All gas anesthetics and most injectable anesthetics are respiratory depressants. As the animal reaches deeper levels of anesthesia respirations will become more depressed. This can result in the patient moving up to a lighter plane of anesthesia. The ventilator will deliver a constant supply of anesthetic gas maintaining a constant plane of anesthesia. Due to the constant delivery of gas concentration by the ventilator the patient responds more rapidly to changes in vaporizer settings and a lower vaporizer setting will maintain the same surgical plane of anesthesia. Lower vaporizer settings mean less anesthetic gas, lower cost and less environmental pollution. The ventilator will provide more control over the patient's depth and smoothness of anesthesia. In other words, because of anesthetic induced respiratory depression hypercapnia often results. The consistent ventilation by the ventilator maintains normocapnia and minimizing respiratory acidosis.

Many lectures now recommend putting all surgical patients on a ventilator. This is especially true for anything brachiocephalic, obese, geriatric, any PU or perianal surgeries where the rear is elevated and the gut is compressing the diaphragm.

In cases which require mechanical ventilation, such as thoracotomies, obese patients, critical care or emergency cases, the technician is much more valuable monitoring the patient and assisting the surgeon rather than just bagging the patient.

The Model 2000 series ventilators are designed for use in the OR during anesthesia. This does not , however, preclude their use in the ICU when needed. They are not as convenient to use in the ICU as a true ICU ventilator would be, nor do they have all the bells and whistles of the more expensive ICU ventilators.

Anesthetic ventilators are essentially breathing bag squeezers. They do not supply the breathing gas as an ICU ventilator does. Therefore, one generally ends up using an anesthesia machine to deliver the breathing gas (with or without some anesthetic). Peep valves are available for use on the anesthesia machine if needed (see peep valves).

This approach works well until you approach the 18 hour point where continued ventilation with 100% oxygen will start to produce irreversible lung damage due to oxygen toxicity. The solution to this is to have your anesthesia machine equipped with an air flowmeter so you can adjust the FiO2. In a nutshell:

Equal flows of air and oxygen yields a 63% oxygen concentration mixture,
three times as much air as O2 yields a 40% concentration and
three times as much oxygen as air yields 80% O2.

Print out this nomograph for greater detail.

NO HALLOWELL EMC PRODUCTS OR ACCESSORIES CAN BE ACCEPTED FOR REPAIR OR RETURN WITHOUT A RETURN AUTHORIZATION FROM HALLOWELL.

To obtain a Return Authorization number call 413-445-4263, fax to 413-496-9254, or email your request to info@hallowell.com. Please have the following information ready and available:

1. The serial number of the item to be returned, if applicable.
2. The nature of the problem, reason for return and action requested.
3. The name, phone number and extension of the party to contact should we have future questions.
4. The billing name, address, phone number and PO number of the responsible party.
5. If the item is to be returned, such as with a repair, the name of the party to whom we should ship the item, the shipping address and receiver's PO number if needed for acceptance.
6. AND a fax number or email address to which we can send a Return Goods Instructions Sheet. This sheet will have the RA # at the top. Clearly mark the RA # on the outside of the box that you will be returning to Hallowell EMC.

Please follow the procedures faxed to you carefully. It is based on our experience of how best to get your items back to us without damage and delay.

Deliveries will not be accepted for packages that are not expected, i.e. that do not have a valid (on file) authorization number clearly marked on them along with a complete return address.

We thank you for your understanding and cooperation.

We can answer this question by weight. For complete descriptions of all the machines please see their pages in the product catalog.

Tafonius:
For the largest animals ranging from 80 lbs to 2000 lbs.
Some examples would be sheep and fols, to horses cows and camels just to mention a few.

Model 2000 and Model 2002:
These ventilators have three different bellows available. The smallest with a range of 0 to 300 mL of tidal volume and an affective weight range form 2 lbs to 40 lbs. The next size up our adult bellows has a range of 300mL to 1600mL of tidal volume with weights of 40 lbs 220 lbs. Lastly we have our XL bellows, 1600mL to 3000mL ranging from 200lbs to 440 lbs.

Anesthesia WorkStation (AWS):
The solution for supplying both gas anesthetic delivery and ventilatory support for pocket pets, avian, exotics and laboratory animal applications in one easy to use package. Can be used for animals ranging from 150 grams to 7 kilos.

MicroVent1:
This ventilator operates in the very small range mice, small birds and the like, with a tidal volume from 1 to 10 CCs.

For cleaning use warm soapy water or a 50/50 alcohol and water solution. DO NOT use any solvents.

The Model 2000 series ventilators are designed for use in the OR during anesthesia. This does not , however, preclude their use in the ICU when needed. They are not as convenient to use in the ICU as a true ICU ventilator would be, nor do they have all the bells and whistles of the more expensive ICU ventilators.

Anesthetic ventilators are essentially breathing bag squeezers. They do not supply the breathing gas as an ICU ventilator does. Therefore, one generally ends up using an anesthesia machine to deliver the breathing gas (with or without some anesthetic). Peep valves are available for use on the anesthesia machine if needed (see peep valves).

This approach works well until you approach the 18 hour point where continued ventilation with 100% oxygen will start to produce irreversible lung damage due to oxygen toxicity. The solution to this is to have your anesthesia machine equipped with an air flowmeter so you can adjust the FiO2. In a nutshell:

Equal flows of air and oxygen yields a 63% oxygen concentration mixture,
three times as much air as O2 yields a 40% concentration and
three times as much oxygen as air yields 80% O2.

Print out this nomograph for greater detail.

Deciding what bellows to use will become intuitive after you have used the ventilator for a little while. The rule of thumb for the tidal volume requirements of an animal is 10 to 20 ml/kg (4.5 to 9 ml/lb). This is a very wide range as a 20 kg animal could require a TV any where between 200 and 400 ml. The TV deliverable from the small bellows is 350 ml because the bellows bottoms out at that point. By the rule of thumb 350 ml / 20 ml/kg would dictate that the absolute maximum would be 17.5 kg (38.5 lbs) ...Please see: Choosing the Correct Bellows Housing

The symptom mentioned is generally a result of a low-pressure value of the Pop-Off-Valve due to contamination:

The Pop-Off-Valve (POV) can be located by removing the clear acrylic housing by twisting counter clockwise (from the top) until the locking tabs are revealed, and pulling upward until free. Removal of the adult bellows requires only a gentle tug vertically. The pediatric bellows is removed in much the same manner, and also requires the removal of the adaptor, (shaped like a bell mouth) by pulling straight up. The POV can now be seen as the round black plastic device held in place by three red thumbscrews. Remove the thumbscrews and the POV.

The POV consists of two plastic housings, a rubber diaphragm, and a stainless steel puck, which rests on a plastic seat. Generally, after repeated use with patients, a breathing condensate will form on both the puck and seat. This will appear as a ring on the puck, and a shiny, glazed residue on the seat. This condensate can be removed from both surfaces with the gentle use of a cotton swab moistened in isopropyl alcohol and dried with clean air. Assembly is the reverse of the above.



THEORY OF OPERATION


During the end of the Expiratory Phase of the ventilator cycle, when the bellows reaches the top of the housing, the patient circuit gas exits through the POV and out the exhaust port of the unit base. This is a controlled escape of air, and is designed to hold the patient circuit system to a PEEP pressure of 1.8 cmH2O minimum to 2.6 cmH2O maximum.

By controlling the weight and surface finish of the stainless puck, as well as the thickness and durometer hardness of the rubber diaphragm, this pressure condition can be maintained.

Cleaning operations may be scheduled on an individual basis, depending on condensate build up, frequency of use, and length of down time between operations.

First you will start by selecting the proper sized bellows and housing for the patient depending on their weight. Small bellows 1 to 40 lbs, adult bellows 40 to 220 lbs, and the XL bellows will do 200 to 440 lbs.
Next you will set the Mean airway pressure limit a few cmH2O above what you expect your working airway pressure to be during the case. This is a safety measure in the event that they airway pressure rises to the limit you set the machine will terminate the breath and start the exhalation.
Turn the volume control(s) all the way down to ensure you have control of the initial tidal volume delivered on the first breathes. And set the rate in breaths per minuet to something that is appropriate for that particular case.
Connect the patient and turn the Hallowell Ventilator on, you will hear the Low pressure alarm because you are not delivering any tidal volume. Slowly increase the volume breath by breath as you watch the air way pressure gauge rise to and appropriate airway pressure somewhere around 10 to 15 cmH2O.
Note: If you are using the small bellows, use the fine (silver) volume control. If you are using either the adult or XL blows the curse (black) volume control will work with those.
Now you are in the ballpark in only about a minuet. Now you can fine-tune your ventilator settings as you assess the patient’s needs and the information your monitoring equipment gives you.

The ventilator may be utilized in any one of three sizes, or volume capabilities.

Pediatric 0-300ml

Adult 300-1600ml

Extra Large 1600-3000ml

All three size clear acrylic housings are attached by placing them over the base assembly O-Ring, pushing straight down, and turning CLOCKWISE (as viewed from the top) until the tabs are locked into two of the bayonet locks. Removal is the reverse of this operation.

The ADULT and EXTRA LARGE Bellows fit on the outside ring (commonly called the bellmouth), with the first convolute over the ring. Holding the Bellows by the white top and extending and lowering the Bellows will eliminate any folds, creases, and ensure a tight seal.

The PEDIATRIC Bellows requires the use of an Adapter, P/N 000A0486, which decreases the ring size down to accommodate the smaller Bellows. The Adapter is placed inside the Base Assembly by placing it O-Ring down into the cavity and pushing straight down. This Bellows is also placed on the ring with the first convolute over the ring.



For cleaning of the Pop-Off Valve as outlined in the CLEANING & STERILIZATION section of this manual, remove the clear acrylic housing, the Bellows, and in the case of PEDIATRIC use, the Adapter, (which pulls straight up). The three red thumbscrews of the Pop-Off Valve are now exposed.

Unfortunately the settings vary with the setup, They especially depend on what you use for and ET tube. You can start out by opening the Paw valve on the side of the ventilator completely.
Connect the intubated mouse to the breathing system with the ventilator off and oxygen flowing at the slowest rate you feel comfortable running through your vaporizer, they all work differently at low flow rates.
Slowly start to close the Paw valve until you observe the mean airway pressure you desire, generally around 5 to 7 cmH2O.
Insure that the Amplitude is turned all the way down and turn on the machine in IPPV mode. Slowly bring the amplitude up until the oscillation of the airway pressure increases as desired, perhaps down the 0 and up to 10.

In either case you will need to ventilate a few mice, observe them, check a blood gas after a while to see how you doing and adjust the settings accordingly.