DYNAMIC SPIROMETRY Dr Taj What is Spirometry It

DYNAMIC SPIROMETRY Dr. Taj

What is Spirometry ? It is a measurement of the breathing capacity of the lungs. It is the most basic and frequently performed test of pulmonary (lung) function.

Why “Dynamic” ? It measures the rate at which the lung changes volume during forced breathing maneuvers.

How is it performed ? Requirements � Vitalograph. � Mouthpiece (disposable). � Nose clip.

Procedure � Make a tight seal around the mouthpiece. � Ask subject to inhale deeply. � Then ask the subject to exhale as strong and as fast as possible.

Two types of curves can be obtained: � Flow-volume curve (Loops). � Forced expiratory volume curve (FEV).

Forced Expiratory Volume Curve

Flow Volume Curve

Normally: Forced expiratory curve Measures: � FEV 1=the volume of air exhaled in the 1 st second. � FVC=the total volume of exhaled air. � FEV 1/FVC ratio= normally ≈ 80%

What is the importance of Spirometry? � Helps in the diagnosis of pulmonary diseases. � Follow disease progression. � Determine strength and function of the chest.

Respiratory Diseases Obstructive Pulmonary Diseases ↑ airway resistance Restrictive Pulmonary Diseases ↓ Lung compliance

Obstructive pulmonary diseases � FEV 1 ↓↓↓↓ � FVC ↓ or ↔ � FEV 1/FVC ↓ Eg: Bronchial Asthma COPD (Emphysema)

Restrictive pulmonary disease � FEV 1 ↓↓ � FVC ↓↓ � FEV 1/ FVC ↔ or ↑ Eg: Pulmonary fibrosis Pneumoconiosis

EXAMPLE � Dynamic Spirometry was done on 3 patients, the results were the following: A. FEV 1= 4 L , FVC=5 L FEV 1/FVC=80% B. FEV 1=1. 2 L , FVC=3 L FEV 1/FVC=40% C. FEV 1= 2. 7 L, FVC=3 L FEV 1/FVC= 90%

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