E2- Breathing System I Flashcards
1
Q
functions/definitions of breathing system
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 ,, + monitors the volume
2
Q
Resistance
- When gas passes through tube – pressure at _______ LOWER than _____
- What part has highest pressure?
- A drop is pressure is a measure of _______.
- P2 = pressure at ____ + P1 = pressure at ____
A
- outlet lower than inlet
- beginning of tube
- resistance
- beginning + end
3
Q
Resistance varies with ________? What can also change resistance?
A
- volume of gas passign through per unit time
- flow types (laminar / turbulent)
4
Q
- Laminar flow is ____ and ______.
- Particles move _____ to tube walls.
- Where is the flow fastest?
- What Law relates to laminar?
A
- smooth + orderly
- parallel
- center
- Poiseuilles law
5
Q
What is A, B, C, D, E, F
A
- A = laminar
- B = generalized turbulent
- C = localized turbulent d/t sharp turn or narrowing
6
Q
- Turbulent flow lines are not parallel + composed of what?
- Where is turbulent flow fastest?
A
- Eddies = particles moving in opposite direction of general flow
- SAME across diameter of tube
7
Q
Generalized vs. Localized Turbulent flow
A
- Generalized
o When flow of gas through tube exceeds critical flow rate - Localized
o Gas flow rate below critical flow rate … but encounters constrictions, curves, or valves
8
Q
- To minimize resistance … gas-conducting pathways should have ??
A
- minimal length
- maximal internal diameter
- without sharp curves or sudden changes in diameter
9
Q
What is the significance of resistance?
A
- imposes strain with ventilatory modes when pt must do work
- change parallels change in WOB
- watch flow volume loops!
10
Q
What causes more resistance than breathing system?
A
ETT
11
Q
- What is compliance?
- Measures _____ (mL/cmH2O)
- What does compliance help determine?
A
- Ratio of change in volume to change in pressure - V/P
- distensibility
- Vt
12
Q
What are the 2 most distensible components?
A
Reservoir bag + breathing tubing
13
Q
What is rebreathing?
What 3 things is it influenced by?
A
- To inhale previously **inspired gases ** – CO2 may or may not be removed
- Fresh gas flow
- Dead space
- Breathing system design
14
Q
- Amt of rebreathing varies _____ with total FGF.
- What FGF is there NO rebreathing?
- At what FGF is there rebreathing ?
- What is the function of exhaled gases in rebreathing?
A
- inversely
- FGF/min = or > Vm – NO rebreathing
- FGF < Vm – YES rebreathing
- make up required volume
15
Q
Types of dead space
- Apparatus? What is it + what decreases it
- Physiologic
- Anatomical
- Alveolar
A
- Apparatus – vol in breathing system by gases rebreathed without change in composition
Decreased by having inspiratory + expiratory limb separation CLOSE to patient as possible
Anything distal to Y piece (elbow, ett) - anatomic + alveolar
- conducting airways - adds H2O vapor
- vol alveoli ventilated but not perfused
16
Q
- What does rebreathing reduce?
- Rebreathing causes 3 altered inspired gas tensions
A
- heat + moisture loss from pt
- reduce inspired oxygen tension
- Inhaled anesthetics (induction = increase ,, emergence = decrease)
- CO2 (increase)
17
Q
What makes up FGF?
A
Air, nitrous, oxygen
NOT anesthetic gases bc they’re a pressure
18
Q
6 desirable characteristics of a breathing circuit?
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
19
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
20
Q
In closed circuit, amt of rebreathing depends on ____?
A
FGF
21
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
22
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
23
Q
- The facemask needs to fit between the _____________ and in the groove between the ___________ and _______.
- Facemask is clear + what allows it to seal the face?
A
- interpupillary line
- mental process
- alveolar ridge
pneumatic cushion
24
Q
The facemask will connect to the Y-piece/connector, how big is the female connection?
A
- 22 mm
25
A fitting that joins together 2 or more components.
* Connectors/ Adapters
26
What are 3 advantages of connectors and adaptors?
*** Extends distanc**e b/w patient and breathing system
*** Change angle** of the connection
* Allow more **flexibility**/ less kinking (The accordion will give you the most flexibility)
27
What are 3 disadvantages of connectors and adaptors?
* Increased **resistance**
* Increased **dead space**
* Additional locations for **disconnections**
28
How long is the breathing tubing?
What is the internal volume of the breathing tubing?
* 1 meter in length
* 400-500 mL for each meter in length
29
Describe the flow in the corrugated breathing tubing.
* ALWAYS **Turbulent** Flow
30
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 to patient d/t unidirectional valves**
31
Pressure check the circuit before use. What value should this be?
* 30 cm H2O
32
With a normal tidal volume. How much air is in the anatomical deadspace?
* 150 mL
*That is why we deliver at least 300 mL of tidal volume in simulation for adequate ventilation.*
33
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.*
34
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
35
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**
36
Proper valve placement and functioning prevents any part of the circle system from contributing to _________.
* Apparatus Dead Space
| If valve no worky = appartus dead space = TEST Q!
37
What composes the apparatus dead space?
* Distal limb of Y-connector
* Tube/mask/LMA
38
The unidirectional valves are located near what 3 parts of breathing system?
* CO2 absorber canister
* Fresh gas inflow site
* APL Valve
39
What are 5 requirements of unidirectional valves?
* 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**
40
How much volume is in a traditional reservoir bag? Range?
* 3 L
*Can range from **0.5 to 6 L***
41
All reservoir bags must have _____ mm female connector on the neck.
* 22 mm
42
reservoir bags must adhere to pressure standards
* minimum pressure of approximately ______ cm H2O
* maximum pressure of approximately ____ cm H2O
* plastic bags have ____ the distending pressure of rubber bags
* 30 cm H2O (minimum)
* *40 - 60 cm H2O (maximum)
* 2x
## Footnote
Although most bags adhere to these standards, some latex-free bags have exceeded the upper pressure limit.
43
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*
44
What are 5 functions of the reservoir/breathing bag?
(1) **Reservoir** for anesthetic gases/oxygen
(2) A means of delivering **manual** ventilation
(3) assisting **spontaneous** breathing
(3) Serving as a **v****isual / tactile monitor** a patient’s spontaneous breathing efforts
*estimates volume of ventilation
(4) Partially **protecting pt from excessive positive pressure** in the breathing system.
45
What is another name for the Gas Inflow site?
* Fresh gas inlet
46
Where is the preferred location of the fresh gas inflow site?
* Between CO2 absorbent + inspiratory valve
47
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.*
48
What is the downside of having the fresh gas inflow valve so close to the CO2 absorbent?
* Fresh gas can dry out the absorbent
49
What is the Adjustable Pressure-Limiting Valve (APL) / Pop-off Valve?
* * “Pop-off valve”
* * Permits **gas to leave circuit **
* **Closed** = gas doesn’t leave .. stays in circuit = higher pressure to open
* **Open** = gas leave … to scavenger
Dome valve loaded by a spring + screw cap
* User-adjustable
* **Controls pressure** in breathing system
* Releases **gases to scavenging system**
50
Clockwise motion of the APL valve will ______ pressure.
* Increase
| clockwise on clock increases #s
51
Counterclockwise motion of the APL valve will ______ pressure.
* decrease
52
How many turns does it take for the APL valve to go from fully open to closing fully?
* 1-2 clockwise turn
53
Explain APL Use (chart)
Spotaneous?
Assisted/manual?
54
APL setting during mechanical ventilation?
BYPASSED
55
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
56
Absorbent Chemical Reaction
* Absorbent is a chemical reaction
* **Carbon dioxide + water** = initial reaction
* **Exothermic** reaction that combines CO2 with Ca hydroxide to form calcium carbonate
* **Hydroxides** – interact with CO2 to form exothermic reaction -- exhausting absorbent
* absorbent turns to **carbonates when exhausted** -- color change
57
5 types of absorbents + brand name?
1. Soda Lime = SODASORB
2. Calcium Hydroxide Lime = AMSORB
3. Lithium Hydroxide
4. Litholyme
5. Spira-Lith
58
Name the 4 components of soda lime.
* Calcium hydroxide (80%)
* Sodium hydroxide/ Potassium hydroxide (5%)
* Water (15%)
* Small amount of **silica/clay** - keep from hardening/drying out
59
Because CO2 does not react quickly with calcium hydroxide, what are the catalysts required to speed up the reaction?
* Sodium hydroxide
* Potassium hydroxide
60
How do you know when the soda lime has been fully exhausted?
* It turns from white to purple
*** All hydroxides have become carbonates**
61
Soda lime can absorb _____% of its weight in CO2.
100 grams of soda lime can absorb _______ L of CO2.
* 19%
* 26 L
62
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%)
63
What is the drawback of Soda Lime? Cause?
* Compound A formation (found in rats) = SEVO
* Carbon Monoxide formation = DES
* Destruction of inhaled gases
Caused by Na/K strong bases
## Footnote
Calcium hydroxide lime decreases Compound A formation, CO formation, and destruction of inhaled gases.
64
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
65
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
66
****Name this Absorbent:
- Anhydrous LiOH powder, hydrated polymer **sheets**
- No activators/strong bases
- ↓ Temperature production
- Cheap
- **No color indicator**, no color change
* Spira-Lith
S = sheets
67
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*
68
Which of the following absorbent is composed of 95% Lithium Hydroxide?
- Soda Lime
- Litholyme
- Spiralith
* Spiralith has 95% LiOH
69
Which of the following absorbent has color indication?
- Soda Lime
- Litholyme
- Spiralith
* Soda Lime
* Litholyme
70
What is the most common dye for absorbent indicators?
* Ethyl Violet
*Ethyl violet causes soda lime to turn from white to purple when exhausted*
71
What color will ethyl orange and cresyl yellow turn when exhausted?
* Yellow
72
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) - **more acidic**
* blue violet (purple)
73
At what pH is the soda lime exhausted + experience color change?
< 10.3
| When im exhausted, im an ass (acidic)
74
When absorbent is exposed to bright fluroscent light for a period, what can happen?
* Bleaching
* Absorbent indicator does not work as well
75
Absorbents have high reliability indicating CO2 rebreathing, but what is the gold standard? Why?
* Capnometry
* bc regeneration can occur + color fades
76
CO absorbent granules are measured in what units? What is normal?
* Mesh Size
* **4-8** mesh size (most optimal for CO2 absorbers)
77
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.
78
The size and shape of the absorptive granules are intended to maximize ________ while minimizing ________ .
* Maximize Absorption
* Minimize resistance to airflow
79
Roughly 50% of volume CO2 canister will be composed of _______.
* gas
80
What factors can decrease the efficiency of CO2 absorption?
*** Excess water in the canister** (change canister if you see liquid)
* Decrease surface area
81
Small passageways that allow gas to flow through low-resistance areas, decreasing functional absorptive capacity.
* Channeling
82
What are 5 ways to minimize channeling?
1. * Circular **baffles** (flow-directing panels)
1. * Placement for **vertical** flow
1. * Permanent **mounting**
1. * **Prepackaged** cylinders
1. * Avoiding **overly tight **packing
83
The decomposition of sevoflurane will form this substance.
* Compound A
## Footnote
2-fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether
84
Compound A causes what toxicity in rats?
* Nephrotoxic in rats
* Possible in humans
85
Compound A formation occurs with 5:
* Low FGF (1-2 L/min)
* Increased absorbent temperature
* Higher inspired sevoflurane concentrations (1.5 to 2 MAC)
* Dehydrated absorbent
* Absorbent containing NaOH or KOH
86
Carbon monoxide can occur due to what factor?
* **Dry absorbent** + leaving FGF on
* 'Monday, 1st case'- gas left on over the weekend
1. * Increased **Temperature**
1. * Increased **Concentration** of anesthetic gases
1. *** Low FGF** rate
1. *** Strong base **absorbents (KOH or NaOH)
87
Rank the order of anesthetic gases from highest to lowest level of carbon monoxide formation.
**Desflurane** ≥ enflurane > isoflurane > > halothane = sevoflurane
88
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),
oxygen or nitrous rich gases w/in the absorber all provide basis for combustion*
89
Which anesthetic gas should be avoided with desiccated strong base absorbents?
What temps can absorbers reach?
What else avoided?
* Sevoflurane
* >200 C
* strong bases ,, desiccated
90
Anesthesia Patient Safety Foundation = 6 Recommendations
* ALL gas flows + vaporizers **turned off** after each case
* 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
