Chapter 3 Pulmonary Function Study Assessments Mosby items

Introduction Pulmonary function studies are used to: Evaluate pulmonary causes of dyspnea Differentiate between obstructive and restrictive pulmonary disorders Ø Assess severity of the pathophysiologic impairment Ø Follow the course of a particular disease Ø Evaluate the effectiveness of therapy Ø Assess the patient’s preoperative status Ø Ø Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 2

Normal Lung Volumes and Capacities Mosby items and derived items © 2011, 2006 by

Table 3 -1. Lung Volumes and Capacities of Normal Recumbent Subjects 20 to 30

Table 3 -2. Restrictive Lung Disorders: Lung Volume and Capacity Findings Mosby items and

Table 3 -4. Obstructive Lung Disorders: (Lung Volume and Capacity Findings) Mosby items and

Table 3 -5. Anatomic Alterations of the Lungs Associated with Obstructive Lung Disorders: (Pathology of the Tracheobronchial Tree) Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 7

Figure 3 -1. Visual comparison of lung volumes and capacities in obstructive and restrictive lung disorders. (From Wilkins RL, Stoller JK, Scanlan CL: Egan’s fundamentals of respiratory care, ed 9, St Louis, 2009, Elsevier. ) Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 8

Indirect Measurements of the Residual Volume and Capacities Containing the Residual Volume Closed-circuit helium dilution test Open-circuit nitrogen washout test Body plethysmography Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 9

Forced Expiratory Flow Rate and Volume Measurements Mosby items and derived items © 2011,

Forced Vital Capacity (FVC) The FVC is the total volume of gas that can be exhaled as forcefully and rapidly as possible after a maximal inspiration. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 11

Figure 3 -2. Forced vital capacity (FVC). A is the point of maximal inspiration and the starting point of an FVC maneuver. Note the reduction in FVC in obstructive pulmonary disease. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 12

Forced Expiratory Volume (FEVT) The maximum volume of gas that can be exhaled over a specific period is the FEVT. This measurement is obtained from an FVC measurement. Commonly used time periods are 0. 5, 1. 0, 2. 0, 3. 0, and 6. 0 seconds The most commonly used time is 1 second (FEV 1 ). Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 13

Figure 3 -3. Forced expiratory volume timed (FEVT). In obstructive pulmonary disease, more time is needed to exhale a specified volume. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 14

Forced Expiratory Volume (FEVT) (Cont’d) In the normal adult, the percentage of total volume exhaled during these time periods: Ø Ø FEV 0. 5: 60% FEV 1: 80% FEV 2: 94% FEV 3: 97% Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 15

Forced Expiratory Volume in 1 Second/Forced Vital Capacity Ratio (FEV 1/FVC Ratio) (also abbreviated as FEV 1%) Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 16

FEV 1/FVC Ratio or FEV 1% The FEV 1/FVC ratio compares the amount of air exhaled in 1 second with the total amount exhaled during an FVC maneuver. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 17

FVC, FEV 1, and FEV 1% Clinically, the FVC, FEV 1, and FEV 1% are commonly used to: 1. Assess the severity of a patient’s pulmonary disorder and 2. Determine whether the patient has an obstructive or a restrictive disease Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 18

FVC, FEV 1, and FEV 1% (Cont’d) The primary pulmonary function study difference between an obstructive and a restrictive lung disorder are as follows: In an obstructive disorder, the FEV 1 and FEV 1% are both decreased. Ø In a restrictive disorder, the FEV 1 is decreased and FEV 1% is normal or increased. Ø Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 19

Forced Expiratory Flow 25%-75% The FEF 25%-75% is the average flow rate generated by the patient during the middle 50% of an FVC measurement. FEF 25%-75% is used to evaluate the status of medium-to-small airways in obstructive lung disorders. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 20

Figure 3 -4. FEF 25%-75%. This test measures the average rate of flow between

Forced Expiratory Flow 200 -1200 The FEF 200 -1200 measures the average flow rate between 200 and 1200 m. L of an FVC. The FEF 200 -1200 provides a good assessment of the large upper airways. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 22

Forced Expiratory Flow 200 -1200 (Cont’d) The FEF 200 -1200 measures the average flow rate between 200 and 1200 m. L of an FVC. The FEF 200 -1200 provides a good assessment of the large upper airways. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 23

Figure 3 -5. FEF 200 -1200. This test measures the average rate of flow between 200 m. L and 1200 m. L of an FVC. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 24

Peak Expiratory Flow Rate The PEFR is the maximum flow rate generated during an

˙ ˙ Figure 3 -6. PEFR. The steepest slope of the DV/DT line is

Maximum Voluntary Ventilation (MVV) The MVV is the largest volume of gas that can be breathed voluntarily in and out of the lungs in 1 minute. Ø Note: The patient effort during the MVV is for only 12 to 15 seconds. The total 1 minute MVV is extrapolated from these data. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 27

Figure 3 -7. Volume-time tracing for an MVV maneuver. Mosby items and derived items

Flow-Volume Loop The flow-volume loop is a graphic illustration of both a forced vital capacity (FVC) maneuver and a forced inspiration volume (FIV) maneuver. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 29

Flow-Volume Loop (Cont’d) Depending of the sophistication of equipment, several important pulmonary function study values can be obtained, including: • • FVC FEVT FEF 25%-75% FEF 200 -1200 PEFR Peak inspiratory flow rate (PIFR) FEF 50% Instantaneous flow at any given lung volume during forced inhalation and exhalation Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 30

Figure 3 -8. Flow-volume loop. Mosby items and derived items © 2011, 2006 by

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. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 32

Figure 3 -7. Volume-time tracing for a maximum voluntary ventilation (MVV) maneuver. Note: the patient actually performs the MVV maneuver for only 12 sec, not 60 sec. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 33

Figure 3 -10. Flow-volume loop demonstrating the shape change that results from a restrictive lung disorder. Note the symmetric loss of flow and volume. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 34

Table 3 -8. Obstructive Lung Diseases: Forced Expiratory Flow Rate and Volume Findings Mosby

Pulmonary Diffusion Capacity The pulmonary diffusion capacity of carbon monoxide (DLCO) measures the amount of carbon monoxide (CO) that moves across the alveolar-capillary membrane. Mosby items and derived items © 2011, 2006 by Mosby, Inc. , an affiliate of Elsevier Inc. 36