1. Pulmonary Function Measurements

2. Why PFTS? To detect the presence or absence of pulmonary disease.
To classify disease as obstructive or restrictive
To quantify severity, progression, and reversibility.

3. Why PFTs To quantify therapeutic effectiveness
To assess risk for post-operative complications
Health Screening
To determine pulmonary disability – Federal requirements

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

5. Factors that affect lung volumes
Age
Sex
Height
Weight
Race
Disease
The main factor in determining reference range is?

6. Lung Volumes
Tidal volume (VT) Inspiratory reserve volume (IRV) Expiratory reserve volume (ERV) Residual volume (RV)

7. Tidal volume
The amount of air inhaled and exhaled with each breath during normal breathing.
Normal is 5 to 7 ml/kg
Often calculated by measuring Ve and dividing by the RR

8. Inspiratory Reserve Volume (IRV)
The amount of air that can be inhaled beyond the tidal volume.

9. Expiratory Reserve volume (ERV)
The amount of air that can be forcibly exhaled after a normal expiration.

10. Residual Volume - RV
The amount of air still in the lungs after a forced ERV

11. Lung Capacities
Vital capacity (VC) Inspiratory capacity (IC) Functional residual capacity (FRC) Total lung capacity (TLC)

12. Vital Capacity - VC
The maximal amount of air that can be exhaled after a maximal inspiration.
Can be an FVC or a SVC
Normal value ml/kg/Acceptable ml/kg
VC = IRV + TV + ERV

14. Inspiratory Capacity (IC)
The volume of air that can be inhaled after a normal exhalation.
Normal or predicted values obtained from a nomogram.
Average range ml
Used very often in bedside Respiratory Care in the form on an incentive spirometer.

15. Lung expansion Therapy - IS

16. Functional Residual Capacity – (FRC)
The amount of air remaining in the lungs after a normal exhalation.
FRC = ERV + RV
Important physiologically for oxygenation and complaince
Explain why

17. Normal Lung Volumes and Capacities
Figure 3-1.

18. Lung Volumes & Capacities

19. Restrictive vs Obstructive Disorders

20. Obstructive Lung Disorders
Figure 3-2.

21. Restrictive Lung Disorders
Figure 3-3.

22. Methods to measure Total Lung Volume/RV
Helium dilution
Based on fact that known amount of helium will be diluted by size of patient’s RV
Nitrogen washout
Based on fact that 79% of RV is nitrogen
Volume of nitrogen exhaled ÷ 0.79 = RV
Body box
Applies Boyle’s law to measure RV

23. Body Plethymography

25. Review the 3 techniques to measure total lung volume in your text books.

26. Pulmonary Mechanics
In addition to measuring volumes and capacities, we also measure rate at which gas flows in and out of lungs
Expiratory flow rate measurements provide data on integrity of airways and severity of airway impairment
Indicate whether patient has large or small airway obstruction

27. 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

28. Pulmonary Mechanics Measurements
Forced vital capacity (FVC) Forced expiratory volume timed (FEVT) Forced expiratory volume1sec/forced vital capacity ratio (FEV1/FVC ratio) Forced expiratory flow25%-75% (FEF25%-75%)

29. Pulmonary Mechanics Measurements
Forced expiratory flow (FEF )
Peak expiratory flow rate (PEFR)
Maximum voluntary ventilation (MVV)
Flow-volume loop

30. FVC
Maximum volume of gas that can be exhaled as forcefully and rapidly as possible after maximal inspiration.
Most commonly performed PFT – effort dependent
Additional measurements made from FVC

31. FVC
Figure 3-4.

32. Forced Expiratory Volume Timed (FEVT)
Maximum volume of gas that can be exhaled within specific time period
Measurement obtained from FVC
Most frequently used time period:
1 second

33. FEVT
Figure 3-5.

34. Normal FEVT
Normal percentage of total FVC exhaled during these time periods:
FEV0.5
60 percent
FEV1
83 percent
FEV2
94 percent
FEV3
97 percent

35. Forced Expiratory Volume1sec/Forced Capacity Ratio (FEV1/FVC Ratio)
Comparison of amount of air exhaled in 1 second to total amount exhaled during FVC maneuver
Commonly referred to as forced expiratory volume in 1 second percentage (FEV1%)

36. FVC, FEV1, and the FEV1%
Collectively, most commonly used pulmonary function measurements to:
Distinguish between obstructive and restrictive lung disorder
Determine severity of patient’s pulmonary disorder

37. Pulmonary Function Differences Between Obstructive and Restrictive Lung Disorder
In obstructive lung disorders, both FEV1 is decreased
In restrictive lung disorders, FEV1 normal or increased

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

39. Forced Expiratory Flow (FEF)25%-75%
Average flow rate that occurs during middle 50 percent of FVC measurement

40. FEF25%-75%
Figure 3-7.

41. FEF 25-75 Interpretation of % predicted: >60% Normal
40-60% Mild obstruction
20-40% Moderate obstruction
<10% Severe obstruction

42. FEF
Figure 3-9.

43. Peak Expiratory Flow Rate (PEFR)
Maximum flow rate that can be achieved during FVC maneuver.
Can be done a single test with a peak flowmeter to assess severity of airway obstruction in asthma and look at bronchodilator response.

44. PEFR
Figure 3-11.

45. Peak Flow Meter

46. Maximum Voluntary Ventilation (MVV)
Largest volume of gas that can be breathed voluntarily in and out of lung in 1 minute

47. MVV
Figure 3-13.

48. Flow-Volume Loop Graphic presentation of FVC maneuver
Plots flow and volume rather than flow and time.

49. FVC

50. Normal Flow-Volume Loop
Figure 3-14.

51. Figure 3-9. Flow-volume loop demonstrating the shape change that results from an obstructive lung disorder. The curve on the right represents intrathoracic airway obstruction.
Figure 3-15.

52. Figure Flow-volume loop demonstrating the shape change that results from a restrictive lung disorder. Note the symmetric loss of flow and volume.
Figure 3-16.

54. Factors Affecting Predicted Normal Values
Height
Taller subjects have greater pulmonary function values
Weight
In general, as weight increases, lung volumes decrease

55. Factors Affecting Predicted Normal Values
Age
After age 25, lung volumes, expiratory flow rates, and diffusing capacity values decrease
Gender
Males typically have greater lung volumes, expiratory rates, and diffusing capacities

56. Factors Affecting Predicted Normal Values
Race
Blacks and Asian subjects tend to have lower pulmonary function values than subjects of European-descent origin

57. Specialized Tests Airway Resistance Lung and Chest Wall Compliance
Airway Hyperresponsiveness
Bronchoprovocation Testing
FeNO

58. Exercise Tests
6-minute walk test
Cardiopulmonary Exercise Testing

59. Diffusion Capacity of Carbon Monoxide (DLCO)
Measures the amount of carbon monoxide (CO) that moves across the alveolar-capillary membrane
The average DLCO value for the resting male is 25 mL/min/mm Hg
Decreases in lung disorders that affect the A-C Membrane. Give some examples