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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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