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SP-2 User Guide
Art. No. 71022-0000 Welch Allyn Schiller ©2000
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Spirometry Tips -How To Do It and Common Pitfalls and Problems
Patient-Related Problems
The most common patient-related problems when performing the FVC manoeuvre are:
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Submaximal effort
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Leaks between the lips and mouthpiece
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Incomplete inspiration or expiration (prior to or during the forced manoeuvre)
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Hesitation at the start of the expiration
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Cough (particularly within the first second of expiration)
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Glottic closure
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Obstruction of the mouthpiece by the tongue
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Vocalization during the forced manoeuvre
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Poor posture.
Once again, demonstration of the procedure will prevent many of these problems, remembering that all effort-dependent measurements
will be variable in patients who are uncooperative or trying to produce low values.
Glottic closure should be suspected if flow ceases abruptly during the test rather than being a continuous smooth curve. Recordings
in which cough, particularly if this occurs within the first second, or hesitation at the start has occurred should be rejected. Vocalization
during the test will reduce flows and must be discouraged - performing the manoeuvre with the neck extended often helps.
