Dräger Babylog 8000SC, Техническое и сервисное руководство, Страница: 19 / 155

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Function description Babylog 8000
3 Airway Monitoring
In the ventilation modes IPPV/IMV and CPAP, the airway pressure (Paw), the flow at the Y-piece V
T
(Babylog 8000/Babylog 8000 plus), and the fraction of inspired O
2
(FiO
2
) are measured.
Depending on the selected mode and the menu settings, the parameters are monitored and displayed on
the screen. Pressure and flow curves as well as their storage can be displayed graphically on the LC
display or EL display. In all ventilation modes, the chronological sequence of the airway pressure (Paw) is
displayed in the LED bargraph.
3.1 Airway Pressure
Two internal pressure sensors measure the pressure at the inspiratory outlet (Pinsp) and the pressure at
the expiratory inlet (Pexp). The airway pressure is calculated as follows:
Paw = Pinsp – 0.7 (Pinsp – Pexp)
The following pressures are calculated from the Paw pressure signal:
Peak pressure (Peak)
Mean airway pressure (Pmean)
Positive end-expiratory pressure (PEEP)
The peak pressure is the maximum positive pressure of the most recent respiratory cycle. After 30 s, at
the latest, a new respiratory cycle must be recognized and a new measured value for the peak pressure
must be generated, otherwise the current measured value is no longer valid and is removed from the
display.
The mean airway pressure is the initial value of a software digital filter.
The PEEP is either the pressure value during the expiratory phase at a zero expiratory flow or the last
measured value before the next inspiration. Like the peak pressure, the PEEP is no longer valid after 30 s
and is removed from the display if a new measured value is not generated within the 30-s period.
3.2 Trigger Signal
In order to generate a trigger signal, the inspiratory flow must be integrated during spontaneous breathing
and compared to the adjustable trigger threshold.
3.3 Measurement of the Fraction of Inspired O
2
A O
2
sensor in the inspiration line measures the O
2
content of the respiratory gas.
Calibration data of the O
2
sensor is maintained after switching off the Babylog. If the Babylog has been
out of operation for more than 24 hours, a calibration will automatically be carried out upon power-on.
The operator may also initiate a calibration manually, e.g. as required after replacing an O
2
sensor.