 INTRODUCTION OF POWERLAB WITH RESPECT TO
RESPIRATION
 Power lab has 2 section for performing respiration
practical's:
 Breathing
 Respiratory flow & volume
BREATHING
 This device was developed by the French scientist ÉtienneJules Marey (1830-1904) to indicate movements of the chest
due to breathing. It is mounted on a spring plate which
returns to its original position when the breath is expired.
An example of an early spirometer: Hutchinsons
spirometer.
OBJECTIVE
 In this laboratory, you will record breathing movements with
a respiratory belt transducer fastened around the abdomen.
 You will investigate various aspects of breathing, including
the ability to hold the breath, hyperventilation, rebreathing,
and the relation between breathing and heart rate.
SET UP
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PROCEDURE
Fasten the respiratory belt around the abdomen of a
volunteer,. The transducer should be:
o At the front of the body, level with the navel.
o Tightened sufficiently that it remains under tension even
when the subject fully exhales.
The respiratory belt transducer can be used over clothing,
and it doesn't matter whether the volunteer is sitting or
standing, so long as they are comfortable (this is quite a long
exercise). Because breathing patterns differ, you may need
to reposition the transducer over the chest rather than the
abdomen to get the best signal.
Connect the plug on the respiratory belt transducer cable to
Input 1 on the front of the PowerLab.
It is important when recording normal respiration that the
volunteer is facing away from the computer screen and is not
consciously controlling breathing. The volunteer may have to
stare out a window or read a book to avoid conscious control
of respiration.
TROUBLESHOOTING
 Safety
 The finger pulse and respiratory belt transducer are perfectly
safe when connected to Input 1 or Input 2 of a PowerLab.
However, those inputs are not isolated and must not be used
for direct electrical connection to human subjects.
 Hyperventilation
 Should the volunteer during the hyperventilation exercise
develop giddiness or dizziness, stop the procedure, but
record the respiratory response. If volunteers feel unwell,
have them re-breathe expired air by cupping hands over
nose and mouth for a few minutes or breathing into the
paper bag provided for the next exercise.
 Incorrect placement of the respiratory belt transducer
 Too low on the abdomen.
 Too loose or too tight. It is better initially to have the belt tight
rather than too loose as the signal depends on the belt being
stretched effectively.
 The writing on the belt should face away from the body (this
ensures that the transducer is correctly oriented).
 Be aware that different people have different patterns of
breathing; volunteers who play wind instruments, or who
have trained voices, will provide a much stronger signal from
the abdomen, whereas most people breathe from the upper
abdomen and lower thorax.
 Noise during recording from the pulse transducer
 The MLT1010 finger pulse transducer is a very sensitive
instrument. Even slight movements by the volunteer can
result in noisy recordings.
 Instruct the volunteer to keep their hand as still as possible
between stimuli.
Respiratory Flow & Volume
OBJECTIVES
 In this laboratory, you will be introduced to spirometry as a
technique for recording respiratory variables.
 You will record and analyze lung volumes and capacities, as
well as design your own experiment to examine some aspect
of respiratory air flow and volume.
Respiration apparatus according to Zuntz.
SPIROMETER, REGISTERING THE MOVEMENTS OF
THE CHEST, THE QUANTITY OF EXPIRED AIR AND THE
TIME DURING WHICH THE PHENOMENA OCCUR
EQUIPMENT SETUP
SPIROMETER
Lung volumes and capacities
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PROCEDURE
Connect the Spirometer Pod to Input 1 on the PowerLab.
Since the Spirometer Pod is sensitive to temperature and
tends to drift during warm-up, turn on the PowerLab for at
least 5 minutes before use. To prevent temperature drift due
to heating of the Pod, place it on a shelf or beside the
PowerLab, away from the PowerLab power supply.
Connect the two plastic tubes from the respiratory flow head
to the short pipes on the back of the Spirometer Pod.
Attach Clean Bore tubing, a filter and mouthpiece to the flow
head.
Make sure you have access to the following equipment for
different parts of the experiment.
o Tape measure for measuring volunteer height.
o Extra mouthpieces and disposable air filters for each
volunteer.
 If you are suffering from a respiratory infection, do not
TROUBLESHOOTING
 Safety
 You should be familiar with the relevant safety notes at the
start of the hardware manual.
 Students with active respiratory infection should not
volunteer for this experiment.
 Volume correction Procedure:
 The volume correction procedure allows more accurate
measurement of volume to be made from the integration of
the flow channel. Humidification of air in the lungs commonly
increases the exhaled volume by 5-10%.
 The determination of the volume correction factor to account
for this increase in volume can create confusion with
students early on in the experiment.
 You may choose to use the default correction factor of 1.0
(no correction), rather than allow students to determine it
themselves.
 Please advise the students whether they should perform this
part of the experiment or not.
POSSIBLE PROBLEMS THAT COULD ARISE IN THIS
EXPERIMENT INCLUDE:
 Unusual or poor forced breath recordings. These usually
arise from faults in technique.
o Failure to take a full inspiration or hesitation early in
expiration will produce a value for FVC significantly
lower than the real value.
o Prolonged forced expirations can result in coughing and
narrowing of the airways, which reduces performance.
This can be overcome by the volunteer discontinuing
the expiration, and waiting until their breathing has fully
recovered before attempting another forced breath.
o Most problems can be avoided if the volunteers clearly
understand the task they are about to perform and if
breath maneuvers are practiced before recording.
 Spirometer Pod does not zero.
o Make sure the Spirometer Pod is attached to Input 1 on
the PowerLab
o Make sure the tubing ports on the back of the
Spirometer Pod are not blocked.
VOLUME CHANNEL DRIFTS EXCESSIVELY.
o Make sure the pod or front-end are connected and
turned on at least 15 minutes prior to any recording.
o If the volume correction procedure is being performed,
check that students have performed it correctly. By
default the volume correction ratio is set to 1.08.
Students should have a value greater than one, but no
greater than 1.3 – 1.4. Values less than one are not
appropriate. The ratio can be set manually in the
Spirometry Panel of LabTutor.
o All recordings should start with a brief portion of zero
flow; hence the instructions to click ‘Start’, then pick up
the flow head and start breathing through it. If flow is
not zero when recording is started the volume channel
will not be calculated correctly.
THANK YOU