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Objectives:Explain the main concepts of lung volumes and capacities.
Describe the Spirometer and explain its importance.
Observe experimentally the Spirometry.
Measure the FEV1/FVC & its interpretation.
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Measurement of lung volumes provides a tool for understanding normal function of the lungs as well as disease states.
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Tidal Volume: volume of air inspired & expired with each normal breath. Normal TV is approximately 500 ml
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Vital Capacity: Is IRV+TV+ ERV. Normal VC is approximately 4600 ml .Is the volume of air that can be expired forcefully after taking maximum inspiration.
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What is Spirometry ? Spirometry: Is the most
common of the Pulmonary Function Tests (PFTs)
Is a method of assessing lung function by measuring the volume(amount)& flow(speed) of air the patient can expel from the lungs after a maximal inspiration
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Why Perform Spirometry?
• Measure airflow obstruction to help make a definitive diagnosis .
•Distinguish between Obstructive and Restrictive diseases of the lungs.
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Spirometers
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Standard Spirometric IndicesThe Spirometer calculates different
ventilation parameters:FVC - Forced vital capacity:
The total volume of air that can be forcibly exhaled in one breath after taking maximum inspiration
FEV1 - Forced expiratory volume in one second:
The volume of air that can be expired in the first second during forceful expiration
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Predicted Normal Values
Age
Height
Weight
Sex
Ethnic Origin
Affected by:
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•Normally the whole FVC is expelled in four seconds•Forced expiratory volume (FEV1): the volume of air expelled in the first
second of a forced Exhalation.•In normal subjects 75-80% of the FVC can be expelled in the first second.•FEV1/FVC : the normal value is 75-80%. Anything below this is considered abnormal.
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FEV1 curve
Spirometry is a valuable tool for analyzing the flow rate of air passing into and out of the lungs. Flow volume loops provide a graphical illustration of a patient's spirometric efforts.
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Spirogram Patterns
Normal
Obstructive
Restrictive
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obstructive and restrictive diseases
• Lung disease is often divided into two broad categories: obstructive disease and restrictive disease.
• Examples of obstructive disease are Emphysema, Chronic Bronchitis, and bronchial Asthma.
• Examples of restrictive disease are abnormalities of the spine and chest and diseases within the lungs that make them less elastic (“stiffer”), such as pulmonary fibrosis.
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Criteria for Normal
FVC: more than 80% of predicted value
FEV1: more than 80% of predicted value
FEV1% : 70 to 80%
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Normal Trace Showing FEV1 and FVC
1 2 3 4 5 6
1
2
3
4
Volu
me,
liters
Time, seconds
FVC5
1
FVC = 5L
FEV1 = 4L
FEV1% = 80%
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Spirometry: Obstructive Disease
Obstructive
Volu
me,
liters
Time, seconds
5
4
3
2
1
1 2 3 4 5 6
FEV1 = 1.8L
FVC = 3.2L
FEV1/FVC = 0.56
Normal
Diagnosis of COPD is confirmed by FEV1% less than 70%
Reduced peak flow Slow rise, reduced volume
expired; prolonged time to
full expiration17
FEV1 = 1.9L
FVC = 2.0L
FEV1/FVC = 0.95
Spirometry: Restrictive Disease
Volu
me,
liters
Time, seconds
1 2 3 4 5 6
5
4
3
2
1
Normal
Restrictive
Normal shape, reduced volume
Fast rise to plateau at reduced
maximum volume 18Diagnosis of Restrictive Lung Disease – FVC
decreased, FEV1 decreased but FEV1 % normal or above normal
Thank You
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