Question

spirometry  

describe the differents devises how to use them , what are the formula and the important of these formula.

talk about the physiology and definition of the formula

Answer 1

Spirometry is the most common pulmonary function tests. It is used to assess how well lungs work by measuring how much air you inhale and exhale.

It is used to diagnose some respiratory diseases such as asthma, COPD etc

–Different devices :

1.spirometer

2.Respirometer(modified spirometer)

3. Computed spirometry ( in use)

4. Plethysmography–to measure lung functional volume such as residual volume as it cannot be measured by spirometer.

1. SPIROMETER - it is made of metal and consists of an outer chamber where water is filled and a drum is placed in inverted position. A weight is attached to the drum by means of a string. A pen is attached to the counterweight and is attached to the recording device.

Inner chamber is inverted and has a small hole at the top. A metal passes upwards towards the top. A rubber tube is connected to the outer end of the metal tube. At the end of rubber tube a mouth piece is attached through which a person respires.

When the subject breathes with spurometer;during expiration drum moves up and couterweight comes down and reverse is for inspiration. Upward and downward movements of counterweight are recorded in graph. It can only be used for one breath as oxygen cannot be provided to subject with spirometer.

2.RESPIROMETER - it is a modified spirometer with provision for removal of carbon dioxide and supply of oxygen. Carbon dioxide is removed by placing soda lime in instrument and oxygen is provided with oxygen cylinder through valve system.

3. COMPUTED SPIROMETRY - computerized spirometer is a equipment in which subject has to respire into a sophisticated transducer which is connected to computer. The computer is preprogrammed and calculates and geaphs the results.

4. PLETHYSMOGRAPHY -  used to measure residual volume. It is based on Boyle's law which states that volume of gas is inversely proportional to pressure of gas at constant temperature. Subject sits in a whole body plethysmograph and breathes normally through mouthpiece connected to a fliw transducer called pneumotachograph which detects the volume changes during different faces of respiration. By mesuring volume and pressure changes inside the chamber, volume of lungs is calculated by