Download REBREATHING

REBREATHING
(HYPERVENTILATION)
Learning Objectives
By the end of today's laboratory you will be able to describe and explain the:
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Effects on the respiratory pattern of rebreathing expired gas
REBREATHING
Inhalation of part or all of gases previously exhaled.
It is breathing in a closed system.
Exhaled gas mixes with the gas in the system, and some of this mixture is then
reinhaled.
Rebreathing, which may result in progressively decreasing concentrations of
oxygen and progressively increasing concentrations of carbon dioxide in the
blood, can occur in poorly ventilated environments.
2 MAIN EFFECTS OF REBREATHING
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Rebreathing from a closed bag results in arterial hypercapnia (raised partial
pressure of carbon dioxide), which stimulates respiration.
Generally breathing becomes deeper and slightly faster.
Importance of rebreathing after hyperventilation
when hyperventilating, the air is moving in and out of the body too rapidly
which, in turn, brings the level of carbon dioxide in the blood below normal.
Low carbon dioxide levels cause the calcium levels in the body's fluids to also
go below normal, which affects the nerves (hence the tingling and dizziness).
When breathing into a paper bag (more calmly and slowly, if possible) will
increase the carbon dioxide level in the bag. Then, as you rebreathe the air you
just exhaled, the increased level of carbon dioxide in the air you're in taking
will increase the level of CO2 in your bloodstream and restore your calcium
levels.
Rebreather
A rebreather is a breathing apparatus that absorbs the carbon dioxide of
a user's exhaled breath to permit the rebreathing (recycling) of the
substantially unused oxygen content of each breath.
Rebreather technology may be used where breathing gas supply is limited,
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such as:
underwater or in space
in firefighting,
mine rescue,
high altitude operations,
or where the breathing gas is specially enriched or contains
expensive components, such as helium diluent or anaesthetic
gases.
Exercise 3
In this exercise, you will observe the effect of rebreathing exhaled gases. You will
need to obtain a medium-sized paper bag. When re-breathing, the volunteer should
place this so that it covers the nose and mouth and forms a tight seal.
Set up
PROCEDURE
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Click Start. Enter a comment: 'baseline', and click Add.
Record the baseline for 2-3 minutes.
Enter a comment: 'rebreathing'.
Click Add and immediately ask the volunteer to place the paper bag over the
nose and mouth, and rebreathe the air in the bag.
Enter a comment: 'breathe'.
After 60 seconds of rebreathing, click Add; then immediately ask the
volunteer to remove the paper bag from the nose and mouth.
Continue recording for 60 seconds.
Click Stop.
ANALYSIS
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Rebreathing from a closed bag results in arterial hypercapnia (raised partial
pressure of carbon dioxide), which stimulates respiration. How was this
evident in this exercise? (That is, did the depth or rate or both increase during
rebreathing compared to normal breathing?)
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