Exam 2 Breathing Systems II [6/24/24] Flashcards
1
Q
What is a Mapleson Circuit used for?
A
- delivery of oxygen and anesthetic agents
- removal of carbon dioxide
S52
2
Q
How many types of Mapleson Circuits are there?
A
- Six Types (A → F)
S52
3
Q
What are the components of the Mapleson Circuit?
A
- Reservoir bag (operator end)
- not all have this
- Corrugated tubing
- not all have this
- APL valve (variable positioning)
- Fresh gas inlet (variable positioning)
- Patient connection/Facemask (Patient end)
S53
4
Q
What components are absent in all Mapleson Circuit Systems?
A
- CO2 absorber
- Unidirectional Valves
- Separate Inspiratory and Expiratory Limbs
S54
5
Q
What is another name for the Mapleson Circuit Systems?
A
- Carbon Dioxide Washout Circuits
- Flow-controlled Breathing Systems
S54
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.
S54- lecture
7
Q
What is another name for Mapleson A?
A
- Magill’s System
S55
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 enters near the reservoir bag (the operator end)
- APL valve located on patient end
S55
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
S55
10
Q
How to prevent rebreathing with Mapleson A?
A
FGF must be ≥ minute volume to prevent rebreathing during spontaneous ventilation
S55
11
Q
In a Mapleson A circuit, rebreathing during controlled ventilation occurs unless minute ventilation is what?
A
- unless minute ventialtion is very high
- more than 20 L/min
S55
normal VE=4-6L, so if 20L/min pt is breathing really fast or Vt is significantly increased. PLEASE CONFIRM
12
Q
Mapleson A Circuit:
What is vented out from the APL valve in spontaneous ventilation during expiration?
A
- Dead space gas (orange)
- Alveolar gas (red)
FGF has to be very high to help vent this off.
S56
13
Q
Mapleson A Circuit:
What is vented out from the APL valve in controlled ventilation during expiration?
A
- APL valve does not open on expiration.
S56 + lecture
14
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)
S56
15
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 at the end of the system
S57
16
Q
Why is the Mapleson B Circuit considered inefficient and obsolete?
A
- Significant fresh gas is vented through APL during exhalation
- Blue (FGF)
- Red (alveolar gas)
S57-58
FGF is right next to the APL, as soon as the pt breaths out & as soon as the FGF comes in, it flows through the APL valve, making this more inefficient.
17
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
S57
18
Q
Where are the APL Valve and Fresh gas inlet located in the Mapleson C Circuit?
A
- APL and FGF located near the patient
S59
19
Q
Mapleson C is identical to Mapleson B except for what specific difference?
A
- Omission of the corrugated tubing
S59
Looks like an ambu bag
20
Q
How much FGF is needed for the Mapleson C circuit to prevent rebreathing?
A
- FGF needs to be 2x minute volume to maintain efficiency
S59
21
Q
When are Mapleson’s C circuits usually used?
A
- Emergency resuscitation
S59
22
Q
What happens with FGF with Mapleson C?
A
- FGF goes in, not losing as much when its vented to APL valve compared to mapleson B
- its based on the expiratory pause [is it better or worse]
S60 Lecture
23
Q
Mapleson D has a 3 way T piece that includes?
A
- pt connection
- fresh gas inlet
- corrugated tuping
S61
24
Q
Where are the reservoir, APL Valve, and Fresh gas inlet located in the Mapleson D Circuit?
A
- Reservoir at the end
- APL valve is located near the reservoir bag
- FGF inlet is located near the patient
S61
25
what can be added to mapleson D?
PEEP valves may be added
| S61
26
Which system is the most efficent system for controlled ventilation?
mapleson D
| S61
27
in Mapleson D FGF is ____x minute ventialtion
FGF 2-2.5x minute ventilation
| S61
28
what is bain modification in mapleson D?
FGF coaxial inside tubing
| S61
29
Which circuits are known to have "T-modifications" or are known as the "T-group"?
* Mapleson D
* Mapleson E
* Mapleson F
| S61, 63, 65
30
What circuit is a modification of Mapleson D?
What is modified?
* Bain Circuit
* Fresh gas flows through a narrow inner tube (coaxial) nested within the outer corrugated tube.
* The central fresh gas tubing enters the corrugated hose near the reservoir bag, but the fresh gas actually empties into the circuit at the patient’s end. Exhaled gases pass down the corrugated hose, around the central tubing, and are vented through the pop-off valve near the reservoir bag.
* Exhaled gases passing down the outer corrugated hose add warmth to the inspired fresh gases by countercurrent heat exchange.
| S61- lecture
31
What is the drawback of the bain circuit?
* disconnection or kinks are not know it bc its inside the corrugated tubing
| S61 Lecture
32
What is happening with mapleson D circuit with spontaneous breathing?
- APL valve is open.
**Inspiration**:
- FGF come in + alveolar gas [pt gets a both]
**Expiration**:
- Some alveolar gas gets vented out via pop off valve.
- Dead space gas might or might not get vented out depending on FGF.
- might stay in the reservoir bag & delivered to the pt when squeezed
| S62- lecture
33
what is happening in mapleson D circuit with assisted breathing?
- Partially closed APL
- If we are increasing the pressure in the system [d/t partially closed APL] when we squeeze on inspiration, the DS gas and alveolar gas can get vented out via the pop off valve
- Depends on how much FGF goes to the reservoir bag.
- Since FGF is towards the the pt end, a lot will go towards the pt.
| S62
34
What is another name for Mapleson E?
* Arye's T-piece
| S63
35
What is missing in the Mapleson E circuit?
* No reservoir bag
* No APL valve
| S63
36
Where does FGF enter the Mapleson E circuit?
* Near the patient
| S63-lecture
37
What forms the reservoir if there is no Reservoir Bag on the Mapleson E circuit?
* Corrugated Tubing atached to the T-piece forms reservoir
| S63
38
What patient population is the Mapleson E circuit designated for? Why?
* Spontaneous breathing pediatric patients to deliver O2
* Age: Less than 5 years
* Weight: Less than 20 kg
* Has decreased resistance in the system bc of no APL valve which is why its preferred in pediatrics.
| S63
39
How would you increase the pressure of the Mapleson E circuit without an APL valve?
* Occluding the end of the corrugated tubing
| S63- lecture
40
What is happening with mapleson E during spontaneous breathing?
- limb is open to the atmosphere.
- great for spontaneous breathing.
| S64 lecture
41
what is happening with mapleson E during controlled breathing?
- can only do controlled by pinching of the end of the tubing.
- will need to pinch, which allows FGF to inflate the lungs, then release the pinch to allow to expire the gases then repeat.
- Closely watch pressures and for chest rise and fall to prevent increases in pressure.
- no way to give extra help without timing it appropriately. Bc we cant read it and say how much pressure is being given.
| S64-lecture
42
What is the other name for the Mapleson F circuit?
* The Jackson Rees Modification (of Mapleson E)
| S65
43
What is missing in the Mapleson F circuit?
What is less likely to develope with this circuit?
* No APL Valve
* Excessive pressure less likely to develope.
| S65
44
* 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 on the operator side
* Reservoir Bag is open (with a hole)
| S65- lecture
45
How can pressure be generated in the Mapleson F Circuit?
* The reservoir bag hole may be occluded by the operator’s hand to control bag distension and pressure or fitted with a pop-off or PEEP valve for more precise control.
| S65- lecture
46
What does the reservoir bag on the Mapleson F circuit allow?
* Allow for easy tactile and visual monitoring of the patient’s respiratory effort.
* Can be used to give breaths
* Can pinch the hole to increase pressure on the breath.
| S65- lecture
47
What is the FGF rate for the Mapleson F circuit?
* 2-2.5 x minute ventilation
| S65
48
What is happening in mapleson F circuit?
- DS gas goes to the reservoir bag and then goes to the atmosphere via the hole
-Pt is getting mostly alveolar gas and FGF.
| S66 Lecture
49
⭐️Improved rebreathing efficiency is due to what factor?
* Location of the pop-off valve relative to FGF
*FGF located near patients will experience less rebreathing.*
| S67
50
⭐️Which Mapleson Circuits will experience significant amounts of fresh gas vented through pop-off at end-expiration?
* Mapleson B
* Mapleson C
| S67
51
⭐️Which systems have FGF that drive exhaled alveolar gas away from pt
* Mapleson D
* Mapleson E
* Mapleson F
| S67
52
⭐️Rank the groupings of the Mapleson Circuit in efficiency for **spontaneous ventilation** from GREATEST to LEAST
* Mapleson A
* Maplesons D,F,E
* Maplesons C,B
**All Dogs Can Bite**
| S67
53
⭐️Rank the groupings of the Mapleson Circuit in efficiency for **controlled ventilation** from greatest to least.
* Maplesons D,F,E
* Maplesons B,C
* Mapleson A
**Dog Bites Can Ache**
| S67
54
What are the advantages of the Mapleson Circuit?
* 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/ VAs
| S68
55
What are the disadvantages of the Mapleson Circuit?
* Require high FGF (can be wasteful)
* Conservation of heat and humidity less efficient
* Scavenging challenging (Except Mapleson D)
* *when APL valve is closer to the pt end, scavenging is challenging bc it’s more wasteful bc a lot of the gas is vented out*.
* Not suitable for patients with MH (May not be possible to increase FGF to remove excess CO2)
| S69
56
How does gas travel through the circle system during spontaneous inspiration?
- Reservoir bag deflates. Whatever mixture is the bag [Alveolar gas, SEVO, DES] travels:
- bypasses pressure guage
- CO2 absorber
- Inspiratory valve
- picking up some FGF
- valve is open
- Pt lungs
- lungs expand
- Gas sampling port
- on exhalation, this will give the ETCO2 readout.
| S70- lecture
57
What does the circle system allow for?
* Allows for circular and unidirectional flow
| S70
58
How does gas travel through the circle system during spontaneous expiration?
- Expiratory valve open, inspiratory valve is closed [no flow here now]
- gas follows path of least resistance so it goes to the expiratory valve.
- FGF makes a U-turn/goes backwards since the inspiratory valve is closed and FGF goes to the CO2 absorber
- Exhaled breath from the patient goes to the expiratory valve then expiratory sensors.
- Exhaled breath meets up with FGF [thats leaving from CO2 absorber]
- Reservoir Bag
- On exhalation, if bag expands too much & pressure increases too much then some will go out to be vented via the APL valve.
| S71- lecture
59
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.
| S71- lecture
60
For the Circle System, the extent of rebreathing and conservation of exhaled gases depends on _____.
* FGF
* Higher FGF = less rebreathing but greater amount of gas wasted
| S72
61
Rules to prevent rebreathing:
* Unidirectional valve must be **located between the pt and the reservoir bag** on both the inspiratory and expiratory limbs
* The fresh gas inflow cannot enter the circuit between the expiratory valve and the pt
* APL valve cannot be located between the pt and the inspiratory valve (You will lose FGF)
| S72
62
* What kind of circle systems are seen with contemporary/modern systems?
* Will there be rebreathing that occurs?
* Semi-closed circle system
* Partial rebreathing occurs, but some waste flow is vented through APL or waste gas valve of the ventilator
| S73
63
What is an example of a semi-closed circle system?
* Low-flow anesthesia
* FGF is less than minute ventilation
| S73
64
What percentage of expired gas is rebreathed after CO2 removal during low-flow anesthesia?
* 50%
| S73
65
* What kind of circle systems are considered non-rebreathing?
* Semi-open Circle System
* Higher FGF with minimal rebreathing and more venting of waste gas
| S74
66
What is an example of a semi-open circle system?
* Post-Op and ICU vents
* Scuba gear
* Mapleson Circuits
| S74
67
In what Circle System will the oxygen inflow rate exactly match the metabolic demand?
* Closed Circle System
| S75
68
in a closed system rebreathing is ____ and no ____ is vented
* Rebreathing is complete; no waste gas is vented
| S75
69
in what system are volatiles are added to the circuit in liquid form in precise amounts or through the vaporizer?
closed circle system
| S75
70
* Example of a closed circle system.
* why is this system impractical for use, and rarely done?
* ⭐️Low- and minimal-flow anesthesia
* bc we can now use semi-closed and still use low flow with partial rebreathing with CO2 absorbed.
| S75-lecture
71
Advantages of Low-Flow Anesthesia
* Decreased use of volatiles
* Improved temperature and humidity control
* Reduced environmental pollution
| S76
72
Disadvantages of Low-Flow Anesthesia
* Difficulty rapidly adjusting the anesthetic depth
* Possibility of accumulating unwanted exhaled gases ( ex: CO, acetone, methane)
* VA degradation by-products (ex: CO, compound A)
| S76
73
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
| S77
74
Disadvantages of Circle System
* Complex design
* CO or compound A
* May compromise Vt during controlled ventilation
* ASA Closed Claims Project (Misconnections/ disconnections)
| S77
75
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
| S78/79
76
Use of Self-Inflating Manual Resuscitators
* Hand ventilation in the absence of an oxygen or air source
* Pt transport
* CPR
* Emergency back-up
| S80
77
What is happening in AMBU bag during inspiration and expiration?
| S79
78
Which piece of equipment should ALWAYS be available and set up with your anesthesia machine?
AMBU bag!
| S80- Lecture
79
Hazards of Self-Inflating Manual Resuscitators
* Barotrauma or gastric insufflation
* Significant variation of tidal volume, PIP, and PEEP
* Nonrebreathing valves generate resistance
| S81
80
What is the purpose of bacteria filters?
* Routine use to prevent contamination or infection by airborne diseases
* TB, COVID, PUI [Person Under Investigation]
* Effective at preventing contamination of anesthesia machine from airborne diseases
| S82
81
Where are bacteria filters placed on the breathing circuit?
* Placed on the expiratory limb
| S82
82
* There are 2 type of arrangements for bacterial filters. What are they?
* What are the 2 types of bacterial filters?
**Arrangment**:
1. Small-Pore compact matrix
2. A less dense, Large-Pore size arrangment
**Type**:
1. Hydrophobic Filter
2. Combination [HMEF]
| S83
83
Describe the small-pore compact matrix bacterial filter.
- resistance
- surface area
* High airflow resistance
* Pleated to create a larger surface area.
| S83
84
Describe the larger-pore size arragement bacterial filter.
- resistance
- surface area
* less resistance
* Smaller surface area
| S83
85
The small pore compact matric and large pore arragment bacterial filter have what polarity?
* Permanent electrical polarity.
| S83
86
Hydrophobic Bacterial Filters will prevent _____.
* water penetration
| S84
87
When the Hydrophobic Bacterial Filters become wet, how does that affect resistance and efficiency?
* Increase resistance
* Decrease efficiency
| S84
88
Where are combination bacterial filters (filter + HME) placed in the breathing circuit?
What does the combination filter cause?
* Placed at the Y-piece
*This will cause a barrier to the inspiratory and expiratory limb, increasing resistance.* (bc air will not flow well through something wet)
| S84
89
Complication of Bacterial Filters.
* Obstruction
* Sputum, edema fluid, nebulized aerosols, or malpositioning
* Leakage around the housing of the gas line filter (best to monitor ETCO2 before the filter)
| S85
90
When is the placement of the filter on inspiratory limb recommended?
* When machine may be been contaminated by the previous patient
| S86
91
When is the placement of the filter on expiratory limb recommended?
* ALL patients
* pleated mechanical filter preferred
| S86
92
When is the placement of the filter by the Y-piece recommended?
* For COVID + or PUI
* HMEF preferred
| S86
93
Humidity
* Amount of water vapor in a gas
| S87
94
* Define absolute humidity
* What is the absolute humidity in mid trachea?
* Mass of water vapor present in gas in mg H2O/L of gas
* 34-38 mg of H2O/ L gas in mid trachea
| S87
95
Relative Humidity
* Percent saturation
* the amount of water vapor at a particular temp
| S87
96
Water Vapor Pressure
The pressure exerted by water vapor in a gas mixture.
| S87
97
Maximal contact of inspired gas occurs with the large mucosal surface area in the ____.
* Nasal Cavity
| S88
98
Most of the heating and humidification of inspired gas has occurred by ____.
What temperature and humidity?
* Mid-trachea
* temperature =34°C
* absolute humidity= 34 to 38 mg/L (95% to 100% relative humidity)
| S88
99
* As gas travels ____, it is heated to ____ ____.
* Absolute humidity of ____ (100% relative humidity)
* ____ saturation boundary which is usually right at the ____, but can vary depending on volume, humidity, and temperature.
* distally, body temperature [37℃]
* 44mg/L
* isothermic, Carina
| S88 and Lecture
100
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
| S89
101
What are the effects of warm ambient temperatures regarding humidification in the airway?
* Little heat energy is expended to warm inspired gases
| S89
102
Cool inspired gases may trigger ____
* Bronchospasm
*Seen more commonly in pts with COPD, asthma, and children with upper respiratory infections/problems*
| S89
103
Effects of underhumidifaction.
* Damage to the respiratory tract
* Secretions thicken
* Ciliary function decreases
* Surfactant activity is impaired
* Mucosa susceptible to injury (friable/dried out, bleeds)
* Body heat loss (longer cases)
* Tracheal tube obstruction (thicken secretions)
* Increases resistance and work of breathing from thickened secretions
Cilvia Secretary Serves Manny Heated Olives
| S90
## Footnote
very important to conserve heat and humidity to our little patients (neonates, peds)!
104
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
| S91
105
Functions of humidification devices.
* Aim to reproduce more normal physiologic conditions in the lower respiratory tract
| S92
106
Types of humidification devices
* Heat and moisture exchanger (HME)
* Passive
* can be modified to have a filter
* Heated humidifiers
* Active
| S92
107
Functions of Heat and Moisture Exchanger (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 w/ exchange medium enclosed in plastic housing
| S93
108
Where is the placement of an HME?
* Placed close to the pt, between Y piece and the proximal end of ETT or LMA
**can increase DS**
| S93
109
What happens to the ETCO2 reading if the sensor is placed:
* **AFTER** the HME?
* **Before** the HME?
* Which is more accurate?
* After = Low ETCO2 reading
* Before = accurate reading
| S94
110
What does the HME do to the resistance and dead space in the circuit?
* ↑ resistance
* ↑ dead space
| S94
111
What happens to the efficiency of the HME with a large tidal volume?
* ↓ Efficiency, specifically with hydrophobic models
| S94
112
What are the 2 types of HME
1. Hygroscopic HME
2. Hydrophobic HME
| S95
113
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
| S95
114
What is Hygroscopic HME most efficient at?
* Most efficient at retaining heat and moisture
| S95
115
What is the drawback of Hygroscopic HME?
* Prone to becoming saturated
- Increased inspiratory/expiratory resistance
- Reduced heat and moisture retention efficiency
| S95
116
What is a Hydrophobic HME?
What is a Hydrophobic HME efficient at?
* Pleated (Lg SA) hydrophobic membrane with small pores
* More efficient filters of pathogens
| S95
117
Devices used to increase the humidity in O2 supplied to pts
* Humidifiers
* May be heated or unheated.
| S96
118
Who will benefit from humidifiers?
* Neonates
* Pts with respiratory secretions
* Hypothermic pts
| S96
119
What are the different ways a humidifier can pass a stream of gas?
* Bubble or cascade
* Pass-over
* Counter-flow
* Inline
| S96
120
Where are the humidifiers placed in the breathing circuit? Where should they NOT be placed?
* Placed in the inspiratory limb downstream of the unidirectional valve
* Heated humidifiers should not be placed in the expiratory limb
| S96
121
Describe the Bubble/Cascade humidifier.
* 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
| S96- lecture
122
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.
| S96, lecture
123
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.
| S96, lecture
124
Describe the inline vaporizer humidifier.
* 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.
| S96, lecture
125
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
| S96
126
Condensation has what effect on tidal volume?
* Decrease Vt
| S96
127
Consideration for water traps in humidifiers.
* Change frequently to decrease the risk of contamination and infection
| S96
128
Advantages of Humidifiers
* Can deliver saturated gas at body temp or higher
* More effective than HME in longer cases in preventing hypothermia
| S98
129
Disadvantages of Humidifiers
* Bulky
* Potential electrical malfunction and/or thermal injury
* Contamination, and cleaning issues
* Higher cost than HME
* Water aspiration risk
Bulky Humidifiers Potentially Contaminate Water
| S98
130
What 3 things can change where the isothermic saturation boundary is?
* Volume of gas inhaled
* humidity
* temperature
