Exam 2- Breathing System I (6/26/23) Flashcards
1
Q
What are the six functions/definitions of the breathing system per Dr. Erickson?
A
- Receives gas mixture from the machine
- Delivers gas to the patient
- Removes CO2
- Provides heating and humidification of the gas mixture
- Allows spontaneous, assisted, or controlled respiration
- Provides gas sampling, measures airway pressure, and monitors the volume
2
Q
What are the six desirable characteristics of a breathing circuit per Dr. Erickson?
A
- 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
3
Q
Name and Describe the four classifications of breathing circuits.
A
- 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
4
Q
When would you want a closed breathing circuit?
A
- Conserve patient’s temperature
- Trying to be economical and not waste any gas
- Trying to perform low flow anesthesia
5
Q
Name the components of the breathing system.
A
- 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
6
Q
The facemask needs to fit between the _____________ and in the groove between the ___________ and alveolar ridge.
A
- interpupillary line
- mental process
7
Q
The facemask will connect to the Y-piece/connector, how big is the female connection?
A
- 22 mm
8
Q
A fitting that joins together 2 or more components.
A
- Connectors/ Adapters
9
Q
What are the benefits of connectors and adaptors?
A
- 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)
10
Q
What are the disadvantages of connectors and adaptors?
A
- Increased resistance
- Increased dead space
- Additional locations for disconnections
11
Q
How long is the breathing tubing?
What is the internal volume of the breathing tubing?
A
- 1 meter in length
- 400-500 mL for each meter in length
12
Q
Describe the flow in the corrugated breathing tubing.
A
- Turbulent Flow
13
Q
True/False: Breathing tubes connected together to increase tube length will increase dead space.
A
- False
- Longer tubes do not create deadspace
- Dead space is only from Y-piece to patient
14
Q
Pressure check the circuit before use. What value should this be?
A
- 30 cm H2O
15
Q
With a normal tidal volume. How much air is in the anatomical deadspace?
A
- 150 mL
That is why we deliver at least 300 mL of tidal volume in simulation for adequate ventilation.
16
Q
What directs respiratory gas flow in the correct direction?
A
- Unidirectional valves
These unidirectional valves must open widely with very little pressure. Low resistance, high competence. Open/Close rapidly with no backflow.
17
Q
The inspiratory valve opens on ___________.
The inspiratory valve close on _________.
What does the inspiratory valve prevent?
A
- The inspiratory valve opens on inspiration.
- The inspiratory valve close on exhalation.
- Prevents backflow of exhaled gas
18
Q
The expiratory valve opens on ___________.
The expiratory valve close on _________.
What does the expiratory valve prevent?
A
- The expiratory valve opens on exhalation.
- The expiratory valve close on inspiration.
- Prevents rebreathing
19
Q
Proper valve placement and functioning prevents any part of the circle system from contributing to _________.
A
- Apparatus Dead Space
20
Q
What composes the apparatus dead space?
A
- Distal limb of Y-connector
- Tube/mask/LMA
21
Q
The unidirectional valves are located near what parts of the breathing system?
A
- CO2 absorber canister
- Fresh gas inflow site
- APL Valve
22
Q
What are the requirements of unidirectional valves?
A
- Arrows/ Directional words
- Hydrophobic - needs to repel water/moisture
- Must open and close appropriately
- Clear dome - need to visualize if valves are working
- Must be placed between patient and reservoir bag
23
Q
How much volume is in a traditional reservoir bag?
A
- 3 L
Can range from 0.5 to 6 L
24
Q
All reservoir bags must have _____ mm female connector on the neck.
A
- 22 mm
25
Anesthesia reservoir bags must adhere to pressure standards, which mandate a minimum pressure of approximately _____ cm H2O and 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)
## Footnote
Although most bags adhere to these standards, some latex-free bags have exceeded the upper pressure limit.
26
Which unidirectional valve is more likely to be stuck? Inspiratory or Expiratory?
* The expiratory valve is more vulnerable because it is subject to greater moisture exposure.
*Miller pg. 605*
27
What are the 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 the patient from excessive positive pressure in the breathing system.
28
What is another name for the Gas Inflow site?
* Fresh gas inlet
29
Where is the preferred location of the fresh gas inflow site?
* Between CO2 absorbent and inspiratory valve
30
When does the fresh gas scrub out the CO2 absorber?
* During expiration
*During expiration, the inspiratory valve will be closed. When this occurs, fresh gas will travel to the CO2 absorber.*
31
What is the downside of having the fresh gas inflow valve so close to the CO2 absorbent?
* Fresh gas can dry out the absorbent
32
What is the Adjustable Pressure-Limiting Valve (APL) / Pop-off Valve?
The APL valve is an operator-adjustable relief valve that vents excess breathing circuit gas to the scavenging system and provides control of the breathing system pressure during spontaneous and manual modes of ventilation.
*Tightened screw cap (closed) = more gas pressure required to open it*
33
Clockwise motion of the APL valve will ______ pressure.
* Increase
34
Counterclockwise motion of the APL valve will ______ pressure.
* decrease
35
How many turns does it take for the APL valve to go from fully open to closing fully?
* 1-2 clockwise turn
36
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
37
Name the components of soda lime.
* Calcium hydroxide (80%)
* Sodium hydroxide/ Potassium hydroxide (5%)
* Water (15%)
* Small amount of silica/clay
38
Most absorbents use calcium hydroxide to react with the expired CO2, producing what byproducts?
* Insoluble calcium carbonate (CaCO3)
* Water
* Heat/Energy
39
Because CO2 does not react quickly with calcium hydroxide, what are the catalysts required to speed up the reaction?
* Sodium hydroxide
* Potassium hydroxide
40
How do you know when the soda lime has been fully exhausted?
* It turns from white to purple
* All hydroxides have become carbonates
41
Soda lime can absorb _____% of its weight in CO2.
100 grams of soda lime can absorb _______ L of CO2.
* 19%
* 26 L
42
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%)
43
What is the drawback of Baralyme?
* Compound A formation (found in rats)
* Carbon Monoxide formation
* Destruction of inhaled gases
## Footnote
Calcium hydroxide lime decreases Compound A formation, CO formation, and destruction of inhaled gases.
44
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
45
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
46
Name this Absorbent:
- Anhydrous LiOH powder, hydrated polymer sheets
- No activators/strong bases
- ↓ Temperature production
- Cheap
- No color indicator, no color change
* Spira-Lith
47
Which of the following absorbent does not have any Calcium Hydroxide in it?
- Soda Lime
- Litholyme
- Spiralith
* Spiralith has 0% CaOH2
*Soda Lime (Sodasorb) and Litholyme both contain about 75% Calcium Hydroxide*
48
Which of the following absorbent is composed of 95% Lithium Hydroxide?
- Soda Lime
- Litholyme
- Spiralith
* Spiralith has 95% LiOH
49
Which of the following absorbent has color indication?
- Soda Lime
- Litholyme
- Spiralith
* Soda Lime
* Litholyme
50
What is the most common dye for absorbent indicators?
* Ethyl Violet
*Ethyl violet causes soda lime to turn from white to purple when exhausted*
51
What color will ethyl orange and cresyl yellow turn when exhausted?
* Yellow
52
Carbonate formation will cause pH to become less ________ and cause the contents of the CO2 canister to turn from white to _______.
* less alkaline (lower pH)
* blue violet (purple)
53
At what pH will the soda lime experience color change?
* pH less than 10.3 (purple, exhausted)
54
When absorbent is exposed to light for a period, what can happen?
* Bleaching
* Absorbent indicator does not work as well
55
Absorbents have high reliability indicating CO2 rebreathing, but what is the gold standard?
* Capnometry
56
CO absorbent granules are measured in what units?
* Mesh Size
* 4-8 mesh size (most optimal for CO2 absorbers)
*Mesh size refers to the number 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*
57
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.
58
The size and shape of the absorptive granules are intended to maximize ________ while minimizing ________ .
* Maximize Surface Area/ Absorption
* Minimize resistance to airflow
59
Roughly half of the volume of the CO2 canister will be composed of _______.
* gas
60
What factors can decrease the efficiency of CO2 absorption?
* Excess water in the canister (change canister if you see liquid)
* Decrease surface area
61
Small passageways that allow gas to flow through low-resistance areas, decreasing functional absorptive capacity.
* Channeling
62
What are ways to minimize channeling?
* Circular baffles (flow-directing panels)
* Placement for vertical flow
* Permanent mounting
* Prepackaged cylinders
* Avoiding overly tight packing
63
The decomposition of sevoflurane will form this substance.
* Compound A
## Footnote
2-fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether
64
Compound A causes what toxicity in rats?
* Nephrotoxic in rats
* Possible in humans
65
Compound A formation occurs with:
* Low FGF (1-2 L/min)
* Increased absorbent temperature
* Higher inspired sevoflurane concentrations (1.5 to 2 MAC)
* Dehydrated absorbent
* Longer anesthetic
* Absorbent containing NaOH or KOH
66
Carbon monoxide can occur due to what factor?
* Dry absorbent from leaving the fresh gas flow on
* If the CO2 absorber hasn't been used for a prolonged period of time (months)
* 'Monday, 1st case'- gas left on over the weekend
* Increased Temperature
* Increased Concentration of anesthetic gases
* Low FRF rate
* Smaller patients (can't rehydrate a desiccated absorbent)
* Strong base absorbents (KOH or NaOH)
67
Rank the order of anesthetic gases from highest to lowest level of carbon monoxide formation.
**Desflurane** ≥ enflurane > isoflurane > > halothane = sevoflurane
68
How does an exothermic reaction leading to fires and explosions occur with anesthetic gases?
* 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*
69
Which anesthetic gas should be avoided with desiccated strong base absorbents?
* Sevoflurane
70
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
