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308
Instructions for use
|
Atlan A300, A300 XL, A350, A350 XL SW 1.0n
Principles of operation
This principle of operation enables the following characteristics, for example:
– Precise application of the set tidal volume, regardless of the inspiratory and
expiratory flow measurement.
– No drive gas is required, i.e., no medical gases are consumed in operating the
ventilator.
– Mechanical ventilation remains available if the gas supply fails, see page 40.
17.3.2 Compliance
compensation
The volume delivered into the breathing circuit is not the same as the volume that
the patient ultimately receives. The determining factors for this difference in volume
are the elasticity of the breathing circuit and the compressibility of the gas contained
within it.
When the pressure in the breathing hose rises during inspiration, there is also
expansion of the hose material. The expanding breathing hose can hold a greater
volume, with the result that a lesser volume reaches the patient.
This device is equipped with dynamic compliance compensation, which
compensates for this volume difference during each breath. Volume is also fed to
the entire system so that the set tidal volume actually reaches the patient.
The basis for the compliance compensation is the breathing hose compliance
determined in the system test or in the leakage test.
17.3.3 Fresh-gas
decoupling
The device is equipped with fresh-gas decoupling.
This function decouples the ventilation from the fresh-gas flow and the O
2
flush.
Consequently, changes to the fresh-gas flow have no influence on the applied tidal
volume and the ventilation pressures. Furthermore, the fresh-gas decoupling valve
passes excess fresh gas to the breathing bag.
Fresh-gas decoupling is particularly important during the ventilation of neonates
and pediatric patients as airway pressures and tidal volumes that are too high must
be avoided.
17.4
Improving the CO
2
measurement by means of an HME
filter
17.4.1 Benefits
of the HME filter
Patient-side gas sampling via an HME filter has the following benefits, among
others:
– The sample gas measurement (e.g., CO
2
) is more reliable, since it is not
impaired by the influence of the ventilation.
– The potential dead space is minimized. This is particularly important when
ventilating neonates and pediatric patients, in order that effective gas exchange
can take place even at small tidal volumes.
The unwanted effects of the dead space are reduced by removing the extracted
CO
2
-containing gas from the patient and the breathing circuit including the HME
at the end of the expiration.