question

Open System

answer

"open cone", "open drop" of anesthetic; control of anesthetic was crude; anesthetist is unable to protect the airway

question

Endotracheal Tube

answer

a flexible tube placed in the trachea of an anesthetized patient used to transfer anesthetic gases directly from the anesthetic machine to the patient's lungs, bypassing the oral and nasal cavities, pharynx, and larynx

question

Murphy Tubes

answer

have a beveled head and a side hole called the "Murphy eye" and may or may not have a cuff

question

Cole Tubes

answer

have no cuff or side hole, but are designed with an abrupt decrease in diameter near the patient end of the tube; used for species that have complete tracheal rings such as birds and some reptiles to prevent damage to the trachea that would be caused by a cuffed tube

question

PVC Tubes

answer

polyvinyl chloride; transparent and are somewhat stiffer than other types; stiffness minimizes the risk of collapse, but increases the risk of trauma to tracheal mucosa during tube placement, when turning the patient, and during patient transfer

question

Red Rubber Tubes

answer

more flexible and less traumatic; more prone to kinking or collapsing, especially if small; may absorb disinfectants, resulting in irritation from contact and tend to dry and crack after prolonged use

question

Spiral or Anode Tubes

answer

contain a coil of metal or nylon embedded in the rubber designed to resist kinking or collapse from external pressure

question

Silicone Tubes

answer

more expensive; combine strength with pliability and are resistant to collapse and are less irritating to tissues than either rubber or vinyl tubes

question

Internal Diameter (ID)

answer

most commonly used to express tube size; written on the surface of each tube

question

Asphyxiation

answer

the act of cutting off the supply of oxygen; suffocation; end hole of tube can become blocked with mucous

question

Endotracheal Tube Parts

answer

-valve with syringe attached -pilot balloon -machine end -connection -tie -measurement of internal diameter -inflated cuff -patient end -Murphy eye

question

Use For a Cuff

answer

-prevent leakage of air and gases around the tube and reduces waste gas pollution in the operating room -minimizes risk of aspiration of blood, saliva, vomitus, and other material into the lungs -prevent animal from breathing room air

question

Points Noted With Endotracheal Tubes

answer

-should not bend during placement -tubes reduce dead space -caution when used with laser surgery

question

Laryngoscope

answer

a device used to increase visibility of the larynx while placing an endotracheal tube; often used in small ruminants, camelids, and swine; helpful in dogs and cats, not generally used in adult cattle and horses

question

Anesthetic Masks

answer

cone-shaped devices used to administer oxygen to non-intubated patients via the nose and mouth; used in patients difficult to intubate, for anesthetic induction and maintenance, or to administer pure oxygen; usually made of plastic or rubber; allows for rapid administration of oxygen; do not maintain an open airway, no protection against pulmonary aspiration, anesthetist is unable to ventilate the patient

question

Anesthetic Chambers

answer

clean, aquarium-like boxes used to induce general anesthesia in small patients that are feral, vicious, or intractable, or cannot be handled without undue stress; made of acrylic or Perspex; have a removable top with 2 ports for a gas source and exit of waste gas; prevent close monitoring of the patient

question

Basic Principles of the Anesthetic Machine

answer

liquid anesthetic is vaporized into a carrier gas which delivers the anesthetic to the patient via a breathing circuit

question

Functions of Anesthetic Machine and Breathing Circuit

answer

-carrier gases must be delivered at a controlled flow rate -precise concentration of a liquid inhalant must be vaporized, mixed with the carrier gases, and delivered to the patient -exhaled gases containing CO2 must be moved away from the patient and either removed through a scavenging system or recirculated to the patient without CO2

question

Compressed Gas Supply

answer

supplies carrier gases-oxygen and sometimes nitrous oxide

question

Anesthetic Vaporizer

answer

vaporizes liquid inhalant anesthetic and mixes it with the carrier gases

question

Vaporizer-Out-of-Circuit (VOC)

answer

a vaporizer in which carrier gas from the flow meter flows into the vaporizer before entering the breathing circuit; precision vaporizers are precisioned this way

question

Vaporizer-in-Circuit (VIC)

answer

a vaporizer that is located in the breathing circuit; non-precision vaporizers are often positioned this way

question

Breathing Circuit

answer

conveys the carrier gases and inhalant anesthetics to the patient and removes exhaled carbon dioxide; classified as rebreathing or non-rebreathing circuits

question

Scavenging System

answer

disposes of excess and waste anesthetic gases

question

In a healthy, conscious patient breathing room air with ___% oxygen, approximate concentration in alveolus is ___%, aterial blood is ___%, capillary blood at tissue level is ___%, and in tissues is ___%.

answer

21%; 13%; 12%; 5%; 2%

question

Tidal Volume (Vt)

answer

the volume of a normal breath (approximately 10-15 mL/kg body weight)

question

Compressed Gas Cylinder

answer

contain a large supply of carrier gas in a highly pressurized state; enables large supply of gas to be stored in a space small enough to be of practical use; either small (E-tanks) or large (H-tanks)

question

Line Pressure

answer

oxygen pressure remaining in the intermediate-pressure lines after the valve is closed

question

Potential Risks From Compressed Gas Cylinders

answer

-oxygen and nitrous oxide support combustion -forceful release of gas from an unprotected outlet port may tear the skin or injure an eye -if a cylinder is dropped and the valve breaks off, the cylinder may cause serious personal injury -if inadvertently attached to a valve, yoke, or hose intended for a different type of gas, the wrong gas will be delivered to the patient

question

Tank Pressure Gauge

answer

a device attached to the yoke of a machine, or the pressure regulator of an H tank, that indicates the pressure of gas remaining in a compressed gas cylinder measured in pounds per square inch (psi) in the U.S. or kilopascals in Europe and Canada

question

Pressure in a full oxygen tank is about __________psi or _________kPa.

answer

2200 psi; 15,000 kPa

question

Pressure Reducing Valve

answer

located near the tank pressure gauge; gas flows through here after exiting the tank then into an intermediate gas line; reduces pressure of a gas to 40-50 psi (275-345 kPa) regardless of pressure changes within the tank

question

Line Pressure Gauge

answer

indicates the pressure in the intermediate-pressure gas line between the pressure-reducing valve and the flow valves; when oxygen is on, gauge should read 40-50 psi

question

Oxygen Flush Valve

answer

a button or lever that, when activated, delivers a large volume of pure oxygen at a flow rate of 35-75 L/min. directly from the line exiting the pressure-reducing valve into the common gas outlet or into the breathing circuit of a rebreathing system, bypassing the anesthetic vaporizer and oxygen flow meters

question

Flow Meter

answer

after leaving the pressure-reducing valve, carrier gas flows through an intermediate-pressure gas line, into the flow meter; a vertical glass cylinder of graduated diameter with a valve attached to the bottom; an indicator within the cylinder rises to indicate the gas flow expressed in liters of gas per minute; reduces pressure of gas in the intermediate-pressure line to 15 psi

question

Pressure Manometer

answer

a gauge that indicates the pressure of the gases within the breathing circuit, and by extension, the pressure in the animal's airways and lungs; expressed in centimeters of water (cm H2O), millimeters of Mercury (mm Hg), or kilopascals (kPa)

question

Non-Rebreathing System

answer

an anesthetic machine fitted with a non-rebreathing circuit; little or no exhaled gases are returned to the patient and removed from the circuit by use of appropriately high flow rates of carrier gas and evacuated by a scavenger connected to a pressure-limiting valve or other exit port; most commonly used for patients under 2.5-3 kg body weight

question

Aensthetic Vaporizer

answer

converts a liquid anesthetic to a gaseous state and adds controlled amounts of the vaporized anesthetic to the gas anesthetic

question

Fresh Gas

answer

oxygen and anesthetic mixture

question

Precision Vaporizer

answer

allows precise control of the amount of anesthetic delivered to the patient; expressed as the percent of the total gases exiting the vaporizer

question

Non-Precision Vaporizer

answer

used in the past to deliver low-pressure anesthetics; practice is uncommon now

question

Factors Affecting Vaporizer Output

answer

-temperature: volatile anesthetics vaporize more readily at higher temperatures than lower; temperature of anesthetic can be affected by carrier gas flow -carrier gas flow rate: amount of carrier gas flowing through the vaporization chamber determines anesthetic output; also influences the concentration of the anesthetic in the breathing circuit -respiratory rate and depth: in VIC non-precision vaporizers, this will affect anesthetic delivery by affecting the flow of carrier gas through the vaporization chamber -back pressure: refers to an increase in pressure at the vaporizer outlet port caused by manual ventilation or activation of the oxygen flush valve -barometric pressure

question

Isoflurane

answer

induction rate: 3-5% maintenance rate: 1.5-2.5%

question

Sevoflurane

answer

induction rate: 4-6% maintenance rate: 2.5-4%

question

Desflurane

answer

induction rate: 10-15% maintenance rate: 8-12%

question

Vaporizer Inlet Port

answer

the point where oxygen and any other carrier gases enter the vaporizer from the flow meters

question

Vaporizer Outlet Port

answer

the point where the oxygen, inhalant anesthetic, and N2O exit the vaporizer on the way to the breathing circuit

question

Common Gas Outlet

answer

the point where the oxygen, inhalant anesthetic, and N2O exit the anesthetic machine on the way to the breathing circuit

question

Breathing Circuit

answer

consists of a group of components that carry anesthetic and oxygen from the fresh gas inlet to the patient and convey expired gases away from the patient

question

Rebreathing System

answer

an anesthetic machine fitted with a rebreathing circuit; also called "circle systems" because exhales gases minus carbon dioxide are recirculated and rebreathed by the patient along with variable amounts of fresh oxygen and anesthesia

question

Closed Rebreathing System

answer

a rebreathing system in which the pop-off valve is kept nearly or completely closed and the flow of oxygen is relatively low, providing only the volume necessary to meet the patient's metabolic needs

question

Semi-Closed Rebreathing System

answer

a rebreathing system in which the pop-off valve is positioned partially open, and the flow of oxygen is relatively high, providing more volume than is necessary to meet the patient's metabolic needs

question

Rebreathing circuit consists of:

answer

-fresh gas inlet -unidirectional or one-way valves -pop-off or pressure relief valve -reservoir bag -carbon dioxide absorber canister -pressure manometer -air intake valve -breathing tubes -y-piece

question

Carbon Dioxide Absorber Canister

answer

the part of a rebreathing circuit that holds the carbon dioxide absorbent granules; these granules; primarily made of calcium hydroxide, remove expired CO2

question

Exhaled gases include:

answer

O2, anesthetic vapor, CO2, nitrogen, water vapor, and nitrous oxide (if used)

question

Flow of gas:

answer

inspiratory unidirectional valve-->inspiratory tube-->animal-->expiratory tube-->expiratory unidirectional valve-->carbon dioxide canister-->past the reservoir bag, pop-off valve, and pressure manometer-->back to the inspiratory unidirectional valve

question

Fresh Gas Inlet

answer

the point at which the carrier and anesthetic gases enter the breathing circuit; permanently attached to the breathing circuit

question

Unidirectional Valves

answer

control the direction of gas flow through the rebreathing circuit as the patient breathes

question

Pop-Off Valve

answer

also called the pressure relief valve, adjustable pressure limiting (APL) valve, or overflow valve; the point of exit of anesthetic gases from the breathing circuit; main function is to allow excess gases to exit from the breathing circuit and enter the scavenging system

question

Functions of a reservoir bag:

answer

1. serve as a flexible storage reservoir 2. allows the anesthetist to observe the animal's respirations 3. may be used to confirm proper ET tube placement 4. allows delivery of anesthetic gases to the patient

question

Why bagging is beneficial:

answer

1. atelectasis occurs to some degree in many anesthetized patients and to compromise gas exchange 2. most anesthetics depress respiratory drive and decrease Vt to as little as 50% of the volume seen in a normal, awake patient 3. anesthetized patients frequently experience a decreased respiratory rate or apnea

question

Atelectasis

answer

collapse of a portion or all of one or both lungs

question

Magill Circuit

answer

Mapleson A system; has an overflow valve at the patient end of the breathing tube; fresh gas inlet and reservoir bag are located away from the patient at the opposite end of the breathing tube; relatively low fresh gas flow required during spontaneous ventilation

question

Lack Circuit

answer

Modified Mapleson A system; has an expiratory tube that runs from the ET tube connector to an overflow valve near the bag; fresh gas inlet, overflow valve, and reservoir bag are located away from the patient at the opposite end of the breathing tube

question

Bain Coaxial Circuit

answer

Modified Mapleson D system; fresh gas outlet at the patient end of the breathing tube; overflow valve and reservoir bag are located away from the patient at the opposite end of the breathing tube; overflow valve may be built into or near the bag; the tube supplying fresh gas is surrounded by the larger, corrugated tubing--allows incoming gases to be warmed by exhaled gases surrounding them before reaching the patient

question

Ayre's T-Piece

answer

Mapleson E system; T-shaped tube with a fresh gas inlet entering the patient end of the breathing tube at a 90-degree angle; does not have a reservoir bag at the opposite end of the breathing tube

question

Jackson-Rees Circuit and Norman Mask Elbow

answer

Mapleson F systems; fresh gas outlet at the patient end of the breathing tube and a reservoir bag at the opposite end; Jackson-Rees Circuit-fresh gas inlet enters the breathing circuit then enters the breathing circuit at a 45- to 90-degree angle; Norman Mask Elbow-ET tube connector is at right angles to the breathing tube

question

Respiratory Drive

answer

the force generated by the respiratory muscles during breathing

question

Choice of system is important in terms of use and setup because it determines:

answer

-the type of equipment required -position of the pop-off valve -carrier gas flow rates

question

Factors in making a system decision:

answer

-cost -control of anesthetic depth -conservation of heat and moisture -production of waste gas

question

Flow rates for anesthetic procedures are calculated by:

answer

-using the patient's body weight and the Vt or RMV -Vt is considered to be approximately 10mL/kg/min. in most anesthetized animals -RMV is Vt x respiratory rate in breaths per minute (average of 20 breaths/min. in most patients) -RMV is considered to be about 200 mL/kg/min.

question

Flow rates with a semi-closed rebreathing system-------after induction with an injectable agent

answer

flow rate should be relatively high (50-100 mL/kg/min.)--results in a flow rate of about 500 mL-5L/min. for smaller animals or large animals connected to a small animal anesthetic machine depending on patient weight; initial flow rate for large animals on a large animal machine range from 8-10 L/min.

question

Flow rates with a semi-closed rebreathing system--------when making changes in anesthetic depth

answer

higher oxygen flow rate (50-100 mL/kg/min.) when patient's level of anesthesia is too deep or too light and a change in anesthetic depth is needed; higher end of range will result in more rapid change in the desired anesthetic concentration within the breathing circuit

question

Flow rates with a semi-closed rebreathing system------during maintenance

answer

rate may be reduced; rebreathing systems require low flow rates compared with non-rebreathing systems during this period because carbon dioxide is removed from the expired gases, whic h are then returned to the patient; rates of 20-40 mL/kg/min. are recommended for small animals and 3-5 L/min. for adult large animals

question

Flow rates with a semi-closed rebreathing system-------during anesthetic recovery

answer

-remove waste gas by: -turning vaporizer off -increase flow rate to 50-100 mL/kg/min. -with pop-off valve open, use gentle pressure to evacuate reservoir bag and refill it using short bursts from oxygen flush valve -maintain higher flow rate for 5 minutes or until patient must be extubated -large animals on large animal anesthetic machine-same procedure but use rate of up to 10 L/min.

question

When minimal rebreathing of anesthetic gases is desired:

answer

when oxygen flow rate matches or exceeds patient's RMV (at least 200-300 mL/kg/min.), rebreathing system can function like a non-rebreathing system; rates help flush exhaled gases from the breathing circuit through the pop-off valve and may be necessary until the problem is rectified

question

Flow Rates When Using a Closed Rebreathing System:

answer

-oxygen flow must equal only the oxygen requirements of the animal -minimum metabolic oxygen requirement for the anesthetized animal is 5-10 mL/kg/min. -when flow rates of less than 250 mL/min. are used, some precision vaporizers and flow meters might not accurately deliver the dialed vaporizer concentration and oxygen flow -large animals, esp. adult horses and cattle, have lower metabolic oxygen requirements and oxygen rates and can be as low as 3-5 mL/kg/min. during maintenance with a closed rebreathing system

question

Safety Concerns With a Closed Rebreathing System

answer

1. carbon dioxide circulation-can build up within the circuit; less likely to happen in a semi-closed rebreathing system 2. increased pressure in the anesthetic circuit; risk is lessened with a semi-closed rebreathing system because the pop-off valve is partially to fully open and excessive gas is vented

question

Flow Rates--Non-Rebreathing System

answer

-relatively high flow rates per unit of body weight during all periods of general anesthesia--removal of carbon dioxide from the circuit is dependent on fresh gas flow -rates based on body weight--typically used on patients 7kg or under, so max rates are based on that

question

Mapleson A, Modified Mapleson A, Modified Mapleson D flow rates

answer

carrier flow gas should be close to RMV (200 mL/kg/min.--should equal 0.5-1.5 L/min.

question

Modified Mapleson D with no rebreathing, Mapleson E, Mapleson F flow rates

answer

-require oxygen flow rate of 2-3 x's the RMV (400-600 mL/kg/min.) with a max flow of 3 L/min. for patients under 7 kg. -equals 1-3 L/min. depending on patient size

question

To remove an E-tank from the machine:

answer

-be sure tank valve is closed and oxygen is purged from the system -place you shoe under the tank to support it -loosen the wing nut and back the valve port off of the yoke -carefully remove your shoe and lower the tank until the valve clears the yoke -tank should be stored in an upright position until it is picked up by the company for refilling

question

When replacing an E-tank on a machine:

answer

-inspect the valve port for cleanliness then place a single washer between the valve port and the nipple -gently raise the tank into place-line the valve port and the pin holes with the corresponding structures on the yoke -tighten the wing nut as securely as you are able to by hand -open the tank slowly and listen for leaks IF LEAKS-->recheck holes for proper alignment, tighten wing nut further, or use a new washer

question

Pressure-Reducing Valve Maintenance

answer

may need to be adjusted if line pressure is not correct; may have an external adjusting screw that is turned left or right to increase or decrease the pressure

question

Flow Meter Maintenance

answer

do not overtighten valve when turning off

question

Testing Flow Meter Accuracy

answer

1. empty reservoir bag completely 2. close pop-off or overflow valve 3. occlude the y-piece or ET tube connector 4. choose a flow setting that corresponds to the size of the reservoir bag in liters 5. accurate if the bag is filled completely in 1 minute

question

Unidirectional Valve Maintenance

answer

periodically disassemble, clean, and inspect to prevent a buildup of water vapor, mucus, and dust from carbon dioxide absorbent, and other material

question

Cleaning the Unidirectional Valve

answer

1. unscrew valve collar and remove valve parts 2. clean dome, collar, valve, valve seal, and gaskets with alcohol or mild disinfectant 3. dry off 4. inspect valve and valve seal to be sure they are not damaged or warped 5. reassemble the valve

question

Testing Integrity of Unidirectional Valves

answer

1. put on a surgery mask 2. detach the expiratory breathing tube from the y-piece 3. place the end of the tube up to your mouth with surgery mask in between so that the air will pass through the mask 4. attempt to inhale through the tube 5. detach the inspiratory breathing tube from the y-piece and place the end up to your mouth 6. attempt to exhale through the tube -any air movement through either tube indicated an incompetent valve

question

Reservoir bag, breathing tubes, and y-piece

answer

removed and cleaned to prevent interpatient transfer of infections agents that collect inside; hang in vertical position until completely dried

question

Changing Absorbent in the Carbon Dioxide Absorber Canister

answer

1. remove the absorber canister and dispose of absorbent granules 2. disassemble canister 3. clean each part with mild soapy disinfectant, rinse thoroughly 4. dry each part 5. check all gaskets for integrity 6. reassemble canister 7. loosely fill with fresh granules, but leave 1cm.-1/2 in. air space at the top to allow unimpended air flow --Handle granueles with gloves

question

Disinfecting Anesthetic Equipment

answer

1. disassemble any parts that can be removed 2. wash any parts thoroughly with disinfectant, rinse, dry, and reassemble

Chapter 4 Notes: Anesthestic Machine – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards