Anesthesia machine 5 Flashcards
The piston ventilator (select 2):
a. relies on fresh gas flow coupling
b. preserves tank oxygen in the event of oxygen pipeline failure
c. allows for more precise delivery of tidal volumes
d. removes the risk of barotrauma
b. preserves tank oxygen in the event of oxygen pipeline failure
c. allows for more precise delivery of tidal volumes
Piston ventilators utilize
an electric motor to compress a piston that generates positive pressure in the breathing circuit
Since the piston ventilator doesn’t use a drive gas, it won’t
consume tank oxygen in the event of an oxygen pipeline failure
The piston ventilator decouples
fresh gas flow from the ventilator
The piston ventilator delivers a consistent tidal volume regardless of changes made in
the fresh gas flow, respiratory rate or the I:E ratio
With the piston ventilator, a collapsed bag signals
a circuit disconnect
What happens to the breathing bag with inspiration and expiration with a piston ventilator?
it inflates during inspiration and deflates during expiration
The piston ventilator has _____ pressure relief valves
two
What are the two pressure relief valves of the piston ventilator?
the negative pressure valve guards against negative end-expiratory pressure
the positive pressure valve guards against excessive pressure in the breathing circuit
When does the positive pressure relief valve open in the piston ventilator?
when circuit pressure exceeds 75 +/- 5 cm H2O
When does the negative pressure relief valve open in the piston ventilator?
when circuit pressure is less than -8 cmH2O
The negative pressure relief valve protects the patient against
negative end-expiratory pressure
If the negative pressure relief valve is activated in the piston ventilator, the mixing of
room air with fresh gas will cause a dilution of oxygen and anesthetic agents
Describe what will happen to the bag with spontaneous breaths on the piston ventilator.
the bag will not move when a patient initiates spontaneous breaths while on the ventilator
Which statement regarding pressure control ventilation is true? (choose 2)
a. the risk of ventilator-associated lung injury is decreased
b. increased lung compliance will decrease tidal volume
c. gas flow decelerates during inspiration
d. the ventilator switches to expiration after a preset pressure is achieved
a. the risk of ventilator-associated lung injury is decreased
c. gas flow decelerates during inspiration
Pressure controlled ventilation reduces the risk of
ventilator-associated lung injury in select patients
Pressure controlled ventilation delivers
a preset inspiratory pressure (with a decelerating flow pattern) over a predetermined time
The tidal volume in pressure controlled ventilation
varies as a function of the patient’s compliance
If a patient’s compliance changes when in pressure control ventilation, you must adjust
the ventilator settings to prevent unintended changes in minute ventilation and PaCO2
Volume controlled ventilation delivers
a preset tidal volume over a predetermined time
With volume controlled ventilation, the peak inspiratory pressure
will vary as a function of the patient’s compliance
With VCV, if airway resistance rises or lung compliance decreases, then
the PIP will increase
The _____________ is held constant during inspiration with VCV
inspiratory flow
With PCV, if airway resistance rises or lung compliance decreases, then
the Vt will decrease
What is fixed with VCV?
tidal volume
inspiratory flow rate
inspiratory time
What is variable with VCV?
peak inspiratory pressure
What is fixed with PCV?
peak inspiratory pressure
inspiratory time
What is variable with PCV?
tidal volume
inspiratory flow
PCV is useful if the patient has
low compliance where high PIP is dangerous or to compensate for leaks
When you’re using PCV, intraoperative events
can change the Vt you’re delivery to the patient
With PCV, Vt is decreased by
decreased compliance- pneumoperitoneum, trendelenburg position
increased resistance- bronchospasm, kinked ETT
With PCV, Vt is increased by
increased compliance- release of pneumoperitoneum, going from Trendelenburg to supine
decreased resistance- bronchodilator therapy
removing airway secretions
Situations in which PCV is better than VCV can be broken down to these three categories:
patient has low compliance
high PIP would be dangerous
need to compensate for a leak
When might PCV be advantageous for patients with low compliance?
pregnancy
obesity
laparoscopy
ARDs
When might PCV be advantageous for patients where PIP would be dangerous?
LMA
neonate
emphysema
When might PCV be advantageous to compensate for a leak?
LMA
uncuffed ETT in children
Which modes of mechanical ventilation are BEST suited for a laryngeal mask airway? (select 2)
a. synchronized intermittent mandatory ventilation
b. inverse ratio ventilation
c. pressure support ventilation
d. controlled mandatory ventilation
a. synchronized intermittent mandatory ventilation
c. pressure support ventilation
No matter what mode of ventilation is used, __________________ indicates a patient triggered a breath
a negative deflection just before the breath
What is controlled mandatory ventilation?
machine initiated breath delivers a preset Vt & RR on a fixed schedule
Controlled mandatory ventilation does not
compensate for patient initiated breaths (risk of patient-ventilator asynchrony)
Controlled mandatory ventilation is best for
apneic patients
What is assist control ventilation?
machine initiated breath delivers a preset Vt and RR
-spontaneous breaths receives the full preset tidal volume
For patients on assist control ventilation, a patient that over breathes the ventilator is
at risk for hyperventilation and respiratory alkalosis
SIMV is useful for
weaning or with an LMA
Synchronized intermittent mandatory ventilation is a
machine initiated breath delivers a preset Vt and RR but this mode allows the patient to breath spontaneously between machine initiated breaths
What is PCV-VG?
gives the benefits of pressure control ventilation but it also guarantees a predetermined tidal volume while applying the minimum pressure required to achieve it
What does the pro in PSV pro stand for?
“protect”
When is PSV pro useful?
weaning or with an LMA
PSV Pro allows
a spontaneously breathing patient to receive pressure-support ventilation and will convert to pressure-control ventilation if the patient becomes apneic
