Week 2 Handout Flashcards
(110 cards)
1
Q
What is the required battery backup duration for an anesthesia workstation?
A
≥30 minutes
Powers machine in power outages.
2
Q
What is the purpose of alarm systems in an anesthesia workstation?
A
Prioritized alerts for critical failures.
3
Q
What monitoring capabilities must an anesthesia workstation have?
A
O₂, agent concentration, pressure, volume.
4
Q
What is the maximum pressure for a pressure-limited circuit?
A
125 cm H₂O
To avoid barotrauma.
5
Q
What is the design requirement for the power cord of an anesthesia workstation?
A
Resists accidental detachment.
6
Q
What is required for high-pressure cylinder supply?
A
Must have check valves and regulators.
7
Q
What is the function of flowmeters in an anesthesia workstation?
A
For gas delivery control.
8
Q
What is the flow rate range for an O₂ flush valve?
A
35–75 L/min
Bypasses vaporizers.
9
Q
What is the purpose of vaporizers in an anesthesia workstation?
A
Precise agent delivery.
10
Q
What is the function of a common gas outlet?
A
Standard diameter; connects to breathing circuit.
11
Q
What is the required pipeline gas supply pressure from the hospital central supply?
A
50–55 psig.
12
Q
What is the purpose of a machine checklist?
A
Mandatory pre-use verification.
13
Q
What is the function of a digital interface in an anesthesia workstation?
A
User interaction and display controls.
14
Q
What are the three pressure zones in the pneumatic system?
A
High, Intermediate, Low.
15
Q
What is the pressure range for the high-pressure zone?
A
Cylinder to first-stage regulator (~2000 psi).
16
Q
What is the pressure range for the intermediate zone?
A
Pipeline to flowmeters (~45–55 psig).
17
Q
What is the pressure range for the low-pressure zone?
A
Flowmeters to common gas outlet (~16–22 psig).
18
Q
What does the pipeline check valve ensure?
A
Pipeline gas (50 psi) is used before cylinder gas (45 psi).
19
Q
What is the mechanism of the pipeline check valve?
A
Unidirectional pressure-sensitive valve.
20
Q
What happens during a pipeline failure regarding the check valve?
A
Automatically switches to cylinder source—no manual switch needed.
21
Q
What is the purpose of the hanger yoke valve?
A
Secures E-cylinder to machine with a gas-tight seal.
22
Q
What safety mechanism prevents connection of the wrong gas cylinder?
A
Pin Index Safety System (PISS).
23
Q
What does the check valve in the hanger yoke valve prevent?
A
Reverse flow.
24
Q
What does a missing washer/O-ring in the hanger yoke valve lead to?
A
Leak or fire hazard.
25
What is the function of the Bourdon gauge?
Reads cylinder pressure (not content).
26
What pressure does the Bourdon gauge read when full for O₂?
High (~2000 psi).
27
What happens to the Bourdon gauge reading as gas depletes?
Drops gradually.
28
What is the exception for N₂O pressure reading on the Bourdon gauge?
Maintains 745 psi until ~75% depleted.
29
What does the first-stage regulator do?
Reduces high cylinder pressure to intermediate (~45–50 psi).
30
What is the function of the second-stage regulator?
Further reduces pressure to low-pressure system (16 psi O₂, 26 psi N₂O).
31
What is the mechanism used by the first and second stage regulators?
Uses diaphragm valves to buffer kinetic energy and equalize pressure.
32
What is the mechanism of the O₂ flush valve?
Ball-and-spring valve—bypasses flowmeters and vaporizers.
33
What are the indications for using the O₂ flush valve?
Emergency O₂/ immediate oxygenation; flush volatile gases/agents for wake-up.
34
What is the danger of pressing the O₂ flush valve during positive-pressure ventilation?
Can cause barotrauma.
35
What is the function of the oxygen failure cutoff valve?
Shuts off or proportionally reduces N₂O when O₂ pressure <20–25 psi.
36
What is the mechanism of the oxygen failure cutoff valve?
Spring-loaded valve activated by O₂ line pressure dropping below threshold.
37
What does the inspiratory one-way valve do?
Allows gas flow toward patient during inspiration.
38
What happens if the inspiratory one-way valve is stuck open?
Rebreathing, hypercapnia.
39
What happens if the inspiratory one-way valve is stuck closed?
Hypoventilation, no inspiratory flow.
40
What is the function of the expiratory one-way valve?
Allows unidirectional flow away from patient during exhalation.
41
What happens if the expiratory one-way valve is stuck closed?
Barotrauma, trapped air.
42
What happens if the expiratory one-way valve is stuck open?
Loss of O₂, anesthetic → hypoventilation.
43
What is the purpose of the APL valve?
Controls the pressure within the breathing circuit.
44
How does the APL valve prevent barotrauma?
By controlling the circuit pressure.
45
What happens when the APL valve is turned clockwise?
Increases pressure (less venting).
46
What happens when the APL valve is turned counterclockwise?
Decreases pressure (more venting).
47
What is the function of flowmeters?
Measure and display the flow rate of gases being delivered.
48
What is the pressure at the flowmeter for N₂O?
~20–22 psi.
49
What is the pressure at the flowmeter for O₂?
~16 psi.
50
What is the purpose of the Link-25 proportioning system?
Automatically restricts N₂O flow to maintain at least 25% O₂ concentration.
51
What does the Oxygen Ratio Monitor Controller (ORMC) ensure?
FiO₂ never falls below 25% when mixing O₂ and N₂O.
52
What is the FiO₂ calculation formula?
FIO2 = (gas flow rate x % O2contained) + (O2 flow rate x 1) / Total flow rate.
53
What is the output of variable bypass vaporizers dependent on?
Splitting ratio + temperature, flow compensation.
54
What is the function of the Tec-6 vaporizer?
Delivers volume % based on set dial.
55
What is the required vaporizer setting at high altitudes?
Required vaporizer setting = (Desired sea level setting x 760 mmHg) / Local barometric pressure.
56
What is the purpose of the fresh gas inlet (FGI)?
Delivers fresh gases into the breathing system.
57
What does the fresh gas flow (FGF) rate affect?
Anesthetic depth, agent consumption, rebreathing fraction.
58
What are the clinical considerations for the inspiratory and expiratory valves?
Valve malfunction risks include stuck open or closed.
59
What is the function of the inspiratory valve?
Allows fresh gas to flow to the patient during inhalation and prevents backflow of gas toward the machine during exhalation.
60
What are the failure modes of the inspiratory valve?
Fails to open (patient receives no fresh gas → hypoxia, apnea) and fails to close (exhaled gas re-enters inspiratory limb → CO₂ rebreathing).
61
How can inspiratory valve failure be detected?
Increased resistance during manual ventilation, abnormal airway pressures or hypoventilation alarms, and capnography may show rising baseline or delayed washout.
62
What should be checked if inspiratory valve failure is suspected?
Check for mechanical obstruction or displaced valve disk, and valve seating or debris interfering with function.
63
What is the function of the expiratory valve?
Opens during exhalation to direct exhaled gases to the CO₂ absorber or scavenger and closes during inspiration to retain fresh gas within the circuit.
64
What are the failure modes of the expiratory valve?
Fails to open (exhaled gas is trapped → elevated circuit pressure, risk of barotrauma) and fails to close (fresh gas escapes prematurely → hypoventilation, inadequate anesthetic delivery).
65
How can expiratory valve failure be detected?
Elevated PIP (peak inspiratory pressure), inadequate tidal volumes, high-pressure alarms, and abnormal bag movement or ineffective exhalation.
66
What should be inspected if expiratory valve failure is suspected?
Inspect for valve obstruction, moisture, or deformation, and dislodgement of valve components.
67
What is the flow sequence in the circle system?
1. FGF enters via fresh gas inlet 2. Travels through inspiratory valve 3. Inhaled by patient via Y-piece 4. Exhaled gas returns through expiratory limb 5. CO₂ removed via soda lime 6. Remaining gas goes to reservoir bag 7. Excess vented via APL valve 8. Cleaned gas recirculated.
68
What are breathing tubes in the circle system?
Breathing tubes are the gas-conducting limbs of the anesthesia circle system, serving as pathways for delivering fresh anesthetic gases to the patient and returning exhaled gases for CO₂ removal and gas recirculation.
69
What are common signs of valve malfunction?
Elevated EtCO₂ baseline on capnography, ineffective ventilation despite adequate settings, and visual cue of improper bag inflation/deflation pattern.
70
What maintenance is required for valves?
Must be checked daily for integrity, cleanliness, and mobility. Clean or replace valves if sticky, cracked, or visibly damaged.
71
What is the role of capnography monitoring?
Continuous waveform analysis can alert you to valve dysfunction (e.g., CO₂ rebreathing pattern).
72
What should be included in leak and function tests?
Include valve function during your low-pressure system leak test and manual breathing test during machine checkout.
73
What is the function of the Inspiratory Limb?
Delivers a mixture of oxygen, air, nitrous oxide, and volatile anesthetics from the anesthesia machine to the patient.
74
What is the function of the Expiratory Limb?
Returns exhaled gases from the patient back to the machine and directs them toward the CO₂ absorber.
75
What are the two types of gas flow in the anesthesia system?
Inspiratory flow: Machine → Patient (fresh gas)
Expiratory flow: Patient → Machine (exhaled gas)
76
What is the importance of bidirectional gas transport?
Supports CO₂ elimination, gas recycling, and maintenance of anesthetic depth.
77
What materials are typically used for the limbs of the anesthesia circuit?
Typically made of corrugated plastic or rubber to provide flexibility and resistance to kinking or collapse.
78
How do the limbs connect to the anesthesia machine and patient?
Each limb connects to the anesthesia machine and to the patient’s airway via a Y-piece.
79
What are the clinical considerations regarding tubing length and diameter?
Longer or narrower tubing can increase resistance to gas flow, especially critical in pediatrics.
80
What is the risk of contamination in the anesthesia circuit?
Must be cleaned or replaced between patients to prevent cross-infection and can retain pathogens if improperly maintained.
81
What can leaks in the anesthesia circuit result in?
Leaks can result in hypoventilation, light anesthesia, or environmental gas exposure.
82
What should be inspected before using the anesthesia tubes?
Look for cracks, loose connections, moisture, or obstruction.
83
What is the role of the Y-Piece in the circle breathing system?
Serves as the critical junction point between the patient’s airway device and the two limbs of the circle system.
84
Where is the Y-Piece located?
Found where the inspiratory and expiratory limbs converge, positioned just before the patient’s airway.
85
What does the Y-Piece do during inhalation?
Guides fresh gas from the inspiratory limb to the patient.
86
What does the Y-Piece do during exhalation?
Channels expired gas from the patient to the expiratory limb.
87
What is the primary role of the Pressure Relief Valve (PRV)?
Limits circuit pressure to prevent excessive buildup that could cause barotrauma.
88
How does the PRV function during pressure buildup?
When pressure exceeds the set threshold, the valve opens and directs excess gas to the scavenging system.
89
What should be checked before using the APL valve?
Turn APL from fully open to closed—ensure smooth adjustment and no sticking.
90
What is the purpose of the Reservoir Bag?
Serves as a gas reservoir for the patient and allows for manual control of ventilation.
91
What happens during exhalation with the Reservoir Bag?
Exhaled gases pass through the expiratory limb and fill the bag.
92
What is the function of the CO₂ absorber?
Removes carbon dioxide from the patient’s exhaled gases, allowing safe rebreathing of anesthetic gases.
93
What is the importance of monitoring the CO₂ absorber?
Always check the color indicator and replace the canister when indicated to prevent hypercapnia.
94
What are the two main types of scavenging systems?
Active: Uses a vacuum to draw gases out.
Passive: Uses gravity or pressure gradient to vent gases.
95
What is the advantage of the Circle Breathing System regarding heat and moisture?
Reduces heat loss and prevents airway desiccation by rebreathed gases.
96
How does the Circle Breathing System reduce agent consumption?
Only the oxygen and agent consumed by the patient needs to be replaced; some exhaled gases are reused.
97
What is a key benefit of low-flow anesthesia?
Decreases volatile agent and O₂ usage, making it ideal for low-flow anesthesia.
## Footnote
Useful in cases with limited supplies or budget constraints.
98
How does the circle system provide precise control of anesthetic depth?
Volatile anesthetic concentration can be finely titrated using vaporizers, with CO₂ absorber ensuring metabolic CO₂ is removed.
## Footnote
Allows depth adjustments with minimal delay.
99
What is the benefit of low resistance to breathing in modern circle systems?
Minimal work of breathing, allowing spontaneous respiration, which is especially important in pediatrics or patients with respiratory compromise.
100
How does the circle system reduce operating room pollution?
Waste anesthetic gases are routed to a scavenger system instead of being vented into the room.
## Footnote
Protects OR staff from chronic exposure to volatile agents.
101
What monitoring features are incorporated in the circle system?
Includes pressure monitoring, APL valve, capnography, and volume monitoring for real-time feedback on ventilation and circuit status.
102
What is a disadvantage of the circle system related to its complexity?
Includes multiple components, increasing potential failure points and creating a steeper learning curve for setup and troubleshooting.
103
What happens if the CO₂ absorber in the circle system is malfunctioning?
CO₂ is rebreathed, leading to hypercapnia, acidosis, and respiratory depression.
## Footnote
Capnography is the best tool to detect early.
104
Why is increased apparatus dead space a concern in the circle system?
Circle system components inherently increase mechanical dead space, which is particularly problematic in neonates and small children.
105
What is a risk associated with contamination in the circle system?
Rebreathing exhaled gases can allow pathogens to persist in the circuit, leading to cross-infection between patients.
106
What is a physical limitation of the circle system?
Circle systems are less portable, with a larger footprint and heavier breathing circuits, making them awkward to use in tight ORs.
107
What maintenance is required for the circle system?
Frequent leak checks are necessary due to the higher risk of leaks from multiple joints and components.
108
What is a key characteristic of a semi-open system?
The patient breathes 100% fresh gas, and all exhaled gases are vented to the atmosphere, eliminating CO₂ entirely.
109
What are the clinical applications of a semi-closed system?
Most commonly used for general anesthesia in modern operating rooms, suitable for a variety of surgical procedures.
110
What defines a closed system in anesthesia?
All exhaled gases are rebreathed after CO₂ removal, requiring very low fresh gas flows and maximizing anesthetic conservation.
