Installing the Respiration Tube Kit

Identifying the "To and From Animal" Ports

Refer to Figure 1.

Locate the port labelled "TO ANIMAL". This is where the inspiration path of the Respiratory Tubing Kit will connect.

Next locate the port labelled "FROM ANIMAL". This is where the expiration path of the Respiratory Tubing Kit will connect. 

Refer to Figure 2.

Locate the port labelled "Source." If using room air for ventilation leave open. If using a pressurized gas source (e.g. gas anesthesia from a vaporizer) please follow the directions outlined in "Installing the Connection Kit for Pressurized Gasses."

Connecting the Respiratory Tubing Kit

After locating the "To Animal" and "From Animal" ports affix the inspiratory path to the "To Animal" and the expiratory path to the "From Animal" ports.

Please see Figure 3 for the Mouse Kit (73-4899) and Figure 4 for the Rat Kit (73-4876). 

Installing the Connection Kit for Pressurized Gasses (73-4872)

Please Note: If you will be using gas anesthesia with your VentElite, or any Harvard Apparatus-Hugo Sachs Elektronik ventilators, proper scavenging must be used to ensure user safety. Do NOT vent anesthesia gasses to your room. If you have any questions surrounding safely scavenging waste halogenated gasses please contact Technical Services for options. 

Please Note: Do NOT connect the VentElite, or any Harvard Apparatus-Hugo Sachs Elektronik ventilators, to pressurized gas sources or pressurized gas scavenging systems (e.g. directly to vacuum lines) without proper pressure regulation. Fresh and waste anesthetic gas tubings must be near atmospheric pressure at all times to avoid damage to the animal's lungs and your equipment. 

To set-up the VentElite and Connection Kit

• Connect the "inspired gas" line to the SOURCE port. Refer to Figures 2 & 5.
• Connect the "expired gas" line to the EXHAUST port. Refer to Figure 2 & 5 .
• Connect the "from Vaporizer" line to the vaporizer. Refer to Figure 5.
• Connect the "to gas evacuation system" line to your scavenging system.
• Finally, always leave the "pressure equilibration" line open to room air when using an active scavenging system (e.g. the HSE MiniVac Gas Evacuation Unit 73-4910 or in-house gas evacuation systems).  Negative pressure in the Connection Kit will lead to lung collapse. If you are using passive scavenging please close this section of tubing. 

Settings for Breathing Rate, Tidal Volume, PIP and PEEP

The choice of the correct settings for dial volume, breathing rate, peak inspiratory pressure (PIP) and positive end expiratory pressure (PEEP) depends both on general parameters such as, but not limited to, species, animal size, experiment with or without an open thorax, and on specific parameters required for your application such as ventilator-induced lung injury. As always settings other than the one's described here may be required for your experiment. We highly encourage speaking with your veterinarian for assistance with your surgical and experimental set-up. 

Example 1:

Recommended settings for Pressure Controlled Mode, closed chest and without a set PEEP.

PEEP = 0cmH₂O

PIP = 14 - 16cmH₂O

Set the breathing rate according to the animal weight (see Figure 6). Tidal volume (TV) is not a user selectable field in Pressure Mode and will be automatically adjusted by the VentElite to maintain the target PIP. 

Example 2:

Recommended settings for Pressure Controlled Mode, open chest with a set PEEP.

PEEP = 3cmH₂O

PIP = 14 - 16cmH₂O

Set breathing rate according to the animal weight (see Figure 6). TV is not a user selectable field in Pressure Mode and will be automatically adjusted by the VentElite to maintain the target PIP.

Example 2:

Recommended settings for Volume Controlled Mode, closed chest and without a set PEEP.

PEEP = 0cmH₂O

PIP = 20-25cmH₂O*

Set the breathing rate and TV according to the animal weight (see Figure 6). Ideally the TV and breathing rate settings will result in a PIP of 15 - 16cmH₂O. If the animal starts gasping increase the TV gradually in steps of 1 or 2cmH₂O. Be aware the higher the TV the higher the PIP.

*In volume controlled mode this value is used as a parameter for the alarms on the VentElite.

Recommended settings for Volume Controlled Mode, open chest and with a set PEEP.

PEEP = 3cmH₂O*

PIP = 25cmH₂O

TV and breathing rates are set according to the animal weight (see Figure 6). Ideally the TV and breathing rate settings will result in a PIP of 15 - 16cmH₂O. If the animal starts gasping increase the TV gradually in steps of 1 or 2cmH₂O. Be aware the higher the TV the higher the PIP.

*See section "Using the Needle Valve for PEEP Maintenance

General Tips and Tricks:

• In pressure control mode the PIP should be set to 14 - 16cmH2O if the experiment is not a lung damage study. In some set ups the PIP will need to be a bit higher, but be aware that pressures greater than 20cmH₂O will start to have ventilator induce lung damage effects.
• If the animal starts breathing against the ventilator (gasping) this is a sign that the animal does not have a proper O₂/CO₂ exchange. The first step to try is to gradually increase the TV, slowly reaching a higher PIP. In most cases gasping is caused by system dead space when not using a recommended cannula. We highly recommend using the HSE intubation and tracheal cannulae.
• Dead space is the volume between the Y-piece and the lung. It must be as small a volume as possible with as little resistance as possible. 

Please note we do not recommend tubing lengths between the ventilator and animal greater than a max of 50cm. 

Using the Needle Valve for PEEP Maintenance

To set and maintain a PEEP on the VentElite the PEEP must be set both in the software and with the PEEP control needle valve. Figures 7 and 8 here show examples with and without the use of the secondary PEEP control needle valve.

How to set:

• Set desired PEEP value in the VentElite settings (see page 18 of the User's manual)
• Ensure that the needle valve is set to all the way open by turning the valve all the way to open in a counter-clockwise direction when looking at the back of the VentElite. If the valve is closed all the way down the unit will immediately stall.
• Press Start on the VentElite to being ventilation.
• As the VentElite is running slowly turn the valve knob in the "closed" direction (as indicated in Figure 9) and adjust until PEEP is well maintained. Opening the valve will lower the PEEP hold and closing the valve will increase the hold plateau. 

Note: The VentElite will allow the user to set PEEP values between 0 and 10cmH₂O. Please note that PEEP settings above 5cmH₂O are considered to be out of physiological range.