E2 - Breathing System I Flashcards
What are the six functions/definitions of the breathing system?
- Receives gas mixture from machine
- Removes CO2
- Delivers gas to the patient
- Provides heating and humidification of the gas mixture
- Provides gas sampling, measures airway pressure, and monitors the volume
- Allows spontaneous, assisted, or controlled respiration
What is considered apparatus dead space?
A. y piece to the patient + inspiratory limb
B. y piece and distal (towards patient)
C. y piece to the patient + insp and exp limbs
D. y piece and proximal (away from patient)
B. Y piece and distal
decrease apparatus DS by having y piece as close to pt as possible
what are the most distensible components of the breathing circuit? select 2.
A. reservoir bags
B. face mask
C. scavenging system
D. breathing tubes
A. reservoir bags
D. breathing tubes
compliance/distensibility helps determine Vt
What are the six desirable characteristics of a breathing circuit?
- Low resistance to gas flow
- Minimal rebreathing
- Removal of CO2 at rate of production
- Rapid changes in delivered gas when required
- Warmed humidification of inspired gas
- Safe disposal of waste gases
Name and Describe the four classifications of breathing circuits.
- Open - No reservoir bag and no rebreathing (nasal cannula)
- Semi-Open - Reservoir bag but no rebreathing d/t FGF > minute ventilation.
- Semi-Closed - Reservoir bag w/ partial rebreathing
- Closed- Reservoir bag and complete rebreathing, FGF equivalent to patient uptake
When would you want a closed breathing circuit?
- Conserve patient’s temperature
- Trying to be economical and not waste any gas
- Trying to perform low flow anesthesia
Name the components of the breathing system.
- Facemask, LMA, ETT
- Y-piece with mask/ tube connectors
- Breathing tube (corrugated tubing)
- Respiratory Valves (unidirectional)
- Fresh gas inflow site
- APL (Pop-off) Valve leading to scavenger
- CO2 absorption canister
- Reservoir Bag
The facemask needs to fit between the ____ and in the groove between the ____ and alveolar ridge.
- interpupillary line
- mental process
The facemask will connect to the Y-piece/connector, how big is the female connection?
- 22 mm
A fitting that joins together 2 or more components.
- Connectors/ Adapters
What are the benefits of connectors and adaptors?
- Extends the distance b/w patient and breathing system
- Change the angle of the connection
- Allow more flexibility/ less kinking (The accordion will give you the most flexibility)
What are the disadvantages of connectors and adaptors? select 2.
A. more distance between patient and breathing system
B. increases resistance and deadspace
C. more kinking of tubing
D. add’l locations for disconnections
E. less flexibility of tubing
B. Increased resistance + Increased dead space
D. Additional locations for disconnections
How long is the breathing tubing?
What is the internal volume of the breathing tubing?
- 1 meter in length
- 400-500 mL/meter of length
Flow is always ___ due to corrugation.
A. laminar
B. generalized laminar
C. turbulent
D. slow
C. Turbulent Flow
True/False: Breathing tubes connected together to increase tube length will increase dead space.
False; Longer tubes do not create deadspace
* Dead space is only from Y-piece and distal (towards patient) due to unidirectional gas flow
Pressure check the circuit before use. What value should this be?
- 30 cm H2O
How much of a normal Vt is anatomical deadspace?
150 mL
That is why we deliver at least 300 mL of tidal volume in simulation for adequate ventilation.
What directs respiratory gas flow in the correct direction?
Unidirectional valves
These unidirectional valves must open widely with very little pressure. Low resistance, high competence. Open/Close rapidly with no backflow.
The inspiratory valve opens on ____.
The inspiratory valve close on ____.
What does the inspiratory valve prevent?
- The inspiratory valve opens on inspiration.
- The inspiratory valve close on exhalation.
- Prevents backflow of exhaled gas
The expiratory valve opens on ___________.
The expiratory valve close on _________.
What does the expiratory valve prevent?
- The expiratory valve opens on exhalation.
- The expiratory valve close on inspiration.
- Prevents rebreathing
What composes the apparatus dead space?
- Distal limb of Y-connector
- Tube/mask/LMA
The unidirectional valves are located near what parts of the breathing system? select 3
A. CO2 absorber
B. O2 flush
C. fresh gas inflow site
D. flowmeters
E. APL valve
F. mask
A. CO2 absorber canister
C. Fresh gas inflow site
E. APL Valve
What are the 5 requirements of unidirectional valves?
- Arrows/ Directional words
- Hydrophobic - needs to repel water/moisture!!!
- Must open and close appropriately
- Clear dome - to visualize if valves are working
- Must be placed between patient and reservoir bag
Which unidirectional valve is more likely to be stuck? Inspiratory or Expiratory?
left from last years class
- The expiratory valve is more vulnerable because it is subject to greater moisture exposure.
Miller pg. 605
What are the 4 functions of the reservoir/breathing bag?
(1) Reservoir for anesthetic gases/oxygen
(2) A means of delivering manual ventilation or assisting spontaneous breathing
(3) Serving as a visual or tactile means of monitoring a patient’s spontaneous breathing efforts
(4) Partially protecting patient from excessive positive pressure in the breathing system.
What is the shape of the reservoir bag which makes it helpful for 1 hand ventilation?
A. ellipsoidal
B. circular
C. conical
D. spherical
A. ellipsoidal
How much volume is in a traditional reservoir bag for adults?
3 L
Can range from 0.5 to 6 L
All reservoir bags must have ___ mm female connector on the neck.
22 mm
Anesthesia reservoir bags must adhere to pressure standards, which mandate:
- a minimum pressure of approximately ____ cm H2O
- a maximum pressure of approximately ____ cm H2O when the bag is filled to four times its stated capacity.
- 30 cm H2O (minimum)
- 60 cm H2O (maximum)
Although most bags adhere to these standards, some latex-free bags have exceeded the upper pressure limit.
What is another name for the Gas Inflow site?
Fresh gas inlet
Where is the preferred location of the fresh gas inflow site?
A. Between patient and inspiratory valve
B. Between CO2 absorber and APL valve
C. Between CO2 absorber and inspiratory valve
D. Between patient and expiratory valve
C. Between CO2 absorber and inspiratory valve
When does the fresh gas scrub out the CO2 absorber?
A. during expiration
B. during inspiration
C. during assisted PPV
D. during spontaneous inspiration
A. During expiration
During expiration, the inspiratory valve will be closed. When this occurs, fresh gas will travel to the CO2 absorber.
What is the downside of having the fresh gas inflow valve so close to the CO2 absorbent?
A. Fresh gas could wet the absorbent
B. Fresh gas could mix with CO2
C. Fresh gas could explode the absorbent
D. Fresh gas can dry out absorbent
D. Fresh gas can dry out the absorbent
and dessicated absorbent = compound A & CO formation
What is the purpose of the Adjustable Pressure-Limiting Valve (APL) / Pop-off Valve? select 2.
A. allow conservation of anesthetic gases or O2
B. control Vt
C. provide control of breathing system pressure
D. to ensure gas gets scrubbed by CO2 absorber
E. vent excess breathing circuit gas to scavenging system
operator-adjustable relief valve that:
E. vents excess breathing circuit gas to the scavenging system and
C. provides control of the breathing system pressure during spontaneous and manual modes of ventilation (NOT DURING MECHANICAL VENTILATION).
Tightened screw cap (closed) = more gas pressure required to open it
Clockwise motion of the APL valve will ___ pressure.
- Increase
“close”
Counterclockwise motion of the APL valve will ___ pressure.
- decrease
“opens” APL valve
How many turns does it take for the APL valve to go from fully open to closing fully?
- 1-2 clockwise turns
Can the absorbent be replaced in the middle of a surgical case?
Yes, the housing compartment incorporate valves that closes when removed to prevent gas loss
think of coffee pot example
Name the components of soda lime (sodasorb).
- Calcium hydroxide (80%)
- Sodium hydroxide/ Potassium hydroxide (5%)
- Water (15%)
- Small amount of silica/clay
Most absorbents use calcium hydroxide to react with the expired CO2, producing what 3 byproducts?
- Insoluble calcium carbonate (CaCO3)
- Water
- Heat/Energy
Because CO2 does not react quickly with calcium hydroxide, what are the catalysts required to speed up the reaction? Select 2.
A. beryllium hydroxide
B. Water
C. Litholyme
D. NaOH
E. potassium hydroxide
F. Lithium Hydroxide
D. Sodium hydroxide
E. Potassium hydroxide
How do you know when the soda lime has been fully exhausted?
Color change: turns from white to purple
means All hydroxides have become carbonates
Soda lime can absorb _____% of its weight in CO2.
100 grams of soda lime can absorb _______ L of CO2.
- 19%
- 26 L
Name the components of Calcium Hydroxide Lime (Amsorb Plus).
- Calcium hydroxide (70%)
- Calcium chloride (0.7%)
- Calcium sulfate (0.7%)
- Polyvinylpyrrolidone (0.7%)
- Water (14.5%)
What is the drawback of Baralyme?
- Compound A formation (found in rats)
- Carbon Monoxide formation
- Destruction of inhaled gases
Calcium hydroxide lime decreases Compound A formation, CO formation, and destruction of inhaled gases.
Name This Absorbent:
- Reacts with CO2 to from carbonate
- More CO2 absorption capacity
- Used in submarines and spacecraft
- Not usually used in anesthesia
- Lithium Hydroxide
Name This Absorbent:
- Has a Lithium chloride catalyst and does not react with inhaled gases
- No activators/strong bases
- Does not form Compound A and carbon monoxide
- Has color change (white to purple) but no regeneration
- ↓ Fire Risk
- Litholyme
Name this Absorbent:
- Anhydrous LiOH powder, hydrated polymer sheets
- No activators/strong bases
- ↓ Temperature production
- Cheap
- No color indicator, no color change
- Spira-Lith
Which of the following absorbent **does not ** have any CaOH in it?
A. Amsorb
B. Spiralith
C. Soda Lime
D. Litholyme
B. Spiralith has 0% CaOH2
Soda Lime (Sodasorb) and Litholyme both contain about 75% Calcium Hydroxide
Which of the following absorbent is composed of 95% Lithium Hydroxide?
A. Soda Lime
B. Litholyme
C. Spiralith
D. Amsorb
C. Spiralith has 95% LiOH
Which of the following absorbent does NOT have color indication?
A. Soda Lime
B. Litholyme
C. Spiralith
D. Amsorb
E. Sodasorb
C. Spiralith
What is the most common dye for absorbent indicators?
- Ethyl Violet
Ethyl violet causes soda lime to turn from white to purple when exhausted
What color will ethyl orange and cresyl yellow turn when exhausted?
- Yellow
Carbonate formation will cause pH to become less (alkaline or acidic) ____ and cause the contents of the CO2 canister to turn from white to _______.
- less alkaline (lower pH)
- blue violet (purple)
The soda lime experiences color change at what pH:
A. pH > 10.3
B. pH < 10.3
C. pH > 10.1
D. pH < 10.1
B. pH less than 10.3
purple = exhausted
When absorbent is exposed to light for a period, what can happen? Select 2.
A. Regeneration
B. Becomes colorless
C. Bleaching
D. Fire can occur
E. Absorbent indicator doesn’t work as well
C. Bleaching
E. Absorbent indicator does not work as well
Absorbents have high reliability indicating CO2 rebreathing, but what is the gold standard?
A. color change
B. capnometry
C. capnography
D. visualization
B. Capnometry
CO absorbent granules are measured in what units?
A. mesh units
B. mL
C. mm
D. mL/cmH2O
A. Mesh Size
* 4-8 mesh size (optimal for CO2 absorbers)
Mesh size - the # of openings per linear inch in a sieve through which the granular particles can pass. For example, a 4-mesh screen means that there are four quarter-inch openings per linear inch
The ability of the workstation’s absorber to remove CO2 is related to three main factors:
- The amount of absorbent surface area exposed to the exhaled gas
- The intrinsic capacity of the absorbent to remove CO2
- The amount of non-exhausted absorbent remaining.
The size and shape of the absorptive granules are intended to maximize ________ while minimizing ________ .
A. drying ; surface area
B. surface area ; absorption
C. surface area ; resistance
D. resistance ; surface area
C. Maximize Surface Area/Absorption while Minimizing resistance to airflow
Roughly half of the volume of the CO2 canister will be composed of _______.
- gas
What factors can decrease the efficiency of CO2 absorption? Select 2.
A. Excess gas in the canister
B. Increase surface area
C. Decrease surface are
D. Excess water in the canister
E. Increased absorbent in canister
C. Decrease surface area
D. Excess water in the canister **(change canister if you see liquid) **
What is the method of small passageways allowing gas to flow through low-resistance areas called?
A. Barreling
B. Cutting
C. Channeling
D. Blowing
C. Channeling
Channeling decreases functional absorptive capacity!
What are ways to minimize channeling?
A. Circular baffles (flow-directing panels)
B. Placement for vertical flow
C. Permanent mounting
D. Prepackaged cylinders
E. Avoiding overly tight packing
F. All of the above
F. ALL OF THE ABOVE
* Circular baffles (flow-directing panels)
* Placement for vertical flow
* Permanent mounting
* Prepackaged cylinders
* Avoiding overly tight packing
The decomposition of sevoflurane will form this substance.
- Compound A
2-fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether
Compound A causes what toxicity in rats?
- Nephrotoxic in rats
- Possible in humans
Compound A formation occurs with:
- Low FGF (1-2 L/min)
- Increased absorbent temperature
- Higher inspired sevoflurane concentrations (1.5 to 2 MAC)
- dessicated absorbent
- Longer anesthetic
- Absorbent containing** NaOH or KOH**
Carbon monoxide can occur due to what factor?
- Dry absorbent from leaving the fresh gas flow on
- If CO2 absorber hasn’t been used for a long period of time (months)
- ‘Monday, 1st case’- gas left on over the weekend
- Increased Temperature
- Increased Concentration of anesthetic gases (ESPECIALLY DESFLURANE)
- Low FGF rate (1-2L/min)
- Smaller patients (can’t rehydrate a desiccated absorbent)
- Strong base absorbents (KOH or NaOH)
Rank the order of anesthetic gases from highest to lowest level of carbon monoxide formation.
Desflurane ≥ enflurane > isoflurane > > halothane = sevoflurane
D E I H S
How does an exothermic reaction leading to fires and explosions occur with anesthetic gases?
A. Desiccated strong base absorbents interact with sevoflurane
B. Hydrated absorbents interact with sevoflurane
C. The oxygen being left on mixes with sevoflurane and causes an explosion
D. Sevoflurane use sparks oxygen to cause fires
A. Desiccated strong base absorbents interact with sevoflurane
* Examples of strong base absorbents: Baralyme, anhydrous LiOH
Buildup of high temperatures, flammable degradation products (formaldehyde, methanol, and formic acid), and oxygen or nitrous rich gases w/in the absorber all provide basis for combustion
Which anesthetic gas should be avoided with desiccated strong base absorbents?
A. Isoflurane
B. Desflurane
C. Halothane
D. Sevoflurane
D. Sevoflurane
Anesthesia Patient Safety Foundation Recommendations
- ALL gas flows turned off after each case
- Vaporizers turned off when not in use
- Absorbent changed regularly
- Change when color change indicates exhaustion
- Change all absorbent
- Change absorbent when uncertain about the state of hydration
- If using compact canisters, change more frequently
