Anesthesia Equipment PowerPoint Presentation

List of equipment used by Anaesthesiologist for Medical Students

1. 1
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Anesthetic Equipment
The purpose, function, use, and maintenance of
machines and equipment used to administer
inhalation anesthetics
Chapter 4

2. 2
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Endotracheal Tubes (ET Tubes)
Flexible tube placed in the trachea
Delivers anesthetic gases directly from the
anesthetic machine to the lungs
Advantages
Open airway
Less anatomical dead space
Precision administration of anesthetic agent
Prevents pulmonary aspiration
Responds to respiratory emergencies
Monitors respirations

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Types of Endotracheal Tubes
Murphy tubes (A, C,D)
Beveled end and side holes
Possible cuff
•A. silicone
•C. PVC
• D. Red rubber
Cole tubes (B)
No side hole or cuff
Abrupt decrease in diameter of the tube
Used in birds and reptiles

4. 4
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Properties of Endotracheal Tubes
Materials
Polyvinyl chloride: clear and stiffer
Red rubber: flexible and less traumatic, absorbent, and may
kink or collapse
Silicone: pliable, strong, less irritating, resist collapse
Length
Standard lengths
Scale marks distance from patient end (centimeters)
Size
Measured by internal diameter (ID)
Range from 1 mm to 30 mm

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Parts of the Endotracheal Tube
Patient end (i)
Machine end (c )
Connector ( D)
Cuff ( H)
Pilot balloon (b)
and valve (a)
Murphy Eye- J
Internal diameter
measurement

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Laryngoscope
Used to increase the visibility of the larynx while
placing an ET tube
Parts
Handle containing batteries
Blade to depress tongue and epiglottis
Light source to illuminate the throat
Sizes
Small animal 0 to 5; large animal up to 18-inch blade
Types
Miller blades A, C, E
McIntosh blades B, D, F

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Masks
Cone-shaped devices used to administer
oxygen and anesthetic gases to nonintubated
patients
Used for induction and maintenance of
anesthesia in very small animals
Plastic or rubber
Variety of diameters and lengths
Rubber gasket

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Anesthetic Chambers
Clear, aquarium-like boxes used to induce
general anesthesia
Used in feral, vicious, or intractable animals
to reduce stress
Acrylic or Perspex
Removable top with two ports
Cannot monitor patient closely

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Anesthetic Machines
Used to deliver precise amounts of oxygen and
volatile anesthetic under controlled conditions

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Principles of Operation of Anesthetic
Machines
Carrier gas: oxygen or nitrous oxide
Liquid inhalant anesthetic: to be vaporized
Mixed gases delivered to patient
Exhaled gases removed from patient:
scavenging system or recirculated

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Components of the Anesthetic Machine
Compressed gas supply
Anesthetic vaporizer
(precision or nonprecision;
VOC or VIC)
Breathing circuit
(rebreathing or
nonrebreathing)
Scavenging system

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Components of the Anesthetic
Machine (Cont’d)

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Components of the Anesthetic
Machine (Cont’d)

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Compressed Gas Supply
Oxygen
Used to increase inspired air to at least
30% oxygen
Level necessary to maintain cellular
metabolism under anesthesia
Used to carry vaporized anesthetic to
patient
Cylinders (tanks)
Contain large volume of gas under
high pressure
E tanks (small), attached directly to
anesthetic machine
H tanks (large), attached remotely to
anesthetic machine

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Compressed Gas Supply (Cont’d)
Control valve (outlet port)
Located on top of the tank
Left loose (open), right tight (closed)
Pressure-reducing valve (B)
Reduces outgoing pressure to a usable level
Tank pressure gauge C
Line pressure gauge D

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Safety Issues with Compressed Gas
Combustibility
Yoke attachment- pins
High-pressure release
Storage
Color coding
Oxygen: green (United States) or white (Canada
and Europe) (right)
Nitrous oxide: blue
Medical air: yellow (United States) or white and
black (Canada and Europe)
Carbon dioxide: gray (left)

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Tank Pressure Gauge
Indicates the pressure of gas remaining in a
compressed gas cylinder
Measured in pounds per square inch (psi) (United
States) or kilopascals (kPa) (Canada and Europe)
Determine the number of liters remaining in a
tank
Label tanks: full, in service, or empty
Keep backup full tank on the machine

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Pressure-Reducing Valve
(Pressure Regulator)
Reduces gas pressure to a constant
40-50 psi (275-345 kPa)
Color coded

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Line Pressure Gauge
Indicates pressure in the gas line between
the pressure-reducing valve and flowmeter
Should read 40-50 psi after the oxygen tank
is opened
After turning the tank off, use the oxygen
flush valve to evacuate line pressure until the
gauge reads 0 psi.

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Flowmeter
Indicates gas flow expressed in liters per
minute (L/min)
Reduces pressure of gas to 15 psi
(~100 kPa)
Specific for each type of gas
Flow rate is controlled by anesthetist

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Oxygen Flush Valve
Delivers a short, large burst of pure oxygen
directly into the rebreathing circuit or common
gas outlet
Bypasses vaporizer and flowmeter
Used to refill breathing bag, to deliver pure
oxygen to a patient, or to dilute the anesthetic
gas remaining in the circuit at the end of
anesthesia

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Vaporizer Inlet Port
Where carrier gas (usually oxygen) enters a
vaporizer from the flowmeter

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Anesthetic Vaporizer
Converts liquid anesthetic agent to a gaseous
state
Adds a controlled amount of vaporized agent
to the carrier gas
Gas mixture leaves vaporizer through the
outlet port
Mixture is known as fresh gas and enters the
breathing circuit
Variable-bypass, flow-over vaporizers

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Types of Anesthetic Vaporizers
Nonprecision vaporizer
Used to deliver low vapor pressure anesthetics
Rarely used
Precision vaporizers
Used to deliver a precise amount of anesthetic to
the patient
Expressed as a percent of total gases leaving the
vaporizer
Used to deliver high-vapor pressure anesthetics
Anesthetist controlled

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VOC vs. VIC Vaporizers
VOC = Vaporizer-
out-of-circuit
Not localized within
the breathing circuit
Oxygen from the
flowmeter enters the
vaporizer prior to
entering the
breathing circuit
Precision vaporizers
High resistance gas
flow
VIC = Vaporizer-in-
circuit
Oxygen enters the
breathing circuit from
the flowmeter
Exhaled gases pass
through the vaporizer
Nonprecision
vaporizers
Low-resistance gas
flow

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Factors That Affect Vaporizer Output
Vaporizer setting
The primary determinant of output in both
compensated and noncompensated vaporizers
Controlled by anesthetist
Carrier gas flow influences the concentration
of anesthetic in breathing circuit in both
compensated and noncompensated
vaporizers

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Factors That Affect Vaporizer Output
(Cont’d)
Factors that affect output of noncompensated
vaporizers
Temperature
•Ambient room temperature
•Temperature of carrier gas
Carrier gas flow rate
Respiratory rate and depth (nonprecision only)
Back pressure
•Due to manual ventilation or activation of oxygen flush
valve

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Use of Vaporizers
Specific-use vaporizers are color coded
Isoflurane = purple
Sevoflurane = yellow
Halothane = red
Desflurane = blue
Induction and maintenance rates
Isoflurane = 3-5% induction; 1.5-2.5% maintenance
Sevoflurane = 4-6% induction; 2-4.5% maintenance
Desflurane = 10-15% induction; 8-12% maintenance

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Precision Vaporizer

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Safety with Vaporizers
Leakage
Human exposure
After using a non-rebreathing circuit, always
be sure to reattach the connector of the
rebreathing circuit to the outlet port or
common gas outlet

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Vaporizer Outlet Port and Common
Gas Outlet
Vaporizer outlet port
Oxygen/anesthetic exits the vaporizer
Connected to the common gas outlet or directly
into the breathing circuit
Common gas outlet
Fresh gas outlet
Connected to the vaporizer outlet port and
breathing circuit

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Fresh Gas Inlet
Where carrier and anesthetic gases enter the
breathing circuit
Connected to the vaporizer outlet port or
common gas outlet

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Breathing Circuit
Carries anesthetic and oxygen from the fresh
gas inlet to the patient
Conveys expired gases away from the patient
Rebreathing or non-rebreathing

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Rebreathing System
Circle systems
Used on all but very small animals
Carbon dioxide removed from exhaled air
Exhaled air is inhaled again with added
oxygen and anesthetic

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Rebreathing System (Cont’d)
Air flow:
Inhalation unidirectional valve →
Inhalation tube → Animal → Exhalation tube
→ Exhalation unidirectional valve →
Carbon dioxide absorber canister →
past reservoir bag → Pop-off valve →
Pressure manometer →
Inhalation unidirectional valve

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Rebreathing System (Cont’d)
Closed rebreathing system
Total system
Pop-off valve is nearly or completely closed and
oxygen flow is low
Used mostly in large animal anesthesia
Semiclosed rebreathing system
Partial system
Pop-off valve is open and oxygen flow is high
Excess air is released into scavenging system
Most common configuration

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Breathing Systems

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Parts of a Rebreathing System
Unidirectional valves
Reservoir bag
Pop-off (pressure relief) valve
Carbon dioxide absorber canister
Air intake valve
Pressure manometer
Corrugated breathing tubes
Y-piece

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Parts of a Rebreathing System
(Cont’d)

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Unidirectional Valves
Control the direction of gas flow
Inspiratory (inhalation)
Expiratory (exhalation)
Open and close as patient breathes
Monitor respiratory rate and depth

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Pop-off Valve
Also known as the exhaust valve,
adjustable pressure limiting valve,
or overflow valve
Allows excess carrier and anesthetic
gases to exit the breathing circuit and
enter the scavenging system
Prevents excessive pressure or
volume of gases in the circuit
Closed when manually ventilating
a patient
Controlled by anesthetist

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Reservoir Bag (Rebreathing Bag)
Flexible air storage reservoir
Indicator of respiratory rate
and depth
Confirms proper endotracheal
tube placement
Allows delivery of anesthetic
gases or pure oxygen to
patient
Manual ventilation or “bagging”
Various sizes: 500 mL to 30 L
Controlled by anesthetist

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Manual Ventilation (Bagging)
Minimize atelectasis
Ventilate every 5-10 minutes
Force fresh gas into alveoli to normalize gas
exchange
Normalize respiratory rate

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Carbon Dioxide Absorber Canister
Contains absorbent granules
Primary absorbent ingredient: calcium
hydroxide
Also: water, sodium hydroxide,
potassium hydroxide, calcium
chloride, calcium sulfate
Granules react with carbon dioxide to
form calcium carbonate
Heat and water produced
Becomes more acidic with more use
Granules must be replaced when
depleted

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Pressure Manometer
Indicates the pressure of gases
within the breathing circuit
Expressed as centimeters of water
(cm H
2
O), millimeters of mercury
(mm Hg), or kPa
Used when manually ventilating
(bagging) the patient to prevent
excessive pressure in the lungs
Monitored by the anesthetist

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Air Intake Valve
Negative pressure relief valve
Admits room air into the circuit if negative
pressure is detected in the breathing circuit
May be separate or incorporated into inspiratory
unidirectional valve or pop-off valve
Negative pressure is indicated by a collapsed
reservoir bag
Patient will develop hypoxemia

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Breathing Tubes and Y-Piece
Breathing tubes
Corrugated breathing tubes or inspiratory and
expiratory breathing tubes
Carry anesthetic gases to and from the patient
Connected to unidirectional valve and Y-piece
Three sizes: 50 mm, 22 mm, and 15 mm in diameter
Y-piece
Connects breathing tubes
Connects to mask or endotracheal tube

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Non-rebreathing Systems
Semiopen system
Used in very small patients (<2.5 kg)
Little exhaled gas is returned to the patient
Exhaled gas is evacuated by the scavenging system
Fresh gas is routed to the patient directly from the vaporizer
No carbon dioxide absorber canister, pressure manometer,
or unidirectional valves
Several configurations are available
Components: Endotracheal tube connector, fresh gas inlet,
reservoir bag, overflow valve, scavenger tube, and scavenger
system

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Configurations of Nonrebreathing
Circuits
Bain coaxial circuit (modified
Mapleson D system)
Ayres T-Piece (Mapleson E system)
Magill circuit (Mapleson A system)
Lack circuit (modified Mapleson A
system)
Jackson-Rees circuit (Mapleson F
system)
Norman mask elbow (Mapleson F
system)

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Operation of an Anesthetic Machine
Daily inspection
Oxygen and liquid anesthetic levels
Leaks
Pop-off valve or overflow valve
Machine choice is based on patient body
weight
Small animal machine <150 kg
Large animal machine 150 kg
Choose rebreathing system

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Choice of Breathing System
Primarily based on patient size
Also based on
Cost
Control of anesthetic depth
Conservation of heat and moisture
Production of waste gas
Choice of breathing system will determine
Type of equipment required
Position of pop-off valve
Carrier gas flow rates

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Carrier Gas Flow Rates
Calculating gas flow rate
Patient body weight
Tidal volume (V
T) 10 mL/kg/min
Respiratory minute volume (RMV) = V
T
×
respiratory rate (~20 bpm)
Type of breathing system
Expected period of anesthesia

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Mask or Chamber Induction Flow Rates
High flow rates required
Mask: ~30 times V
T
for dogs, cats, neonate
large animals, pigs (1-5 L/min)
Chamber: 5 L/min for small animals

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Flow Rates in a Semiclosed
Rebreathing System
After induction with injectable agent:
50-100 mL/kg/min (SA machine) and 8-10 L/min (LA
machine)
When making changes in anesthetic depth:
50-100 mL/kg/min (SA machine) and 8-10 L/min (LA
machine)
During maintenance: 20-40 mL/kg/min (SA machine)
and 3-5 L/min (LA machine)
During recovery: 50-100 mL/kg/min (SA machine)
and 8-10 L/min (LA machine)

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Flow Rates in a
Closed Rebreathing System
Normally used during maintenance only
Oxygen flow must equal oxygen requirements
of the patient
Minimum requirement = 5-10 mL/kg/min

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Safety Concerns with a
Closed Rebreathing System
Carbon dioxide accumulation
Increased pressure in anesthetic circuit

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Flow Rates in a
Non-rebreathing System
Require high flow rates per unit body weight
during all periods
Rates are based on patient body weight and
Mapleson classification of circuit
Usually used on patients weighing <7 kg

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Care and Maintenance of
Anesthetic Equipment
Compressed gas cylinders
Inspected and maintained by company that owns
them
Silicone or Teflon-based lubricants safe for difficult
tank valves
Tank and line pressure gauges, pressure
manometer, and oxygen flush valve
Require no regular maintenance
Pressure-reducing valve adjusted to 40-50 psi
Flowmeters require no regular maintenance
Check accuracy occasionally

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Care and Maintenance of
Anesthetic Equipment (Cont’d)
Vaporizer
Serviced and maintained by manufacturer or
service professional
Vaporizer inlet port, outlet port, common gas
outlet, and fresh gas inlet
Check and replace hoses as necessary
Routine low-pressure leak tests

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Care and Maintenance of
Anesthetic Equipment (Cont’d)
Unidirectional valves
Disassemble, clean, inspect
Prevent water vapor, mucus, and dust buildup
Check integrity of the valves
Pop-off valve
Check for proper operation and adjust as
necessary
Daily and during an anesthetic procedure

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Care and Maintenance of
Anesthetic Equipment (Cont’d)
Reservoir bag, breathing tubes, and Y-piece
Remove and clean after each procedure
Prevents patient-to-patient transfer
Hang to dry
Check integrity of each part before use
Carbon dioxide absorber canister
Change granules and clean canister as per
guidelines
Wear gloves and a mask when handling granules
Check integrity of each part before use

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Disinfecting Anesthetic Equipment
Endotracheal tubes, laryngoscope blades,
face masks
To prevent spread of disease from patient to
patient
Wash with disinfectant, rinse, dry, reassemble
Check integrity of each part before use

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Disinfecting Anesthetic Equipment
(Cont’d)
Disinfectants
Chlorhexidine gluconate: not 100% effective
Glutaraldehyde solutions (2%): short shelf life,
toxic, absorbed
Ethylene oxide gas: special equipment needed,
toxic, absorbed
Steam under pressure (autoclave): damages
rubber surfaces
Discard damaged equipment