Intermittent Assisted Controlled Ventilation (Synchronised Intermittent Mandatory Ventilation) Simv And Psimv - ResMed Elisee 150 Clinical Manual

Intermittent Assisted Controlled Ventilation (Synchronised
Intermittent Mandatory Ventilation) SIMV and PSIMV
In the Intermittent Assisted Controlled Ventilation modes, the device alternates between cycles
of assisted controlled ventilation (with regulated flow (SIMV) or regulated pressure (PSIMV)) and
spontaneous cycles with pressure support (PS) triggered by the patient.
This mode allows spontaneous breathing.
Principle
Controlled ventilation cycles (CC) are triggered according to the respiratory rate, or "mechanical
respiratory rate (frequency)" (Fmecha). The mechanical respiratory rate (frequency) dicates the
mechanical cycle time Tmecha (seconds) = 60/Fmecha. One minute of ventilation is therefore
divided into fixed mechanical cycle times, and the mechanical respiratory rate (frequency) is
unchanged.
To allow patient-ventilator synchronisation, a triggering window (Wsync) of assisted controlled
cycles (ACC) is defined before the start of each controlled ventilation cycle. This window lasts for
5 seconds in adult mode and 1.5 seconds in paediatric mode. If the patient triggers a cycle during
this window, or zone, the cycle will be an assisted controlled cycle (ACC) with either the pressure
(PSIMV) or the volume (SIMV) regulated (zone 1).
Following each trigger window (Wsync) (assisted or controlled), is an interval of time (W
which the patient can trigger a cycle of spontaneous ventilation with pressure support (5 cmH
minimum) (zone 3). The delivered cycle will be a pressure support cycle. The parameters for the
cycles of spontaneous ventilation with pressure support (PS) can be adjusted.
Cycles of spontaneous ventilation are always delivered with pressure support. If pressure support
was not provided with spontaneous ventilation, the patient would have to work harder to
overcome the resistance of the tubing and the ventilator. By adding a minimum pressure support
of 5 - 8cmH
effort needed to overcome the combined resistance of the machine-circuit-filter-water trap.
If after an assisted controlled cycle (ACC) is triggered the patient does not trigger a cycle within
the next trigger window (Wsync), the Elisée 150 will deliver a controlled cycle based on the
mechanical respiratory rate (frequency) (Fmecha) defined by the user (zone 2). This means that
the expiratory time (Texp) of the assisted controlled cycle is extended by the anticipated time T
allowed prior to triggering of the controlled cycle. The set mechanical respiratory rate (frequency)
remains unchanged.
However, the value of T is limited by the value of Tmax: 5s for adult ventilation, 1.5s for
paediatric ventilation.
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