PHILIPS Respironics Trilogy 202 User Manual page 90

Circuit Type
There are three circuit types you can select:
•
Passive
•
Active PAP
•
Active Flow
The Passive circuit type uses a passive exhalation device. The Active
PAP circuit type uses an active exhalation device with a proximal air
pressure sensing connection. The Active Flow circuit type uses an
active exhalation device with a proximal flow sensor.
When using the Passive circuit, the ventilator displays estimated
patient pressures based on the resistance of the standard patient
circuit (passive exhalation device with 1.8 meter tubing). Adding
accessories to the patient circuit (humidifier, water trap, etc.) may cause
an increase in circuit resistance and cause the device to display slightly
higher pressures than what is actually delivered to the patient.
With the Active PAP or Active Flow circuit type selected, patient
pressure is measured directly and is not affected by any change in
circuit resistance.
The Passive circuit provides leak compensation. When using the Passive
circuit in Volume Ventilation, the set Vti is delivered to the patient above
the calculated circuit and cuff (or mask) leak. This is different from
traditional active circuit ventilation where the cuff (or mask) leak reduces
the tidal volume delivered to the patient. Volume ventilation with the
Passive circuit delivers an inspiratory tidal volume close to the device
setting regardless of leak; this should be considered when transitioning
a patient from an active to a passive circuit. With a Passive circuit, Vte is
estimated based on the calculated sum of circuit and cuff (or mask) leak.
The Active Flow circuit monitors proximal flow and proximal
pressure. When using the Active Flow circuit configuration, flow
trigger with leak compensation may be enabled. The default setting
when using the Active Flow Circuit is Leak Compensation On. The
clinician has the option to turn off leak compensation; however,
unintentional leak will not be compensated. Both options measure
the flow at the proximal flow sensor. Leak compensation is not
available in the Active with PAP circuit configuration.
Note: To change the circuit
type, you must be in the
Setup screen with the airflow
turned off. See the Full Menu
Access Mode section for more
information.
Note: When the Circuit Type
setting is set to Passive Circuit,
all Ramp Start Pressure settings
in all modes will maintain the
minimum range.
Note: When the Circuit Type
setting is set to Active PAP or
Active Flow, the Flex and AVAPS
features are unavailable.
Chapter 5 Viewing and Changing Settings
81