E2- Breathing Systems II Flashcards
1
Q
What is a Mapleson Circuit?
A
- The Mapleson Circuit Systems are used for the delivery of oxygen and anesthetic agents and the removal of carbon dioxide
2
Q
How many types of Mapleson Circuits are there? Mneumonic?
A
- Six Types (A → F)
3
Q
What are the components of the Mapleson Circuit?
A
- Patient connection/Facemask - Patient end
- Reservoir bag - operator end
- Corrugated tubing
- APL valve - variable positioning
- Fresh gas inlet - variable positioning
4
Q
What 3 components are absent in all Mapleson Circuit Systems?
A
- CO2 absorber
- Unidirectional Valves
- Separate Inspiratory and Expiratory Limbs
5
Q
What are 2 other names for the Mapleson Circuit Systems?
A
- Carbon Dioxide Washout Circuits
- Flow-controlled Breathing Systems
6
Q
How does the Mapleson Circuit System prevent rebreathing without a CO2 absorber?
A
- FGF must be significantly greater than minute ventilation to “washout” the CO2.
7
Q
What is another name for Mapleson A?
A
- Magill’s System
8
Q
Where does fresh gas flow enter in the Mapleson A circuit?
Where is the APL valve located in the Mapleson A circuit?
A
- FGF = near reservoir bag
- APL valve = patient end
9
Q
Of all the systems, what is Mapleson A best at?
What is Mapleson A the worst at?
A
- Best efficiency of all systems for spontaneous ventilation
- Worst efficiency of systems for controlled ventilation
10
Q
Mapleson A
Spontaneous :: prevent rebreathing?
Controlled ventilation : rebreathing occurs unless Vm greater than ______ ?
A
FGF must be greater than or equal to Vm
20 L/min
11
Q
Mapleson A Circuit:
What is vented out from the APL valve in spontaneous ventilation during expiration?
A
- Dead space gas (yellow)
- Alveolar gas (red)
12
Q
Mapleson A Circuit:
What is vented out from the APL valve in controlled ventilation during expiration?
A
- APL valve does not open
13
Q
Mapleson A Circuit:
What is vented out from the APL valve in controlled ventilation during inspiration?
A
- Mostly fresh gas (blue)
- Some alveolar gas (red)
- Increase the risk of rebreathing alveolar gas (red)
14
Q
Where are the APL Valve and Fresh gas inlet located in the Mapleson B Circuit?
Where is the reservoir bag?
A
- APL and FG inlet located near the patient
- Reservoir bag = end of system
15
Q
Why is the Mapleson B Circuit considered inefficient and obsolete?
A
- FGF is vented through APL during exhalation = Inefficient
- Blue (FGF)
- Red (alveolar gas)
16
Q
FGF should be ______ times the minute volume during spontaneous and controlled ventilation to prevent rebreathing in the Mapleson B circuit.
A
- FGF should be 2x minute volume
17
Q
Where are the APL Valve and Fresh gas inlet located in the Mapleson C Circuit?
A
- APL and FGF located near patient
18
Q
Mapleson C is identical to Mapleson B except for what specific difference?
A
- Omission of the corrugated tubing
19
Q
Mapleson C is almost as efficient as ____ .
What is it based on?
A
A
based on expiratoy pause (longer pause = less efficient)
bc losing to atmosphere
20
Q
How much FGF is needed for the Mapleson C circuit to prevent rebreathing?
A
- FGF 2x minute volume to maintain efficiency
21
Q
When are Mapleson’s C circuits usually used?
A
- EmergenCy resuscitation
22
Q
Where are the APL Valve and Fresh gas inlet located in the Mapleson D Circuit?
A
- APL valve= near reservoir bag
- FGF inlet = near patient
23
Q
Which circuits are known to have “T-modifications” or are known as the “T-group”?
What makes up 3 way T-Piece?
A
- Mapleson D
- Mapleson E
- Mapleson F
- pt connection ,, fresh gas inlet ,, corrugated tubing
24
Q
Which circuit is the MOST efficient for controlled ventilation?
A
- Mapleson D
25
What kind of valve can be added to Mapleson D circuits?
* PEEP Valve
26
FGF rate should be _______ times minute ventilation in Mapleson D circuits.
* 2 to 2.5 times
27
What circuit is a modification of Mapleson D?
What is modified?
* Bain Circuit
* Fresh gas inlet through a narrow **inner tube (coaxial)**
* Disconnection / kinking = problem if don't realize it
28
What is another name for Mapleson E?
* AryE's T-piece
29
What is missing in the Mapleson E circuit?
* No reservoir bag
* No APL valve
30
Where does FGF enter the Mapleson E circuit?
* Near the patient
31
What forms the reservoir if there is no Reservoir Bag on the Mapleson E circuit?
* Corrugated Tubing
32
What 3 patients is the Mapleson E circuit designated for?
* Spontaneous breathing patients to deliver O2
* Pediatrics - *bc decreased resistance d/t no APL*
* transport from OR
33
How would you increase the pressure of the Mapleson E circuit without an APL valve?
* Occluding / pinching end of corrugated tubing
34
Mapleson F is a modified mapleson __.
What is the modification for the Mapleson F circuit called + what is it adding?
* E
* Jackson Reese Modification
* Resorvoir bag added
## Footnote
*Guys named Jackson + Reese think they're **F**unny*
35
What is missing in the Mapleson F circuit?
* No APL Valve
36
Where is the FGF inlet on the Mapleson F circuit?
Where is the Reservoir Bag on the Mapleson F Circuit?
Is there anything special about the Reservoir Bag on the Mapleson F Circuit.
* FGF inlet = near patient
* Reservoir Bag = operator side
* Reservoir Bag is open (hole)
37
How can pressure be generated in the Mapleson F Circuit?
* reservoir bag hole occluded by operator’s hand to control bag distension + pressure
38
What does the reservoir bag on the Mapleson F circuit allow?
* Allow for easy tactile and visual monitoring of the patient’s respiratory effort.
39
What is the FGF rate for the Mapleson F circuit?
* 2-2.5 x minute ventilation
40
Improved rebreathing efficiency is due to what factor?
* Location of APL valve relative to FGF
*FGF located **near patients** will experience less rebreathing.*
41
Which Mapleson Circuits will experience significant amounts of fresh gas **vented** through APL at end-expiration?
* Mapleson B
* Mapleson C
42
Which systems have FGF drives that drive exhaled alveolar gas away from pt?
* Mapleson D
* Mapleson E
* Mapleson F
43
Rank the groupings of the Mapleson Circuit in efficiency for **spontaneous** ventilation.
Mapleson A > DFE > **CB**
44
Rank the groupings of the Mapleson Circuit in efficiency for **controlled** ventilation.
Mapleson DFE > **BC** > A
45
What are the 5 advantages of the Mapleson Circuit?
* Simple, inexpensive, and lightweight
* Changes in FGF composition result in **rapid changes** in the circuit
*** Low resistanc**e to gas flow
* **No toxic products **d/t lack of CO2 absorbent
*** No degradation** w/ VAs
46
What are the 4 disadvantages of the Mapleson Circuit?
* Require high FGF (can be wasteful + have full O2 tank)
* Conservation of heat + humidity = less efficient
* Scavenging challenging (**Except Mapleson D**)
* Not suitable for patients with **MH **(May not be possible to increase FGF to remove excess CO2)
47
Circle System: Spontaneous Inspiration
(Allows for circular and unidirectional flow)
Ventilator ???
Ventilator NOT ON !! Bc spontaneous
48
Circle System: Spontaneous Expiration
49
During what respiratory cycle phase will the CO2 absorber experience the highest potential of drying out?
* End of expiratory cycle d/t the fresh gas flow traveling retrograde because the inspiratory valve is closed.
50
For the Circle System, the extent of rebreathing and conservation of exhaled gases depends on _______.
* FGF
* Higher FGF = less rebreathing + greater waste gas
51
3 Rules to prevent rebreathing:
* **Unidirectional valve** = must be located between **pt + reservoir bag** on **both** the inspiratory + expiratory limbs
* **fresh gas inflow**= CANNOT enter circuit between **expiratory valve and pt**
* **APL valve**= CANNOT be located between the **pt and the inspiratory valve** (You will lose FGF)
52
What kind of circle systems are seen with contemporary/modern systems?
Will there be rebreathing that occurs?
Wast flow vented through?
* **Semi-closed** circle system
* **Partial** rebreathing occurs
* some waste flow is vented through **APL or waste gas valve** of the ventilator
53
What is an example of a semi-closed circle system?
* Low-flow anesthesia (what we do)
* FGF < Vm
54
What percentage of expired gas is rebreathed after CO2 removal during low-flow anesthesia?
* 50%
55
What kind of circle systems are considered non-rebreathing? Why?
* Semi-open Circle System
* **Higher FGF** = minimal rebreathing + more venting of waste gas
56
What is an example of a semi-open circle system?
* Post-Op + ICU vents
* Scuba gear
* *Mapleson Circuits**
57
In what Circle System will the oxygen inflow rate exactly **match the metabolic demand**? Rebreathing is ________ .
What is added to circuit in liquid form ?
* Closed Circle System
* Rebreathing is **complete**; no waste gas vented
* **Volatiles** = circuit in liquid form or through vaporizer
58
Example of a closed circle system.
* **Low**- and minimal-flow anesthesia
* Impractical for use – rarely done
* **OBSOLETE**
59
3 Advantages of Low-Flow Anesthesia
* Decreased use of volatiles
* Improved temperature + humidity control
* Reduced environmental pollution
60
3 Disadvantages of Low-Flow Anesthesia
* Difficulty rapidly **adjusting** the anesthetic depth *(why we overpressurize)*
* Possibility of accumulating **unwanted exhaled gases** *( ex: CO, acetone, methane)*
* VA **degradation** by-products *(ex: CO, compound A)*
61
5 Advantages of Circle System
* **Low FGF** can be used
* Elimination of **CO2**
* Relatively **stable inspired gas** concentration
* **Conservation** of moisture/heat/gases
* Prevention of **OR pollution**
62
4 Disadvantages of Circle System
* Complex design
* CO or compound A
* May **compromise Vt** during controlled ventilation **
* **ASA Closed Claims Project **(Misconnections/ *disconnections*) **
63
6 Components of the Self-Inflating Manual Resuscitators (AMBU bags)
* Self-expanding Bag
* T-shaped non-rebreathing Valve
* Bag Inlet Valve
* Pop-off valve
* Excess oxygen venting valve
* Oxygen reservoir
64
Use of Self-Inflating Manual Resuscitators
* Hand ventilation in absence of oxygen / air source
* Pt transport
* CPR
* Emergency back-up
* **ALWAYS** have set up with machine
65
4 Hazards of Self-Inflating Manual Resuscitators
* Barotrauma
* gastric insufflation
* Significant variation of :: **Vt, PIP, + PEEP**
* **Nonrebreathing valves** = generate resistance
66
What is the purpose of bacteria filters? What 3 diseases
* prevent contamination / infection by **airborne** diseases
* TB, COVID, PUI
* preventing **contamination of anesthesia machine** from airborne diseases
67
Where are bacteria filters placed on the breathing circuit?
***** Placed on the **expiratory limb**
68
Bacteria Filters - Small-pore
Due to the small-pore compact matrix, there will be ________ airflow resistance.
The small-pore compact matrix is also _______ to create a larger ________.
* high
*pleated -- surface area
69
# Bacterial Filters
Larger Pore size = _____ resistance + ______ surface areas (compared to small pore)
Less ,, smaller
70
Bacterial filters = permanent electrical _____
polarity
71
Hydrophobic Bacterial Filters will prevent _____.
* water penetration
72
When the Hydrophobic Bacterial Filters become wet, it will increase ________ and decrease __________.
* Increase resistance
* Decrease efficiency
73
Where are combination filters (filter + HME) placed in the breathing circuit?
* Placed at the Y-piece
*This will cause a **barrier** to the inspiratory and expiratory limb, increasing resistance.*
74
2 Complication of Bacterial Filters.
*. **Obstruction** (Sputum, edema fluid, nebulized aerosols, or malpositioning)
* **Leakage** of the housing of the gas line filter (best to **monitor ETCO2 before the filter)**
75
When is an inspiratory limb filter recommended? Airway filter?
* When machine may be been **contaminated by previous **patient
* Airway = **COVID + PUI **pts
* Expiratory limb = preferred for ALL
## Footnote
**Expiratory limb filter recommended for ALL patients.**
76
Humidity
* Amount of water vapor in a gas
77
Absolute humidity
***** Mass of water vapor present in gas in **mg H2O/L** of gas
* 34-38 mg of H2O/ L gas in mid trachea
78
Relative Humidity
* **Percent saturation**; the amount of water vapor at a particular temp
79
Water Vapor Pressure
The pressure exerted by water vapor in a gas mixture.
80
Maximal contact of inspired gas occurs with the large mucosal surface area in the _______.
* Nasal Cavity
81
Most of heating and humidification of inspired gas has occurred by _______.
At ___ degrees with absolute humidity of __________ + a relative humidity of _______%
* Mid-trachea
* 34 degrees -- 34-38 mg/L -- 95-100%
82
Where is the Isothermic Saturation Boundry ? What 3 things does it depend on?
* at carina
* vol gas inhaled ,, humidity ,, temp
82
* As gas travels _____ it is heated to body temperature.
* At 37 degrees = Absolute humidity of ___ mg/L + relative humidity of ____%
* distally
* 44 mg/L + 100%
83
What are the effects of cold ambient temperatures regarding humidification in the airway?
* Little capacity to hold water vapor
* Low absolute humidity
* Upper airway **transfers large amounts **of heat and moisture
84
Cool inspired gases may trigger _________.
* Bronchospasm
85
8 Effects of underhumidifaction.
* Damage to the respiratory tract
* Secretions thicken
* **Ciliary function** decreases
* **Surfactant activit**y is impaired
* Mucosa susceptible to injury
* **Body heat loss** (longer cases)
* Tracheal tube **obstruction** (thicken secretions)
* Increases **resistance and work of breathing** from thickened secretions
86
Effects of overhumidifaction.
* Condensation of water in the airway
* Reduced mucosal viscosity and risk of **water intoxication **
* **Inefficient mucociliary** transport
* Airway resistance, risk of **pulmonary infection, surfactant dilution, atelectasis, **and V/Q mismatch
* **Obstruction** to sensors - *ETCO2 sample line obstruction*
87
Functions of humidification devices.
reproduce normal physiologic conditions in ***lower*** respiratory tract
88
Types of humidification devices
* Heat and moisture exchanger (HME- **Passive** and can be modified to have a filter
* Heated humidifiers- **Active**
89
Functions of Heat and Moisture Exchanger (HME)
* **Conserves** some exhaled heat and water + **returns** to pt
* **Bacterial/viral** filtration and prevention of **inhalation of small particles** (***HMEF***)
90
Where is the placement of an HME?
* Placed close to the pt, between **Y piece and proximal end of ETT** or LMA
91
What happens to the ETCO2 reading if the sensor is placed *AFTER* the HME?
* Low ETCO2 reading
92
What does the HME do to the resistance and dead space in the circuit?
* ↑ resistance
* ↑ dead space
93
What happens to the efficiency of the HME with a **large tidal volume**?
* ↓ Efficiency
* **Hydrophobic** models
94
What is a Hygroscopic HME?
* Paper or other fiber barrier coated with **moisture-retaining chemicals**
* May have some electrostatic properties
* **Absorb** water in exhalation and **release** it in inspiration
95
What is Hygroscopic HME most efficient at?
* Most efficient at retaining **heat and moisture**
96
What is the drawback of Hygroscopic HME?
* Prone to becoming saturated
* Increased inspiratory/expiratory resistance
* Reduced heat and moisture retention efficiency
97
What is a Hydrophobic HME?
What is a Hydrophobic HME efficient at?
* **Pleated** hydrophobic membrane with small pores
* More efficient filters of **pathogens**
98
Devices used to increase the humidity in O2 supplied to pts
* Humidifiers
99
Who will benefit from humidifiers? 3
* Neonates
* Pts with respiratory secretions
* Hypothermic pts
100
What are the different ways a humidifier can pass a stream of gas?
* Bubble or cascade
* Pass-over
* Counter-flow
* Inline
101
Where are the humidifiers placed in the breathing circuit? Heated humidifer placed?
* Placed in the **inspiratory limb downstream of unidirectional valve**
* Heated humidifiers = **NOT** in expiratory limb
102
Describe the Bubble/Cascade humidifier.
* Bubble humidifiers are a type of active humidifier that work by passing the fresh gas flow down a tube through a water reservoir causing the gas to “bubble.” Water vapor is absorbed as the bubbles pass through the reservoir
103
Describe the Passover humidifier.
What are the two varients of this humidifier?
* Passover humidifiers work by passing gas over a heated water reservoir.
* There are two variants: one that utilizes a wick and one that utilizes a hydrophobic membrane.
104
Describe the Counter-flow humidifier.
* Water is heated outside the vaporizer in counter-flow humidifiers.
* After the water is heated, it is pumped to the top of the humidifier, entering small diameter pores and running down a large surface area.
* Gas, flowing in the opposite direction, is warmed and humidified to body temperature.
105
Describe the inline vaporizer humidifier.
* Inline vaporizer humidifiers utilize a plastic capsule that injects water vapor and heat directly into the inspiratory limb of the ventilator circuit just before the patient's y-piece.
106
Most unheated humidifiers are disposable that use the bubble-through humidifier that increases the humidity in oxygen supplied to patients via a face mask or nasal cannula. They cannot deliver more than about ______ mg H2O/L.
* 9 mg H2O/L
107
Condensation has what effect on tidal volume?
* Decrease delivered Vt
108
Consideration for **water traps**.
* Change frequently to decrease the risk of contamination and infection
109
Advantages of Humidifiers
* Can deliver saturated gas at body temp or higher
* **More effective than HME** in longer cases in preventing hypothermia
110
Disadvantages of Humidifiers
* Bulky
* Potential **electrical malfunction and/or thermal injury**
* Contamination, and cleaning issues
* Higher **cost** than HME
*** Water aspiration** risk
