MidiVent Ventilator for Large Mice and Small Rats (Model 849), Single Animal, Volume Controlled

The MidiVent Model 849 Ventilator is a quiet, compact and light weight ultra low volume ventilator designed specifically for large mice. It can be used for any animal (e.g. small rats, shrew, hamster) which requires tidal volumes in the range of 60 to 700 µl and respiratory rates of 60 to 400 breaths per minute.

Key Features

• Ideal for large mice and small rats up to 100 grams
• Stroke volume range from 60 to 700 µl
• Ventilation rate from 60 to 400 breaths/minute 
• Simple adjustment of stroke volume while running 
• Valveless piston pump, no valves to clog 
• Very small instrument/circuit dead space volume 
• Compact construction, easy to install close to animal 
• No vibrations, very low noise

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How it Works

The MidiVent Ventilator is a constant-volume respiration pump operating on the Starling principle. Unlike conventional units for larger animals, this ventilator employs a rotary plunger and has no valves. During each ventilation cycle, the plunger performs a synchronized forward and rotating movement. Cleverly arranged bores and channels in the cylinder and plunger control inspiration and expiration during each stroke of the plunger.

The extremely light weight and compact construction, in addition to the convenient rod clamp, allow the MidiVent ventilator to be positioned directly next to the animal. Typical setups with larger ventilators produce large tubing and instrument dead space volumes. These larger volumes introduce greater system compliance which can affect the accuracy with which the full tidal volume is introduced into the animal's lungs. With the MidiVent, the tidal volume error due to system compliance is reduced to 5 µl.

Tidal volume and respiration rate can be set exactly to the values required for mouse ventilation. The level of precision and control available to the investigator minimizes the danger of hyperventilation or hypoventilation.

The tidal volume can be varied continuously from 60 to 700 ul during operation without having to interrupt ventilation. The respiration rate is also continuously adjustable from 60 to 400 strokes/min. The expired air can be recovered at the collection port for sampling, recycling or for the generation of a positive end-expiratory pressure (PEEP). Room air or any non-explosive gas mixture can be used to feed the pump intake using the special connection tubing PY2 73-3077.

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Components

The system is supplied with Silicone Tubing (1.5mm ID, 3.0mm OD, 14cm long), a 1.5 mm OD tracheal cannula and a 1.5 mm OD intubation cannula for the mice. For other size animals, additional intuubation or tracheal cannula sizes may be needed.

A multi-gas inlet adapter is available for the MidiVent so that alternate gas mixtures and nebulized substances are delivered to thr MidiVent inlet port at atmospheric pressure. The adapter provides ports for multiple selectable gas mixture (hypoxic, anesthetic...) and a port for the Aerosol Nebulizer.