because spirometry is an expiratory maneuver, it
Lung volumes.
Because spirometry is an expiratory maneuver, it
measures exhaled volumes or vital capacity but
doesn`t measure RV, FRC or TLC.
TLC is measured from FRC+ IC
IC is measured by spirometry.
FRC is measured by gas dilution technique.
9/16/2018

49. 3. Measurement of lung volumes-Plethismography 4. Gas transfer factor
Peak flow meter
2. Spirometry
3. Measurement of lung volumes-Plethismography
4. Gas transfer factor
5. Exercise test- walk test, ergometer test
6. ABG
9/16/2018

50. DLCO
DLCO measures the ability of the lungs to transfer gas from inhaled air to the red blood cells in pulmonary capillaries.
The DLCO is low in ILD,but normal in disorders of pleura, chest and neuromuscular disorder causing restrictive lung function.
DLCO is also useful for following the course of or response to therapy in ILD.
9/16/2018

51. 3. Measurement of lung volumes-Plethismography 4. Gas transfer factor
Peak flow meter
2. Spirometry
3. Measurement of lung volumes-Plethismography
4. Gas transfer factor
5. Exercise test- walk test, ergometer test
6. ABG
9/16/2018

52. Exercise Tests uses Exercise testing with spirometry: EIB
6 MWT: provide simple, repeatable assessments of disability and response to treatment.
Finally, cardiopulmonary exercise testing using cycle or treadmill exercise with measurement of metabolic gas exchange, ventilation and cardiac responses is useful in distinguishing cardiac limitation from respiratory limitation in the breathless patient.
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53. ABG
Arterial blood gases (ABGs) may be a helpful adjunct to pulmonary function testing in selected patients.
The primary role of measuring ABGs in stable outpatients is to confirm hypoventilation when it is suspected on the basis of clinical history (eg, respiratory muscle weakness, advanced COPD), an elevated serum bicarbonate level, and/or chronic hypoxemia.
ABGs also provide a more accurate assessment of the severity of hypoxemia in patients who have low normal oxyhemoglobin saturation
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54. Question 1 Q. Spirometry is indicated for all except?
Unexplained cough.
Unexplained shortness of breath.
Follow up of Asthma treatment.
Hemoptysis.
Follow up of Interstitial lung disease.
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55. Question 2 Q. Spirometry measures all except.
Total lung capacity(TLC).
FEV1.
FVC.
FEV1/FVC.
FEF 25-75%.
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56. Question 3 Q. In obstructive airway disease all are true except.
FEV1 is low.
FVC is low.
FEV1/ FVC is low.
FEV1 is high.
FVC can be normal.
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57. Question 4 Q. Pulmonary function testing includes all except. PEFR.
Spirometry.
Echocardiography.
Timed six minute walk test.T6MWT.
ABG.
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58. Question5 Q. In restrictive defect all are correct except?
FEV1/ FVC is high/ N.
TLC is low or normal.
FEV1 can be normal.
DLCO is always low.
FEF 25-75% is normal.
9/16/2018