17 Guide to Volume Guarantee (VG) 115
fabian +nCPAP evolution | SW V5.1.x
Ref: 122003.EN / Date : 26Jan2021
17 Guide to Volume Guarantee (VG)
Mechanical Ventilation is required to manage Neonates with severe respiratory failure. Pressure-
limited Ventilation (PLV), delivering an operator set Peak Inspiratory Pressure (PIP), has
traditionally been used to control the arterial Carbon dioxide (PaCO
2
). However the Tidal
Volume (VT) may fluctuate due to the patient's breathing effort, changes in lung mechanics and
variable Endotracheal Tube (ETT) Leak.
For some patients, a strategy of targeting an operator set exhaled tidal volume (VTe) while
maintaining pressure within a prescribed range can maintain consistent delivered tidal volume.
Strategy for targeting expired VTe can reduce variability from ETT Leaks unless they are very
large. In case of an improvement of lung compliance, the inspiratory pressure is automatically
reduced.
The fabian series of neonatal/pediatric microprocessor-controlled ventilators allow volume-
targeted ventilation (VTv). Tidal volume measurements are done with the flow sensor placed at
the patient circuit wye piece. The flow sensor measures inspired, expired VT, and ETT Leak
percentage.
Volume Guarantee (VG) Ventilation on fabian is a VTv-mode which targets the operator’s set VTe.
17.1 fabian (VG) operation (Conventional ventilation)
Fabian VG function automatically adjusts proximal inspiratory pressure to achieve the operator’s
set targeted VTe. There are three key operator settable parameters related to VG operation:
1. Vguarant: Targeted/guaranteed patient's expired volume (VTe).
2. Pinsp: Initial inspiratory pressure for VG first breath (also known as “test breath”).
A test breath is needed to determine the patient’s lung mechanic at a starting
target pressure. Targeted inspiratory pressure for the test breath is at the operator
set PEEP + 75% of (set Pinsp – set PEEP).
3. Pmax: Maximum inspiratory pressure VG can adjust.
The VG function can be enabled once all VG related settings and alarm limits are appropriately
set per the patient’s condition. Pushing the VG ON/OFF push-button (between the “Pmax” and
“Vguarant” buttons) enables VG function.
The ventilator delivers a test breath after VG function is enabled. It will then automatically
increase or decrease the inspiratory pressure for each subsequent breath so that the measured
VTe reaches the set Vguarant. The maximum targeted inspiratory pressure change between two
consecutive breaths of the same triggering category (i.e. time-triggered or patient-triggered) is
limited to no more than 3 mbar. PSV breaths are not volume guaranteed.
The ventilator will activate the “VTe not reached / check settings” alarm if the set Pmax or set I-
Flow is insufficiently high for the measured VTe to reach 94% of the set Vguarant for a
predetermined duration (5 consecutive breaths for non-HFO modes; 10 seconds for HFO mode).
An upward arrow will be displayed in each of the Pmax and I-Flow setting area. When this
happens, increase one or both settings (make sure this is safe for the patient) to allow the
ventilator to increase delivered volume and therefore more VTe.
The minimum pressure difference between PEEP and target inspiratory pressure is 2 mbar.
If the flow sensor measurements become unavailable, the VG function will be disabled and the
pre-set Pinsp is used for ventilation. VG function will restart once flow sensor measurements
become available again.
To Next Page
Loading...
Need help?
General
