Sibelmed DATOSPIR MICRO A, Руководство пользователя

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Chapter 7: Spirometry Technique
DATOSPIR MICRO User’s Manual 201
511-A00-MU2 • REV. 2.06
shown to be similar or to have equivalent results. The volume
extrapolated using this method must be below 5% of the vital
capacity or 150 ml, without exceeding either of the two criteria.”
“To ensure good spirometry, the technician will pay particular
attention to ensure that the patient has made the utmost effort,
that the start has been good and that no coughing or Valsava’s
manoeuvre due to glottis closure has occurred. Special attention
must be paid to preventing expiration from ending too soon,
which would be detected in the end of the curve, which would
be too perpendicular to the horizontal base line. Sometimes
the patient inadvertently partially obstructs the mouthpiece
with his tongue or false teeth. It is essential that the best two
expirations from the best three acceptable curves do not vary by
more than 200 ml of FVC or FEV1. The best effort cannot only
be determined by merely inspecting the spirometric curve but
also by checking the measurements to determine the maximum
values. The independent selection of FVC and FEV1 sometimes
causes greater variability, as factors such as learning, tiredness or
bronchial spasms caused by expiration come into play. The best
FEV1 does not have to be rejected when the manoeuvre from
which it originates has ended prematurely. However, FEF25-75%
is influenced by the vital capacity of the curve chosen. Falsely
high values may be recorded if a manoeuvre with a shortened
or lower vital capacity than the real vital capacity of the patient
has been chosen. It seems that the most practical criterion is
to choose the manoeuvre containing the FVC and FEV1 with the
highest sum among the three chosen for calculation.”
7.2 CALIBRATIONS
“As well as the calibration procedures included by the manufacturer
in the appliance to quickly check the working order of the basic
pneumotachometer circuits and mechanisms, it must be possible
to check the appliance through external signals. These signals
must be as similar as possible in terms of flows, volumes and
times to the biological signal for which the instruments were
designed, i.e. forced expiration. This is not always possible,