Ventway Sparrow User Manual
Page 47 of 144
9.6. NUMERICAL REPRESENTATION OF BREATH PARAMETERS
The measured and computed values that are displayed in the system are
calculated using the filtering and smoothing techniques described below.
Patient pressure is displayed to the user by a bar (graphic refreshing
frequency is 10 Hz). The sample rate of the pressure value is 500 Hz. The Peak
Inspiratory Pressure is displayed as a blue background, remaining
throughout the current breath, while the current pressure is displayed in
green.
Altimeter input is averaged per second and linearly interpolated.
Oxygen percentage correction factor for density correction is taken from a
table. Oxygen value is determined by the user.
Oxygen level is determined by the external Oxygen Mixer. However, the user
is required to determine the oxygen correction factor (determined in the O
2
enrichment screen) in accordance with the actual oxygen level given.
Flow correction factor is taken from the last performed volume calibration.
Real time flow values are calculated using linear interpolation and corrected
by the oxygen percentage, altitude (atmospheric pressure) and calibration
correction factors.
Inspiratory and expiratory tidal volumes are calculated by integrating the
positive and negative flows over time. The negative (expiratory) tidal volume
and minute volume are displayed to the user. The positive tidal volume is
used to determine timing of the current breath termination and for blower
speed corrections.
Please note that due to possible leaks when using non-invasive ventilation,
VTe and VTi may vary substantially. Nevertheless, in non-invasive mode, a
correction to leaks is performed by the ventilator.
BPM is calculated as one minute divided by the latest breath length.
Minute volume is calculated as the latest BPM multiplied by the latest
expiratory tidal volume.
I:E is displayed to the user and is calculated per each breath as the inspiration
time divided by the expiration time.
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