4b. Anesthesia Equipment Flashcards
What are the two functionaly systems of safe delivery of inhalant anesthetics?
- life support - oxygen and everything associated w/ breathing and assisted ventilation
- Inhalant drug delivery - getting a safe amount of gas into patient to keep them under
What are the basic continuous machine design
High pressure system: high pressure supply of gases by cylinders or pipelines, pressure gauges (regulators) to control flow of gases into the machine
Flow meters: intermediate pressure system
Low pressure system: vaporizer to create accurate mix of gases at known concentration, breathing circuit - to deliver to patient
What is the high pressure system?
o2 and n2o source
can be pressurized cylinder or pipeline supply
pipeline oxygen supply: 50psi, tans located elsewhere in building, chainted to wall
Cylinders: O2 supplied around 2000psi (needs to be reduced to about 45psi when entering anesthetic machine
What are the gas tank color doding system?
oxygen tank colors: white, green, white + green
N2o - blue
What are the most common size for O tanks?
Etanks
What is the hanger yoke assembly?
connects cylinder to machine; ensures unidirectional gas flow; creates seal btw cylinder and machine
What is the pin index safety system?
used with e-cylinders
medical gases to ensure correct cylinder being fitted to yoke w/ specific pins
Do not change/move safety pins; check pins; keep cylinder attached to prevent pin damage
What is the cylinder pressure guage and regulator?
gauge measures gas pressure in tank
pressure is read when tank is turned on
regulators reduces pressure from as high as 2200 PSIG to 45-60PSIG
What is the o2 flush valve?
direct tube that connects o2 source to breathing circuit (bypasses flow meter and vaporizer)
gives 35-70L/min flow (45-60psi) of pure oxygen as a straight shot
can be used to flush anesthetic agent from lines
never use with baine - too high pressure can pressure damage to small animals
can ignore and obtain similar effect by turning up oxygen flow meter
What is the o2 flow meter assembly?
controls, measures and indicates rate of flow of gas passing through it
control knob is color coded for each gas (white = o2; blue = n2o)
opening stem inc flow rate, closing dec rate
specific for each machine and calibrated for 20C, 101.3 kPa
How do we correctly read a flow meter?
read from TOP of bobbin (screw shaped)
Read from MIDDLE of ball
What are o2 alarms?
standard in newer machines
alarms sounds if too high pressure, sustained high pressure or negative pressure detected
What is the low pressure system?
everything located downstream of flow meter
Vaporizor or precision plenum vaporizor
delivers a set partial pressure of inhalant gas; and mixes with O2
has lock and key system that matches anes. bottle to ensure only one agent used
*never tip
SVMA bylaws vaporizers must be serviced every 2 years but 1 year is recommended
If we tip the anesthetic machine, what might happen to the low pressure system?
liquid anes gas may enter the lines = unpredictable amount of gas delivered to patient next time it is used
if tipped have machine services prior to next use
How is the vaporizer and inhalant drugs color coded?
Halothane = red
Isoflurane = Purple
Sevoflurane = Yellow
Desflurane = Blue
What is the common gas outlet?
Where mixture of oxygen and inhalant are delivered into the breathing system
usually has a valve that allows switching btw non-rebreathing and breathing circuits
What is the pop-off valve?
aka APL valve, exhaust valve
pressure relief valve
allows excess gas to escape system
Opens at a pressure of 5psi
prevents damage to the vaporizer and flow meters if there is outlet obstruction
keeping closed will cause pressure in system to build - patient can’t breathe, barotrauma
Always keep open
always check to make sure not obstructed
only close to manually ventilate or f auto-ventilating
What is the rebreathing bag?
resevoir bag - patient breathes from the bag
the average tidal volume is 10-15ml/kg (SA like kittens on higher end), lower is COPD or other airway disease
Converts to working volume of 1 -1.5L/10kg when selecting size of bag
As patient draws from bag, can use to monitor RR, depth and to ventilate
How do you know what size a breathing bag is? How do you wash it?
size is indicated on bag
need to be rinsed with soapy water and hung to dry btw every ptient
What is the breathing circuit manometor?
measures pressure in breathing circuit
0-2cm H2O when breathing spontaneously
Max 10-15cm H2O (K9/fel(
Man 20cm H2O (eq/boc) (lower in textbook to allow for response and prevent trauma)
higher pressures will cause lung damage, pneumothorax
What is soda lime and what does it do?
calcium and sodium hydroxide
specific to removing CO2 from a breathing circuit (so patient is not breathing in the excess CO2)
exhaled gas flows through one-way valve to co2 canister > scavenger (soda lime) selectively absorbs CO2 that was breathed out > O and inhalant gas that was not absorbed continues to patient or exhaust
only used in rebreathing systems
When do we change soda lime?
inc CO2 build-up in patient, color change, lack of heat in canister, hardness of granules (dried out granules don’t absorb)
time of function
gain of 50g in canister (weight before attaching to machine)
How do we determine when soda lime is exhausted?
color change w/ pH indicator
change when 2/3 of canister has changed color
not reliable on its own bc only works with packed properly granules, reverts to white if not used for awhile
What are waste anesthetic gas?
WAGs - personnel safety concern
nitrous oxide, halogenated anesthetic gases, metabolic by-products of anesthetic gases
measured in parts per million (ppm) - number of molecules of iso per 1 mil molecules of air
Controlled by avoiding spills, testing equipment for leaks, exhaust and scavenging of WAGs
