Flashcards in Chpt. 4 - Key Points Deck (18):
What does ET tube placement offer?
It offers many advantages and increases patient safety for both injectable and inhalant anesthetic techniques.
What is of primary importance in any GA procedure?
Proper ET tube selection, preparation, placement, and monitoring.
What are anesthetic machines good for?
They deliver precise amounts of carrier and anesthetic gases, remove carbon dioxide, and permit manual ventilation of anesthetized patients.
What can be used as a source of oxygen in emergencies?
An anesthetic machine
What do compressed oxygen cylinders store?
They store carrier gases under high pressure. Cylinders come in various sizes and capacities, and the gas contained within is identified by the color of the cylinder.
What does the pressure-reducing valve do?
It decreases carrier gas pressure to a safe operating pressure of 40 to 50 psi before the gas enters the flow meters.
How is the flow rate set?
The flow rate of each carrier gas is set by its respective flow meter. Flows are generally expressed in liters per minute. The flow rate indicates to the anesthetist how much gas is being delivered to the patient at any given time.
What is "fresh gas"?
Liquid anesthetic is vaporized and added to the carrier gas in the vaporizer. the combination of anesthetic vapor, oxygen, and nitrous oxide (if present) is called "fresh gas".
What kind of vaporizers are there?
Vaporizers may be precision or nonprecision, based on their construction. Precision vaporizers are commonly used for anesthetics with high vapor pressures and provide compensation for variations in temperature, gas flow rate, and back pressure.
Where are precision and nonprecision vaporizers found?
Precision vaporizers are found outside of the anesthetic circuit (VOC), whereas nonprecision vaporizers are found inside the anesthetic circuit (VIC).
What is the reservoir bag and what is it used for?
The reservoir bag (rebreathing bag) serves as a reservoir to receive and provide gas during the respiratory cycle. It can be used to monitor the animal's ventilation and to deliver oxygen (with or without anesthetic) to the patient by a process called bagging.
What do unidirectional valves do?
Inhalation and exhalation unidirectional valves permit only one-way flow of gas through the breathing circuit and prevent rebreathing of CO2.
Where does waste gas exit?
Waste gas exits the machine at the pop-off valve and is removed by the scavenging system.
How is carbon dioxide removed?
Carbon dioxide is removed from a rebreathing circuit by absorbent granules (soda lime). These granules must be replaced when saturated, or at least every 6 to 8 hours, to prevent rebreathing of carbon dioxide.
What does the pressure manometer do?
The pressure manometer measures the pressure of gases within the breathing circuit and the patient's lungs.
What are anesthetic circuits classified as?
They may be classified as rebreathing (either closed or semiclosed) or non-rebreathing.
Rebreathing systems use lower oxygen flow rates but must provide for carbon dioxide absorption. Non-rebreathing systems, such as the Bain system, require relatively high flow rates and are commonly used in small patients.
How do carrier gas flow rates vary?
They vary with the period of anesthesia and type of anesthetic circuit used (i.e. rebreathing or non-rebreathing).
With a rebreathing system, high flow rates are used during induction, recovery, and changing of anesthetic depth, and lower rates are used during maintenance.
When a non-rebreathing system is used, high flow rates are used at all times.