Transcript Anesthesia Assistant Course Module 3

Sept 26, 2009
Ashley Meister
1
Objectives
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Case set up
Compare cases for set up
Positions, effects on patient, risks
Fluid replacement, scavenging
Suction
Ventilator set up
2
Patient Positioning
 Indications, precautions, complications and procedure for each of the following patient
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positions:
Supine
Prone
Lithotomy
Beach chair
Lateral decubitus
Supine/ fracture table
3
General Concepts in positioning
 sedated/ anesthetized patients should not be placed in
positions they are not comfortable in when they are
awake
 Compromise between what patient can tolerate
structurally and physiologically, and what is required
for surgical access
 Physiologic instability may be magnified by rapidly
moving seriously ill patients
4
Positioning
 Bony prominences can produce ischemic necrosis of
overlying tissue unless proper padding is required
 Enhanced by hypothermia and hypotension
 Caution particularly with ulnar nerve
5
Supine
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Lying horizontally
Arm pressure points padded and either tucked to side or abducted
Abduct less than 90 degrees
Extend hands ventrally
Ensure perfusion to the hand, no skin to metal contact and no
stretch on brachial neurovascular bundle
 No compression in the axilla
 Bony contacts at occiput, elbows & heals padded
6
Supine
 Horizontal supine, minimal changes to vascular
system
 If tipped into trendelenburg or reverse trendelenburg,
effects of gravity on blood flow significant.
 Pressures change 2mmHg for each 2.5cm above or
below level of the heart
7
Supine
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Reverse trendelenburg
Blood pools in legs, decreasing effective circulating volume
Decreased cardiac output
Decreased systemic perfusion
Perfusion pressure in brain correspondingly decreased compared to if
measured at level of the heart
 Ventilation dynamics are enhanced
8
Supine
 Trendelenburg
 Increased pressure in cerebral veins
 Can increase ICP
 Congestion around eyes and airway
 Negative impact on ventilation
9
Supine
 Respiratory “Zones of West” shift
 Diaphragm is pushed cephalad
 Decreased FRC
10
Supine
 Pregnant uterus rests on great vessels of the abdomen
 Aortocaval compression- therefore tilt into Left
lateral decubitus position/ left uterine displacement
11
Supine
 Excessive flexion or extension of the spine in
anesthetized patients who are placed in unique
surgical positions may contribute to spinal cord
ischemia and catastrophic neurological damage
12
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Considerations with Prone
positioning?
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Prone
 Venous pooling in legs, decreased preload and decreased cardiac output
 If pressure is on abdominal viscera, transmitted to veins in spinal canal,
causes increased bleeding in spine procedures
 Extensive spine procedures in the prone position is associated with post
operative visual loss (associated with blood loss, anemia & hypotension)
15
Prone
 Importance of secure airway
 Always have stretcher outside room in case airway is
lost
 Congestion of face and airway
 Check eyes & ears carefully
 Ensure arms not extended > 90 degrees, and well
padded
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What would you do?
 A/W is lost when prone
 Key point- prevention
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1
18
Lithotomy
 Gynecologic and urologic procedures
 Supine, arms crossed on trunk or extended laterally on
arm boards
 Flex lower extremities at hip and knee
 Both limbs simultaneously elevated and separated
 Nerve injury possible if hips flexed greater than 90
degrees
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Lithotomy
 Ensure padding over lower extremities if pressure
points exist
 Can get hypotension if legs lowered quickly or
decreased effective circulating blood volume
 Decreases diaphragmatic excursion and impairs
ventilation
 Caution with hands and watch BP when leveling table
back to neutral
20
Lithotomy
 Elevated lower extremity positions may reduce
perfusion pressure in the elevated extremities
 conditions for developing compartment syndromes,
especially when extremities are elevated for prolonged
periods
 Maintain perfusion pressure to extremities
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22
Beach Chair
 Often intubated as access to airway is difficult
 Ensure ETT well secured and stays in place while
moving patient and bed
 Caution with elevating head of table with venous
pooling and hypotension
 Case reports with decreased cerebral perfusion
23
Lateral Decubitus
 Turned onto one side
 (left side down = left lateral decubitus position)
 Place an axillary roll just under chest to take pressure
off axillary neurovascular bundle
 V/Q mismatch may occur, particularly with co-existing
pulmonary disease
 Caution with pressure to eyes & ears
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25
Fracture Table
 For repair of fractured femur
 Pelvis is retained in place by a vertical pole at
perineum with the foot of the injured extremity fixed
to a mobile rest
 Traction is applied between the foot and pelvis
 Perineal crush injury possible
26
Setting up the case
 Assist with surgical draping, while maintaining the
integrity of the sterile field
 Avoid walking between or crossing over sterile fields
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Setting up the case
 Prepare, in consultation with the anaesthesiologist,
medication needs for general and regional anesthesia
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Emergency Drugs
 Selection and preparation of medications, checked and labelled for
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usage as appropriate
For every case:
Succinylcholine 20 mg/ml 10mL syringe
Atropine 0.4mg/ml- 0.6 mg/ml vials, 1mL syringe
Ephedrine 5mg/ml (50mg vial/ 10cc)
Phenylephrine 100mcg/ml (10mg/100cc)
29
Equipment to Prepare
 Local
 Sedation
 Regional
 Neuraxial – spinal/ epidural/ CSE
 General
30
CAS monitors
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Required:
Pulse oximeter
Apparatus to measure blood pressure, either directly or noninvasively
Electrocardiography
Capnography, when endotracheal tubes or laryngeal masks are inserted.
Agent-specific anesthetic gas monitor, when inhalation anesthetic agents
are used.
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CAS monitors
 Exclusively available for each patient:
 Apparatus to measure temperature
 Peripheral nerve stimulator, when neuromuscular
blocking drugs are used
 Stethoscope - either precordial, esophageal or
paratracheal
 Appropriate lighting to visualize an exposed portion of
the patient.
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CAS monitors
 Immediately available:
 Spirometer for measurement of tidal volume.
33
Preparation for Local/ standby
 Standard CAS standard monitors in use
 Anesthesia available to provide sedation
 Local anesthetic as per surgeon (watch doses)
 Have emergency drugs available
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Preparation for Sedation
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CAS monitors
Emergency drugs available, IV, oxygen
Useful to monitor capnography
Many drugs can be used to provide sedation
Midazolam
Fentanyl
Remifentanil
Ketamine
35
Preparation for Regional
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CAS monitors
Emergency Drugs available, iv, oxygen
Again, variety of drugs may be used
Midazolam
Fentanyl
ketamine
Titrate to effect
36
Preparation for Regional
 Neuromuscular stimulator, electrodes
 Surface electrode
 Skin prep
 Local anesthetic for skin infiltration
- ultrasound available
- dressing if catheter
- local anesthetic for skin
- gloves
 Local anesthetic for nerve block
 Nerve stimulating needle for block
37
Regional Setup
38
Preparing for Spinal/Epidural
 CAS monitors, iv, oxygen may be required
 Emergency drugs available
- skin prep
 Prepackaged trays
- trays
 Local anesthetic/ opiod for injection - local anesthetic
 Ready to assist with patient positioning
39
Preparing for General Anesthesia
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CAS monitors
iv fluids
Machine checked
Other lines as necessary
Emergency drugs ready
( Drugs for case ready )
Any other lines, procedures, equipment ready if anticipated
40
Preparing for General Anesthesia
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Suction
Oxygen
Laryngoscope
ETT
Stylet
Consider Airway and location of A/W backup
equipment
41
How to manage emergencies
 Anaphylaxis
42
Emergency Situation- Anaphylaxis
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ABC’s
Fluid resuscitation
Large bore iv access available
Epinephrine titrated to response
start at 10 mcg, escalate dose as required,
50-100mcg if hypotensive,
1mg ACLS dose
43
Emergency Situation- Anaphylaxis
 H1 blocker
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Benadryl 50mg
 Corticosteroid
 Hydrocortisone 50-100mg
 Stop inciting allergen exposure
44
How to manage emergencies
 Cardiovascular collapse
45
Emergency Situations- Cardiovascular
Events
 ABC’s
 ACLS protocols
 Responses dictated by clinical scenario
 Crash cart available
 Ensure CPR started
46
How to manage emergencies
 Increased ICP
47
Emergency Situations- Increased ICP
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Head of bed 30 degrees elevated
Ensure adequate cerebral venous drainage
General goals:
Avoid hypoxemia
Avoid hypotension/ maintain cerebral perfusion
CPP= MAP - ICP
Avoid abrupt hypertension
48
Emergency Situations- Increased ICP
 Pharmacologic measures to lower ICP
 Moderate hyperventilation pCO2 30-35, (short term)
 Mannitol 0.5-1g/kg through 50 micron filter
 Lasix 0.5mg/kg
49
How to manage emergencies
 Malignant Hyperthermia
50
How to manage emergencies
 Malignant hyperthermia
 Hypermetabolic disorder of skeletal muscle
 Intracellular hypercalcemia in muscle activates metabolic
pathways
 Energy depletion, acidosis, membrane destruction, cell death
 Heritable component, not invariably present by family history
 Hallmark- hypercarbia, tachycardia, tachypnea, hyperthermia,
rigidity, arrhythmias, hyperkalemia, renal failure, DIC, death
51
Emergency Situations- Malignant
Hyperthermia
 ABC’s
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Ensure MH crisis issued
- MH cart
Stop triggering agents
- hyperventilate, 100% O2,
Finish case ASAP
high flows
Dantrolene 2.5mg/kg, repeat q5min prn until 10mg/kg
(20mg mix with 60ml sterile H2O
52
Emergency Situations- Malignant
Hyperthermia
 Arterial line- blood work and blood gasses
 Begin cooling patient
 Treat supportively
 Patient will need ongoing treatment in ICU
53
 Determine case requirements for suction; such as:
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Airway suction
Gastric suction
Thoracic suction
Surgical suction
Post-surgical wound drainage
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Suction
 Airway
 Have suction ready as part of any induction
 Attached to bronchoscopy port
 Gastric
 Bowel obstructions- low intermittent suction
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Cell Saver
 Cell saver
 Intraoperative blood salvage
 Anticoagulate salvaged blood as it leaves the surgical
field
 Separates rbc’s from other components and debris
 Washes the rbc’s for return to patient
56
Cell Saver
 Useful for procedures with anticipated significant
blood loss
 Reduce the use of autologous rbc transfusion
 Contraindications:
 infection
- malignant cells
 Contamination with urine, bowel contents, amniotic
fluid
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Cell saver
 Complications
 Dilutional coagulopathy
 Reinfusion of contaminants- fat, leukocytes, red blood
cell stroma, air, free hemoglobin, heparin, bacteria,
debris from surgical field
58
The Anesthesia Machine
High
Intermediate
Low Pressure
Circuit
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Anesthesia Workstation
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High pressure circuit
Cylinders including N2O, O2 & Air
O2 2200psi -> 50 psi
N20 750 psi -> 50 psi
Decreased through pressure regulators
60
High Pressure System
 Receives gasses from the high pressure
E cylinders attached to the back of the
anesthesia machine (2200 psig for O2,
745 psig for N2O)
 Consists of:
 Hanger Yolk (reserve gas cylinder holder)
 Check valve (prevent reverse flow of gas)
 Cylinder Pressure Indicator (Gauge)
 Pressure Reducing Device (Regulator)
 Usually not used, unless pipeline gas
supply is off6161
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E Size Compressed Gas Cylinders
Cylinder
Characteristics
Oxygen
Nitrous Oxide
Carbon Dioxide
Air
Color
White
(green)
Blue
Gray
Black/White
(yellow)
State
Gas
Liquid and gas Liquid and gas
Gas
Contents (L)
625
1590
1590
625
Empty Weight
(kg)
5.90
5.90
5.90
5.90
Full Weight (kg)
6.76
8.80
8.90
Pressure Full
(psig)
2000
750
838
1800
Example ½ full E cylinder, 30 L gas, at 10 L/min, approximately 30 min of oxygen available
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Hanger Yolk
 orients and supports the
cylinder, providing a gastight seal and ensuring a
unidirectional gas flow into
the machine
 Index pins: Pin Index Safety
System (PISS) is gas
specific prevents
accidental rearrangement of
cylinders (e.g.. switching O2
and N2O)
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Anesthesia Workstation
 Intermediate pressure circuit
 Includes pipeline O2 and N20 at 50-55psi
 Extends to flow control valves
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Intermediate Pressure System
 Receives gasses from the regulator
or the hospital pipeline at
pressures of 40-55 psig
 Consists of:
 Pipeline inlet connections
 Pipeline pressure indicators
 Piping
 Gas power outlet
 Master switch
 Oxygen pressure failure devices
 Oxygen flush
 Additional reducing devices
 Flow control valves
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Pipeline Inlet Connections
 N2O and O2, usually have air
and suction too
 Inlets are non-interchangeable
due to specific threading as per
the Diameter Index Safety
System (DISS)
 Each inlet must contain a check
valve to prevent reverse flow
(similar to the cylinder yolk)
66
Low Pressure System
 Extends from the flow control valves to the common
gas outlet
 Consists of:
 Flow meters
 Vaporizer mounting device
 Check valve
 Common gas outlet
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Anesthesia Workstation
 Cylinder supply source is back-up if pipeline supply
fails
 Fail-safe valve located downstream from N2O supply
sources
 Interface between O2 & N20 with proportioning
system
 Prevent delivery of hypoxic gas mixtures
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Anesthesia Workstation
 High priority alarm- if O2 supply pressure is less than a critical
pressure (<30psi)
 Regulated flow enters low pressure circuit with adjustments in
flowmeters
 Gas mixture travels through a common manifold directed to vaporizer
 Precise amounts of inhaled anesthetics added, controlled by dial flow
69
Anesthesia Workstation
 Fresh gas flow with added anesthetic vapor travel to common gas outlet
 Datex-Ohmeda have one-way check valves between vaporizer and
common gas outlet
 Prevent back flow into the vaporizer during PPV
 Minimize effects of downstream intermittent pressure fluctuations on
inhaled anesthetic concentrations
 One-way check valve influences preoperative leak test
70
Pipeline Supply Source
 Critical errors have occurred if incorrect supply
attached to machines
 Pipeline inlet fittings are gas specific with threaded
fittings
 Diameter Index Safety System (DISS)
 If pipeline crossover suspected: turn on back-up O2
cylinder
 Pipeline supply must then be disconnected
71
Cylinder Supply Source
 E cylinders
 Pin Index Safety System
 Pressure reducing valve downstream
 If not turned off, will be preferentially used
 Volume of gas remaining in the cylinder is
proportional to cylinder pressure
72
Oxygen supply pressure failure safety
device
 Designed to not allow hypoxic mixture delivery
 Alarm sounds if oxygen pressure falls
 O2 linked with delivery of other gasses to be oxygen
dependent
 If O2 pressure falls, other gas delivery falls
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Flowmeters
 Indicator float position is where upward force from gas
flow equals downward force on float from gravity
 O2 flow knob physically different from other gas
knobs
 N2O and O2 interfaced mechanically/ pneumatically,
maximum 3:1 ratio
 Oxygen flowmeter located downstream from other
flowmeters in case of a leak
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Limitations of Proportioning Systems
 Machines equipped with proportioning systems can
still deliver a hypoxic mixture under the following
conditions:
 Wrong supply gas
 Defective pneumatics or mechanics (e.g.. The Link-25 depends on a
properly functioning second stage regulator)
 Leak downstream (e.g.. Broken oxygen flow tube)
 Inert gas administration: Proportioning systems generally link only
N2O and O2
 In general, an oxygen analyzer is the only machine
safety device that can detect these problems (gas
sampling done at the Y-piece of the patient circuit)
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Oxygen Flush Valve
 Direct communication with high pressure and low
pressure circuit
 Enters circuit downstream from vaporizers and from
machine outlet check valve
 100% O2 at 35-75 L/min (50 psi)
 Potential problems: barotrauma, decreasing volatile
anesthetic concentration, awareness
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Oxygen Flush Valve (O2+)
 Receives O2 from pipeline inlet or
cylinder reducing device and
directs high, unmetered flow
directly to the common gas outlet
(downstream of the vaporizer)
 Machine standard requires that
the flow be between 35 and 75
L/min
 The ability to provide jet
ventilation via the O2 flush valve
is presence of a check valve
between the vaporizer and the O2
flush valve (otherwise some flow
would be wasted retrograde)
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Vaporizers
 Instrument designed to change a liquid anesthetic agent into its vapor
and add a controlled amount of this vapor to the fresh gas flow
 Important that each volatile anesthetic is in type specific vaporizer
 Physical properties of volatile anesthetics
 If incorrectly filled with inappropriate anesthetic, resulting output
drastically changes
78
Vaporizers
 Variable bypass- regulating anesthetic agent output
 Concentration control dial determines ratio of flow
through the bypass chamber and enters the vaporizer
inlet
 Gas channeled through the vaporizing chamber flows
over the liquid anesthetic and becomes saturated with
vapor
 Flow over- method of vaporization
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Vaporizers
 Temperature compensated- maintains a constant
vaporizer output over a wide range of operating
temperatures
 Agent specific
 If vaporizer is overfilled or tilted, liquid anesthetic can
spill into the bypass chamber
 Final concentration of inhaled anesthetic is the ratio of
the flow of the inhaled anesthetic to the total gas flow
80
Generic Bypass Vaporizer
 Flow from the flowmeters
enters the inlet of the
vaporizer
 The function of the
concentration control
valve is to regulate the
amount of flow through
the bypass and vaporizing
chambers
Splitting Ratio = flow though vaporizing
chamber/flow through bypass chamber
 Examples include the Tec
3, Tec 4, Tec 5 and the
Drager 19.1
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Vaporizers- safety features
 Agent- specific, keyed filling devices
 Overfilling minimized because the filler port is located
at the maximum safe liquid level
 Firmly secured to a vaporizer manifold
 Interlock system to prevent administration of >1
anesthetic agent
82
Desflurane’s Tec 6 Vaporizer
 Because of physical properties of Desflurane, supplying it in a
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conventional vaporizer would lead to excessive cooling of the vaporizer
Vapor pressure is much higher than other volatile anesthetics
Much less potent (higher MAC)
Would vaporize many more volumes of Desflurane than other agents
Tec 6 electrically heated and vaporized
83
Tec-6 Vaporizer
 Electronically heated and
pressurized to achieve
controlled vaporization of
desflurane
 2 independent circuits
(fresh gas and vaporizer)
 Vaporizer output is
controlled by adjusting the
concentration control valve
(R2)
 Pressure in the two limbs is
equalized by the pressure
regulating valve
84
Desflurane’s Tec 6 Vaporizer
 Essentially a dual gas blender
 By controlling the dial, the operator controls a variable
restrictor valve
85
The Circuit: Circle System
 So-called because the
components are arranged in a
circular manner
 Arrangement is variable, but to
prevent re-breathing of CO2, the
following rules must be followed:
 Unidirectional valves between the
patient and the reservoir bag
 Fresh-gas-flow cannot enter the
circuit between the expiratory
valve and the patient
 Adjustable pressure-limiting valve
(APL) cannot be located between
the patient and the inspiratory
valve
86
Circle Breathing System
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Prevents rebreathing of CO2 by use of CO2 absorbents
Allows partial rebreathing of other exhaled gasses
Components:
Fresh gas inflow source
- CO2 absorbent
Inspiratory and expiratory unidirectional valves - reservoir bag
Adjustable Pressure Limiting (APL) valve - Y-piece connector
87
Circle Breathing System
 Unidirectional flow
 Maintenance of relatively stabile inspired gas
concentrations
 Conservation of respiratory moisture and heat
 Prevention of OR pollution
 Disadvantage is- many possible sites for
misconnections and leaks
88
The Adjustable Pressure Limiting (APL) Valve
 User adjustable valve that releases gases to
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the scavenging system and is intended to
provide control of the pressure in the
breathing system
Increased pressure in the breathing system
(from patient) pushes the diaphragm off its
seat venting the excess gas into the
scavenging system
The control knob controls the position of the
diaphragm
Bag-mask Ventilation: Valve is usually left
partially open. During inspiration the bag is
squeezed pushing gas into the inspiratory
limb until the pressure relief is reached,
opening the APL valve. At this point the
additional volume the patient receives is
determined by the relative resistances to flow
exerted by the patient and the APL valve
Mechanical Ventilation: The APL valve is
excluded from the circuit when the selector
switch is changed from manual to automatic
ventilation
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CO2 absorber
 2 clear plastic canisters arranged in series
 Soda lime, Baralyme and calcium hydroxide lime
 Soda lime- calcium hydroxide, water, sodium hydroxide and potassium
hydroxide, silica
 CO2 + H2O <-> H2CO3
 H2CO3 + 2NaOH (KOH) <-> Na2CO3 (K2CO3)+2H20 + heat
 Na2CO3 (K2CO3) + Ca(OH)2 <->CaCO3 +2NaOH (KOH)
90
CO2 Absorber
 pH indicator added to assess absorbent
 Changes to violet color when pH of the absorbent
decreases as a result of CO2 absorption
 Indicates absorptive capacity of material has been
consumed
91
Scavenging System
 Collection and subsequent removal of waste anesthetic gases from the
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operating room
Minimizes OR pollution by removing excess gasses
National Institute for Occupational Safety and Health (NIOSH) standards
2ppm for halogenated agent alone
25 ppm for N2O
Halogenated with N20 0.5 ppm
92
Scavenging Systems
 Scavenging Interface: Protects the
breathing circuit or ventilator from
excessive positive or negative
pressure. There are 2 kinds of
scavenging interfaces:
 Open: Contains no valves and is open
to the atmosphere allowing both
positive and negative pressure relief
 Closed: Communicates with the
atmosphere through valves
 Gas Disposal Assembly: This
assembly ultimately eliminates the
waste gas. There are 2 kinds of gas
disposal assemblies:
 Passive: Uses the pressure of the waste
gas itself to produce flow through the
system
 Active: Uses a central vacuum to
induce flow in the system, moving the
waste gas along. A negative pressure
relief valve is mandatory (in addition
to positive pressure relief)
93
Scavenging System
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Adds to OR pollution:
Failure to turn off gas flow at end of case
Poorly fitting masks, flushing the circuit
Filling vaporizers
Other circuit types which are difficult to scavenge
94
Scavenging System
 Active or passive
 Active- uses central evacuation system to eliminate
waste gases
 Passive- pressure of waste gas itself produces flow
 Waste anesthetic gases are vented through the APL
valve or through the ventilator relief valve
95
Scavenging System
 Potential problems:
 Obstruction- excessive positive pressure in the
breathing circuit and barotrauma
 Excessive vacuum- negative pressures within the
breathing circuit
96
Generic Ascending Bellows Ventilator
 Bellows physically separates the
driving gas circuit from the
patient gas circuit
 During the inspiratory phase the
driving gas enters the bellow
chamber resulting in:
 Compression of bellows
delivering the anesthetic gases
within the bellows to the patient
 Closure of the overflow valve,
preventing anesthetic gas from
escaping into the scavenging
system
 During the expiratory phase the
driving gas exits the bellows
chamber.
 Exhaled gas fills the bellows
 Excess gas opens the overflow
valve (PEEP of 2-3 cmH2O)
allowing scavenging of excess
gases to occur
97
Machine Check
 Anesthesia Apparatus Checkout Recommendations, FDA.
1993.
 Categories of check:
• Emergency ventilation equipment
- high pressure
system
• Low-Pressure system
- low pressure system
• Scavenging system
- breathing system
• Monitors
- final position
• Manual and automatic ventilation system
• Final Position
98
Checking Anesthesia Machines
99
Preoperative Checklist- High Pressure
System
 Check O2 cylinder supply
-open cylinder and verify at least ½ full
-close cylinder
 Check central Pipeline Supplies
- check connections and pipeline gages
100
Preoperative Checklist- Low Pressure
System
 Check initial status of low pressure system
- close flow control valves and turn vaporizers off
- check fill level and tighten vaporizer’s filler cap
• Perform Leak Check
- machine master switch and flow control valves OFF
- attach suction bulb to common gas outlet
- squeeze bulb until fully collapsed
- verify bulb fully collapsed > 10 seconds
- check same for each vaporizer
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Low Pressure Circuit Leak Test
 Checks the integrity of the anesthesia machine from the flow control
valves to the common outlet (e.g. leaks at flow tubes, O-rings,
vaporizer)
 Two types of leak test (depending on presence or absence of check
valve)
 Oxygen Flush Positive-Pressure Leak Test: Only used in machines without
check valves; basically just pressurize the low pressure circuit using the O2+
flush valve and look for leak
 Negative Pressure Leak Test: Used in machines with or without check valves (i.e.
Ohmeda). Attach suction bulb to common gas outlet, squeeze repeatedly until
fully collapsed and ensure that it remains collapsed for 10 seconds. Will detect
leaks as small as 30 ml/min.
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Preoperative Checklist- Low Pressure
System
 Turn on Machine Master Switch
 Test flowmeters
- adjust flow off all gasses checking for smooth
operation of floats and undamaged flow tubes
- attempt to create a hypoxic N2O/O2 mixture and
verify correct changes in flow
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Preoperative Checklist- Scavenging System
 Adjust and check scavenging system
- ensure proper connections between scavenging
system and APL valve and ventilator relief valve
- adjust waste gas vacuum
- fully open APL valve and occlude Y-piece
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Preoperative Checklist- Scavenging System
- with minimum flow, allow scavenger reservoir
bag to collapse completely and verify that absorber
pressure gauge reads zero
- with O2 flush activated, allow scavenger
reservoir bag to distend full, and verify that absorber
pressure gauge reads <10 cm H2O
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Preoperative Checklist- Breathing
System
 Calibrate O2 monitor
- ensure monitor reads 21% on room air
- verify low O2 alarm is enabled and functioning
- reinstall sensor in circuit and flush breathing
system with O2
- verify that monitor now reads > 90%
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Preoperative Checklist- Breathing
System
 Check Initial Status of Breathing System
- set switch to “bag” mode
- check that circuit is complete, undamaged and
unobstructed
- verify that CO2 absorbent is adequate
- install breathing circuit accessory equipment to
be used during case (HME)
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Preoperative Checklist- Breathing
System
 Perform Leak Check of the Breathing System
-
Set all gas flows to zero
Close APL valve and occlude Y-piece
Pressurize breathing system to 30 cmH2O with O2
flush
Ensure that pressure remains fixed > 10seconds
Open APL valve and ensure pressure decreases
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Preoperative Checklist- Manual and
Automatic Ventilation Systems
 Test Ventilation systems and unidirectional valves
flush
-place a second breathing bag on Y-piece
-switch on automatic ventilation
-turn ventilator on and fill bellows and breathing bag with O2
-set O2 flow to minimum, other gasses off
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Preoperative Checklist- Manual and
Automatic Ventilation Systems
- verify that during inspiration bellows deliver
appropriate TV and that during expiration bellows fill
completely
- set fresh gas flow to approximately 5 L/min
-Verify ventilator bellows and simulated lungs
fill and empty appropriately without sustained
pressure and end expiration
-Check for proper functioning of unidirectional
valves
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Preoperative Checklist- Manual and
Automatic Ventilation Systems
switch to bag/APL mode
- Ventilate manually and assure inflation and
deflation of artificial lungs and appropriate
feel of system resistance and compliance
- Remove second breathing bag from Y-piece
-
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Preoperative ChecklistMonitors
 Check, calibrate and/or set alarm limits of all monitors
-
Capnometry
O2 analyzer
Pressure monitor with high and low A/W
pressure alarms
Pulse oximeter
Respiratory volume monitor
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Preoperative Checklist- Final Position
of Machine
 Check final status of machine
- vaporizers off
- APL valve open
- selector switch to “bag”
- all flowmeters to zero/minimum
- patient suction level adequate
- breathing system ready to use
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Oxygen Analyzer Calibration
 only machine safety device that evaluates the integrity
of the the low-pressure circuit continuously
 Other machine safety devices are upstream from flow
control valves
 Expose O2 concentration sensing element to room air
for calibration to 21%
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The Virtual Anesthesia Machine
 http://vam.anest.ufl.edu/
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