AGM Flashcards

1
Q

Check valves

A

Prevent backflow of gas
Gas can only flow in one direction
Found all over AGM

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2
Q

Pressure regulator

A

Drops pressure
Drops pressure from tanks (2000psi) to intermediate pressure (50psi)
2nd stage pressure regulator drops pressure from intermediate to low pressure (16psi)

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3
Q

High pressure system

A

750-22200psi
Cylinders
Cylinder pressure gauge
Cylinder pressure regulator
Hanger yoke
Yoke block with check valve

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4
Q

Intermediate pressure

A

40-50psi
Ventilator power inlet
Check valves
Pressure gauges
Flow meter valves
Oxygen pressure failure devices
Oxygen second stage regulator
Flush valve

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5
Q

Low pressure system

A

16psi
Flow meter tube
Vaporizers
Check valves
Common gas outlet

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6
Q

Low pressure leak test

A

Fail if suction bulb inflates within 10 seconds
Needs to be done everyday before 1st case
Should be repeated with vaporizers off and on

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7
Q

High pressure leak test

A

Fail if circuit does not remain pressurized at 30cm h2o
Close APL valve to pressurize circuit
Should be done between every patient and when circuit is changed

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8
Q

SPDD

A

Supply
Processing
Delivery
Disposal

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9
Q

Supply (SPDD)

A

Gases from cylinders and wall
Electricity from power cord

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10
Q

Processing (SPDD)

A

How AGM prepares gases before delivery

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11
Q

Delivery (SPDD)

A

Circuit brings gases to the patient

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12
Q

Disposal (SPDD)

A

Scavenger system removes gases from the breathing circuit
Can only remove an amount equal to FGF minus volume lost to 02 consumption
Too much removal - negative pressure in circuit
Too little removal- risk of barotrauma
APL (spontaneous breathing) and ventilator spill valve control gas going to scavenger

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13
Q

Parts of the scavenger

A

Gas collection assembly
Gas disposal tubing
Gas disposal system (gets gas from scavenger to earths atmosphere, active uses suction, passive relies on positive pressure and no suction)
Transfer tube
Interface (open vs closed)

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14
Q

Convenience receptacles

A

Found on back of AGM
Protected by circuit breakers or fuses
In theory, blowing a fuse should not affect operating of the AGM

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15
Q

Devices not requiring electricity

A

Spontaneous ventilation
Mechanical flow meters
Scavenging
Laryngoscope
IV bolus or infusion
Peripheral nerve stimulators
Five senses
Bypass vaporizers

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16
Q

Devices requiring electricity

A

Ventilators
Monitors
Lights
Digital flow meters
Bypass pumps and oxygenators
Warming blankets
Gas vapor blenders (Tec-6) or vaporizers with electronic controls (Aladin, Aisys)

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17
Q

Open interface

A

No mask on face
Open to atmosphere
Only used with active systems (suction)
Risk of healthcare team exposure
Contains reservoir
Too much suction- room air entrained
Too little suction- waste gas goes to healthcare team
No positive or negative pressure valves
No risk of barotrauma

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18
Q

Closed interface

A

Mask on face
Uses pressure valves
Doesn’t remove fresh gas from circuit
If passive- needs positive pressure relief
If active- needs both positive and negative pressure relief
Contains reservoir

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19
Q

5 tasks of oxygen in AGM

A

O2 flush valve (25-75 LPM)
O2 supply failure (less than 30 psi)
O2 pressure failure (fail safe, prevents hypoxic mixture)
Ventilator drive gas (to bellow, jet devices, auxiliary flow meter)
Flow meters (circle system-> patient)

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20
Q

PISS

A

Pin index safety system
Prevents cylinder from misconnection to AGM
Defeated if more than one washer used, or pins are removed or missing

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21
Q

PISS for air, O2, and Nitrous oxide

A

1,5
2,5
3,5

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22
Q

DISS

A

Diameter index safety system
Prevents gas hose from misconnection

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23
Q

Cylinder sizes

A

E- 2x4 (travel size, what we mostly see)
H- 4x9 (bedside when no pipeline available, in OR as N2 compressed gas)

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24
Q

Capacity and PSI of O2

A

660L, 1900-2200psi

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25
Capacity and psi of air
600L, 1800psi
26
Capacity and psi for N2O
1600L, 745psi
27
How to determine what is left in N2O?
Weigh cylinder Tank will read 745psi until all liquid is gone Once liquid is gone, tank has 1/4 left Change tank if psi drops below 745psi
28
Most fragile part of cylinder?
Cylinder valve
29
Cylinder valve parts
Body Gas exit port PISS Safety relief Conical depression for securing screw
30
What is the safety relief device of the cylinder valve?
Releases contents in a controlled fashion in the case of a fire (rather than exploding)
31
Hanger yoke
Orients cylinder Provides gas tight seal Ensure unidirectional flow Contain a filter Check babe to minimize transfilling
32
What is the safety release device made of?
Fusible plug made of woods metal Frangible disc that bursts under pressure Valve that opens under extreme pressure
33
Cylinder safety
No oils Keep closed when not using Don’t interchange regulators or gauges Open slowly Don’t stand up in their own Temperature under 130 F New washer for every tank
34
How is oxygen produced? How is it delivered to hospital? How does hospital deliver it?
Fractional distillation of liquid air Delivered to hospital and stored as liquid at 184c Hospital converts to gas and supplies pipeline at 50psi
35
Shut off valves in OR suite
To isolate leaks and interrupt supply in case of fire
36
Possible problems with pipeline supply
Pressure loss Cross contamination Cross connection Leaks Theft
37
How will you know of loss of pipeline supply? What alarms will sound?
Indicated by pipeline pressure gauge If pressure loss is profound, oxygen low pressure alarm sounds, and fail safe valves halt delivery of other gases
38
Guideline for oxygen pipeline supply failure
Trust that there is failure Turn in back up oxygen cylinder Call for help Use low flow oxygen Turn off vent and bag Calculate time on cylinder Do not reconnect patient until pipeline is tested Ventilate with oxygen or room air via bag valve mask
39
Oxygen pressure failure device
“Failsafe” Alarms when oxygen pressure is below 30psi (depleted tank, drop in pipeline pressure, disconnected oxygen hose) Monitors for low oxygen pressure Does NOT alarm for pipeline crossover and won’t detect a crack in flow meter When this alarms, flow of N2O will stop
40
Hypoxia prevention safety device
Does not allow a hypoxic mixture Flow meters are mechanically linked Flows are pneumatically connected Maintains O2:N2O at 1:3, or 25% oxygen minimum
41
When will a hypoxic mixture not be detected with hypoxia prevention safety device?
Pipeline crossover Leaks distal to flow meter valves Administration of 3rd gas Defective mechanic or pneumatic components
42
Flow meters
Delivers gas to patient circuit Receives low pressure Needle valve Thorpe tube is gas specific and tapered with largest diameter at top Float ball - read in the middle (all other read at top)
43
Reynolds number
Predicts flow rate = (density x diameter x velocity) / viscosity <2000- laminar 2000-4000- transitional flow >4000- turbulent
44
Fio2 calculation
((Air flow rate x .21) + oxygen flow rate) / total gas flow rate
45
Nasal canula delivered fio2
0-21% 1-24% Then add by 4 Max at 44%
46
Steps in fresh gas coupling
1- convert FGF to ml/ min 2- multiple FGF by IE ratio 3- divide by breathes per minute 4- add this to tidal volume on vent to get final answer
47
Things that increase delivered tidal volume
Decreased RR Increased IE ratio (from 1:2 to 1:1) Increased fresh gas flow Increased bellows height
48
Things that decrease delivered tidal volume
Increased RR Decreased IE (from 1.2 to 1.3) Decreased fresh gas flow Decreased bellows height
49
Compliance
change in volume / change in pressure Positive pressure in breathing circuit causes gas to expand, this won’t reach patient and must be subtracted from Vt
50
Variable bypass vaporizer
Does not require electricity Agent specific Temperature regulated Splitting ratio
51
Output and flow rates accuracy
Inaccurate at low rates below 250ml/ min and will output less than dial setting Inaccurate at extremely high flow rates and will output less than dial setting
52
Pumping effect
From positive pressure ventilation or use of O2 flush valve Causes gas to re enter vaporizing chamber Increases vaporizer output
53
Pumping effect is enhanced by
Low FGF Low concentration dial setting Low levels of liquid anesthetic in vaporizing chambers
54
Most common cause of vaporizer leak
Loose filler cap
55
Most common location of vaporizer leak
Internal leak in vaporizer
56
When is a vaporizer leak detected?
Only when turned on
57
What to do when vaporizer is tipped
Disconnect patient ? Possible overdose Drain vaporizer Turn dial to highest setting and run it with high FGF for 30 minutes
58
Tec 6 Desflurane vaporizer
Electricity required Heats to 39c Pressurizes to 2 ATM Does not compensate for pressure changes- higher altitude requires higher dial setting, lower altitude requires lower dial setting
59
First device to detect oxygen pipeline crossover?
Oxygen analyzer
60
Are the oxygen pressure device and hypoxia prevention safety device designed to detect oxygen pipeline crossover?
No
61
What is the last line of defense for hypoxic mixtures?
Oxygen analyzers
62
2 types of oxygen analyzers
Galvanic fuel cell - needs daily calibrations Pragmatic device - self calibrating and faster response
63
What does the oxygen analyzer do?
Monitors oxygen concentration
64
Oxygen flush valve
25-75LPM 50psi Can cause barotrauma Excessive use can lead to patient awareness
65
Ventilator spill valve
When open- during exhalation, excess gas goes to scavenger When closed- Ensures Vt goes to patient and not scavenger Intrinsic PEEP Pneumatic ventilators only Prevents build up of volume and pressure in breathing circuit
66
HME advantages
Filters large particles Filters bacteria and viral Retains heat and moisture from breathing circuit Inexpensive No water or electricity required No risk of hyperthermia, overhydration, burns, electrical shock
67
Disadvantages of HME
Not as effective as water based electrical devices Increase dead space Obstruction can occur If increased airway resistance is noted, pressures should be measured with and without HME to assess for mechanical deficits
68
Pneumatic bellow ventilator
Classified based on movement of bellow Double circuit Force of compressed gas (air or O2) as driving mechanism Leaks in bellows may dilute gas with driving gas and cause hypoxia (if bellows are driven on air), increased fio2 (if bellows are driven on O2), or awareness (loss of agent)
69
Ascending bellows
Standing Ascend during expiration Safer Will not fill if a total disconnection occurs
70
Descending bellows
Hanging Descend on expiration Will continue motion if disconnection occurs Must have co2 / apnea alarm
71
Modern Piston ventilator
Uses an electric motor to compress the position to generate positive pressure Doesn’t use oxygen to run the ventilator Doesn’t deplete o2 tank in pipeline failure situation 2 pressure relief valves - positive (opens when pressure is too high) and negative (entrains air when too much negative pressure occurs) Decouples FGF for consistent Vts
72
Volume controlled
Delivers preset Vt over predetmines time Pressure depends on compliance Inspiration flow is constant during inspiration Resistance increases PIP
73
Pressure controlled
Set pressure for every breath Vt and flow vary based on lung compliance Resistance decreases Vt Inspiratory flow is decelerating; starts high to achieve pressure then slows to maintain pressure
74
What decreases Vt in PCV
Pneumoperitoneum Trendelenburg Brochospasms Kinked ETT
75
What increases Vt in PCV?
Release of pneumoperitoneum Going from trendelenburg to supine Bronchodilator Removing secretions
76
When is PCV better than VCV?
Low compliance- obesity, pregnancy, ARDS, laparoscopy High PIP would be dangerous- LMA, neonate, emphysema Need to compensate for a leak- LMA, children with an ETT
77
Breathe types
Controlled- machine triggered and machine cycled Assisted- patient triggered but machine cycled Spontaneous- patient triggered and cycled
78
Controlled mandatory ventilation (CMV)
Machine initiates breathe and gives preset Vt and RR Asynchrony can occur Best for apneic patients
79
Assist control
Machine initiates breathe and gives preset Vt and RR Spontaneous breathe receives full Vt Can lead to hyperventilation
80
SIMV
Machine initiates breathes at preset Vt and RR Patient can breathe between machine breathes Better synchrony Spontaneous breathes can be augmented with pressure support Great for weaning and LMAs Guarantees minute ventilation
81
PCV- VG
Pressure control mode Only uses pressure needed to achieve goal Vt Great for cases with compliance changes like laparoscopic procedures
82
PSV
Augments spontaneous breathes with set amount pressure support Only supports inspiration No machine initiated breathes Great for weaning and LMAs
83
PSV-Pro
Spontaneous breathing patient will get PSV Apneic patient will get PCV Once patient starts breathing, will resume PSV Great for weaning and LMAs
84
CPAP benefits
Augments spontaneous breathing Reduces airway collapse on expiration
85
Bipap benefits
COPD patients
86
Airway pressure release ventilation
Spontaneous ventilation only Like bipap but high level of CPAP through most of respiratory cycle Good for ARDS
87
Inverse ratio ventilation
Respiratory cycle is divided into inhalation and exhalation (IE determines time in each) Exhalation is typically longer IRV gives more time to inspiration Pt must be paralyzed Used in ARDS with small FRC
88
High frequency ventilation
Vt below dead space is delivered at high RR Gas transport occurs via molecular diffusion, coaxial flow, and high velocity flow Types- jet, oscillation, percussive
89
CO2 absorber
Removes exhaled CO2 Base neutralizes an acid Needed for closed and semi closed circuits
90
Mesh size
Must balance surface area and airflow resistance Best balance with 4-8 mesh granules Each granule 1/4 to 1/8 inch and pass thru mesh screen with 4-8 holes per square inch
91
Exhaustion
No longer able to neutralize CO2 Must change double canister at same time Increasing MV will not decrease ETCO2
92
CO2 Desiccation
Absorbent is too dry Don’t add water - fire risk
93
Soda lime
When exhausted and PH below 10.3- REPLACE Best indicator for changing- inspired CO2 Does not regenerate even when colors go back to normal color Produces CO- mostly with Sevo, then iso, des
94
How to minimize Compound A
Low FGF Turn off between cases Change all absorbent at once Change canister when it’s purple Change canister if unsure
95
Calcium hydroxide Lime
Uses calcium hydroxide instead of a strong base Also contains calcium chloride which keeps it moist Benefits over soda Lime- no CO, no compound A, lower fire risk Drawback- needs more frequent changes, costs more
96
Most common cause of low pressure in breathing circuit
1- Circuit disconnect (most common Y piece) 2- CO2 absorber (poor seal, defective canister)
97
What to do if circuit won’t hold pressure
Ambu bag TIVA
98
Monitors for circuit disconnect
Pressure Volume ETCO2 Vigilance
99
What to do when sustained high pressure curcuit
Bag mode Manually ventilate patient Treat causes If pressure is sustained- scavenger obstructed, scanner relief valves failed, disconnect scavenging system if possible, ambu If pressure is relived- ventilator relief valve is malfunctioning - DO NOT USE!
100
OSHA recommendations
Halogenated- <2ppm N2O- <25ppm Both combined- <0.5 ppm and 25ppm
101
Determinants to excess of waste gas
OR ventilation and air turnover Functional status of anesthesia equipment Mask fit Gas on only after mask fit Turn of gas before suctioning patient Cuff ETT Evacuate gasses to scavenger at end of case Monitor AGM for leaks TIVA Avoid N2O Use low FGF Do not spill agents
102
APL
Controls gas going to scavenger system in spontaneously breathing patients
103
Ventilator spill valve
Controls gas going to scavenger in mechanically ventilated patients
104
Valves of the anesthesia machine
Free floating valve Ball and spring valve Diaphragm valve
105
Free floating valve
Only valve that floats in the middle Moves in the direction of push of gas flow Prevents gas from leaking Found in DISS and dual hanger yoke system
106
Ball and spring valve
O2 flush 40-50psi Anesthesists panic button
107
Diaphragm valve
First stage regulator (high to intermediate) Second stage regulator (intermediate to low)