Exam 2 Breathing Systems: Part 2 (6/24/24) Flashcards
(92 cards)
1
Q
Why are Mapleson Circuits thought to be mostly obsolete?
A
They do not have a CO2 absorber
2
Q
Components of Mapleson Circuits:
A
- Reservoir Bag (Not all of them)
- Corrugated Tubing (Not all of them)
- APL Valve (Not all of them)
- Fresh Gas Inlet
- Patient Connection
3
Q
What is missing in the Mapleson Circuits? (3)
A
CO2 Absorbers
Unidirectional valves
Seperate inspiratory/expiratory limbs
4
Q
What determines how much rebreathing occurs in the Mapleson Circuits?
A
Fresh Gas Flow
5
Q
How would we know if CO2 is being rebreathed while using a Mapleson Circuit?
A
Monitor ETCO2
6
Q
Location of FGF entrance and APL valve in a Mapleson A (Magill’s System)?
A
FGF enters near reservoir bag (opposite of the pt.)
APL is near the pt.
7
Q
In regard to efficiency, what kind of ventilation is the Mapleson A circuit the best and worst at?
A
Best: Spontaneous
Worst: Controlled
8
Q
Rebreathing will occur while using a Mapleson A during controlled ventilation unless the patient’s FGF minute ventilation is greater than ___.
A
> 20 L/min
9
Q
Location of APL valve, FGF inlet and reservoir bag in a Mapleson B?
A
APL anf FGF inlet are near pt
Reservoir Bag is at the end of the system
10
Q
The Mapleson C is almost identical to the Mapleson B, but the ____ is omitted.
A
Corrugated Tubing
11
Q
Compare the efficiency of the Mapleson C to Mapleson A with spontaneous ventilation:
How does the expiratory pause change the efficiency?
A
Mapleson C is almost as efficient as Mapleson A.
If expiratory pause is longer, this circuit becomes less efficient
12
Q
The Mapleson C closely resembles a ___.
A
Ambu Bag
Used for emergency resuscitation
13
Q
Location of the Reservoir Bag, APL and FGF inlet in a Mapleson D?
A
Reservoir at the end
APL near reservoir
FGF inlet near pt.
14
Q
This Mapleson circuit does not have a reservoir bag or an APL valve:
A
Mapleson E (Ayre’s T-Piece)
15
Q
The Mapleson E circuit is preferred in this population:
Why?
A
Preferred in Pediatrics:
There is a decreased amount of resistance
16
Q
What is the modification made to the Mapleson E that makes it a Mapleson F (Jackson Rees)?
A
Addition of a Reservoir bag with a hole at the end
17
Q
Select the 2 correct systems:
Significant amounts of fresh gas is vented through pop-off at end expiration :
Mapleson A
Mapleson B
Mapleson C
Mapleson D
Mapleson E
Mapleson F
A
Mapleson B
Mapleson C
18
Q
Select the 3 correct systems:
FGF drives exhaled alveolar gas away from pt:
Mapleson A
Mapleson B
Mapleson C
Mapleson D
Mapleson E
Mapleson F
A
Mapleson D
Mapleson E
Mapleson F
19
Q
Rank the efficiency of the Mapleson Circuits from Most efficient to least efficient for spontaneous ventilation:
A
- Mapleson A
- Mapleson D, F, E
- Mapleson C, B
20
Q
Rank the Mapleson circuits from most efficient to least efficient for controlled ventilation:
A
- Mapleson D, F, E
- Mapleson C, B
- Mapleson A
21
Q
Which Mapleson circuit is termed “Obsolete”?
A
Mapleson B
22
Q
This Mapleson Circuit is the most efficient system for controlled Ventilation:
A
Mapleson D
23
Q
This Mapleson circuit is used in spontaneously breathing pts to deliver O2:
A
Mapleson E
24
Q
Advantages of Mapleson Circuits:
A
- Simple, inexpensive, and lightweight
- Changes in FGF composition result in rapid changes in the circuit
- Low resistance to gas flow
- No toxic products d/t lack of CO2 absorbent
- No degradation w/ Volatiles
25
A couple disadvantages to using Mapleson circuits is that they require ___ and are not suitable for patients with ___.
Require **high FGF**
Not suitable for **Malignant Hyperthermia** patients
26
All of the Mapleson circuits have a challenge with scavenging except for ___.
Mapleson D
27
# Rules to prevent rebreathing in a Circle System
Where must the unidirectional valves be located on both the inspiratory and expiratory limbs?
Between the patient and the reservoir bag
28
# Rules to prevent rebreathing in a Circle System
Where must the Fresh gas flow inlet NOT enter the circuit at?
Between the patient and the **Expiratory Valve**
29
# Rules to prevent rebreathing in a Circle System
True or False:
The APL valve must be located between the pt and the inspiratory valve
False:
APL valve **cannot** be located between the pt and the inspiratory valve
30
In a circle system these 2 things are dependent upon the Fresh Gas Flow:
The extent of rebreathing
Conservation of exhaled gases
31
Describe the function of a circle system in a "Semi-Closed" circuit:
"Contemporary system"
Partial rebreathing occurs but some waste flow is vented through APL or waste gas valve of ventilator
(Semi-wasted/Semi-rebreathed.)
32
Example of a semi-closed circuit for a circle system: (Type of Anesthesia)
What does this mean? (2)
Low Flow Anesthesia:
* FGF is less than Minute ventilation
* 50% of expired gas is rebreathed after CO2 removal
33
Describe the function of a circle system in a "Semi-Open" circuit: (3)
Non-rebreathing systems
Higher FGF with minimal rebreathing and more venting of waste gas
34
Examples of semi-open circuits for a circle system: (3)
* Post-Op/ICU Vents
* Scuba Gear
35
Things to remember about a "Closed" circle system: (5)
* Use of Low/minimal Flows
* Complete rebreathing
* No waste gas is vented out
* Obsolete
* Rate of oxygen inflow matches patient's metabolic demand (dropper method)
36
Advantages to low flow anesthesia:
* Decreased use of VAs
* Improved temperature and humidity control
* Reduced environmental pollution
Low-Flow =
1. Lower VA, 2. Lower heat loss 3. Lower Pollution
37
Disadvantages to low flow anesthesia:
* Difficulty in rapidly adjusting anesthetic depth
* Possibility of accumulating unwanted exhaled gases ( ex: CO, acetone, methane)
* VA degradation by-products (ex: CO, compound A)
38
Advantages of Circle Systems: (5)
* Low FGF can be used (and High FGF).
* Elimination of CO2 (Scrubber + APL + Scavenging System)
* Relatively stable inspired gas concentration (Gases are dialed in)
* Conservation of moisture/heat/gases (circle so humidity is maintained)
* Prevention of OR pollution (not open to environment)
39
Disadvantages of Circle Systems: (4)
* Complex design
* CO or compound A
* May compromise Vt during controlled ventilation (D/t Corrugated tubing distinction)
* ASA Closed Claims Project
40
The number 1 problem (according to the ASA Closed claims project) associated with use of a circle system had to do with ___.
Misconnections or disconnections
41
Components of Self-Inflating Manual Resuscitators or "Ambu-bags": (6)
* Self-expanding Bag
* T-shaped non-rebreathing Valve
* Bag Inlet Valve
* Pop-off valve
* Excess oxygen venting valve
* Oxygen reservoir
BOPETS
42
Important uses of Self-Inflating Manual Resuscitators: (4)
* CPR
* Transport
* Hand ventilation in the absence of an oxygen or air source
* Emergency Back-Up
43
Hazards associated with the use of Self-Inflating Manual Resuscitators: (3)
* Barotrauma or gastric insufflation
* Significant variation of tidal volume, PIP, and PEEP
* Nonrebreathing valves generate resistance
44
Bacterial Filters are effective at preventing what?
Where should they be placed?
Effective at preventing contamination of the anesthesia machine from airborne diseases (TB, Covid, PUI)
Placed on the Expiratory Limb
45
What does PUI stand for?
Person Under Investigation
46
Different types of Bacterial Filters discussed in lecture: (4+1)
* Small-pore compact Matrix
* Larger pore arrangement; Less Dense
* Hydrophobic
* Combination (Filter + HME)
Permanent electrical polarity; Designed to enhance VanderWaals forces that hold organisms in the matrix.
47
Describe the small-pore compact matrix:
* High Airflow resistance
* **Pleated** = creates a larger surface area
48
Compared to the small-pore compact matrix the larger, less dense pore arrangement has _____ and ____.
Less resistance & Smaller surface area
49
Hydrophobic Bacterial Filters prevent___. They have _____ resistance and _____ efficiency.
Prevent **water penetration**
**Increased** Resistance
**Decreased** efficiency
50
Where should the Combination bacterial filter be placed?
At the Y-Piece
51
What is one thing that can happen that would decrease the efficiency and increase the resistance in any and all of these bacterial filters?
Accumulation/condensation of water, secretions, blood or any liquid.
52
4 things that can obstruct a bacterial filter:
1. Sputum
2. Edema Fluid
3. Nebulized aerosols
4. Malpositioning
53
Per the APSF recommendations, what is the best location for the bacterial filters to be placed?
The Expiratory Limb
54
What is the ONLY time that placement of the bacterial filter on the inspiratory limb is warranted?
Only recommended when the machine may have been contaminated by a previous patient.
55
For Covid positive patients or PUI patient's placement of an ____ is recommended, but is optional for all others.
Airway Filter
56
# Definitions:
Amount of water vapor in a gas:
Humidity
57
# Definitions
Mass of water vapor present in gas in mg H2O/L of gas:
Absolute Humidity
58
# Definitions
Percent saturation; amount of water vapor at a particular temp:
Relative Humidity
59
# Definitions
Pressure exerted by water vapor in a gas mixture:
Water Vapor Pressure
60
Usually, by this point heating and humidification has occurred.
Mid-Trachea
61
A temperature of 34 degrees C, with an absolute humidity of 34-38 mg/L corresponds to what relative humidity?
95%-100% relative humidity
62
An absolute humidity of ___ corresponds to 100% relative humidity.
At what degree C does this also correspond to?
What is this called?
44 mg/L
37 degrees C
Isothermic Saturation Boundary
63
At what anatomical landmark is 100% relative humidity reached?
At the carina
64
What can cool inspired gas possibly trigger?
Bronchospasm
Asthmatics are more likely to have bronchospasm in the Winter.
65
Under-humidification can cause these 3 issues:
1. Damage to Respiratory Tract (Drying out)
2. Body Heat Loss
3. Tracheal Tube Obstruction (ICU: adding liquid to thin out secretions to improve suctioning..)
66
What specific respiratory tract issues can arise with under-humidified inspired gas? (4)
* Thick Secretions
* Decreased Ciliary Function
* Impaired surfactant activity
* Mucosa is susceptible to injury
67
Over-humidification is caused ____ in the airway.
Condensation of Water
68
Complications associated with over-humidification (4)
* 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
69
What do humidification devices aim to do?
To reproduce more normal physiologic conditions in the lower respiratory tract
70
Functions of an HME:
* Conserves some exhaled **heat** and **water** and returns them to the pt
* Bacterial/viral **filtration** and prevention of inhalation of small particles (HMEF)
* **Disposable** with exchange medium enclosed in plastic housing
71
Location of the HME:
Placed close to the pt, between Y piece and proximal end of ETT or LMA
72
Disadvantages to HME use:
* **Low ETCO2** reading (if ETCO2 is placed after the HME)
* Increases **resistance** and **dead space** in circuit
* Efficiency may be reduced with large Vt (unable to humidify larger Vt as efficiently).
Especially in Hydrophobic models (filters?)
73
This type of HME absorbs water in exhalation and release it in inspiration:
Hygroscopic
74
This type of HME has a pleated hydrophobic membrane with small pores:
Hydrophobic
75
This type of HME is a more efficient filter of pathogens
Hydrophobic
76
This type of HME is the most efficient at retaining heat and moisture.
Hygroscopic
77
In which patient population is the use of a humidifier important? (3)
Neonates, pts with difficult respiratory secretions, or hypothermic pts.
78
Various Ways in which humidifiers can pass a stream of gas:
* Bubble or cascade
* Pass-over
* Counter-flow
* Inline
79
Where should humidifiers be placed?
Where should they definitely NOT be placed?
Placed in inspiratory limb downstream of unidirectional valve
Heated humidifiers **should not** be placed in expiratory limb
80
Condensation in the humidifier can decrease ___?
Delivered Tidal Volume
81
These need to be changed frequently to decrease risk of contamination and infection.
Water Traps
82
Advantages to Humidifier use:
* Can deliver saturated gas at body temp or higher
* More effective than HME
83
Disadvantages to Humidifier use: (5)
* Bulky
* Potential electrical malfunction and/or thermal injury
* Contamination, cleaning issues
* Higher cost than HME
* Water aspiration risk
84
Why do we get ETCO2 during esophageal intubation?
Gastric insufflation with Ambubag
85
What are 2 categorical complications that can occur with bacterial filters?
Obstruction
Leakage - at housing/in line filter.
86
What is our natural HME?
Nasal Cavity - maximal contact of inspired gas with large mucosal surface area.
87
At mid-trachea what is the expected temperature, absolute humidity, and relative humidity?
Temp: 34
Absolute Humidity: 34-38mg/L
Relative Humidity: 95-100%
88
What is isothermic saturation boundary?
Absolute Humidity 44mg/L
Relative Humidity. 100%
Location: at the Carina.
89
What is estimated body temperature or the temp of inhaled air at isothermic saturation?
37C
90
Cold Ambient Temperatures such as in the OR have what capacity to hold water vapor/absolute humidity?
1. Little capacity to hold water vapor
2. Low absolute humidity
91
What are 4 ways that underhumidification can cause damage to the respiratory tract?
1. Secretions thicken
2. Ciliary function decreases
3. Surfactant activity is impaired.
4. Mucosa susceptible to injury (Dried out)
92
HME are _____ , and can be modified to have a _______; While Heated humidifiers are ____.
(Heat and Moisture exchanger) are PASSIVE
FILTER
Heated Humidifiers are ACTIVE
