MANUAL PHYSIOLOGY PRACTICAL - Repository:The Medical ...
MANUAL PHYSIOLOGY PRACTICAL - Repository:The Medical ...
MANUAL PHYSIOLOGY PRACTICAL - Repository:The Medical ...
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FM/UOJ<br />
This method is based on Weir’s formula:<br />
Where,<br />
EE = (Oi – Oe) X Ve X 21.1 Kj/hr.<br />
Oi = oxygen fraction in inspired air,<br />
Oe = Oxygen fraction expired air,<br />
Ve = Volume of expiratory air in liters, and 21.1 is Weir’s constant.<br />
This method is easy because Oi is a constant atmospheric air) and Oe and Ve can<br />
be measured accurately. <strong>The</strong> volume should be in STP<br />
Instruments<br />
Douglas bag, Wet gas meter, oxygen analyzer (with drying agents)<br />
Method<br />
Take a Douglas bag and roll it empty and turn the tap so that it is closed and any<br />
air coming through the tube will go out. Seat the subject comfortably and connect<br />
Douglas bag through appropriate mouth piece, one way valve and tubing and apply the<br />
nose clip. When the subject is accustomed to the instruments, turn the tap and collect the<br />
expired air for five minutes.<br />
At the end of the time, disconnect the bag and connect it to the gas meter (after<br />
bringing the pointers of the gas meter to zero) and roll the bag to empty the air trough the<br />
gas meter. Hold a thermometer in the outlet of the air stream to measure the temperature<br />
at which the volume is measured. Take a sample of the air and pass it through the Oxygen<br />
analyzer and measure the concentration of Oxygen. Record the pressure at the barometer.<br />
Calculation<br />
Divide the Oxygen concentration by 100 to make it the fraction. Look at the<br />
saturated vapour pressure chart and get the vapour pressure at temperature recorded<br />
which will help to calculate the pressure of the dry expiratory gas. Convert the volume to<br />
STP and calculate the volume of expired air for one hour (Vs), Oi is a constant Oe is<br />
measured. Using these values, calculate the energy expenditure.<br />
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Exercise<br />
Metabolism & Temperature<br />
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