1. Measurement of Lung Function
School of
Medicine
New York
University
Measurement of Lung Function
Beno Oppenheimer, M.D.
NYU/Bellevue Medical Ctr.
Div. Pulmonary & Critical Care Medicine

2. Lung Volumes TLC IC TV VC FRC ERV RV Time
Vol (L)
TLC IC TV VC
FRC
ERV
PIc 3 vol. that are conventional. At 0 flow. FRC balance TLC max insp effort giving sense of stiffness ( compliance) RV at max expirat giving sense of resistance and mostly infl by resistance. RV
Time

4. Spirometry Now we see determinants of RV!!! 3 TLC Vol (L) 1 VC FRC 2 4
Time (s)
Flow( L/sec)
Now we see determinants of RV!!! 1 4 2 3
TLC
FRC RV
Vol (L)

5. Lung Volumes Flows Diffusion
Normal Physiology
Lung Volumes
Flows
Diffusion

6. Determinants of Lung Volumes

7. Determinants of FRC
FRC

8. Normal Lung Structure

9. Lung Compliance. Determinant of TLC
120%
100%
Normal
80%
60%
Lung Volume (% predicted TLC)
Palv DV
Ppl
40% DP
20%
Recoil pressure 0% 10 20 30 40 50 60 70
Transpulmonary Pressure (cm H O) 2
(Palv - Ppl)

10. Exhaled Volume (liter)
Assessment of Airflow
1sec
TLC
Flow( L/sec) 1
FEV1 2
FVC
Exhaled Volume (liter) 3
FRC 4
During exhalation, diameter decr res increases flow decreases in a homogeneous manner with a normal lung. 5
TLC
FRC RV
FEV1 = 4.0
FVC = 5.0
% = 80
Vol (L)

11. Determinants of flow Flow = Alveolar Driving Pressure / Resistance
Altered driving pressure
Lung recoil
Muscle strength
Altered resistance
Size of the airways
Number of parallel airways
Collapsibility of airway walls
P musc
P recoil DP
Flow = R
Remember driving pressure relative to mouth pressure and /or PIP

12. Increasing # of Parallel Airways Decreases Resistance in Periphery
Pedley et. at. Respir Physiol 1970; 9:387
West JB. Respiratory Physiology

13. Effect of Airway Collapsibility on Flow- +
No Flow
Inspiration
Expiration

14. Maximal Expiratory Flow – Volume Curve
Adapted from West JB. Respiratory Physiology

15. Effort Independence of Maximal Expiratory Flows (at mid – low lung volumes)
FVL powerful tool because even with suboptimal flow, terminal ,loop unafected (caveat, extremely poor effort still problematic)
Why does this behavior occur?
West JB. Respiratory Physiology

16. Maximal Airflow at TLC “effort dependent”
“driving pressure”
45-0 = 45
“driving pressure”
145-0 = 145 10 10
100
100 20
120 35
135
Palv= 45
Palv= 145
Precoil = 35
Precoil = 35
Pmusc = 10
Pmusc = 100
Volume V V
Volume

17. Maximal Airflow at 50% VC “effort independent”
106
102
Palv= 108
100
Pmusc = 100
Precoil = 8 10 10
“driving pressure”
18-10 = 8
“driving pressure”
= 8 12 16
Palv= 18
Precoil = 8
Pmusc = 10
Volume V
Volume V

18. Effort Independence of Maximal Expiratory Flows (at mid – low lung volumes)
FVL powerful tool because even with suboptimal flow, terminal ,loop unafected (caveat, extremely poor effort still problematic)
Why does this behavior occur?
West JB. Respiratory Physiology

19. Diffusion Capacity
[CO] i
[CO] e

20. Clinical Application

21. Emphysema

22. Maximal Expiratory Airflow
Normal
Emphysema
Low flow, normal VC
Role for recoil

23. Emphysema
Effort dependent V
Volume
Effort independent

24. Emphysema

26. Lung Histology
Normal
Emphysema

27. Lung Volumes and Diffusion
Hyperinflation

28. Increased Static Lung Compliance
120%
Emphysema
100%
Normal
80%
60%
Lung Volume (% predicted TLC)
(high expiratory flow rates)
Same DP yields
a larger DV = high compliance
40%
20% 0% 10 20 30 40 50 60 70
Transpulmonary Pressure (cm H O) 2

29. Summary
Increased static lung compliance (loss of lung parenchyma → low lung recoil)
Increased lung volumes (hyperinflation)
Decreased flows (airway collapsibility and reduced recoil)
Decreased diffusion capacity

30. Asthma

31. Exhaled Volume (liter)
Normal
Asthma
1sec
1sec
TLC
TLC 1 1
FEV1
FVC IC IC 2 2
Exhaled Volume (liter) 3
FRC 3
FRC
ERV 4
ERV 4 5 5 RV RV RV
FEV1 = 4.0
FVC = 5.0
% = 80
FEV1 = 2.13
FVC = 3.11
% = 68

33. Normal Static Lung Compliance
120%
100%
Normal
80%
Recoil pressure
60%
Lung Volume (% predicted TLC) DV
40% DP
20% 0% 10 20 30 40 50 60 70
Transpulmonary Pressure (cm H O) 2

34. Narrowed airway
Mucus
Contracted muscle
Inflammation

35. Effect of Heterogeneity of Disease on Gas Distribution

36. Effects of Heterogeneity on the Shape of the Maximal Expiratory Flow Volume Curve

37. Summary Airway Obstruction Decreased flows
Air trapping (Increased RV, Decreased ERV)
Normal static lung compliance (Normal lung parenchyma)
Normal diffusion capacity

38. Pulmonary Fibrosis

39. Maximal Expiratory Airflows
Normal
Fibrosis
Lung recoil important for max flow

40. Pathology
Normal
Fibrosis

41. reduced
increased
reduced

42. Reduced Static Lung Compliance
120%
100%
Normal
80%
Lung Volume (% predicted TLC)
60%
Pulmonary Fibrosis
(high expiratory flow rates)
40%
Same DP yields
a smaller DV = low compliance
20% 0% 10 20 30 40 50 60 70
Transpulmonary Pressure (cm H O) 2

43. Summary Decreased static lung compliance (increased lung recoil)
Decreased lung volumes
Increased flows (in relation to volume: ↑ FEV1/FVC)
Decreased diffusion capacity

44. Normal Asthma Emphysema Pulmonary Fibrosis
Flow [l/s]
Emphysema
Pulmonary Fibrosis

45. Kyphoscoliosis

46. PFT’s

47. Pulmonary Function Tests