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The photographs are taken from behind (a) and from the right side (b) of one of the paediatric subjects
'Jonathon'that was testing the procedure (used with permission) as he performs a single exhalation
into the mouthpiece. I have labelled the connections and analysers as seen below (not all visible in
both photographs):
1. Mouth piece.
2. Connector.
3. NO analyser (Model2107, Dasibi Corporation).
4. CO2 analyser (Morgan capnograph).
5. Low flow pneumotachograph (CT Platon Limited).
6. Mouth pressure analyser (Medex Straingauge pressure transducer).
7. Galtec pressure amplifier (Galtec Limited).
8. GM electrospirometer (GM Instruments Limited).
9. Four channel pen chart recorder (Linseis Limited).
10. Timing device.
11. NO zero calibration column.
12. Calibration gases (BOC gases Ltd).
13. The f irst of the pages listing instructions on the wall.
5.4 Assessments of the analysers
The response time of each analyser had to be determined to enable direct comparisons. The
chart recorder recorded continuously at a paper speed of 50mm/second and was set so that as
the recording came off, the signals were read from right to left. An oscilloscope was
connected to the system with a three way tap which on turning allowed the test gas to flow
down at the apparatus at a rate comparable to the subjects' expiratory flow rate (500mls/min
was chosen) starting at the subject mouthpiece. The output of the analyzers was displayed on
the same oscilloscope. The measurement of the delay time and the response time was then
measured with a stop watch.
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