Gas delivery Flashcards Preview

Gas Delivering system > Gas delivery > Flashcards

Flashcards in Gas delivery Deck (114)
Loading flashcards...

Most efficient Mapleson during controlled ventilation

Mapleson D


During spontaneous respiration, FGF = 2-3 x MV
During controlled ventilation, FGF = 1-2 x MV

Mapleson D


Mapleson D is also called

Bain System


What is the order of effectiveness in controlled ventilation in the the Mapleson system

D > B > C > A (Dog bites can ache)


What is the order of effectiveness in spontaneous ventilation in the Mapleson system

A>D>C>B(All dogs can Bite)


What system consists of inner tubing that delivers FGF directly to the patient who then exhales down the outer corrugated tubing to the reservoir bag and APL valve

The Bain System


Which Mapleson system eliminates rebreathing, where higher fresh-gas flows are needed during SV than during controlled ventilation

Mapleson D


A patient has a fever of 103.5,what should be done with the FGF and whats the rational

Increase the fresh gas flow due to the increase in co2 production


Adjustments to the ventilatory pattern that allow the fresh-gas flow to constitute a larger proportion of the inspired gas includes all of the following except:
A.Slow inspiratory time
B.Low inspiratory flow
C.Long Expiratory Pause
D.Slow Rate
E.Fast Total cycle time



What are the disadvantages of the Bain Circuit

Kinks,Leaks,Disconnection of the the Inner tubing


What is the advantage of the Bain Circuit

1.Exhaled gas warms the fresh gas flow in the inner tubing thereby preserving humidity and warmth
2.Ease of Scavenging through the overflow valve.
3.Useful for head and neck surgery.
4.Conserves humidity due to partial rebreathing
5.Low Resistance to breathing by the tubing or circuit


The rapid flow of gas through the expiratory limb, resulting in a slight negative pressure and collapse of the breathing bag.

Venturi Effect and used to test for leaks in The Bain Circuit.
With a leak from the inspiratory limb into the expiratory limb, the pressure in the latter rises, tending to inflate the reservoir bag if there was a leak


Mapleson E is a is used in ?

Ayre's T piece.


which system has NO RESERVOIR BAG (the expiratory limb is the reservoir) AND NO POP-OFF VALVE!!!

Mapleson E


What is rate of FGF during SV in the Mapleson E system



Name the characteristics of the Mapleson E system

No reservoir
No pop-off-valve
limited resistance in the tubing


SInce there is no reservoir bag in the Map E system.
What acts as a reservoir

The open end corrugated tubing acts as the reservoir and should be have a lenght that exceeds the Tidal Volume of the patient.


What is the sole determinant of rebreathing occuring in the Map E system

The FGF is ultimately the sole determinant of whether rebreathing occurs and directly influences the O2 concentration of inspired gas – if the FGF is not equal to the inspiratory flow rate then air will be entrained creating a dilutional effect.


In the Map E system the FGF should Be equal to the inspiratory flow rate.True or false



With what kind of patients is the Map E used with

Pediatric patients weigh less that 20kg


A modification of the Mapleson E Ayre’s T piece with an adjustable pop-off valve at the end of reservoir bag is called?

MAP F or Jackson Reese.


Which Mapleson system Allows the application of continuous positive airway pressure or hand ventilation

Map F


what Mapleson system Provides a visual indicator of respiration with the reservoir bag

Map F


FGF equal to 2-3x mve is recommended to prevent rebreathing of exhaled gases in the Map F system,true or false



Disadvantages of the Mapleson F system include the floowing except:
(1) the need for high fresh gas inflow to prevent rebreathing, (2) the possibility of high airway pressure and barotrauma should the overflow valve become occluded, and (3) the lack of humidification. Lack of humidification can be offset by allowing the fresh gas to pass through an in-line heated humidifier
4.Air liquefication.



What are the Basic Functions of a breathing circuit

1) Interface between the anesthesia machine and the patient

2) Deliver O2 and other gases

3)Eliminates carbon dioxide
CO2 absorbents eliminate CO2 in circle systems
Other breathing circuits require fresh gas flow (FGF) for elimination of CO2


3 Essential components of a breathing circuit

1.low resistance conduit for gas flow
2.reservoir for gas that meets inspiratory flow demand
3.expiratory port or valve to vent excess gas

humidifiers,pressure gauges,spirometers,peeps,waste gas scavengers


Requirements of a breathing circuit.

1)Deliver the gases from the machine or device to the alveoli in the same concentration as set and in the shortest possible time.
2)Effectively eliminate carbon dioxide
3)minimal apparatus dead space
4)low resistance to gas flow
5)allow rapid adjustment in gas concentration and flow rate


Name the Factors that will eliminate resistance in a breathing circuit.

1.Short tubing,
2. large diameter tubing,
3. avoid sharp bends,
4.caution with valves,
5. minimize connections


Beneficial effects of Rebreathing

1.Cost reduction
2.Adds humidification/heat to gases


Higher FGF is associated with less re-breathing in any system. T/F



Increase Dead space increases the chances of rebreathing T/F



What size of filter should placed in the anesthesia circuit to protect the machine from bacterial contamination

0.3micrometre filter


What is the meaning of HME

Heat and moisture exchanger


where will the HME be placed in the circuit

In the Y piece


What is the function of the HME

Inspiratory and expiratory barrier


Where would a standard filter be placed

In the Expiratory limb of the circuit.


When rebreathing is absent or minimal the concentration of Inspired oxygen is equal to that from the common gas outlet.True or false



What are the classifications of anesthetic delivery system and their specifications.

Open system:No reservoir/No rebreathing
semi open:Reservoir/no rebreathing
semi close:Reservoir/partial rebreathing
close:Reservoir and complete rebreathing


Examples of Insufflation system

Blow by
open drop
simple face mask
nasal cannula


components of open system

No gas reservoir
No valve
No rebreathing


What rate of MVE should FGF be to prevent rebreathing

1-1.5 MVE


Advantages of Insufflation

Avoid direct pt contact
No rebreathing
No valves


Disadvantages of Insufflation

No ability to assist or control ventilation
May have CO2/ O2 accumulation under drapes
No control of anesthetic depth /FiO2
Environmental pollution


Name Mapleson system components

connection point to a facemask or ETT
reservoir tubing
fresh gas inflow tubing
expiratory pop-off valve or port


Which Mapleson system has no reservoir bag>

Mapleson E


When are the Mapleson system used

transport of patients
procedural sedation
weaning tracheal intubation (the T-piece)
Pre-02 during out-of-the-OR airway management


Best measure of optimal FGF to prevent rebreathing



Name the differences present in the Mapleson system

locations of pop-off valve, fresh gas input, and whether or not a gas reservoir bag is present


ADvantages of Mapleson are

simplicity of design
ability to change the depth of anesthesia rapidly
lack of rebreathing of exhaled gases(With adequate fresh gas flow)


Disadvantages of the mapleson system

lack of conservation of heat and moisture
limited ability to scavenge waste gases
high requirements for FGF


Co2 rebreathing depends on

Fresh gas inflow rate
Minute ventilation of patient
Mode of ventilation (spont v controlled)
CO2 production of individual patient (increased with fever, catabolism, etc)
Respiratory waveform characteristics
e.g., inspiratory flow, inspiratory and expiratory times, I:E ratio, and expiratory pause
Type of ventilation (spontaneous or controlled)


what are the components of an Ambu Bags

1.Non-Rebreather Valve
2.Self Inflating Bag
3.Co2 Washout depends on MVE
4.Will deliver high Fio2 if o2 source is ATTACHED


Is Mapleson System a flow inflating device or a self inflating device?

Flow inflating device that needs oxygen source to function.


Is ambu bag a flow inflating device or a self inflating device

Ambu bag is a self inflating device


Differences between Mapleson and Circle system

1.Bi-directional flow
2.Depends on Fresh gas flow to Eliminate C02
3.No Co2 absorber used


Some characteristics of the Circle systems are

1.Changes in anesthesia concentration can take some time to reach equilibrium.Hence higher FGF use in needed.
2.Unidirectional valves can be stuck causing higher resistance.
3.Minimizes pollution
4.conserves heat,humidity and anesthetic agent.


The circle system eliminates CO2 in the following ways

1.Allows carbon dioxide absorption during low-flow anesthesia and
2. elimination through the pop-off valve during high-flow anesthesia


The open circuit system is useful in the case of CO2 absorbent failure because?

Expired gas does not return to the patient since fresh gas flow is sufficient to get rid of C02 and hence create an open circuit


The Inspired CO2 should Zero if a circle system is used properly.True or False



If the CO2  absorbent becomes saturated and can no longer absorb carbon dioxide, How can we tell that the inspired CO2 has increased?

The waveform Capnogram will indicate inspired carbon dioxide throughout inspiration and will not return to baseline.


If the Co2 absorbent material has become saturated and the inspired Co2 has increased.Name 2ways to fix the issue of breathing in more Co2

2.Change the saturated absorbent material
1.Increase Fresh gas flow to exceed the MVE...this will create an open system


What limb should the Co2 absorber be placed in the circle system

The inspiratory limb and on the side of the reservoir bag


What is the rational of placing the co2 absorber on the side of the reservoir bag

This is done so that the resistance to inspiration can be overcome with assist or controlled ventilation


What limb shoulf the Co2 absorber be placed in the circle system

The inspiratory limb


What is the rational of placing the co2 absorber on the side of the reservoir bag

This si done so that the resistance to inspiration can be overcome with assist or controlled ventilation


Name the two ways to get rid of co2 in anesthesia systems



In Low Fresh gas flow what technique can we use to get rid of co2

Absorption(Co2 absorber)


In High fresh gas state What technique can we use to get rid of co2

Dilusion(High FGF dilutes the concentration Of Co2)


Using Co2 absorber ,conserves humidy and heat.True or false



What is the preffered location for FGF inlet valve on the circle system

This location is after the co2 absorber on the Inspiratory Limb,before the Inspiratory valve


what is the optimal position for the pop off valve to be placed in the circle system

Placement should be after the expiratory valve and before the reservoir bag on the expiratory limb


What is the preffered location for FGF inlet valve

This location is after the co2 absorber on the Inspiratory Limb,before the Inspiratory valve


The essential characteristics of the unidirectional respiratory valves in breathing circuits are?

1.low resistance
2.high competence


The primary sources of resistance in an anesthesia delivery system are?

The valves
The Co2 absorber
The Tracheal tube


When expiratory valve is wet, A much higher resistance is exerted into the system.t/f



Name the characteristics of the unidirectional valve material

1.Hydrophobic: so that water does not accumulate and cause it to stick to the knive edge and unable to open when needed.
2.light weight and thin
3.Should be able to lift the valve with 0.31cm of h20 pressure.


Fairlure for the unidirectional valves to seal will result in?

Co2 rebreathing


Characteristics of the reservoir bag

Made of rubber or neoprene
Means for manual ventilation
Reservoir for oxygen and anesthetic gases
Adult size 3L(range 0.5-6L)


What are the standards of pressure that the anesthesia reservoir bag must adhere to?

Anesthesia reservoir bags must adhere to pressure standards, which allow a minimal pressure of approximately 30 cm H2O and a maximal pressure of approximately 60 cm H2O


What is the purpose of the Apl valve/pop-off valve.

AKA: pressure relief, pop-off, safety-relief valve•Purpose: 1.permits PEEP during SV or allows for pressure- limited controlled respiration•
2.Releases gases to scavenge or atmosphere exhaust port•
3.User-adjustable: clockwise – closes valve & increases pressure within system•
4.Provides control of pressure in system – pressure gauge on absorber•
5.Spontaneous Respiration:•valve fully open•close partially only if reservoir bag collapses•
6.Assisted Ventilation:•valve partially open•bag squeezed on inspiration•careful & frequent adjustments necessary•
7.Mechanical Ventilation- APL left open


What is the position of the APl valve during spontaneous respiration

valve fully open
close partially only if reservoir bag collapses


What is the position of the Apl valve during Assisted Ventilation

valve partially open
bag squeezed on inspiration
careful & frequent adjustments necessary


What is the position of the Apl Valve during mechanical Ventilation

APL left open


At what pressure should the Apl Open

Pressure < 1cm of water


What are the characteristics of a breathing tube

Large bore, non rigid corrugated tubing
Clear plastic (historically rubber was used)
22 mm female fitting w/machine
Patient end – T piece 22 mm male, 15 mm female coaxial fitting
I meter in lenght with 400-500 Ml/m of lenght per internal volume


Functions of breathing tube



What is the most common breathing circuit used in the usa

Semi closed circle


what are the characteristics of a semi-closed circle

1.Allows for some re-breathing of agents and exhaled gases (minus CO2 due to CO2 absorption)
2.Uses relatively low flow rates (about 1-3L/min)
3.FGF is less than minute ventilation
4.Conserves some heat and gases
5.APL valve is partially closed and adjusted as needed; or ventilator is in use


What is the most common breathing circuit used in the usa

Semi closed circuit


When is the close circle used

Used in long surgical cases and in third world countries


Characteristics of a closed system

Inflow gas exactly matches metabolic needs/ O2 consumption of the patient using very low flows (O2 flow rate ~ @ 250 mL/min)
Total re-breathing of all exhaled gases after absorption of CO2
APL is closed
Change in gas concentrations is VERY slow


If the Inspired Co2 level is high or the waveform does not return to baseline,name the 2 steps to resolve these.

Increase the Fresh gas flow.
check the unidirectional valve there may be a stucked valve.
Change the co2 absorber.


Disadvantages of the circle system are?

Complex design
Has at least 10 connections
This sets the stage for potential leaks, obstruction, or disconnection
A third of malpractice claims are related to disconnects or misconnects of the circuit
Potential of malfunctioning valves
Stuck open= rebreathing
Stuck closed= airway obstruction
Increased resistance to breathing (above Mapleson)
Less portable and convenient than the Mapleson systems due to its bulkiness
Increased dead space BUT dead space ends at the Y piece


If the Inspired Co2 level is high,name the 2 steps to resolve these.

Increase the Fresh gas flow.
check the unidirectional valve there may be a stucked valve.
Change the co2 absorber.


Explain the Leak test

Set all gas flows to zero, occlude the Y-piece, close the APL valve, pressurize the circuit to 30 cm of water pressure using the O2 flush valve, ensure pressure holds for 10 seconds, listen for sustained pressure alarm, open APL valve and ensure pressure decreases


Explain flow test

Attach breathing bag to Y- piece, turn on ventilator, and assess integrity of unidirectional valves


What are issues we have with circle delivery system

misconnections or disconnections
valve failure
carbon dioxide absorber defect
bacterial filter occlusion


Which of the mapleson system is wasteful for Gases

B and C


what are the Characteristics of the Breathing Tube in the circle system

Low resistance
Light weight connection
flexible...prevents kinking


Name the components of a circle system

1.FGF source
2.Inspiratory and expiratory unidirectional valves
3.Inspiratory and expiratory limbs/ corrugated tubing
4.Y-piece connector
4.Adjustable pressure-limiting valve (APL valve, over-flow valve, or Pop-off valve )
5.Reservoir bag
6.CO2 absorber


Name the Desirable breathing system features

economy of fresh gas
conservation of heat (adequately warm gases)
adequate humidification of inspired gas
light weight
convenience during use
efficiency during spontaneous as well as controlled ventilation
adaptability for adults, children and mechanical ventilators
provision to reduce environmental pollution- safe disposal of waste gas


disadvantages of map A

proximal location of the overflow valve makes scavenging difficult
difficult to adjust during head and neck surgery
heavy valve can dislodge a small tracheal tube


Using Map A(Magill),how can we prevent rebreathing during controlled ventillation

Requires high FGF


Which of the Mapleson system is used in rescucitation situations

Mapleson C(water's Circuit)


Map B and C need high Fresh gas flows thereby making them Impractical to use.True or False



Which Mapleson system should be choosed theat will be most optimal for both controlled and spontaneous ventillation

Mapelson D


What are the characteristics of the Circle system

1.unidirectional gas flow via unidirectional valves
2.Components are arranged in a circle
3.Can be used as a semi-open, semi-closed, or closed system
4.Depends on the adjustment of the APL valve
5.Depends on FGF rate
6.Prevents re-breathing of CO2 by chemical neutralization
7.Allows re-breathing of other exhaled gases


advantages of Circle system

Relative stability of concentration of inspired gases
Conservation of moisture and heat
Low resistance (but not as low as Mapleson)
Can be used for closed-system anesthesia
Can be used with fairly low flows with no rebreathing of CO2
Economy of anesthetics and gases
Can scavenge waste gases
Prevention of OR pollution


The Mapleson F system is used in what scenario

The Mapleson F system is commonly used for controlled ventilation during transport of intubated patients


what happens in The Mapleson E system If the Fresh Gas flow is not Equal to the Inspiratory flow rate

It will entrain room air and create a dilusional effect


What is the difference in Fresh gas content between Map A and other Mapleson devices

Map A has only new Fresh gas Flow and other Map devices have a mixture of gases.


Why does Map A have only fresh gas and not a mixture of gases?

The other gases ..alveoli gas,dead space gas was vented out end expiration.


Characteristics of a Semi-open Circle system

1.No re-breathing occurs; very high flow of FGFs (10-15L/min) are used and eliminates rebreathing of gases
2.No conservation of wastes gases and heat .
3.APL valve is open all the way or ventilator in use