lung volumes and gas distribution - report interpretation ret 2414l pulmonary function testing...
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Lung Volumes and Gas Distribution- Report Interpretation
RET 2414LPulmonary Function TestingModule 3.0
Lung Volumes / Gas Distribution
Lung Volumes
The most significant volumes for evaluating the effects of pulmonary disorders are VC, FRC, RV, and TLC
Lung Volumes / Gas Distribution
RV and TLC Determination
Determination of RV and TLC are based on the FRC from indirect spirometry and volumes measured during direct spirometry
RV = FRC – ERV or RV = (FRC+IC) - VC
TLC = FRC + IC or TLC = (FRC – ERV) + VC
Lung Volumes / Gas Distribution
Lung Volume Changes
Restrictive patterns
Obstructive patterns
Demonstrate reductions in ALL lung volumes
Demonstrate increases in only some lung volumes
Exception: VC may be normal or even decreased
Lung Volumes / Gas Distribution
Significance/Pathophysiology
Obstructive Pattern
Increase FRC is considered pathologic
FRC values >120% of predicted represent air trapping
Emphysematous changes Obstruction caused by asthma or
bronchitis
Lung Volumes / Gas Distribution
Significance/Pathophysiology
Obstructive Pattern
Increased RV often results in a equivalent decrease in VC
Increased RV is characteristic of: Emphysema Bronchial obstruction
RV and FRC usually increase together
Lung Volumes / Gas Distribution
Significance/Pathophysiology
Obstructive Pattern
As RV becomes larger, increased ventilation is needed to adequately exchange O2 and CO2
Requires increased VT and/or respiratory rate
Work of breathing is increased Often display hypoxemia or CO2
retention
Lung Volumes / Gas Distribution
Obstructive Pattern
Two types of obstructive patterns
•Increases in RV with a proportional reduction in VC; TLC remains constant (normally 80-120% of Predicted)
Air Trapping
Lung Volumes / Gas Distribution
Obstructive Pattern
Two types of obstructive patterns
•RV increases with little or no change in VC; TLC increased proportional to RV(TLC >120% of predicted)
Hyperinflation
Lung Volumes / Gas Distribution
Significance/Pathophysiology
Restrictive Pattern FRC, RV and TLC typically decreased
Usually lung volumes are decreased equally
When TLC is <80% a restrictive process is present
RV/TLC is relatively normal
Lung Volumes / Gas Distribution
Significance/Pathophysiology
Restrictive Pattern
Asbestosis Sarcoidosis Complicated silicosis Neuromuscular disorders Respiratory depression Diaphragmatic paralysis CHF
Lung Volumes / Gas Distribution
Significance/Pathophysiology
Restrictive Pattern
Kyphoscoliosis Obesity Pleural effusion Pneumonia Tumor Atelectasis Surgical excisions
Lung Volumes / Gas Distribution
RV/TLC Ratio
Describes the percentage of total lung volume that must be ventilated by tidal breathing
Lung Volumes / Gas Distribution
RV/TLC Ratio
The RV/TLC ratio also known as RV/TLC% and is expressed as a percentage
RV/TLC% = RV x 100 TLC
In normal, young, healthy adults, the RV/TLC% ranges between 20% and 35%
Lung Volumes / Gas Distribution
TLC and RV/TLC Ratio
RV/TLC% >35% + Normal TLC =
RV/TLC% >35% + >Normal TLC =
AIR TRAPPING
HYPERINFLATION
Lung Volumes / Gas Distribution
Lung Volume Changes
Patterns of Lung Volume Changes
Volume Restrictive Air Trapping HyperinflationTLC N VC NFRC RV RV/TLC% N
Case 3 – 1
History
M.B. is a 27-year-old male high school teacher whose chief complaint is dyspnea on exertion. He states that his breathlessness has worsened over the past several months. He has smoked one pack of cigarettes per day for 10 years (10 pack years). He denies a cough or sputum production. No one in his family ever had emphysema, asthma, chronic bronchitis, carcinoma, or tuberculosis. There is no history of exposure to extraordinary environmental pollutants.
Case 3 – 1
Personal Data
Sex: MaleAge: 27 yrHeight: 65 inWeight: 297 lbBody surface area (BSA): 2.28 M2
Case 3 – 1
Spriometry and Airway Resistance
Predrug Pred %PredFVC (L) 2.90 4.7 62FEV1 (L) 2.47 3.86 64FEV1% 85 82 -FEF 25%-75% 4.62 4.35 106FEF 50% 4.94 5.82 85MVV (L/M) 178 130 137Raw 2.33 0.6-2.4SGaw 0.23 0.12-0.50
Case 3 – 1
Lung Volumes by (plethysmograph)
Predrug Pred %PredVC (L) 2.90 4.7 62IC (L) 1.96 2.91 67ERV (L) 0.94 1.8 59FRC (L) 1.87 3.29 57RV (L) 0.93 1.49 57TLC (L) 3.83 6.2 62RV/TLC% 25 24
Case 3 – 2
History
R. B. is a 37-year-old pipe fitter whose chief complaint is shortness of breath at rest and with exertion. His dyspnea has worsened in the past 6 months, so much so that he is no longer able to work. Additional symptoms include a dry cough. He admits some sputum production when he has a chest cold. He has smoked one pack of cigarettes per day for 19 years (19 pack years). He quit smoking approximately 3 weeks before the tests. His father died of emphysema, and his mother of lung cancer. His brother is in good health. His occupational exposure includes working for the past 13 years in the assembly room of a boiler plant. He admits to seldom using the respirators provided at work despite a dusty environment.
Case 3 – 2
Personal Data
Sex: MaleAge: 37 yrHeight: 69 inWeight: 143
Case 3 – 2
Spirometry
Predrug Pred %Pred Postdrug %Pred %
FVC (L) 3.04 5.05 60 3.10 61 2%FEV1 (L) 2.03 3.90 52 2.26 58 11%FEV1% 67 77 - 73 -FEF 25%-75% 1.3 4.09 32 1.60 39 23%FEF 50%2.12 5.78 37 2.42 42 14%FEF 25%0.78 2.95 26 1.2 41 54%MVV (L/M) 83 141 59 91 65 10%Raw 2.51 0.6-2.4 - 2.47 -SGaw 0.14 0.11-0.44 0.15 -
Case 3 – 2
Lung Volumes (by N2 Washout)
Predrug Pred %PredVC (L) 3.04 5.05 60IC (L) 1.62 3.18 51ERV (L) 1.42 1.87 76FRC (L) 2.75 3.81 72RV (L) 0.33 1.94 69TLC (L) 4.37 6.99 63RV/TLC% 30 28 -