Mandatory Breaths; The Intra-Breath Demand System In Volume Ventilation; Volume Breaths - CareFusion AVEA Operating Instructions Manual

74
Breath Types
This section contains a brief description of the breath types and ventilation mode combinations available for adult,
pediatric and neonatal patients.
There are two basic breath types:
Mandatory
breaths (delivered according to set ventilator parameters)
•
and
Demand
breaths (triggered by the patient)
•
All breaths are defined by four variables:
Trigger
(initiates the breath),
•
Control
(controls the delivery),
•
Cycle
(primary breath termination), and
•
Limit
(secondary breath termination).
•

Mandatory Breaths

Mandatory breaths can be triggered by the machine, the patient, or the operator. There are 4 mandatory breath types
delivered by the AVEA.
1.
Volume
breaths, which are:
Controlled by flow (inspiratory);
•
Limited by pre-set volume or maximum inspiratory pressure.
•
Cycled by volume, flow, and time.
•
Note:
The Volume Controlled breath is the default breath type for adult and pediatric patients.

The Intra-Breath Demand System in Volume Ventilation

AVEA features a unique intra-breath demand system in Volume Controlled ventilation, designed to provide
additional flow to the patient during periods of demand. AVEA measures the Peak Inspiratory Pressure (Ppeak)
every 2 milliseconds throughout the breath cycle and sets a "virtual" Pressure Support Target of the greater of:
PEEP + 2 cmH
The minimum "virtual" Pressure Support level is set PEEP + 2 cmH
The maximum is 2 times the set PEEP.
Simultaneously, the ventilator monitors and compares the Ppeak measurement to its previous value. Should the
Ppeak decrease by the 2 cmH
deliver a Pressure Support breath at the virtual Pressure Support Target. This allows flow to exceed the set Peak
Flow, thereby meeting the patient's demand.
Once the set tidal volume has been delivered, the ventilator "looks" at the inspiratory flow. If the Peak Inspiratory
Flow is greater than set peak flow, the ventilator determines that the patient is continuing to demand flow and cycles
the breath when inspiratory flow falls to 25% of peak inspiratory flow. If the Peak inspiratory Flow is equal to the set
flow, the ventilator determines that there is no continued patient demand and ends the breath as a Volume Control
breath.
Chapter 3: Ventilator Operation
O or Ppeak – 2 cmH
O.
2 2
O, the ventilator will recognize the patient demand and automatically "switch over" to
2
O.
2
Operator's manual
L2786 Rev. M