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Physiology Lab Spirometry. 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. Lung volumes and capacities.
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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.
Lung volumes and capacities Measurement of lung volumes provides a tool for understanding normal function of the lungs as well as disease states.
Tidal Volume: volume of air inspired & expired with each normal breath. Normal TV is approximately 500 ml
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.
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
Why Perform Spirometry? • Measure airflow obstruction to help make a definitive diagnosis . • Distinguish between Obstructive and Restrictive diseases of the lungs.
Standard Spirometric Indices • The 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
Predicted Normal Values Affected by: • Age • Height • Weight • Sex • Ethnic Origin
FEV1 curve • 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.
Flow- volume loop • 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.
Spirogram Patterns • Normal • Obstructive • Restrictive
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.
Criteria for Normal • FVC: more than 80% of predicted value • FEV1: more than 80% of predicted value • FEV1% : 70 to 80%
Normal Trace Showing FEV1 and FVC FVC 5 4 FVC = 5L FEV1 = 4L FEV1% = 80% Volume, liters 3 2 1 1 2 3 4 5 6 1 Time, seconds
Spirometry: Obstructive Disease 5 4 Normal Obstructive 3 Volume, liters FEV1 = 1.8L FVC = 3.2L FEV1/FVC = 0.56 2 1 Reduced peak flow Slow rise, reduced volume expired; prolonged time to full expiration 1 2 3 4 5 6 Diagnosis of COPD is confirmed by FEV1% less than 70% Time, seconds
Spirometry: Restrictive Disease Normal 5 4 3 FEV1 = 1.9L FVC = 2.0L FEV1/FVC = 0.95 Volume, liters Restrictive 2 1 Normal shape, reduced volume Fast rise to plateau at reduced maximum volume 1 2 3 4 5 6 Time, seconds Diagnosis of Restrictive Lung Disease – FVC decreased, FEV1 decreased but FEV1 % normal or above normal