Vetland EX3000, Руководство оператора

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5-2 Operation
10. Check ventilator function (if used) as follows:
a. Verify the connection of the breathing circuit.
b. Check the ventilator for performance according to manufacturer’s specifications.
Inspiratory Pressure Adjustment
The operator can also determine the inspiratory pressure for ventilating the patient by adjusting the pop-
off valve while observing the cmH
2
O pressure gauge. The more the pop-off valve is opened, the lower the
inspiratory pressure; the more the valve is closed, the higher the inspiratory pressure.
Note: The pop-off valve must never be closed completely during manual or spontaneous ventilation
while using a closed patient breathing circuit. A complete closure of the valve causes an
excessive build-up of pressure, which may be harmful to the patient.
During the ventilation process, the operator should monitor the pressure gauge at all times. Again, close
attention must be paid to the cmH
2
0 pressure gauge to avoid excessively high, negative, or continuing
pressures. The operator may adjust the pressure alarm parameters via the Setup Menu.
When fully opened (counterclockwise) the pop-off valve keeps a small 1 to 2 cmH
2
O pressure in the
system. This maintains a fully distended breathing bag and allows the equipment operator to bag without
having to adjust the pop-off. This small pressure does not create any danger to the patient.
The pop-off valve has a 19mm scavenger port, which must be connected to 19mm tubing. When using a
rebreathing circuit, this tubing is routed to a waste gas disposal system (such as an active scavenging
system, charcoal canister, or routed passively out of the room).
During many veterinary anesthesia procedures, the patient will breathe spontaneously. In those cases, it
will be much easier to determine the correct fresh gas flow and pop-off valve setting. The oxygen flow
control setting and the pop-off valve should be set so that the breathing bag neither collapses during
inspiration nor over-inflates during exhalation. The inspiration/expiration pressures should be in the low
range of the cmH
2
O pressure gauge.
It is often believed that when a closed patient breathing circuit is used, a patient has to exhale against a
high resistance. This is not the case under normal conditions. The patient exhales via the expiratory valve
into the breathing bag and bypasses the CO
2
absorber. The resistance of the expiratory valve should be 1
cmH
2
O or less. Neither is it correct that a patient will rebreathe a large amount of exhaled gas due to the
distance between the wye connector and the expiratory valve. The patient will only rebreathe the volume
of gas between the wye connector of the breathing circuit and its mouth, nose, or endotracheal tube.
Rebreathing Circuit vs. Non-rebreathing Circuit
The EX3000 has a semi-closed circle breathing system (rebreathing circuit) or a connector for non-
rebreathing applications. In a rebreathing patient breathing circuit, a portion of the exhaled breath is
recycled. In a non-rebreathing system, all exhaled gases, including the anesthetic agent, are lost to a
scavenging system and not recycled. The non-rebreathing circuit can be connected directly to the 15mm
fresh gas outlet located just below the Isoflurane filler. When using a non-rebreathing circuit, the fresh
gas flow must be adjusted high enough to prevent the rebreathing of exhaled CO
2
. It is strongly
recommended that a CO
2
monitor be used to monitor proper ventilation.
The reason for using a non-rebreathing circuit instead of a rebreathing patient breathing circuit is not only
to decrease the resistance during respiration, but also to control the inspired gases. Therefore, it may be
desirable to use a non-rebreathing circuit for patients that weigh 10 pounds or less. For more information,
consult a veterinary anesthesiologist at any university.