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Note added at 10 mins (2008-08-28 07:00:25 GMT)
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A spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs.
You can read a full description by clicking on the link below.
http://en.wikipedia.org/wiki/Spirometer

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Note added at 28 mins (2008-08-28 07:17:39 GMT) Post-grading
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Thank you, Casey. I was looking online and the pronunciation of spirometer in English is given both with the short "i" sound as in the word, "it"(which I would tend to prefer, myself), but it is also given with the long "i" sound as an alternative pronunciation which would explain the "supAI" in the katakana of your term.
The only other possibility I could think of is "spyrometer" which is not even in my big dictionary, but can be found if you search it on the internet. But if it makes sense in your document that the term means an apparatus for measuring breathing, then "spirometer" should be it. I assume that the "SPIR" part of spirometer comes from the same root as respiration.