1. Pulmonary Function Tests
Wanida Paoin

2. Objectives Review basic pulmonary anatomy and lung volume.
Indication for PFTs.
Technique and basic interpretation of spirometry.
Difference between obstructive and restrictive lung disease.
Clinically application

3. Conducting Airways
Air travels via laminar flow through the conducting airways:
trachea,
lobar bronchi,
segmental bronchi,
subsegmental bronchi,
small bronchi,
bronchioles, and
terminal bronchioles.

4. From Netter Atlas of Human Anatomy, 1989

5. Gas Exchange Capillaries are wrapped around alveoli.
Approximately 300 million alveoli
Alveolar-capillary barrier: 0.3 μm in some places, surface area of square meters! (size of a tennis court)
Murray & Nadel: Textbook of Respiratory Medicine, 3rd ed., Copyright © 2000 W. B. Saunders Company

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

7. Pulmonary Function Tests
Pulse oximetry
Blood gases
End tidal CO2
Spirometry
Peak expiratory flow rate
Bronchial challenge testing
Exercise tests
Respiratory muscle pressure measurement
Lung volumes by helium dilution or body plethysmography
Diffusing capacity

8. Pulmonary Function Tests
Evaluates 1 or more major aspects of the respiratory system
Lung volumes
Airway function
Gas exchange

9. Indications Detect disease
Evaluate extent and monitor course of disease
Evaluate treatment
Measure effects of exposures
Assess risk for surgical procedures
Assess bronchial hyperreactivity

10. Evaluate extent and monitor course of disease
Obstructive disease
- asthma
- FB
- subglottic, tracheal stenosis
- tracheomalacia
- vascular ring
- vocal cord paralysis

11. Evaluate extent and monitor course of disease
Restictive disease
- external compression: thoracic cage abnormality, pleural effusion, pneumothorax, obesity, scoliosis
- unexpanded lung: interstitial fibrosis, pulmonary edema
- neuromuscular disease: poliomyelitis, myasthenia grevis

12. 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

13. Spirometry
Measurement of the pattern of air movement into and out of the lungs during controlled ventilatory maneuvers.
หายใจเข้าเต็มที่ หายใจออกแรงเต็มที่ ส่วนใหญ่ทำได้ในเด็ก > 6 ปี
Silhouette of Hutchinson Performing Spirometry, From Chest, 2002

14. Limitation They do not act alone.
They act only to support or exclude a diagnosis.

15. Mechanical Properties
Compliance
Describes the stiffness of the lungs
volume / 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

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

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

18. Special Considerations
Ability to perform spirometry dependent on developmental age of child, personality, and interest of the child.
Patients need a calm, relaxed environment and good coaching. Patience is key.
Even with the best of environments and coaching, a child may not be able to perform spirometry.

19. Parameter from spirometer
PEFR
Spirogram
FVC
FEV1
FEF25-75
Flow-Volume Curve

20. Technique Give instructions and demonstrate
Acceptable criteria
< 10 y: > 3 min
> 10 y: > 6 min
or no more volume > 1 min
Not inhale
No air leak
No pause
Give instructions and demonstrate
Patient performs the maneuver
Sit / Stand direct
Puts nose clip on
Inhales maximally
Puts mouthpiece on mouth and closes lips around mouthpiece
Exhales as hard and fast and long as possible
Repeat minimum of three times (check for reproducibility.)
Use the best value for interpretation as %predicted of control (age, height, sex, race)
2 maximum FVC different < 10%
(adapted from ATS, 1994)

21. FVC 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

22. FEV1 Forced expiratory volume in 1 second: (FEV1)
Volume of air forcefully expired from full inflation (TLC) in the first second
Normal people can exhale more than 80% of their FVC in the first second (FEV1/FVC)

23. FEF25-75 Forced expiratory flow 25-75% (FEF25-75)
Mean forced expiratory flow during middle half of FVC
May reflect effort independent expiration and the status of the small airways
Highly variable
Depends heavily on FVC

24. PEFR

25. PEFR Peak flow meter device Technique Sit/Stand direct
Inhales maximally
Puts mouthpiece on mouth and closes lips around mouthpiece
Blow out as hard and fast as possible
Repeat minimum of three times
Use the best value for interpretation as %predicted / personal best
Clinical application: monitor severity, daily variability, pre and post bronchodilator
Green : > 80%
Yellow : 50-79%
Red : < 50%
Normal < 20%
Normal < 12%

26. Categories of Disease
Obstructive
Restrictive
Mixed

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

28. FEV1 Interpretation of % predicted: >80% Normal
65-79% Mild obstruction
50-64% Moderate obstruction
<49% Severe obstruction

29. Spirometry Interpretation:
% predicted
FVC
> 80%
FEV1
FEF25-75%
> 70%
PEFR
FEV1/FVC
> 80% absolute value

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

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

32. Spirometry Interpretation: Obstructive vs. Restrictive Defect
What parameter is the most sensitive in airway obstruction?
Parameter
Obstructive Disorders
Restrictive Disorders
FVC
FEV1
FEF25-75%
FEV1/FVC
PEFR
N or ↓ ↓
↓ ↓
↓ N to ↓
↓ N or ↑
↓ N to ↓

33. Spirometry Interpretation:
Obstructive Disorders
Characterized by a limitation of expiratory airflow
Examples:
Asthma
Bronchiectasis
COPD
Cystic Fibrosis
Restrictive Disorders
Characterized by reduced lung volumes/decreased lung compliance
Examples:
Interstitial Fibrosis
Kyphoscoliosis
Obesity
Lung Resection
Neuromuscular diseases
Cystic Fibrosis
Improve FEV1 เมื่อ asthma ดีขึ้น

34. Flow-Volume Loop
PEFR
Do FVC maneuver and then inhale as rapidly and as much as able.
The expiratory and inspiratory flow volume curves put together make a flow volume loop.
flow
expiration
volume
inspiration
TLC RV
Ruppel GL. Manual of Pulmonary Function Testing, 8th ed., Mosby 2003

35. Restrictive Lung Disease
Characterized by diminished lung volume
Decreased TLC, FVC
Normal or increased: FEV1/FVC ratio

36. Obstructive Lung Disease
Characterized by a limitation of expiratory airflow
Examples: asthma, COPD

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

38. Incomplete exhalation Variable extrathoracic ob
Flow-Volume Loops L1 R1 L2 R2 L3 R3
Incomplete exhalation
Variable extrathoracic ob L4
Variable intrathoracic ob
Fixed central or up aw ob
Inadq effort
Restrictive lung disease
(Rudolph and Rudolph, 2003)

39. Spirometry: Pre and Post Bronchodilator
Obtain spirogram and flow-volume loop.
Pre and 15 minutes after administration of the bronchodilator
Salbutamol MDI 4 puffs via valve spacer
Slow inhale
Breath hold 5-10 sec.
5-10 sec pause between each puff.
Reversibility: FEV1 / PEFR > 12%
Improve flow-volume loop.

40. PEFR Inhales maximally Exhales as hard and fast and short as possible
Repeat minimum of three times
Use the best value for interpretation as %predicted of control / personal best
Highly effort dependent
Diurnal variation (normal < 20%)
Different value in each devices

41. Exercise challenge test
Perform spirometry
Exercise 6-8 min (tread mill) till HR /min
Repeat spirometry at 5, 10, 15, 20, 30 min
EIB: FEV %, or wheezing

42. Respiratory muscle testing
Measure maximum inspiratory P. (PImax, MIP) or negative inspiratory force (NIF)
Maximum inhale via pressure manometer
Normal < -60 cmH2O
Useful for evaluation neuromuscular dis: myasthenia grevis, Guillian-Barre syndrome, diaphragmatic paralysis, pre-extubation
Other parameter: FVC, PEFR

43. Clinical Applications

44. Case #1 Case #1 Parameter Actual %Predicted FVC (L) 4.11 116 FEV1 (L)
3.28
108
FEV1/FVC (%) 80 93
FEF25-75% (L/s)
6.94 88
PEFR (L/s)
3.15
107

45. Case #2 Parameter Actual (best) Predicted %Predicted FVC (L) 4.31 4.4497
FEV1 (L)
2.15
3.83 56
FEV1/FVC (%) 50 86 58
FEF25-75% (L/s)
0.93
4.27 22
PEFR (L/s)
5.23
8.01 65

46. Case #3 Parameter Actual (best) Predicted %Predicted FVC (L) 1.24 3.6034
FEV1 (L)
1.19
3.09 38
FEV1/FVC (%)
95.65
86.00
111
FEF25-75% (L/s)
1.69
3.48 48
PEFR (L/s)
4.37
6.70 65

47. Case #4 Parameter Actual (best) Predicted %Predicted FVC (L) 3.40 4.9369
FEV1 (L)
2.17
4.25 51
FEV1/FVC (%)
63.72
84.68 75
FEF25-75% (L/s)
1.09
4.75 23
PEFR (L/s)
6.65
9.00 73

48. Case #5 Parameter Pre %Pred Post FVC (L) 1.58 84 1.91 102 21.07
%Change
FVC (L)
1.58 84
1.91
102
21.07
FEV1 (L)
1.04 63
1.44 87
38.62
FEV1/FVC
66.05 77
75.63 88
14.50
FEF25-75%
0.55 27
1.10 55
101.64
PEFR (L/s)
2.39 73
3.42
104
42.85