of this document may be copied or otherwise reproduced, or stored in any electronic informat ion
retrieval system, except as specifically permitted under U.S. Copyright law, without the prior written
consent of the Company. For more information, contact:
AVEA® is a registered trademark of VIASYS Respiratory Care Inc. in the U.S. and some other
countries. All other brand names and product names mentioned in this manual are trademarks,
registered trademarks, or trade names of their respective holders.
EMC Notice
This equipment generates, uses, and can ra diate radio frequency energy. If not installed and use d in
accordance with the instructions in this manual, e lectromagnetic interference may result. The
equipment has been tested and found to comply with the limits set forth in EN60601-1-2 for Medical
Products. These limits provide reasonable protection against electromagnetic interference when
operated in the intended use environments described in this manual.
The ventilator has been tested to conform to the following specifications:
MIL-STD-461D:1993, MIL-STD-462D:1993, EN55011:1991, IEC 1000-4-2:1994, IEC 1000-4-3:1994,
IEC 1000-4-4:1994, IEC 1000-4-5:1994, QUASI-STATIC:1993
This ventilator is also designed and manufacture d to co mply with the safety requirements of IEC 601-1,
IEC 601-2-12, CAN/CSA-C22.2 No. 601.1-M90, and UL 2601-1.
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AVEA Ventilator Systems
MRI Notice
This equipment contains electromagnetic components whose operation can be affected by intense
electromagnetic fields.
Do not operate the ventilator in an MRI environment or in the vicinity of high-frequency surgical
diathermy equipment, defibrillators, or short-wave therapy equipment. Electromagnetic interference
could disrupt the operation of the ventilator.
Intended Use Notice
The AVEA Ventilators are designed to provide ventilator support for the critical care management of
infant, pediatric or adult patients with compromised lun g fu nction. They are intended to provide
continuous respiratory support in an institutional health care environment. They should only be
operated by properly trained clinical personnel, under the direction of a physician.
Regulatory Notice
Federal law restricts the sale of this device except by or on order of a physician.
IEC Classification
Type of Equipment: Medical Equipment, Class 1 type B
Adult/Pediatric/Infant Lung Ventilator
Declaration of Conformity Notice
This medical equipment complies with the Medical Dev ice Directive, 93/42/EEC, and the following
Technical Standards, to which Conformity is declared:
EN60601-1
EN60601-1-2
ISO 13485
EU Notified Body:
BSI (Reg. No. 0086)
Trade names:
AVEA Ventilator
If you have a question regarding the Declaration of Conformity for this product, please contact VIASYS
Respiratory Care Inc. at the number given in Appendix A.
0086
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Service Manual
Warranty
THE AVEA® ventilator systems are warranted to be free from defects in material and workmanship and
to meet the published specifications for TWO (2) years or 16,000 hours, whichever occurs first.
The liability of VIASYS Respiratory Care Inc., (referred to as the Company) under this warranty is
limited to replacing, repairing or issuing credit, at the discretion of the Company, for parts that become
defective or fail to meet published specifications during the warranty period; the Company will not be
liable under this warranty unless (A) the Company is promptly notified in writing by Buyer upon
discovery of defects or failure to meet published specifications; (B) the defective unit or part is returned
to the Company, transportation charges prepaid by Buy er; (C) the defective unit or part is received by
the Company for adjustment no later than four weeks following the last day of the warranty period; and
(D) the Company’s examination of such unit or part shall disclose, to its satisfaction, that such defects
or failures have not been caused by misuse, neglect, improper installation, unauthorized repair,
alteration or accident.
Any authorization of the Company for repair or alteration by the Buyer must be in writing to prevent
voiding the warranty. In no event shall the Company be liable to the Buyer for loss of profits, loss of
use, consequential damage or damages of any kind based upon a claim for breach of warranty, other
than the purchase price of any defective product covered hereunder.
The Company warranties as herein and abov e set forth shall not be enlarged, diminished or affected
by, and no obligation or liability shall arise or grow out of the rendering of technical advice or service by
the Company or its agents in connection with the Buyer's order of the products furnished hereunder.
Limitation of Liabilities
This warranty does not cover normal maintenance suc h as cleaning, adjustment or lubrication and
updating of equipment parts. This warranty shall be voi d a nd shall not apply if the equipment is used
with accessories or parts not manufactured by the Company or authorized for use in writing by the
Company or if the equipment is not maintained in accordance with the prescribed schedule of
maintenance.
The warranty stated above shall extend for a period of TWO (2) years from date of shipment or 16,000
hours of use, whichever occurs first, with the following exceptions:
1. Components for monitoring of physical vari ables such as temperature, pressure, or flow are
warranted for ninety (90) days from date of receipt.
2. Elastomeric components and other parts or components subject to deterioration, over which the
Company has no control, are warranted f or sixty (60) days from date of receipt.
3. Internal batteries are warranted for ninety (90) d ays fro m the date of receipt.
4. External batteries are warranted for one (1) year from th e date of receipt.
The foregoing is in lieu of any warranty, expressed or implied, including, without limitation, any warranty
of merchantability, except as to title, and can be amended only in writing by a duly authorized
representative of the Company.
Index .................................................................................................................................1
xii L1524
Service Manual AVEA Ventilator Systems
Chapter 1 Introduction
Safety Information
Please review the following safety information prior to operating the ventilator. Attempt ing to
operate the ventilator without fully understanding its features and functions may result in unsafe
operating conditions.
Warnings and Cautions which are general to the use of the ventilator under all circumstances are
included in this section. Some Warnings and Cautions are also inserted within the manual where they
are most meaningful.
Notes are also located throughout the manual to provide additional information related t o specific
features.
If you have a question regarding the installation, set up, operation, or maintenance of the ventilator,
contact VASYS Respiratory Care customer care as shown in Appendix A, Contact & Ordering
Information.
Terms
WARNINGS identify conditions or practices that could result in serious adverse reactions or
CAUTIONS identify conditions or practices that could result in damage to the ventilator or other
NOTES identify supplemental information to h elp you better understand how the ventilator
Warnings
Warnings and Cautions appear throughout this manual where they are relevant. The Warnings and
Cautions listed here apply generally any tim e you work on the ventilator.
• Alarm loudness must be set above ambient sound in order to be heard.
• Due to possible explosion hazard, the ventilator should not be used in the presence of
• An audible alarm indicates an anomalous con dition and should never go unheeded.
• Anti-static or electrically conductive hoses or tubing should not be used within the patient
• If a mechanical or electrical problem is recognized wh ile running the Operational Verification
potential safety hazards.
equipment.
works.
flammable anesthetics.
circuit.
Tests, or while operating the ventilator, the ventilator must be removed from use until the
problem has been identified and resolved.
•The functioning of this equipment may be adversely affected by the operation of other
equipment nearby, such as high frequency surgical (diathermy) equipment, defibrillators,
short-wave therapy equipment, “walkie-talkies,” or cellular phones.
•Water in the air supply can cause malfunction of this equipment.
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•Do not block or restrict the Oxygen bleed port located on the instrument back panel.
Equipment malfunction may result.
•Electric shock hazard – Ensure the ventilator is disconnect ed from the AC power supply before
performing and repairs or maintenance. When you remove any of the ventilator cover panels,
immediately disconnect the internal battery “quick rele ase” connector before working on the
ventilator. If the ventilator has an external battery installed, ensure that the external battery is
unplugged from the rear panel before pr oceeding
•A protective ground connection by way of the grounding conductor in the power cord is
essential for safe operation. Upon loss of protective ground, all conductive parts including
knobs and controls that may appear to be insulated, can render an electric shock. To avoid
electrical shock, plug the power cord into a properly wired receptacle, use only the power cord
supplied with the ventilator, and make sur e the power cord is in good condition.
The following warnings must be read and understood before performing the procedures described in
this manual.
•Under no circumstances should this medical device be operated in the presence of flammable
anesthetics or other volatile materials due to a possi ble explosion hazard.
•Liquid spilled or dripped into the unit may cause damage to the unit or result in an electrical
shock hazard.
•Oxygen vigorously accelerates combustion. To avoid violent ign ition, do not use any gauges,
valves, or other equipment that has been exposed to oil or grease contamination.
•Do not use this device if any alarm/alert function is inoperative. To do so could r esu lt in a
malfunction without warning, possibly resulting in personal injury, including death or property
damage.
•All tubing and fittings used to connect high pressure gas from the source to the test equipment
and from the test equipment to the device being tested must be capable of withstanding a
minimum supply pressure of 100 psi (7.03 kg/cm2). The use of tubing and fittings not capable
of withstanding this pressure could cause the tubin g to rupture, resulting in personal injury or
property damage.
•When verifying the operation of this medical device, do not breathe directly from the machine.
Always use a fresh bacterial filter and test circuit. Failure to do so may constitute a hazard to
the health of the service person.
•If any of the procedures outlined in this document cannot be verified, do not use this device
and refer it to VIASYS Respiratory Care or a VIASYS Respiratory Care authorized service
facility or a VIASYS Respiratory Care trained hospital service technician.
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AVEA Ventilator Systems
Cautions
The following cautions apply any time you work with the ventilator.
•Ensure that the voltage selection and installed fuses are set to match the voltage of the wall
outlet, or damage may result.
•A battery that is fully drained (i.e. void of any charge) may cause damage to the v entilator and
should be replaced.
•All accessory equipment that is connected to the ventilator must comply with
CSA/IEC601/UL2601.
•To avoid damage to the equipment, clean the air filter regularly.
The following cautions apply when cleaning the ventilator or when sterilizing ventilator
accessories.
•Do not sterilize the ventilator. The internal components are not compatible with steri liz ati on
techniques.
•Do not gas sterilize or steam autoclave tubing adapters or connectors in place. The tubing will,
over time, cause poor connection and possible leaks.
• DO NOT submerge the ventilator or pour cleaning liquids over or into the ventilator.
• Do not use MEK, Trichloroethylene or similar solutions as damage to su rface may result. Do
not allow any liquid to spill or drip into the ventilator.
•Circuit boards are subject to damage by static electricity. Do not touch compo nents, circuit, or
connector fingers with hands. Handle only by edges.
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Equipment Symbols
The following symbols may be reference d o n the ventilator or in accompanying documenta t ion
Symbol Source/Compliance Meaning
Symbol #03-02 IEC 60878
Symbol #5016 IEC 60417
Symbol #5034 IEC 60417
Symbol #01-36 IEC 60878
Symbol #5035 IEC 60417
Symbol #01-37 IEC 60878
Symbol #5019 IEC 60417
Symbol #01-20 IEC 60878
This symbol indicates a FUSE.
This symbol indicates INPUT.
This symbol indicates OUTPUT
This symbol indicates protective EARTH (ground).
This symbol indicates the EQUIPOTENTIAL connection used to
Symbol #5021 IEC 60417
Symbol # 01-24 IEC 60878
connect various parts of the equipment or of a system to the
same potential, not necessarily being the earth (ground) potential
(e.g., for local bonding).
This symbol indicates TYPE B equipment, which indicates
Symbol # 5333 IEC 60417
Symbol #02-03 IEC 60878
Symbol #5032 IEC 60417
Symbol #01-14 IEC 30878
Symbol #5007 IEC 60417
Symbol #01-01 IEC 60878
Symbol #5008 IEC 60417
Symbol #01-02 IEC 60878
equipment that provides a particular degree of protection against
electric shock, particularly with regards to allowable leakage
current and reliability of the protective earth connection.
This symbol is located on the rating plate. It indicates the
equipment is suitable for alternating current.
Indicates ON (Power)
Indicates OFF (Power)
Horizontal return with line feed. Indicates ACCEPT entered
values for a specific field.
Indicates PATIENT EFFORT
ACCEPT
Symbol #0651 ISO 7000
VIASYS Respiratory Care Symbol
VIASYS Respiratory Care symbol
Indicates MANUAL BREATH
VIASYS Respiratory Care Symbol
MAIN SCREEN
Symbol #417 IEC 5102
EVENT READY
1-4 L1524
AVEA Ventilator Systems
VIASYS Respiratory Care Symbol
MODE
VIASYS Respiratory Care Symbol
VIASYS Respiratory Care Symbol
VIASYS Respiratory Care Symbol
MDD Directive 93/42/EEC
Symbol #5307 IEC 60417
Symbol #5319 IEC 60417
VIASYS Respiratory Care symbol
ADVANCED SETTINGS
SET-UP for patient Data
SiPAP Duration
CE Mark
ALARM RESET
ALARM SILENCE
ADULT patient
CANCEL
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
Graphical Symbol in general use
internationally for “DO NOT”
VIASYS Respiratory Care symbol
Symbol 5467 IEC 60417
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
PEDIATRIC patient
NEONATAL (Infant) patient
CANCEL, do not accept entered values.
Select DISPLAYED SCREEN function.
FREEZE the current display.
Enable the ALARM LIMITS screen
This symbol indicates a CONTROL LOCK.
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VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
NEBULIZER port
Increase OXYGEN
PRINT SCREEN
SUCTION port
VARIABLE ORIFICE FLOW SENSOR connection
HOT WIRE FLOW SENSOR connection
ANALOG IN/OUT connection
Display the MAIN SCREEN
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
VIASYS Respiratory Care symbol
DO NOT BLOCK PORT
EXTERNAL BATTERY connection
Indicates GAS ID port
OXYGEN SENSOR connection
OVERPRESSURE relief
REMOTE NURSE CALL connection
1-6 L1524
AVEA Ventilator Systems
VIASYS Respiratory Care symbol
VIASYS Respiratory Care Symbol
VIASYS Respiratory Care Symbol
VIASYS Respiratory Care Symbol
VIASYS Respiratory Care Symbol
VIASYS Respiratory Care Symbol
UNIVERSAL INTERFACE MONITOR connection
This symbol indicates an EXTERNAL BATTERY INPUT
This symbol indicates an INTERNAL BATTERY FUSE
This symbol indicates ALARM LOUDNESS
Operating on Battery Indicator
Operating on Heliox
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Service Manual AVEA Ventilator Systems
Chapter 2 Theory of Operation
General Description
AVEA is a software driven, servo-controlled ventilator designed to meet the requirements of neonate to
adult patients. The design intent of the device is to provide a high performance software-driven gas
delivery engine, which is capable of providing a full range of volume and pressure ventilation including
dual limb NIPPV. This affords the flexibility of developing new modes of ventilation with no impact to
the basic gas delivery engine. In addition, the device will contain a graphical user interfac e (GUI) that
utilizes a 12.1-inch SVGA color LCD screen with integral touch screen. The GUI will be used to change
settings and operating parameters as well as providing real time waveforms, digital monitors, and
alarms. The device also contains an internal battery that serves as a backup in case of loss of hospital
AC power. The Custom Cart may be equipped with tank holder, external batteries and battery tray for
use of the AVEA during inter-facility transport .
There are three models of AVEA; comprehensive, plus and standard. These are shown in table 2.1
based on the same basic platform. Additional models may be developed in the future by adding or
removing software and/or hardware features to the existing platform.
The AVEA is a fourth generation, servo-controlled, software-driven ventilator. It has a dynamic range of
breathing gas delivery that provides for neonatal through adult patients. Its revolutionary user interfac e
module (UIM) provides maximum flexibility with simple operator interaction. It has a flat panel color
LCD with real time graphic displays and digital monitoring capabilities, a touch screen for eas y
interaction, membrane keys and a dial for changing settings and operating parameters. A precision gas
delivery engine with servo controlled active inhalation and exhalation improves performance over
previous generations.
The AVEA has been designed to function using most commonly available accessories. It is easy to
clean and its design does not allow liquids to pool on the casing, reducing the likelihood of fluid leakage
into the body of the ventilator.
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There are three models of AVEA to choose from: The Comprehensive, Plus, and the Standard. The
following matrix details the standard and optional functions available with eac h model.
Functions & Accessories Standard Plus Comprehensive
Modes
Proximal Hot Wire Flow Sensing
Synchronized Nebulizer
24 Hour Trending
Internal Battery
Full Color Graphics Display
Loops and Waveforms
Standard Cart
Proximal Variable Orifice flow sensing
Proximal Airway Pressure Monitoring
Tracheal Pressure Monitoring
Esophageal Pressure Balloon
Internal Compressor
Heliox Delivery
Optional Functions & Accessories
Custom Cart Option Option Included
External Battery (on custom cart only) Option Option Option
Gas Tank Holder (on either cart) Option Option Option
Internal Compressor Option Option Included
All All All
Heliox Delivery Option Option Included
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AVEA Ventilator Systems
High Level Design
AVEA has been designed with three basic modules, the user interface module (UIM), the pneumatics
module (PM), and the stand (see Figure 1). The UIM contains a graphic al user int erfac e (GUI) which
utilizes a 12.1-inch SVGA color LCD screen with integral touch screen. The UIM also contains a control
PCB that has two microprocessors, control and monitor. The monitor processor manages the GUI,
while the control processor has the real time control system that controls all of the mechanical valves in
the PM. The UIM communicates with the PM via a high-speed serial channel (HSSC). The HSSC also
provides power to the UIM.
The pneumatics module (PM) contains all of the m echanical valves, sensors, analog electronics, power
supply including the internal batteries, and the optional internal compressor. The pneumatics module
takes high-pressure air or 80/20 heliox and oxygen from an external wall source or other high-pressure
source. It filters the gas and blends them through a step per motor controlled blender according to the
front panel settings. It then delivers the appropriate pressure or volume via a high-speed proportional
solenoid with flow sensor feedback. The high-speed control system occurs every 2 msec and is
computed in the control microprocessor in the UIM. The deli vered gas flows to the patient through a
safety valve that has a mechanical over pressure relief valve as well as a sub-ambient valve. The gas is
forced into the patient by closing the servo-controlled voice coil exhalation valve, which is also
controlled by the control microprocessor in the UIM. The patient is a llowed to exhale by the voice coil
exhalation valve, which also maintains baseline pressure or PEEP. The exhaled gas exits the patient
through the expiratory limb of the patient circuit to an inte gral heated expiratory filter to an external flow
sensor and out the exhalation valve to ambient air.
The pneumatics module has several additional capabilities. First it uses either air or 80/20 heliox for an
input gas, and corrects all blending, volume delivery, volume monitoring and alarming, and FiO
monitoring and alarming based on the correct gas density. The system knows what the gas is, by a
patent pending gas ID that identifies the appropr iate inlet DISS fitting with the gas that is being
delivered, which creates an inherently safer system for delivering heliox. The second capability is the
optional back up compressor that is battery backed up for a minimum of 30 minutes by a fully charged
internal battery, which allows for uninterrupted ventilation during a loss of AC power. The third feature is
the ability to monitor volume either at the expiratory limb of the ma chine or at the patient wye. This
allows for more accurate patient monitoring especially in infants while allowi ng the convenience of an
expiratory limb flow sensor protected by a heated filter. Fina lly, the fourth feature is the ability to
measure tracheal and esophageal pressures, which is currently commercially available only on other
VIASYS (Bear/Bird) ventilators.
The stand is used to support the ventilator at an ergonomically correct height. It may contain an optional
external battery for extended use with AC power (custom stand only). It also has an optional O
bracket so that the unit can be used without wal l oxygen during inter-hospital transport. The st and does
not contain active electronic or mechanical components other than the optional external batteries, which
are charged when connected to A/C Power.
2
tank
2
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Printer
User Input
INTERFACE
MODULE
Power
USER
(UIM)
High
Speed
Serial
Channel
(HSSC)
RS232 x 2
MIB
VGA
Air/Heliox
O2 Supply
AC Power
24 VDC
Nurse Call
Analog I/O,
ILV
Ambient Air
Gas ID
O2
sensor
COMPRESSOR
(Optional)
PNEUMATICS MODULE
EXTERNAL BATTERY
(Optional)
Enhanced Pt.
Monitors
(Optional)
Pes
Paux
Faw
Nebulizer
Drive gas
Humidfier
(Optional)
Exhaled Gas
from patient
Exhaust,
Exhaled Flow
Delivered Gas
Patient
CART
Figure 2-3 High End Device Modular Diagram
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AVEA Ventilator Systems
Detail Design
User Interface Module (UIM)
The UIM consists of a 12.1-inch, 800x600 active matrix LCD with an analog resistive touch screen
overlay, a back light inverter, a set of membrane key pan els, an optical encoder, and a Control PCB.
Software and the touch screen provide a set of context sensitive soft keys. The membrane panel
provides a set of hard (permanent) keys for dedicated functions. Selecting the function wit h a soft key
and adjusting the setting using the optical encoder changes a parameter. The parameter is accepted or
canceled by pressing the appropriate membrane key.
LCD & TOUCHSCREEN
(1 & 2)
(3 & 4)
BACK LIGHT AC VOLTAGE
DIGITAL
CONTROL PCB
(7)
DC-DC
CONVERTERS
24VDC
TOUCH
SCREEN
5V
5V, PRN PORT
3.3V, DIG LOGIC
BACK LIGHT INVERTER
HIGH SPEED
(6)
SERIAL
DIGITAL
UNIVERSAL SERIAL BUS (FUTURE)
Figure 2-4 User Interface Design Module Block Diagram
MEMBRANE PANEL WITH
(5)
EMBEDDED LED'S
PRINTER
RS232
RS232
RS232 (MIB)
(CRT)
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The UIM performs all ventilator control functions, gas cal c ulations, monitoring and user interface
functions. The UIM uses a Graphical User Interface (GUI) via the active matrix SVGA LCD and resistive
touch screen to provide system and patient information to the user and to allow the user to modify
ventilator settings. The Control PCB (with two micro-controllers, RAM, ROM and support electronics)
provides all ventilator functions. The Control micr o-controller (MCU) performs all gas calculations;
controls all valves, solenoids, and electronics required to deliver blended gas to the patient. The
Monitor MCU handles all user interface requirements, including updating the active m atrix liquid crystal
display (LCD), monitoring the membrane keypad, analog resistive touch screen, and optical encoder for
activity. The Monitor MCU also performs all the input/output functions of the UIM, including RS-232,
printer, video output, and communication to patient monitors. Communication between the Control and
Monitor MCU’s is accomplished via an 8 bit dual port SRAM. In addition, both MPU's monitor each
other and both are independently capable of activating the fail safe system.
The UIM is self-contained and is tethered to the pneumatics module with a high-speed data and power
cable. All valves are contained in the pneumatics module; the control MCU controls all ventilator
functions via the high-speed serial channel (HSSC). The Monitor MCU provides additional input/output
functions contained in the ventilator. These functions include analog outputs, independent lung
ventilation, and nurse call and are updated by the Monitor MCU via the HSSC.
Liquid Crystal Display
The liquid crystal display (LCD) provides graphical and digital feedback to the clinician. The panel is a
12.1” SVGA, 800x600 pixel, active matrix LCD. The LC D is used to implement the graphical user
interface (GUI). It provides all of the adjustable controls and alarms, as well as displays waveforms,
loops, digital monitors and alarm status in real time.
Touch Screen
The touch screen in conjunction with the LCD provides a set of software configurable soft keys. The
software allows the keys to be context sensitive. The touch screen is a 12.1” analog resistive overlay on
a piece of glass, which is placed over the LCD. It has a resolution of 1024x1024. Physica lly the touch
screen, consists of two opposing transparent resistive layers separated by insulating spacers. Actuation
brings the two opposing layers into electrical contact. The Y coordinate is determ ined by applying a
voltage from top to bottom on the top resistive layer. This creates a voltage gradient across this layer.
The point of contact forms a voltage divider, which is read b y the analog-to-digital converter. The X
coordinate is determined by applying a voltage from left to right on the bottom resistive layer. Again this
creates a voltage gradient and the point of contact forms a divider, which is read with an analog-todigital converter.
Membrane Panel
The membrane panel provides a set of permane nt d edicated keys, which allow the clinician to change
certain ventilator functions. The membrane panel will provide visual status to the clinician via embedded
light emitting diodes (LEDs). The membrane panel consists of membrane switches, which are read by
the monitor CPU. The switches form a matrix of rows and columns. A key closure causes an interrupt to
the monitor CPU, which responds by scanning the key matrix to determine which key has been
pressed.
Light Emitting Diodes (LEDs)
Some of the membrane keys require LED’s to indicate when the key is active. The LED’s are
embedded into the membrane panels.
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AVEA Ventilator Systems
Optical Encoder
The optical encoder allows the clinician to change settings. The setting to be changed is selected by
pressing a soft key on the LCD and then turning the optical encoder to change the value. When the
encoder is rotated two pulse streams ar e generated, phase A and B. When the encoder is turned
clockwise, phase A leads B by 90 degrees. When the direction is counter clockwise, phase B leads A
by 90 degrees. The electronics uses the pha s e information to drive an up-down counter, which is read
by the monitor CPU. The optical encoder is not interrupt-driven and therefore must be polled by the
monitor CPU.
Back Light Inverter
The back light inverter converts 5 VDC into the high frequency AC voltage necessary to power the LCD
back light, which is used to illuminate the LCD.
Control PCB
The control PCB consists of two micro-controllers, the control CPU and the monitor CPU, both of which
are 100 MHz ELAN 410’s. The control and associated circuitry (RAM, ROM, etc) micro controllers
perform all ventilator control functions including the 2 msec closed loop flow control servo and the 2
msec closed loop exhalation valve control servo. The monitor micro-controller manages the GUI and
performs all user input and output including the RS-232 ports, printer port, video out, and MIB port. The
two processors communicate with each other via a dual port RAM. The control processor
communicates with the pneumatics module via a high-speed serial channel (HSSC - 4 Mbits/sec).
Each processor has 8 Mbytes of DRAM, and one Mbyte of flash memory for program storage. In
addition, the monitor circuitry also has a second one Mbyte of flash memory for saving control settings
and trended data for clinical parameters. The control PCB also contains a DC-to-DC converter to
regulate the incoming 24 VDC to the voltages used by the UIM. Finally, the control PCB also contains
all of the circuitry necessary to scan the membrane panels, touch screen, and optical encoder, a s well
as the video controller necessary to drive the SVGA LC D screen.
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Pneumatics Module
The pneumatics module (PM) consists of a power supply system including internal NiMH batteries, a
transducer/ communication/alarm PCB (TCA PCB), the pneumatics, a heated expiratory system, a fan,
an optional internal compressor, a built-in nebulizer system, and an audible alarm. The PM
communicates with the UIM (User Interface Module) via the HSSC described above.
The power supply system, consists of a power inlet module, and a medical grade 350-watt power
supply, the power driver PCB, and a set of internal 12 VDC NiMH batteries connected in series. The
power inlet system accepts a standard IEC medical grade power cord and allows the system to be
configured externally for use with 100 to 240 VAC 5 0/60 Hz power. AC power is converted to 34 VDC
by the internal medical grade power supp ly, which is also power factor corrected. The power driver PCB
converts the 34 VDC from the power supply or the 24 VDC from the internal or external batteries to the
appropriate voltages used by the rest of th e system. The power driver PCB also contains the charging
circuit for both the internal and external batteries, as well as the drivers for the flow control, exhalation
valve, and multiple solenoids. The internal 4.5 Ah NiMH batteries can power the entire system including
the internal compressor for 30 minutes, or 2 hours without the compressor. With the external 17 Ah lead
acid batteries combined with the internal battery powers the entire system, including compressor, will
run for 2 hours on batteries, and greater than 8 hours without compressor.
Transducer/Alarm PCB (TCA PCB)
The TCA PCB consists of circuitry for the audible alarm, the wy e hot wire flow sensor, the gas ID, the
inspiratory and expiratory pressure transducers, the source gas pressure transducers, the exhaled flow
sensor, the FiO2 cell, and communications with the UIM. It also contains the nurse call, and analog
input and output.
A 68HC705 micro-controller is used to generate ala r m waveforms for an ASTM F1463-93 compliant
alarm. A super capacitor is used to provide a minimum if 120 seconds of power without wall AC or a
battery.
Analog circuitry is provided to signal condition the wye Hot Wire Flow Sensor signal and a 12 bit ADC is
used to digitize the signal. A Flow Sensor Fail s ignal is provided to allow the Control Process or to
determine when the flow sensor wire is broken. The Flow Sensor EEPROM is SPI bus compatible and
is read at power up and when a Flow Sensor is co nnected.
The air inlet fitting contains a resistor for determining which gas source is connected to the Air inlet, Air
( 5K ohm) or Heliox (10K ohm). The type of gas connected is determined with a resistor divider, one
half of the divider is contained in a connector and the other half is located on the TCA. The resistor
contained in the connector is different for each gas source and therefore produces a different voltage
output from the divider. The output of the divider is read via an ADC.
Inspiratory and expiratory pressure transducers and associated signal conditioning are digitized on the
TCA PCB. The control processor reads the digitized data via the HSSC. The air, oxygen, and blended
gas pressure transducers and associated signal conditioning are on separate PCBs for ease of
mounting. The amplified signals are cabled to the TCA where they are digitized and communicated to
the control processor via the HSSC.
Exhaled flow is measured with a VARFLEX
a variable orifice with pressure taps on either sid e of th e orifice. The TCA uses a low-pressure
pressure transducer and analog circuitry to measure the flow proportional pressure drop across the
orifice.
Integrated circuit temperature sensors are signal conditioned and digitized by the TCA electronics. The
exhalation and ambient temperature sens ors are cabled to the TCA PCB. The output of oxygen cell is
also signal conditioned and digitize d on the TCA.
®
Exhaled Flow Sensor. The VARFLEX® Flow Sensor uses
There are four 10-bit analog output channels on the TCA for pressure, flow, volume, and breath p hase
respectively. They have a full scale of 0 to 5 VDC with 10- bit resolution. In addition, there are 8
programmable analog inputs that can be used to display external signals. They are digiti zed with a 10
bit DAC, and are scalable from 0 to 1VDC, 0 to 5 VDC, an d 0 to 10 VDC.
L1524
2-9
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