CWE SAR-1000 User manual

SAR-1000
Advanced Small Animal Ventilator
©CWE 2023
Read instructions carefully before operating this device.
This device is not to be used for Human Life Support applications.
To avoid possible electrical shock, do not operate this device if is wet or has had liquids spilled onto it.
Service or calibration procedures should only be performed by qualified personnel familiar with the
electrical hazards of line-powered devices.
Ardmore PA 19003 U.S.A.
[phone]
[email protected]
Instruction Manual
www.cwe-inc.com

SAR-1000 Instruction Manual 2
© 2023 CWE, Inc.
STATEMENT OF WARRANTY
IF THIS INSTRUMENT FAILS WITHIN A PERIOD OF ONE YEAR FROM THE DATE
OF DELIVERY OR INSTALLATION, CWE, INC. WILL, AT ITS OPTION, REPAIR OR
REPLACE IT FREE OF CHARGE. THIS WARRANTY EXCLUDES DAMAGE
INCURRED THROUGH MISUSE OR ACCIDENT. CWE, INC. DOES NOT ASSUME
ANY LIABILITY FOR ANY CONSEQUENTIAL DAMAGES RESULTING FROM THE
USE OF THIS INSTRUMENT.
DEFECTIVE UNITS SHOULD BE RETURNED TO THE FACTORY ALONG WITH A
NOTE DESCRIBING THE NATURE OF THE FAULT. THIS WARRANTY IS
APPLICABLE TO THE ORIGINAL PURCHASER OF THE INSTRUMENT ONLY, AND
IS NOT TRANSFERABLE.
FACTORY SERVICE
Out of warranty or damaged instruments may be returned to the factory freight prepaid
for service at prevailing rates. Upon request, a written or verbal quotation for such
service will be issued after examination of the unit but prior to commencing repairs or
service. Address requests for service or technical information to:
CWE, Incorporated
Technical Support
Ardmore, PA 19003 U.S.A.
[phone]
[email protected]
LIFE SUPPORT POLICY
Instruments manufactured by CWE, Incorporated are not authorized for use as critical
components in human life support devices or systems. "Life support devices or
systems", as used herein, are devices or systems whose failure to perform, whether
through misuse, failure, or proper operation, can reasonably be expected to result in
significant injury to the operator or subject persons.
This document was last updated May 5, 2023

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© 2023 CWE, Inc.
TABLE OF CONTENTS
1.0 INTRODUCTION........................................................................................................ 4
2.0 BASIC VENTILATOR CONNECTIONS..................................................................... 5
3.0 VENTILATOR OPERATION...................................................................................... 6
4.0 TUBING CONNECTIONS.......................................................................................... 9
5.0 REAR PANEL INPUTS AND OUTPUTS................................................................. 10
6.0 REMOTE CONTROL USING THE USB PORT ....................................................... 13
7.0 USING ANESTHESIA WITH THE SAR-1000.......................................................... 15
8.0 SPECIFICATIONS................................................................................................... 17
9.0 ORDERING INFORMATION.................................................................................... 17
Figure 1: Model SAR-1000 Front Panel ....................................................................... 4
Figure 2: SAR-1000 LCD Display Panel....................................................................... 6
Figure 3: Top trace: Airway pressure, bottom trace: Sync Out ................................ 7
Figure 4: Auto-Sigh setup screen................................................................................. 8
Figure 5: SAR-1000 Rear Panel.................................................................................... 9
Figure 6: Connecting an external valve set .............................................................. 12
Figure 7: SAR-1000 anesthesia connections............................................................. 16
APPENDIX 1: TIDAL VOLUME VS. BODY WEIGHT CHARTS.................................... 18
APPENDIX 2: TYPICAL VENTILATOR SETTINGS FOR RODENTS.......................... 19

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© 2023 CWE, Inc.
1.0 INTRODUCTION
The SAR-1000 Small Animal Ventilator is designed to provide safe and reliable
mechanical ventilation for mice, rats, and other small laboratory animals.
This ventilator operates on the flow-time principle, where a measured airflow is gated
into the animal for a set time, thus producing a known tidal volume. In addition, the SAR-
1000 can operate in pressure-cycled mode, where the airway pressure is automatically
limited to a user-set value. This approach to ventilator design permits great flexibility,
since airflow, timing, and pressures are all independently adjustable over a wide range.
Special sigh breaths can be manually initiated or programmed to occur automatically at
user determined intervals.
The SAR-1000 is completely self-contained, with a built-in air pump to provide airflow. All
settings are made from the front panel and are displayed on an LCD display along with
computed measurements.
Besides being a stand-alone ventilator, the SAR-1000 has a built-in USB interface for
remote control applications. In addition, there is a DATA PORT for external logic signals,
which maintains compatibility with the SAR-830 series ventilators.
The SAR-1000 is compatible with anesthetic gasses, and complete anesthesia setups
are available. To ventilate multiple, or larger, animals, it can be used with any of the
CTP-VA series external valve assemblies. These accessories are available for a range
of animals (see: Ordering Information).
The following sections of this Manual explain how the ventilator works, and how to set it
up to suit your particular experimental needs. We encourage you to read through this
Manual and welcome you to the next generation of CWE ventilators.
Figure 1: Model SAR-1000 Front Panel

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© 2023 CWE, Inc.
2.0 BASIC VENTILATOR CONNECTIONS
Setting up the SAR-1000 is straightforward. For basic operation, only a mains power
cord and a cannula tubing set need be connected.
Power connections
Plug an appropriate mains cord into the MAINS INLET receptacle on the right of the rear
panel. This instrument uses a universal voltage input, so no mains voltage switch is
required.
CAUTION! To maintain electrical safety, use only a
3-wire grounded power cord. Operating this device from an
un-grounded receptacle could result in a dangerous electrical
shock hazard.
Cannula Tubing Set connections
The cannula tubing set connects the front panel tubing ports to the animal’s
endotracheal tube. For rats and similar size animals, the INSP and EXP ports connect to
the distal “W” connector using 0.125” ID x 0.250” OD (3 x 6mm) Tygon or similar flexible
tubing. For mice, use 0.063” x 0.125” (1.5 x 3mm) tubing and appropriate barbed tube
fittings. The PRESSURE MONITOR port is a female Luer connection and connects to the
center tap of the distal “W” connector (rat), or to a miniature “Y” connector (mouse). Both
rat and mouse tubing sets are provided with the instrument.
To reduce compression effects of large tubing volumes, these tubes should be as short
as is convenient, but their length does not affect dead-space, since flow is unidirectional
from the CANNULA I →tracheal tube →CANNULA E port. The only dead-space is the
volume from the distal end of the “W” connector to the tracheal tube.
It is highly recommended that the new user become familiarized with how the ventilator
operates before connecting an experimental animal. A test balloon is provided for this
purpose.

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© 2023 CWE, Inc.
3.0 VENTILATOR OPERATION
Volume mode
Once the ventilator is set up and operational, a few important settings need to be
determined. The appropriate respiratory rate (RR) and tidal volume (VT) are mainly
dependent on body weight. Appendix 1 contains tidal volume and rate vs. body weight
charts. For example, if we have a 250g rat, the chart shows a suitable VTof about 2.0ml
at a RR of 55 breaths/min.
To set up the SAR-1000 for this example, first adjust the RESP RATE knob until 55 bpm is
displayed. Adjust the %INSP knob until 50% Insp is displayed. Now adjust the INSP FLOW
knob until VT2.0 ml is displayed.
Note that you are setting the tidal volume by adjusting the inspiratory airflow, rather than
just dialing in VTdirectly. This may at first seem unintuitive, but it follows from the basic
flow-time ventilator principle: VT= flow x time. The time (TI) was set as a fraction (%Insp)
of the total respiratory cycle time (1/RR). VTis then dependent on the flow rate setting.
All the calculations are performed by a microprocessor so you don’t have to!
Figure 2: SAR-1000 LCD Display Panel
Pressure mode
Pressure mode operation is similar to the above description, except that inspiration is
terminated when a certain airway pressure (PP) is reached, rather than when the
inspiration time (TI) has elapsed.
This pressure is set using the PRESSURE knob, and is displayed, for example, as
PP 10.0 cm. Now, inspiratory flow will cease on each breath when the set PPpressure is
reached.
Inspiratory hold
Note that the SAR-1000 has another important feature that applies to pressure mode: If
PPis reached before the set TIhas elapsed, the lung volume will be clamped for the
duration of TI. This inspiratory hold feature is known to improve the efficiency of
ventilation and gas exchange by maintaining the end-inspiratory pressure, instead of
simply releasing the lung volume immediately when PPis reached. You can observe this
via the INSP, EXP, and INSP HOLD LED’s, which indicate exactly what is happening during
the respiratory cycle. Figure 3 illustrates this by observing the pressure signal.

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© 2023 CWE, Inc.
NOTE: By default, the INSP HOLD function is enabled. You can disable it by pressing the
SIGH pushbutton while turning POWER ON. You will hear two beeps to indicate the
function is disabled. Repeat this to re-enable INSP HOLD and you will hear four beeps to
indicate that the function is active. This setting is stored and will apply from now on until
the user changes it.
Figure 3: Top trace: Airway pressure, bottom trace: Sync Out
Manual Sigh function
Sighs, or periodic delivery of larger tidal volumes, are often used to maintain good lung
ventilation and gas exchange. The SAR-1000 has a manual sigh function actuated by
pressing the SIGH pushbutton. When this pushbutton is pressed, the ventilator is armed
to deliver a sigh breath on the next inspiration. A short beep will indicate that a sigh
breath is about to be delivered.
During a sigh breath, the inspiration will continue until the sigh pressure (PS) is reached.
This function is available regardless of whether the ventilator is in VOLUME or PRESSURE
mode. On the sigh breath, the lung volume will be clamped once the PSis reached, and
held for the programmed sigh time (see Programming the Auto Sigh function).
To set the sigh pressure, press and hold the SET SIGH PRES pushbutton while adjusting
the PRESSURE knob. The LCD display indicates the PSsetting in cmH2O.
NOTE: The sigh pressure (PS) setting is normally several cmH2O
greater than the pressure limit (PP) setting. However, it is possible to
set the sigh pressure to a lower setting if desired. In this case, the
sigh breath will deliver a lower than normal end-inspiratory
pressure.
Programming the Auto Sigh function
As described above, a single sigh breath can be initiated simply by pressing the SIGH
pushbutton. You can also automate the delivery of periodic sigh breaths by using the
auto sigh setup routine. You enter this routine by simultaneously pressing the SIGH and
INSPIRATORY HOLD
INFLATION
DEFLATION
SYNC:
Airflow
going
To animal

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© 2023 CWE, Inc.
SET SIGH PRES pushbuttons and holding for about ½ second. The setup screen shown in
Figure 4 will then be displayed:
Figure 4: Auto-Sigh setup screen
The two settings you can change here are the sigh frequency and sigh ratio values. In
the example shown, sigh frequency is set to 1:050, or a sigh every 50 normal breaths.
The sigh ratio is set to 250%, so the inspiratory time (TI) of the sigh breath will be 2.5X
(or 250%) of the normal TI. The other sigh variable, sigh pressure (PS) is set from the
main display screen as described earlier.
To change the sigh frequency setting, use the RESP RATE knob. To change the sigh ratio,
use the %INSP knob. (These controls are shown in brackets on the right side of the
display as a mnemonic aid.)
Any changes to the auto sigh settings take effect immediately. To exit the setup screen,
press the SET SIGH PRES pushbutton. After 15 seconds of inactivity, the screen will
automatically timeout and return to the main operating screen.
When Auto Sigh is in effect, the symbol ASwill be displayed on the bottom line of the
main operating screen.
Minute Ventilation
Minute ventilation (MV) is the sum of the inspired volumes delivered to the animal per
minute. This measurement is a useful indicator of adequate ventilation and is normally
proportional to body weight. MV is computed automatically and reported on the bottom
line of the LCD display.

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© 2023 CWE, Inc.
4.0 TUBING CONNECTIONS
Figure 5: SAR-1000 Rear Panel
Pump In / Pump Out ports
The SAR-1000 is equipped with an internal air pump to provide compressed gas for use
as the inspiratory flow. The inlet and outlet connections of this pump are brought out to
the rear panel as the PUMP IN and PUMP OUT ports, respectively.
The air pump has a capacity of approximately 2.5 lpm. For most setups, a tubing jumper
should be placed between the PUMP OUT and the GAS INLET ports.
NOTE: Never apply a pressure to the PUMP IN port. A collapsible bag
with a gas mixture can, however, be connected to this port.
Gas Inlet port
This port receives the compressed gas used for generating the controlled inspiratory
flow. Although normally this will connect to the PUMP OUT port, in some circumstances it
is desirable to connect a gas source directly to the GAS INLET port, thus bypassing the
internal air pump.

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© 2023 CWE, Inc.
Expired Air port
The EXP AIR port is connected directly to the lungs during expiration. In most cases, this
port should be left unconnected. However, there are some circumstances where a
connection is made:
PEEP (Positive End-Expiratory Pressure) --- PEEP is a commonly used
technique to maintain a small pressure in the lungs during expiration. For
example, in open-chest preparations, PEEP is essential to keep the lungs from
collapsing. To apply a PEEP, connect a flexible tubing to the EXP AIR port, and
submerge it under a few cm of water (the depth under water = the PEEP
pressure). This is illustrated in Figure 7.
Anesthesia --- If inhalational anesthesia is used, it is necessary to collect and
evacuate the gas from the exp air port. A tube connected to this port can be
directed to an anesthetic absorber or exhaust system.
NOTE: Never connect a vacuum source directly to this port,
as it will cause serious injury to the animal!
In Vent port
During the inspiration phase of ventilation, the inspiratory flow is directed to the animal.
During expiration, this same flow is gated out the IN VENT port. Thus, this is clean
inspiratory gas. In anesthesia setups, this gas can be sent to an anesthetic evacuation
system (see Figure7).
5.0 REAR PANEL INPUTS AND OUTPUTS
PRESSURE OUT
This BNC jack provides a continuous analog voltage signal corresponding to
airway pressure. The scaling of this signal is 50mV/cmH2O.
SYNC OUT
This BNC jack provides a TTL-compatible signal corresponding to the phase of
respiration. During inspiration, the output is HIGH (+5V); during expiration the
output is logic LOW (0V).
GROUND
This binding post is connected to chassis ground, or earth. If required, this post
can be connected to a system-wide ground connection.