pulmonary function testing1
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Pulmonary Function Testing
The Basics o f In terp retat ion
Jennifer Hale, M.D.
Valley Baptist Family Practice Residency
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Objectives
Identify the components of PFTs
Describe the indications
Develop a stepwise approach to interpretation
Recognize common patterns
Apply this information to patient care
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Pulmonary Function TestingJennifer Hale, M.D.
Which of the following is used to follow disease severity in
COPD patients?
a. Total lung capacity (TLC)
b. Degree of responsiveness to bronchodilators
c. Forced vital capacity (FVC)
d. Forced expiratory volume in 1 second
e. Diffusing capacity (DLCO)
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Pulmonary Function TestingJennifer Hale, M.D.
A 36yo WF, non-smoker, presents to your office for follow-upof recurrent bronchitis. You suspect asthma and decideto order spirometry. Which of the following would youinclude in your prescription for testing?
a. Diffusing Capacity (DLCO)
b. If no obstruction present, add trial of bronchodilator
c. If no obstruction present, perform methacholine challenge
d. Flow volume loop
e. b and c
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Pulmonary Function TestingJennifer Hale, M.D.
A 68yo HM is admitted to the ICU with acute respiratorydistress. A CXR obtained in the ED demonstratesbilateral pulmonary infiltrates, and his DLCO is
elevated. What is the most likely diagnosis?
a. Pulmonary edema
b. Aspiration pneumonitis
c. Pulmonary emboli
d. Alveolar hemorrhage
e. Interstitial lung disease
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The Purpose
Provide quant i f iab le, reproducib lemeasurement of lung function
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Description
Spirometry
Flow Volume Loop
Bronchodilator response Lung volumes
Diffusion capacity (DLCO)
Bronchoprovocation testing
Maximum respiratory pressures
Simple and complex cardiopulmonary exercise
testing
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Indications Diagnosis
Evaluation of signs and symptoms
- SOB, exertional dyspnea, chronic cough
Screening at-risk populations
Monitoring pulmonary drug toxicity
Abnormal study
- CXR, EKG, ABG, hemoglobin
Preoperative assessment
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Indications Diagnosis
Evaluation of signs and symptoms
- SOB, exertional dyspnea, chronic cough
Screening at-risk populations Evaluation of occupational symptoms
Monitoring pulmonary drug toxicity
Abnormal study
- CXR, EKG, ABG, hemoglobin
Preoperative assessment
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Indications Prognostic
Assess severity
Follow response to therapy
Determine further treatment goals
Referral for surgery
Disability
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Lung Volumes
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Spirometry
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Normal Spirometry
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Obstructive Pattern
Decreased FEV1
Decreased FVC
Decreased FEV1/FVC
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Obstructive Lung Disease
DifferentialDiagnosis
Asthma
COPD
- chronic bronchitis
- emphysema
Bronchiectasis
Bronchiolitis
Upper airway obstruction
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Restrictive Pattern
Decreased FEV1
Decreased FVC
FEV1/FVC normalorincreased
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Restrictive Lung Disease
DifferentialDiagnosis
Pleural
Parenchymal
Chest wall
Neuromuscular
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Spirometry Patterns
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Bronchodilator Response
Degree to which FEV1 improves with inhaled
bronchodilator
Documents reversible airflow obstruction
Significant response if:
- FEV1 increases by 12% and >200ml
Request if obstructive pattern on spirometry
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Flow Volume Loop
Spirogram
Measures forced inspiratory and expiratoryflow rate
Augments spirometry results
Indications: evaluation of upper airway
obstruction (stridor, unexplained dyspnea)
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Flow Volume Loop
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Upper Airway Obstruction
Variable intrathoracic obstruction
Variable extrathoracic obstruction
Fixed obstruction
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Lung Volumes
Measurement:
- helium
- nitrogen washout
- body plethsmography
Indications:
- Diagnose restrictive component- Differentiate chronic bronchitis from
emphysema
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Lung Volumes Patterns
Obstructive
- TLC > 120% predicted
- RV > 120% predicted
Restrictive
- TLC < 80% predicted- RV < 80% predicted
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Diffusing Capacity
Diffusing capacity of lungs for CO
Measures ability of lungs to transport inhaled gasfrom alveoli to pulmonary capillaries
Depends on:
- alveolarcapillary membrane
- hemoglobin concentration
- cardiac output
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Diffusing Capacity
Decreased DLCO
(120-140% predicted)
Asthma (or normal)
Pulmonary hemorrhage
Polycythemia
Left to right shunt
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DLCO Indications
Differentiate asthma from emphysema
Evaluation and severity of restrictive lungdisease
Early stages of pulmonary hypertension
Expensive!
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Case1
CC/HPI:A 36yo WM, nonsmoker, presents to yourclinic with c/o episodic cough for 6mo. Alsoreports occasional wheezing and dyspnea withexertion during softball practice.
Exam: Heart RRR, no murmurs; Lungs CTAB, nolabored breathing
Based on your exam and a thorough review ofsystems, you suspect asthma and decide toorder spirometry for further evaluation.
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Continued
PFTs: FEV1 86% predicted
FEV1/FVC 82% predicted
Flow Volume Loop: normal inspiratory and
expiratory pattern
You still suspect asthma. What is your next
step in the workup of this patient?
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Bronchoprovocation
Useful for diagnosis of asthma in the
setting ofnormalpulmonary function tests
Common agents:
- Methacholine, Histamine, others
Diagnostic if: 20% decrease in FEV1
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Continued
SYMPTOMS
PFTs
OBSTRUCTION?
YES NO
TREATBRONCHOPROVOCATION
Obstruction?
TREAT
No Obstruction?
Other Diagnosis
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PFT Interpretation Strategy
What is the clinical question?
What is normal?
Did the test meet American Thoracic Society
(ATS) criteria?
Dont forget (or ignore) the flow volume loop!
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Obstructive Pattern Evaluation
Spirometry
FEV1, FVC: decreased
FEV1/FVC: decreased (
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Restrictive Pattern Evaluation
Spirometry FVC, FEV1: decreased
FEV1/FVC: normal or increased
FV Loop witchs hat
DLCO decreased
Lung Volumes TLC, RV: decreased
Muscle pressures may be important
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PFT Patterns
Emphysema
FEV1/FVC
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PFT Patterns
Asthma
FEV1
/FVC normal or decreased
DLCO normal or increased
But PFTs may be normalbronchoprovocation
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Pulmonary Function TestingJennifer Hale, M.D.
Which of the following is used to follow disease severity in
COPD patients?
a. Total lung capacity (TLC)
b. Degree of responsiveness to bronchodilators
c. Forced vital capacity (FVC)
d. Forced expiratory volume in 1 second
e. Diffusing capacity (DLCO)
-
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Pulmonary Function TestingJennifer Hale, M.D.
Which of the following is used to follow disease severity in
COPD patients?
a. Total lung capacity (TLC)
b. Degree of responsiveness to bronchodilators
c. Forced vital capacity (FVC)
d. Forced expiratory volume in 1 second
e. Diffusing capacity (DLCO)
-
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Pulmonary Function TestingJennifer Hale, M.D.
A 36yo WF, non-smoker, presents to your office for follow-upof recurrent bronchitis. You suspect asthma and decideto order spirometry. Which of the following would you
include in your prescription for testing?
a. Diffusing Capacity (DLCO)
b. If no obstruction present, add trial of bronchodilator
c. If no obstruction present, perform methacholine challenged. Flow volume loop
e. b and c
-
7/27/2019 Pulmonary Function Testing1
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Pulmonary Function TestingJennifer Hale, M.D.
A 36yo WF, non-smoker, presents to your office for follow-upof recurrent bronchitis. You suspect asthma and decideto order spirometry. Which of the following would you
include in your prescription for testing?
a. Diffusing Capacity (DLCO)
b. If no obstruction present, add trial of bronchodilator
c. If no obstruction present, perform methacholine challenged. Flow volume loop
e. b and c
-
7/27/2019 Pulmonary Function Testing1
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Pulmonary Function TestingJennifer Hale, M.D.
A 68yo HM is admitted to the ICU with acute respiratorydistress. A CXR obtained in the ED demonstratesbilateral pulmonary infiltrates, and his DLCO is
elevated. What is the most likely diagnosis?
a. Pulmonary edema
b. Aspiration pneumonitis
c. Pulmonary embolid. Alveolar hemorrhage
e. Interstitial lung disease
-
7/27/2019 Pulmonary Function Testing1
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Pulmonary Function TestingJennifer Hale, M.D.
A 68yo HM is admitted to the ICU with acute respiratorydistress. A CXR obtained in the ED demonstratesbilateral pulmonary infiltrates, and his DLCO is
elevated. What is the most likely diagnosis?
a. Pulmonary edema
b. Aspiration pneumonitis
c. Pulmonary embolid. Alveolar hemorrhage
e. Interstitial lung disease
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Quest ions?
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References
1. Aboussouan LS, Stoller JK: Flow volume loops. UpToDate, 2006.
2. Bahhady IJ, Unterborn J: Pulmonary function tests: an update. Consultant.
2003.
3. Barreiro, TJ, Perillo I: An approach to interpreting spirometry. Am Fam
Physician. 2004 Mar 1;69(5):1107-14.
4. Chesnutt MS, Prendergast TJ. Current Medical Diagnosis and Treatment.New York: Appleton and Lange, 2006.
5. Enright PL: Diffusing capacity for carbon monoxide. UpToDate, 2007.
6. Enright PL: Overview of pulmonary function testing in adults. UpToDate,
2007.
7. Irvin CG: Bronchoprovocation testing. UpToDate, 2006.8. West JB. Respiratory Physiology: The Essentials. Lippincot Williams &
Wilkins, 2000.