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DOCA3667B Pro Series Operating Manual.doc
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ALARMS
Maximum Working Pressure Limit (MWPL):
The MWPL feature allows the operator to set
an upper limit above which the airway pressure will not exceed. The ventilator will terminate the
inspiratory phase of the breathing cycle and begin an expiratory phase when the pressure
transducer senses a pressure above the MWPL setting. The MWPL is settable over a range from
10 to 60 cm H
2
O. When the airway pressure reaches the set limit, the yellow light on the front
panel blinks and a short tone is heard. If the excessive pressure is not immediately relieved,
cycling is paused and the alarm sounds continuously. Note that the INSPiratory HOLD feature is
designed to not function when the MWPL setting is exceeded. Therefore, a holding inspiration
will be released when the MWPL setting is exceeded.
Low Breathing System Pressure Alarm (LO BSP):
The LO BSP alarm is activated at the end
of inspiration if there is not at least 5 cm H
2
O pressure sensed by the pressure transducer. This
alarm is sometimes commonly referred to as a "disconnect" alarm; however, it should be
understood that a patient disconnect is not always nor the only cause of low breathing system
pressure. During the alarm condition a yellow light is illuminated on the front panel and the
sound of a raspy siren is heard. The alarm is automatically reset at the end of the next
inspiratory
phase in which there is a minimum of 5 cm H
2
O pressure sensed by the pressure transducer.
Low 50 psi Supply Gas Alarm:
The Low Supply Gas alarm is activated when the supply gas
pressure drops below 35 psi (2.4 bar). The sensor for this alarm is located downstream of the
internal 40-micron filter and may also indicate a clogged filter condition. During an Alarm
condition, the yellow light on the front panel is illuminated and a steady, continuous tone is
heard. This alarm automatically resets when the pressure increases above 40 psi (2.7 bar).
VERIFICATION OF PROPER FUNCTION
A Note on Test Lungs
The most readily available test lung will probably be the breathing bag you removed to connect
the ventilator. A breathing bag is a very poor model of a lung. It can be used if one understands
how poor a model of the lung it is and how to avoid using it in such a way that it creates problems
that will not occur with a real patient.
A far better test lung is a ridged walled container such as a gas can, water fountain bottle, or beer
keg. The compliance of these containers is equal to their volume in liters and will be linear as is
that of a real lung over normal operating ranges. Most importantly they will maintain a
functional residual capacity (FRC) that is hard to maintain in a breathing bag.
The breathing bag has an unpredictable FRC from breath to breath if bumped or squeezed beyond
the point of relaxation, more gas than would normally be popped off at the end of exhalation
escapes from the breathing system. The bellows then abnormally fails to remain at the top of the
bellows housing at the end of exhalation. To use the bag successfully, connect it to the patient
wye, hang it vertically, and do not disturb it.
Verification of proper ventilator operation requires that you first complete the system setup, as
described on page 7 and connect a test lung to the patient wye piece. During verification, you
will be observing the operation of the entire system configuration, checking for leaks, and
monitoring the ventilator for consistent cycling.
