PHILIPS Respironics Trilogy 202 User Manual page 48

Tracking the patient's flow pattern with the Shape Signal provides a
sensitive mechanism to trigger to inspiration or cycle to expiration in
response to changing breathing patterns and circuit leaks.
Spontaneous Expiratory Threshold (Inspiration to Expiration):
A second method used to cycle to expiration during spontaneous
breathing in all modes except T, CV, AC, and SIMV, is called
Spontaneous Expiratory Threshold (SET). The SET rises in proportion
to the inspiratory flow rate on each breath. When the SET and actual
patient flow value are equal, the unit cycles to expiration.
I PAP
Pr es s ur e
EPAP
Fl ow
Flow Reversal (Inspiration to Expiration):
As flow begins to decrease during inspiration, a flow reversal can
occur due to a large leak around the mask or because the patient's
mouth is open. When the device senses this flow reversal, it
automatically cycles to expiration.
Maximum IPAP Time (Inspiration to Expiration):
The maximum inspiratory time is determined by the adjustment of
the Inspiratory time setting. A maximum IPAP time of 3.0 seconds
acts as a safety mechanism to limit the time spent in inspiration
during spontaneous breathing. For mandatory or assisted breaths,
the maximum inspiratory time will equal the Inspiratory time setting
up to 5.0 seconds.
Spont aneous
Expi r at or y
Thr es hol d
Spontaneous Expiratory
Threshold
Chapter 3 Modes, Features, and Alarms
39