Ali intro Final- Things I Can't Remember Flashcards
Desired breathing circuit features
Economy of FGF
Conservation of heat/humidity
Light weight
Convenient
Effective in SV and CV
Adaptability for kids/adults/mechanical ventilation
Little environmental pollution — safe disposal waste system
Considerations of breathing circuit
Resistance Rebreathing Dead space Dry gases/humidification Manipulation of inspired content Bacterial colonization
Advantages of Bain
Warm/humidify
Light weight, easily sterilized, reusable
Good for cases with little access to pt head
Ease of scavenge waste gas
Advantages of Mapleson E
Less resistance
Minimal dead space
No valves (decr resistance)
Good for peds/neonatal (due to less resistance)
Parts of Ambu Bag (5)
Gas inlet One way flap valve Reservoir Non rebreathing valve Small bore nipple to allow for O2 addition/attachment
Ambu bag safety features
Elasticity of outer cover to limit pressure to 7 kPa
Peds have pressure limiting valve (4 kPa)
Similarities of Mapleson and Circle System
Both have FGF
Both supply volume/flow to patient
Both eliminate CO2 in some way
Difference between Mapleson and Circle System
Mapleson: bidirectional valve, no rebreathing (FGF high enough to eliminate CO2)
Circle: uni valves, rebreathing occurs, CO2 scrubber, vaporizer, scavenger
Benefits of Circle System
Stability of concentration of gases Conservation of heat/moisture Low resistance Can do closed system anesthesia Low FGF Economy of gases Ability to scavenge Prevent OR pollution
Hallmark component of Circle System
Unidirectional gas flow via unidirectional valves
Primary source of resistance in circle system
Tracheal tube (ETT) (larger if possible) Valves (keep dry) CO2 scrubber (short and wide help)
Closed circle system
APL closed
Concentration of gases - if want to change them happens SLOWLY
FGF low
Rebreathing occurs
Advantages of Circle System
Retained heat/humidity Stability of gas concentration Low resistance Closed system anesthesia Low FGF with no rebreathing of CO2 Recycles gas Scavenge waste
Disadvantages of Circle System
Increase resistance from uni valves Complex Malfunction of valves can occur Less portable Increases dead space
2 tests of circle systems
Leak test- occlude y piece, o2 flush to 30 cm h2o for 10 seconds, ensure holds, listen for sustained pressure alarm
Flow test- breathing bag on y piece, ventilator on, check unidirectional valves
Safe handling of cylinders (NEVER DO THIS…..)
- Stand alone upright w/o support
- Leave empty cylinder on back of machine
- Leave plastic tape on port while installing cylinder
- Rely on cylinders for color identification
- Oil valves
- Open towards you (SHOULD OPEN AWAY DUE TO ADIABETIC PROCESS-fire, dust)
- Have valve half open (SHOULD BE FULLY OPEN WHEN CYLINDER IN USE due to result in delivering inadequate amounts of gas)
Vapor pressure depends on…
- Temperature
- Vapor pressures
- Amount of carrier gas (carrier gas flow)
Latent Heat of Vaporization
calories needed to change 1g liquid into vapor WITHOUT a temp change
Specific Heat
calories to increase temp of 1g of substance by 1 degree Celsius
Vaporizer desired features (with regards to specific heat and thermal conductivity)
Want a HIGH specific heat
Want a HIGH thermal conductivity
What happens to temp/vaporization rate as liquids start vaporizing
(In absence of outside source of energy)…
Temp of liquid itself will DECREASE during vaporization so rate of vaporization will further DECREASE (heat released to environment, out of liquid itself)
If rate of vaporization decreases, less will turn into vapor (not good)
We need a system where temp of liquid remains constant——specific heat/thermal conductivity comes into play
Thermal Conductivity
Measure of speed with which heat flows through a substance
Higher conductivity—> better a substance conducts heat (allows heat to flow through)
Vaporizers constructed of metals—high thermal conductivity—helps them maintain uniform internal temp during evaporation
Vaporizers: absorb the environmental heat that is given off during vaporization process to prevent the temp of liquid from decreasing
Keeps rate of vaporization more constant
Vaporizers: (temp compensating valve)
COLD vs HOT situations
Cold: bends to the LEFT, more FGF goes INTO vaporizer
(Helps overcome decr vaporization rate from decr temp)
Hot: bends to RIGHT, more FGF through BYPASS chamber, less through vaporizer
(Helps overcome increase in vaporization rate that occurs from incr temp)
Vaporizers: Concentration Control Vial
Controls how much saturated FGF with anesthetic leaves the vaporizer to join FGF to go to pt
Dial turned down (goes into system, less vaporized saturated FGF let out to patient)
Dial turned up (dial comes out of system, less blocked, more vaporized saturated FGF let out to patient)
Aladdin Cassets
Computer controlled VARIABLE BYPASS
Each has a central processing unit
Able to tirade how much gas is being delivered (precise)
Fresh gas over anesthetic
Desflurane (still has a tec 6 like feature in its Aladdin cassette)
Altitude Effects on Vaporization
Increased altitude—> decreased barometric pressure (more gas goes into vapor)
Decreased altitude—> increased barometric pressure (less gas goes into vapor)
DESFLURANE REQUIRES RECALIBRATION of dial setting : normal dial setting % * 760/altitude now
Chem Physics applied to Vaporization
Altitude applies what law?
Dalton law of partial pressures
Chem Physics applied to Vaporization
Calibration of vaporizers applies what law?
Avogadro’s Hypothesis
Chem Physics applied to Vaporization
Tec 6 applies what law?
Ideal Gas law
Gay Lussac
Chem Physics applied to Vaporization
To properly make a vaporizer applies what laws/ideas?
Specific heat
Thermoconductivity
Components of High pressure system
Cylinder gas supply (E)
Yoke assembly
Bourdon gauge
High pressure regulator
Components of Intermediate Pressure System
O2 flush Second stage pressure regulator Auxiliary O2 supply Pipeline gas supply Pneumatic safety systems/electrical system
Components of Low pressure system (6)
(Between flow control devices and common gas outlet)
Flowmeters Hypoxia prevention safety devices Uni valves Pressure relief valves Vaporizer Common gas outlet
Required monitors for anesthesia machine
Inspired O2/CO2
Expired O2/CO2
O2 supply failure
Hypoxic guard system
Anesthetic vapor concentration
Vital signs
Cylinder Safety Systems
Frangible disk- bursts under extreme pressure
Fusible plug- bismuth, lead, tin cadmium, melts at predetermined temp
Yoke Assembly
Connection of cylinder to machine (PISS)
Orient tanks, gas tight seal, uni flow of gases, filter, check valve (on some)
High pressure regulator location
Inside of hanger yoke
Hospital Supply Connection of Gas to Machine
DISS Sized and threaded differently Body, nipple nut combo Contains a filter, check valve (uni flow), pressure gauge Gas specific, color specific
During power outage, what still works?
Monitors DO NOT
Backup battery 30 min/generator hopefully
Auxiliary flowmeters STILL WORKS
Pneumatic Safety Systems
Part of intermediate pressure system
Help prevent delivery of hypoxic gas mixture to pt
If O2 supply reduced, delivered O2 concentration should never be below 19% O2 at common gas outlet
Fail safe devices (2)- proportioning system, pressure sensor shutoff valve
Fail Safe Device- O2 proportioning System
Pneumatic Safety Device (intermediate pressure system)
O2 pressure supply opens valve which allows delivery of N2O, as O2 pressure decreases, (when hits 30 psi), valve starts closing and reduces delivery of N2O (in proportion to O2)
Does not prevent anesthesia gases from flowing (just works on N2O)
Works even if wrong gas is supplied
PROPORTIONING DECREASE IN N2O with O2
Fail Safe Device (pressure sensor shutoff valve)
Pneumatic Safety Device (intermediate pressure system)
Once O2 supply reaches 20 psi, valve closes completely and allows nothing but O2 to flow through
THRESHOLD OF 20 to completely CLOSE VALVE
Second Stage Pressure Regulator
Part of intermediate pressure system
Protects against fluctuations of pipeline pressure
Lowers pressure of O2 to 14 psi and N2O to 26 psi
Ensures O2 is last gas flowing
Located downstream from gas supply sources in intermediate system
Supplies constant pressure to flow control valves and proportioning system
Flowmeters
Low pressure system
Regulates flow of gases entering breathing circuit
Traditionally mechanically controlled (newer ones are electrically controlled)
Flows are directed into vaporizer
Narrow at bottom, widen at top (laminar low flow bottom-viscosity, turbulent high flow gas- density)
Calibrated for a specific gas
Components of Flowmeters
Flow control knob Tapered needle valve Valve seat Valve stop Float Float stops
Hypoxia Prevention Devices
Designed to prevent delivery of hypoxic mixtures (O2 can’t be less than 21%)
Link proportioning system (Datex Ohmeda)
Sensitive Oxygen Ratio Controller System (Drager)
Sensitive O2 Ratio Controller System
Hypoxia prevention device- low pressure system component
On Drager
Pneumatic-mechanical interlock
Opening of O2 flow creates a back pressure in the chamber opening N2O flow
Maintains a 25% O2 to 75% N2O flow into breathing system
Needs at least 200 ml/min to operate this device
Lowest amount of O2 delivered is 25%
Link 25 Proportion Limiting System
Hypoxia Prevention Device on low pressure system
Mechanical integration of O2 and N2O flow control valves
3:1 Ratio
Maintains O2 concentration at least 25%
15 teeth N20, 29 teeth O2, 3:1 ratio N20 to O2
5 pathways of O2
O2 flush Flowmeters Compresses bellows of ventilator Activates fail safe valve/mechanism Activates o2 supply low pressure alarm
