Quiz 2 Flashcards
(18 cards)
The emergency oxygen tank is being used due to a significant drop in pipeline pressure. The pressure of the E-cylinder oxygen tank reads 1300 psig. The flow is set to 3L/min. How long will the tank last at this flow rate?
A. 125 minutes
B. 90 minutes
C. 153 minutes
D. 143 minutes
E. Unable to calculate
Answer: D
tank capacity (L) / service pressure (psig) = contents remaining (L) / current tank pressure (psig).
current tank pressure (psig) * tank capacity (L) / service pressure (psig) = contents remaining (L)
1300psig * 625L / 1900psig = 428L
428L / (3L/minutes) = 143 minutes
Which of the following describe the risks and proper use of the oxygen flush valve? (Select all that apply)
A) The flush valve should only be used cautiously when the patient is connected to the breathing circuit.
B) It can result in backflow of gases into the low-pressure circuit, diluting anesthetic concentrations.
C) The flush valve should be used for routine breathing circuit maintenance to ensure proper gas exchange.
D) A protective rim around the flush button helps prevent unintentional activation.
E) The oxygen flush valve uses a flow rate of 1–5 L/min to prevent excessive lung pressures.
.
Correct Answers: A, B, D
Rationale:
“The oxygen flush valve provides a high flow (35–75 L/min) of oxygen directly to the common gas outlet, bypassing the flowmeters and vaporizers.
It is used to rapidly refill or flush the breathing circuit, but because the oxygen may be supplied at a line pressure of 45 to 55 psig, there is a real
potential for lung barotrauma to occur. For this reason, the flush valve must be used cautiously whenever a patient is connected to the breathing circuit.
Moreover, inappropriate use of the flush valve (or a situation of a stuck valve) may result in the backflow of gases into the low-pressure circuit,
causing dilution of inhaled anesthetic concentration. A protective rim around the flush button limits the possibility of unintentional activation” (Butterworth, 2022)
Which of the following are reasons that active humidifiers are valuable in pediatric anesthesia applications? Select all that apply.
Contribution to an increase in apparatus dead space
Reduced occurrences of hypothermia due to increased heat conservation
Filtration of respiratory gases reducing infectious concerns
Prevention of smaller tracheal tube plugging via dried secretions
Correct Answer: B & D - Reduced occurrences of hypothermia due to increased heat conservation & Prevention of smaller tracheal tube plugging via dried secretions
Rationale
The answers to this question are B & D. These answers are correct because active humidifiers are more effective at contributing to a greater preservation of heat and humidity within the breathing circuit. This retainment of heat and moisture aids pediatric patients in the prevention of hypothermic conditions as well as occlusions of small-bore tracheal tubes due to dried secretions (Butterworth et al., 2022). Answer choice A is incorrect because active humidifiers do not increase dead space within the system, this corresponds to passive humidifier applications. Answer choice C is incorrect because active humidifiers do not actively filter gases within the breathing circuit (Butterworth et al., 2022).
Which of the following are purposes of oxygen in the anesthesia workstation (Select all that apply)
A) To supply fresh gas to the oxygen flow meter
B) To drive ventilator bellows
C) To absorb carbon dioxide
D) To activate low pressure oxygen alarms
Answer: A, B, D
Rationale: Oxygen has five roles in the anesthesia workstation: Supplying fresh gas to the oxygen flow meter, driving ventilator bellows, activating low pressure oxygen alarms, activating fail safe mechanisms, and supplying the oxygen flush system (Elisha, et al., 2022). The CO2 absorbing canister removes CO2 from the system through a series of chemical reactions.
Which component of the SPDD model ensures the provision of gases like oxygen and nitrous oxide to the anesthesia machine?
A. Common Gas Outlet
B. Pipeline Supply System
C. Vaporizer
D. Scavenging System
Answer: B
Rationale: The SPDD model is the supply, processing, delivery, and disposal model. The Supply phase in the SPDD model involves pipeline systems and gas cylinders that deliver medical gases to the anesthesia workstation. The pipeline supply system provides a steady and regulated supply of oxygen, nitrous oxide, and air to the anesthesia machine. If the pipelines fail, emergency E-cylinders are required, and the tanks should be checked before the start of any case.
Which of the following statements best describes the relationship between vapor pressure, temperature, and the characteristics of a volatile agent?
A) Vapor pressure is independent of temperature but depends entirely on the characteristics of the volatile agent.
B) Vapor pressure decreases as temperature increases because fewer liquid molecules escape into the gaseous phase.
C) Vapor pressure increases with temperature due to a greater tendency of liquid molecules to escape into the gaseous phase.
D) Vapor pressure remains constant regardless of changes in temperature or the characteristics of the volatile agent.
Answer: C) Vapor pressure increases with temperature due to a greater tendency of liquid molecules to escape into the gaseous phase.
Rationale:. For the physics of vaporization, the molecules of a volatile anesthetic in a closed container are distributed between the liquid and gaseous phases. The gas molecules bombard the walls and create the saturated vapor pressure of the agent. The vapor pressure depends on the characteristics of the volatile agent and the temperature. The greater the temperature, the greater the tendency for the liquid molecules to escape into the gaseous phase and the greater the vapor pressure (Butterworth et al., 2022).
Which of the following is the only system that determines the presence of oxygen in the pipeline or cylinder?
A. Hypoxic Guard System
B. Low Pressure Alarms
C. Inspired Oxygen Analysis
D. Fail-Safe Mechanism
Answer: C. Inspired Oxygen Analysis
Rationale:
The presence of oxygen in medical pipelines, cylinders, or circuits is ensured through inspired oxygen analysis. While low-pressure alarms and hypoxic guard mechanisms alert users to possible issues in oxygen supply, they rely on pressure measurements throughout the circuit rather than direct gas content measurement. In other words, these systems monitor pressure within the workstation and are activated only if oxygen pressure drops without sampling the oxygen lines. These systems would not protect the patient in the case of a crossover in which the gas does not contain oxygen
Which of the following components are part of the flow control circuits in an anesthesia machine? (Select all that apply)
A. Pressure regulators
B. Oxygen flush valve
C. Oxygen supply failure protection devices
D. Flow valves and flowmeters
E. Vaporizers
F. Common (fresh) gas outlet
G. Soda lime canister
Answers:
A, C, D, E, F
Rationale:
Oxygen flush valve and Soda lime canister are not part of flow control circuit.
The oxygen flush valve bypasses the flow control circuit and delivers high-flow, high-pressure oxygen directly to the patient.
The soda lime canister is part of the breathing circuit, responsible for CO₂ absorption, but it is not part of the flow control circuit.
Which patient will benefit the most from humidifying and heating inspiratory gases during general anesthesia? Select 2:
A. Young adults who say she is cold
B. Post-MVC teenager going for an ORIF
C. 3-year-old patients with cystic fibrosis
D. Middle-aged adults undergoing knee replacement surgery
E. Grandpa with COPD
Correct Answer: C and E
Humidification and heating of inspiratory gases may be most important for small pediatric patients and older patients with severe underlying lung pathology.
Which of the following safety features on a modern anesthesia machine prevents the simultaneous activation of multiple vaporizers?
A. Agent-specific keyed filling port
B. Interlocking or exclusion device
C. Flow control valve
D. Agent-specific, color-coded cassette
Answer: B. Interlocking or exclusion device
Rationale:
Modern anesthesia machines are equipped with interlocking or exclusion device to prevent the simultaneous activation of multiple vaporizers. This feature reduces the risk of delivering multiple volatile anesthetic agents to the patient and accidental overdosing.
The oxygen/nitrous oxide ratio controller is a safety feature of the anesthesia machine and ensures what minimum oxygen concentration?
A) 21%
B) 25%
C) 30%
D) 35%
Answer: B
Rational: The oxygen/nitrous oxide ratio controller delivers a minimum of 25% FiO2 to prevent the delivery of a hypoxic mixture. The oxygen/nitrous oxide ratio controller links the flow valves either pneumatically or mechanically. This device does not protect against other possible causes of hypoxic delivery like oxygen pipeline crossover, leaks distal to the flowmeter valve, administration of a third gas, or defective mechanic or pneumatic components.
When is the Adjustable Pressure-Limiting (APL) valve usually fully open?
A. Manual ventilation
B. Spontaneous ventilation
C. Both manual and spontaneous ventilation
D. It is never fully open
Correct Answer: B. Spontaneous ventilation
Rationale: The APL valve is usually fully open during spontaneous ventilation but must be partially closed during manual or assisted bag ventilation. If it is not closed sufficiently, excessive loss of circuit volume due to leaks prevents manual ventilation (Butterworth et al., 2022).
Select the three types of oxygen analyzers from the list below:
A. Polarographic
B. Variable Bypass
C. Galvanic
D. Paramagnetic
Answer: A, C, and D
Rationale: The three types of oxygen analyzers available are polarographic (Clark electrode), galvanic (fuel cell) and paramagnetic. Variable bypass is a type of vaporizer not an oxygen analyzer. (Butterworth et al., 2022).
Which anesthetic gas has the highest vapor pressure and lowest boiling point?
A. Halothane
B. Sevoflorane
C. Desflurane
D. Isoflurane
Correct answer: C, Desflurane
Rationale: The higher the vapor pressure, the more vapor will be released. ALL modern vaporizers are agent-specific, and filling the vaporizer with the incorrect gas can cause incorrect doses of anesthetic gas. Filling a vaporizer specified for sevoflurane with halothane instead can cause an overdose due to the increased amount of vapor being released. Desflurane is the answer with the highest vapor pressure; its boiling point is near room temperature (22.8°C at 760 mmHg). Due to this low boiling point, desflurane requires specific electronic vaporizers.
Causes of flowmeter malfunction include: (Select three of the following)
A. Debris in the flow tube
B. Flow tube interior being coated with a conductive substance.
C. Vertical tube misalignment
D. A float stuck at the top of the tube
Correct answer: A, C, & D.
Rationale: Flowmeters can malfunction when there is debris in the flow tube, a misalignment of the vertical tube, and a float that is sticking or concealed at the top of the tube. The inner tube of the flowmeter should be coated with a conductive substance in order to reduce the effect of static electricity (Butterworth et al., 2022).
On modern anesthesia machines, where is the location of the oxygen flowmeter, and why?
A. Farthest to the left ; This prevents hypoxia if there is a leak from another flowmeter located upstream
B. In the middle ; Oxygen must be in the middle to adequately mix with the other gases before delivery to the patient
C. Farthest to the right ; This prevents hypoxia if there is a leak from another flowmeter located upstream
D. Farthest to the right ; The weight of oxygen requires it to be farthest downstream, otherwise it would never reach the patient if positioned farthest to the left
Answer: C
Rationale: Positioning the oxygen flowmeter furthest to the right (furthest downstream) prevents hypoxia in the case of leakage from a different flowmeter further upstream. With oxygen positioned furthest downstream, this makes it the last gas to enter the common gas outlet before reaching the patient. Having a different gas furthest downstream, such as nitrous oxide or medical air, could result in delivery of a hypoxic mixture of gas to the patient if there was a leak in the upstream flowmeter (Butterworth et al., 2022).
What is the upper limit of pressure in cm H2O for the adjustable pressure-limiting (APL) valve?
A: 30-40 cm H2O
B: 70-80 cm H2O
C: 40-50 cm H2O
D: 10-20 cm H20
Answer: B: 70-80 cm H20
Rationale: The APL valve is a pressure-limiting device that can never be completely closed. The upper limit is 70-80 cm H2O. The APL valve is open when the patient is spontaneously ventilated, but it is partially closed during manual ventilation or assisted bag ventilation. If the APL valve is closed off too much, and there is a progressive rise in pressure, it could cause pulmonary barotrauma.
How fast does Oxygen flow when the Oxygen flush valve is activated
A. 35-75 L/min
B. 5-10 L/min
C. 75 mL/min
D. 20 L/min
Answer: A
Rationale: The oxygen flush valve provides a high flow (35–75 L/min), not mL/min, of oxygen directly to the common gas outlet, bypassing the flowmeters and vaporizers
