Dräger Technology Insight - Protective Ventilation

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Technology Insight
Protective ventilation in the OR creates significant demands towards
the anaesthesia workstation. Dräger works closely together with
clinicians around the world to understand the needs and requirements
for protective ventilation in the OR.
This ebook describes the latest ventilator technologies deployed in
our latest anaesthesia workstations, enabling successful protective
ventilation strategies.
DL-18812-2014
CLINICAL REQUIREMENTS
OF AN ANAESTHESIA VENTILATOR
Dräger is continuously monitoring the trends in clinical
routine and clinical research. When designing therapy
devices, patient protection and positively influencing
clinical outcome is Dräger‘s mission.
One important trend clearly shows that the clinical
requirements for ventilation in the Operating Room
have changed significantly over time, in order to improve
outcome. For decades, bellows-driven ventilators have
been the standard in anaesthesia.
Given the variety of patients who require anaesthesia for
surgery today (e.g. multimorbid patients, ICU patients,
obese patients, neonates…), the performance demands
for the anaesthesia ventilator have increased significantly,
compared to the traditional performance of bellows-driven
ventilators. Since clinicians expect to deliver anaesthesia
gases while ventilating their patients with ICU-like quality,
it was Dräger’s motivation for redesigning anaesthesia
ventilators and breathing systems accordingly, introducing
electronically driven ventilators to replace the traditional
bellow-driven ventilators.
TODAY’S REQUIREMENTS FOR VENTILATION IN
PERIOPERATIVE AND INTENSIVE CARE MEDICINE
COMPRISE:
Ventilation Performance
––
Precise and stable pressures in controlled ventilation
––
Accurate and stable volume delivery in volume controlled
ventilation
––
Fast and sensitive trigger response
––
Reduced Work-of-Breathing for spontaneously breathing
patients
Safety and Ease-of-Use Aspects
––
Rapid start-up procedure for emergency cases
––
Easy handling of parts in contact with patient gas during
the reprocessing procedure
––
Safe and easy handling in case of gas supply failures
TWO TECHNOLOGIES ARE CURRENTLY IN USE
1) E-Vent* / E-Vent plus (piston driven technology)
2) TurboVent** / TurboVent 2 (blower driven technology)
*Electronic ventilator
**Turbine driven ventilator

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TECHNOLOGY INSIGHT | E-VENT AND E-VENT PLUS
E-Vent and E-Vent plus
PISTON VENTILATOR TECHNOLOGY FROM DRÄGER
The electrically driven piston ventilator E-Vent was
introduced in 1990’s with the first Fabius® anaesthesia
device. It is based on the proven design of the predecessor
generation of electronically controlled piston
ventilators, the DIVAN ventilator in the Cicero/Cato
anaesthesia devices.
Today, the E-Vent ventilator is used in the complete Fabius®
product line and the further optimized E-Vent plus ventilator
in the Primus® product family. The main difference between
these 2 ventilators is the performance level of the system;
e.g. with regard to the trigger sensitivity and the available
ventilation modes.
The piston ventilator has a built-in safety system enabling
safe and accurate tidal-volume delivery and operation in
low- and minimal-flow anaesthesia. In addition its operation
is independent from any driving gas.
Technical operating principle of piston ventilator
The general operation principle is the same for both, E-Vent
and E-Vent plus. The piston ventilator is electrically driven
and electronically controlled. This results in unmatched
accuracy, allowing for cost effective ICU level ventilation.
First, the piston moves downwards. This is realized by a
high precision electrically driven motor (1) and a ventilator
spindle. This movement pulls in volume from the breathing
system (3). To transfer the gas mixture from inside the
piston (4) towards the patient, the piston then moves
upwards – transferring the volume into the breathing circuit
towards the patient.
3
the volume delivered by the piston is directly related
to the linear movement of the piston (2). This makes the
tidal volume delivery extremely accurate – and even in the
unlikely event of a flow-sensor failure, ventilation with set
volume delivery is still functioning. When the user sets a
volume for ventilating the patient, the piston moves the
distance necessary to deliver the required volume (4) into
the breathing system (3). Furthermore, since the connection
between piston and motor (1) is rigid, the position of the
piston (2) is always identified and the volume delivered by
the piston is, hence, always known.
Compliance Compensation
Irrespective of the type of ventilator being used, the volume
delivered into the breathing circuit and the volume the
patient receives are not identical. One major determinant of
the difference between the two volumes is the compliance
of the breathing system. As the ventilator delivers gas to
the circuit, the pressure increases. The increased pressure
compresses the gas in the system and also expands the
circuit tubing, therefore reducing the volume that reaches
the patient. Every breathing circuit has a certain compliance
factor which defines the amount of volume stored in the
circuit for a given change in pressure. Without means
of compensating for the effect of circuit compliance,
the volume the patient receives will decrease as pressure
in the circuit increases.
Advanced piston ventilator designs are able to compensate
for the compliance of the breathing system by delivering
sufficient additional volume with each breath to ensure
that the patient receives the volume set to be delivered.
Dräger’s piston ventilators measure the compliance of the
system during the start-up self-test procedure. Once the
compliance factor is determined, only a pressure sensor is
required to calculate how much additional volume should
be delivered with each breath to compensate for the loss
due to the breathing system compliance. As a result,
the set tidal volume is delivered to the patient’s airway.
4
1 Ventilation motor
2 Ventilator piston
3 Breathing system
4 Ventilation chamber
1
2
Schematic of E-Vent ventilator Primus
ACCURATE TIDAL-VOLUME DELIVERY
The most common ventilation mode in anaesthesia is
volume-controlled ventilation. The clinician sets a tidal
volume to be delivered to the patient. The piston ventilator
design is uniquely suited to deliver this tidal volume
accurately. Since the surface area of the piston is fixed,
Gas Flow Diagram Primus®

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TECHNOLOGY INSIGHT | TURBOVENT AND TURBOVENT 2
TurboVent and TurboVent 2
BLOWER-DRIVEN VENTILATOR TECHNOLOGY
FROM DRÄGER
TurboVent was introduced as a ventilator in an anaesthesia
machine with the Zeus® system in 2004. Prior to that, this
technological principle had only been used in Intensive
Care ventilators.
To understand the operating principle, one can think
of a hair dryer. It draws in ambient air, heats it up and
accelerates it in one direction.
The TurboVent ventilator works in a very similar way, just
without heating. Through the one-directional rotation of an
impeller (1), a gas mixture is sucked in from the reservoir
bag in the breathing system (through 2), gets compressed
(1 and 3), and it is then emitted towards the patient (4).
2
4
This ventilator is also one of the core components of
the Perseus® A500 anaesthesia workstation, brought to
the market in 2012. Designed to fit perfectly into the
breathing system, the TurboVent 2 ventilator achieves
quick gas change and features a new ventilation mode in
perioperative care: Airway Pressure Release Ventilation
(APRV).
CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP)
Continuous Positive Airway Pressure is a ventilation mode
where the ventilator establishes and maintains the set
pressure level in the patient lung for patients breathing
spontaneously without any additional support from the
ventilator, just utilizing the circular flow of the TurboVent2
ventilator.
The TurboVent2 ventilator is designed to reach changing
pressure levels quickly and maintain pressures – which
is especially important for the application of CPAP. With
the Perseus® A500 and the Zeus® IE, CPAP can either be
activated in MAN/SPONT mode or in Pressure Support
mode.
1
3
If a CPAP value (in MAN/SPONT mode) or a PEEP value
(in controlled and supported ventilation modes) is set,
the ventilator will use the circular flow, controlled by the
PEEP/Pmax valve in the expiratory line to actively reach and
maintain the CPAP level. This continuous pressure level is
especially important for spontaneously breathing patients
as well as for protective ventilation strategies when the
maintenance of PEEP is important.
Schematic of TurboVent ventilator
In MAN/SPONT mode it is important that the APL valve is
set to the appropriate position (SPON or below the CPAP
level) allowing the patient to exhale without any additional
resistance.
Quick responses to spontaneous breathing efforts of
the patient as well as the ability to reach pressure levels
quickly and hold them actively are important attributes of
this ventilator technology. The ventilator is allowing for
spontaneous breathing during ventilation at any time and
allows for a Work-of-Breathing as low as in ICU ventilators.
With the introduction of the 2nd generation of this ventilator
(TurboVent 2) as part of the Zeus® Infinity® Empowered
in 2009, Dräger even improved the turbine design with
regards to better handling for infection prevention and
maintenance efficiency, making it easy to detach from
the breathing system and dismantle for cleaning and
sterilization.
Gas Flow Diagram Zeus® Infinity® Empowered

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TECHNOLOGY INSIGHT
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6643 | 16.08-2 | BM | PR | Subject to modifications | © 2016 Drägerwerk AG & Co. KGaA
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