Anesthesia machine 4 Flashcards
Choose the statement that BEST describes the Tec 6 vaporizer (select two):
a. it is pressurized to two atmospheres
b. it uses a flow-over design
c. it is heated to 42 degrees
d. its output is increased inside a hyperbaric chamber
a. it is pressurized to two atmospheres
d. its output is increased inside a hyperbaric chamber
The Tec 6 is different than a variable bypass vaporizer in that it
injects a precise amount of vaporized desflurane directly into the fresh gas flow
To ensure precise vaporizer output, the desflurane vaporizer heats the liquid anesthetic to ________ and pressurizes it to _______
39 C and 2 atmospheres
The Tec 6 vaporizer does not
compensate for changes in elevation
With the Tec 6, a lower ambient pressure (high altitude) requires
a higher setting on the dial
With the Tec 6, a higher ambient pressure (hyperbaric oxygen tank) requires
a lower setting on the dial
Which device will be the FIRST to detect an oxygen pipeline crossover?
a. proportioning system
b. oxygen analyzer
c. fail-safe device
d. pulse oximeter
b. oxygen analyzer
The oxygen analyzer typically resides in the
inspiratory limb of the breathing circuit
The oxygen analyzer is the final defense against
the delivery of a hypoxic mixture
The only safety device in the anesthesia machine that measures oxygen concentration is
the oxygen analyzer
If O2 consumption increases, but O2 delivery remains constant, then it’s possible
to create a hypoxic mixture
What are the three roles of the oxygen analyzer?
it monitors oxygen concentration (not pressure)
it can detect an oxygen pipeline crossover
it can detect a hypoxic mixture caused by a leak in the oxygen flowmeter
The galvanic fuel-cell oxygen analyzer must be
calibrated daily and the components are consumable so must be replaced over time
The paramagnetic device oxygen analyzer is
self-calibrating and has no consumale parts
Compared to the galvanic fuel-cell, the paramagnetic device
has a faster response time
What are the MOST critical actions to perform during an oxygen pipeline crossover? (select 2)
a. disconnect the pipeline supply
b. replace the oxygen analyzer
c. ventilate with an ambu with the auxillary oxgyen flowmeter
d. turn on the oxygen tank
a. disconnect the pipeline supply
d. turn on the oxygen tank
When the oxygen analyzer alarms, it’s best to assume
that a pipeline crossover has occurred until other causes can be ruled out
If you have a pipeline crossover, you must perform these two critical steps:
turn on the oxygen cylinder AND disconnect the pipeline oxygen supply
The second step of a potential pipeline crossover is to,
verify that the oxygen concentration in the circuit is increasing; if not, ventilate the patient with an Ambu bag connected to a different oxygen tank & convert to a TIVA
With a pipeline crossover, it is important to conserve tank oxygen by _________. If your machine uses oxygen as the ventilator drive gas, then convert to
using low flows; hand ventilation
Select the true statements regarding the oxygen flush valve. (select 2).
a. the risk of barotrauma is minimized by ventilators with fresh gas decoupling
b. it will deliver a continuous pressure of 35-75 psi
c. excessive use can lead to awareness
d. it will cause the ventilator spill valve to close during inspiration
a. the risk of barotrauma is minimized by ventilators with fresh gas decoupling
c. excessive use can lead to awareness
The oxygen flush valve provides a path for oxygen to travel from the
intermediate-pressure system to the breathing circuit
Pressing the oxygen flush valve exposes the breathing circuit to oxygen flow of
~35-75 L/min.
Pressing the oxygen flush valve exposes the breathing circuit to oxygen pressure of
~50 psi (pipeline pressure)
Most manufacturers do not recommend using the oxygen flush valve for
jet ventilation- its use in this context is considered “off label”
The gas from the oxygen flush does not pass through
the vaporizers which can dilute the partial pressure of the volatile agent and may lead to patient awareness
During mechanical ventilation, the ventilator spill valve is
closed during the inspiratory phase
Pressing the oxygen flush during the inspiratory phase
transfers pressure to the patient’s lungs leading to risk of barotrauma
Describe what happens to the bellows and spill valve during inspiration.
drive gas compresses bellows
drive gas closes spill valve
fresh gas form the ventilator goes to the patient
Describe what happens to the bellows during expiration.
expired gas refills the bellows
bellows fills completely
when circuit pressure >2-4 cm H2O expire gas is directed through the spill vale to the scavenger
Methods on anesthesia machines to minimize the risk of barotrauma include
isolating the tidal volume delivered to the ventilator from the flowmeters and oxygen flush valve- known as fresh gas decoupling
inspiratory pressure limiter- limits the breathing circuit pressure where excess gas is vented out the scavenger
A stuck open flush valve will result in
barotrauma
What 2 functions does the drive gas on a pneumatic ventilator serve?
it compresses the bellows
it opens and closes the ventilator spill valve
What is the minimum expiratory pressure needed to open the ventilator spill valve?
~3 cmH2o
Select the true statements about the pneumatic ventilator bellows. (select 2)
a. a descending bellows is made safer by fresh gas coupling
b. a descending bellows cannot rise and fall with a circuit disconnect
c. a leak in the bellows may cause the reading on the oxygen analyzer to increase
d. a hole in the bellows may cause barotrauma
c. a leak in the bellow may cause the reading on the oxygen analyzer to increase
d. a hole in the bellows may cause barotrauma
The bellows is classified by its movement during
expiration
An ascending bellows_______ during expiration, and a descending bellows _______during expiration.
rises; falls
The ___________ bellows design is generally regarded as safer
ascending bellows
The ascending bellows design is generally safer because the
descending bellows continue to rise and fall if there is a circuit disconnect; newer descending bellows designs mitigate this risk
A leak in the bellows creates a path between
the ventilator drive gas (the gas that compresses the bellows) and the gas inside the patient breathing circuit
What is fresh gas flow decoupling?
tidal volume set on the ventilator is what the patient actually receives
What is the equation for fresh gas flow coupling?
total tidal volume= Vt set on ventilator + FGF during inspiration - volume lost to circuit compliance
A bellows leak could allow
anesthetic vapor to escape from the breathing circuit leading to risk of awareness
