Anesthesia Machine III Flashcards
what are the two types of drive mechanisms of a ventilator?
piston
or bellows
true/false: there are volume issues on piston ventilators?
FALSE- no volume issues
name the advantages and disadvantages of the piston driven design
advantage: quiet, tidal volume is precise, capable of all modern vent modes
disadvantageS: not visible, quiet
Historically, an important difference between ascending
and descending bellows is that when there is a
disconnection or major leak, the _____ bellows will
collapse.
ascending
When a disconnection occurs with a ______
bellows ventilator, the ventilator will continue its upward
and downward movements, drawing in room air and
driving gas during its descent and discharging it during
the upward movement.
descending
what is the ascending bellows doing during exhalation?
it expands upward- it ASCENDS
what is the descending bellows doing during inhalation?
it compress upward during inspiration
what is the other name for the descending bellow?
the hanging bellow
to know how much oxygen is consumed during mechanical ventilation, you must add the minute ventilation to the ____
desired flow rate
what is the standard alarm requirements and safety features?
the ASTM F1850
what is the low oxygen safety alarm assembly and when is it activated?
what machine has this?
also known as the ritchie whistle
warns the operator when the oxygen pressure in the machine is low and needs to be reestablished
it is activated when oxygen pressure falls below 30PSIG
Ohmeda
what is the purpose of the oxygen pressure failure alarms?
warn the operator when oxygen supply pressures are critically low
what alarm MUST sound for a minimum of 30 seconds?
the low oxygen safety alarm
in the drager, what warns operator when oxygen supply pressure is low?
oxygen suppply pressure alarm switch
in the ohmeda, what does the fail safe system do in the presence of insufficient oxygen pressure?
shuts OFF gases
(all or nothing effect)
in the drager, the oxygen failure protectice device _______ the flow of gases other than oxygen in the event of a partial or complete loss of oxygen supply pressure?
proportionately restricts
(conical shaped valve)
the link 25 proportion limiting control system helps prevent the secondary regulator from exceeding a ____ ratio or ____% oxygen fresh gas mixture
3:1 ratio or 25%
the drager sensitive oxygen ratio controller guarantees a minimum oxygen concentration of ____%
23%
the drager sensitive oxygen ratio controller shuts off nitrous oxide if the oxygen flow is less than ____mL/min
200 mL/min
the hypoxic guard/proportioning systems can still permit hypoxic breathing mixtures when:
wrong supply gas in oxygen pipeline or cylnder
pneumatic or mechanical components are detective
leaks exist downstream of flow control valves
what is the only way to discern a contaminated oxygen supply?
the oxygen analyzer
contains two electrodes, a lead anode, and a gold cathode, surrounded by an electrolyte bath:
galvanic cells in the oxygen analyzer
once again, explain what to do when you suspect contaminated oxygen supply:
Open emergency E cylinder
– Disconnect DISS anesthesia machine hose fitting from the wall or
boom arm
■ E cylinder may not flow (45 psi) if the anesthesia machine remains
fitted to the DISS wall connection (50 psi)
– Use low fresh gas flows – Manually ventilate the patient
what prevents more than one inhalational anesthetic from being
administered by the operator? it is An interlock system allows only one vaporizer to be used at a time
the ohmeda selectatec vaporizer manifold system
what Combines cams, pins and levers to allow only one
vaporizer to be turned on at a time. For example, when
the vaporizer on the right is turned on, the top of the
handwheel acts as a cam, forcing the pin backward.
the drager vaporizer exclusion system
what are the clinical implications of the ohemda tidal volume monitor?
patient disconnect
failure to ventilate the paptient
anoxic encephalopathy
what are the advantages of the drager ultrasonic flow sensor:
no moving parts
easy to clean
autoclavable
accuracy independent of gas composition
low resistance
how do you calibrate an oxygen analyzer?
two types: galvanic sensor (an older “plug in” type), and the
paramagnetic. Galvanic sensor- calibrate to room air (15-20 seconds, takes longer than 40-60 seconds to read 21%, change the sensor). Expose to 100% oxygen and ensure it reads close
■ Newer paramagnetic sensors use internal calibration
routines. So they only need periodic (every 3-6 months)
exposure to calibration gas, and they last for years.
what can you do to fix an oxygen analyzer that is reading an FiO2 of 16% during general anesthesia?
Don’t attempt to fix it- trust monitors until you can prove they
are wrong. – Call for help –
Tu r n o n e m e r g e n c y ox yg e n c y l i n d e r a n d d i s c o n n e c t p i p e l i n e
from wall
can you give an anesthetic when there is no connection for hoses? or if a cylinder is missing?
yes- can give anesthetic even when there is no connection to hospital pipeline or if a tank is missing
The pipeline supply of oxygen has failed. How can you
make your emergency E tank of oxygen last as long as
possible?
Driving a vent with cylinders will cause their rapid depletion.
Manually ventilate the patient, assist spontaneous ventilation
if possible, use air or nitrous oxide with oxygen if possible,
and use low flows
Your pipeline supply fails, and your cylinder gauge
shows 1000 psi. How long will your emergency oxygen
supply last if you are giving 2L O2/min?
Contents L / Gauge Pressure = Capacity L / Service Pressure
x L/1000 psi = 660 L/1900 psi; and x = 347 L. If
you are flowing 2 L/min oxygen, the tank will last
17 3 . 5 m i n u te s .
What is the most common site of disconnections?
What is the most important monitor for
disconnection?
The most common site is the Y-piece. Monitors for
disconnection (apnea alarms) can be based on gas flow (tidal
volume), circuit pressure (if peak inspiratory pressure is below
threshold an alarm rings), chemistry (carbon dioxide) or
acoustic (sound of the precordial, or normal sounds of the
ventilator cycle).
In the middle of a case, your soda lime is exhausted.
Should you change it?
No. Increase fresh gas flow (FGF) to 5 to 8 L/min for an adult (1 to 1.5 times minute ventilation). Soda lime can be more easily changed in the ADU, without interrupting ventilation.
What do you do to the machine if a patient has a
history of malignant hyperthermia?
Preferably scheduled for first case of the day ■ Remove or at least drain all vaporizers and tape over
the dial. ■ Change all breathing circuit disposables and soda lime. ■ Flush with high (10 L/min) fresh gas flow for at least 10
minutes. ■ Monitor ETCO2 and core temperature in all patients ■ Avoid triggers (volatile agents and succinylcholine)
What is the main disadvantage of the descending bellow design?
When a disconnection occurs, the ventilator will continue its upward and downward movements, drawing in room air.
the drager sensitive oxygen ratio controller (S-ORC) has audible and visible alarms sound if pipeline pressure is less than ___ PSI
20
Fabius
the drager oxygen ratio monitor controller shuts off nitrous when oxygen pressure is less than ___ PSI
10
you’re at a new clinical site and you have a vent you’ve never used before. what is the best and safest way to learn about the machine?
use the manual or the internet, find a PDF manual or instructions for use
what are you testing when you do a low pressure leak test?
flowmeters, vaporizers, and common gas outlet
calculate the FiO2 if you have 2L air 3L O2
(0.4+3 = 3.5) 3.4/5L= 0.69 or 0.7 FiO2
what is an advantage that the Bain system has?
it has a pressure relief valve
what single anesthestic agent would you theoretically avoid on a patient with a creat of 2.4?
sevo
if you smell vapor in the OR, what is the first thing you should look at?
the scavenger for a disconnect
name the two types of oxygen analyzers:
galvanic cells and polargraphic cells
name the gases
in order:
desflurane
isoflurane
halothane
enflurane
sevoflurane
name the problems with each picture of the circle circuit:
a: normal function
b: incompetent inspiratory valve
c: incompetenet expiratory valve
d: incompetenece of both valves- creates dead space
the Bain system has what 3 components?
entry point of fresh gas
resevoir bag
an APL valve
what system is a tube inside a tube or circuit inside a circuit?
the king system
what machine are these safety features for?
PISS/DISS
oxygen supply pressure alarm switch
oxygen failure protection device
oxygen ratio monitor control
vaporizer exclusion system
vaporizer safe T fill
minute volunteer
breathing pressure monitoring system
oxygen analyzer
the Drager
what machine has these safety features?
PISS/DISS
low oxygen supply alarm assembly
pressure sensor shut off valve
secondary regulator
link 25 proportion limiting control
selectatec vaporizer manifold
vaporizer safe T fill
tidal volume monitor
airway pressure transducer
oxygen analyzer
Ohmeda
Airspace is occupied at what % of Volume of absorber canister?
50%
What is the average CO2 production of soda lime?
200mL/min or 12L/hr
What provides positive or negative pressure to prevent gasses from going to the ventilator?
The interface (part of scavenger)
What is a major problem of an open system?
FIREEEEE
Gas is more soluble at _____ temps?
HIGH
What is the PSI of oxygen at the common gas outlet for GE vs Drager?
14 PSI GE
24 PSI drager
there is a CO formation risk with CO2 dessicated absorber materials containing higher concentrations of what two things?
potassium hydroxide and sodium hydroxide
what kind of reaction is in the CO2 absorber?
exothermic
what are 3 important factors for absorbent granules?
size
porosity
nature of granule surface
