Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Intro to Anesthesia Summer 18 > Delivery Systems > Flashcards

Delivery Systems Flashcards

1
Q

Function of Delivery Systems

A

The function of anesthetic breathing systems is to deliver oxygen and +/- anesthetic gases to the patient and to eliminate carbon dioxide

  • CO2 eliminated friom the breathing circuit by washout with adequate fresh gas flow/FGF or by the use of CO2 absorbent media
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Essential Requirements of a Breathing System

A
  • Deliver the gases from the machine or device to the alveoli in the same concentration as set and in the shortest possible time
  • Effectively eliminate CO2
  • Minimal apparatus dead space
  • Low Resistance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Desirable Requirements of a Breathing System

A
  • Economy of fresh gas
  • Conservation of heat
  • Humidification of inspired gas
  • Light weight
  • Convenience
  • Efficiency during spontaneous and controlled ventilation
  • Adaptability for adults, children, and mechanical ventilators
  • Provisions to reduce environmental pollution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Considerations for a Delivery System

A

Resistance- want low resistance

  • Short tubing, large diameter tubing, avoid sharp bends, caution with valves, minimize connections

Rebreathing- may be beneficial

  • Cost reduction
  • Adds humidification/heat to gases
  • BUT: Do not want rebreathing of CO2
  • *Higher FGF is associated with less rebreathing in any type of circuit

Dead Space- increases the chance of rebreathing CO2

  • Dead space ends where the inspiratory and expiratory gas streams diverge
    • Apparatus dead space can be minimized by separating the inspiratory and expiratory streams as close to the patient as possible

Dry gases/humidification

Manipulation of inspired content

  • The concentration inspired most closely resembles that delivered from the common gas outlet when rebreathing is minimal or absent

Bacterial colonization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Classification of Anesthetic Delivery System

A
  • Open
  • Semi-Open
  • Semi-Closed
  • Closed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Open System

A
  • Characterized by:
    • NO- gas reservoir bag, valves, rebreathing of exhaled gas
  • 2 Types
    • Insufflation/Blow by
    • Open drop
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Insufflation Types

A
  1. “Blow by” Tent
  2. Bronchoscopy port
  3. Nasal Cannula
  4. “Steal” Induction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Insufflation Advantages

A

Simplicity

  • Avoids direct pt contact
  • No rebreathing of CO2
  • No reservoir bag or valve
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Insufflation Disadvantages

A
  • No ability to assist or control ventilation
  • May have CO2/O2 accumulation under drapes
  • No control of anesthetic depth of FiO2
  • Environmental pollution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Schimmelbush Mask

A
  • True “open circuit” consisted of a bit of cloth saturated with either ether or chloroform or halothane and held over the patients face
  • Perhaps Sevo could be use nowadays?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Open Drop Method: example

A

Ether mask (Schimmelbusch)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Open Drop Method Advantages

A

Simplicity

Low Cost Apparatus

Portable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Open Drop Method Disadvantages

A
  • Poor control of inspired concentration of anesthetics
  • Accumulation of CO2 under mask
  • Predisposes to hypoxia risk
  • Spontaeous ventilation only/ cannot control ventilation
  • OR Pollution/Health care provider risk
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Semi-Open Systems Components

A
  1. Facemask or ETT
  2. Pop-off valve (APL valve)
  3. Reservoir tubing
  4. Fresh gas inlet
  5. Reservoir bag
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Semi-Open System Example

A

Mepleson A-F

Bain

Circle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Mapleson A-F

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Mapleson Functional Groups

A

3 Distinct Functional Group

  • Group 1
    • A: pop-off located near facemask, FGF located at the opposite end
  • Group 2
    • B & C: pop-off and FGF near facemask
  • Group 3: opposite set up of Mapleson A
    • D, E, F: FGF located near facemask and pop off located at opposite end
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

CO2 Rebreathing will depend on

A
  • Fresh gas inflow rate
  • Minute ventilation of patient
  • Type of ventilation (spontaneous or controlled)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

End Expiration

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Mapleson D

A
  • Reversed configuration of Mapleson A
  • Can be used for both spontaneous and controlled ventilation
    • Spontaneous respiration FGF=2-3 x MV
    • Controlled ventilation FGF=1-2 x MV
  • Most efficient Mapleson during controlled ventilation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Mapleson E (T-Piece)

A
  • Modification of Ayre’s T-Piece commonly used to administer O2 in ICU and PACU settings
  • NO RESERVOIR BAG (the expiratory limb is the reservoir) AND NO POP-OFF VALVE!!!

If SV, FGF = MV x 2-3

22
Q

Mapleson F (Jackson-Rees)

A
  • A modification of the Mapleson E Ayre’s T piece with adjustable pop-off valved at the end of reservoir bag
  • Popular in pediatrics
23
Q

Bain Circuit

A
  • Coaxial modification of Mapleson D
  • FGF tubing w/i large bore corrugated tubing
    • Allows exhaled gas to warm inspired gas
    • Preserves heat and humidity
  • For controlled OR spontaneous ventilation
  • FGF requirements- same as Mapleson D
  • Disadvantage
    • Potential for inner tube leaks, kinking or disconnection
24
Q

Ambu Bag

A
  • Modified Mapleson A w/ non-rebreathing valve
    • Contain non-rebreathing valve
    • Capable of delivering high FiO2
    • Reservoir self filling w/ intake valve
    • Requires high fresh gas flow
    • CO2 wash-out depends on minute ventilation
25
Q

Advantages of Mapleson System

A
  • Simple components
  • Lightweight
  • Can provide positive pressure ventilation
  • Low resistance
  • Portable
  • If using inhaled anesthetics, more predictable anesthetic concentration and decreased room pollution when compared to open systems
26
Q

Disadvantages of Mapleson System

A
  • Requires calculation of FGF which varies with both type of circuit and mode of ventilation (SV or CV).
  • Control of anesthetic depth is variable- anesthetic gases will be diluted as FGF increases (BUT control is better than with open systems).
  • If FGF not maintained, possibility of CO2 buildup and rebreathing is present.
  • Minimal rebreathing of other gases- poor conservation of heat and humidity.
  • FGF costly
  • Requires special assembly and function is complex
27
Q

Circle System Standard size

A

Available Lengths: 40’’, 60’’, 72’’

28
Q

Single-limb Universal F Circuit

A
29
Q

Circle System

A
30
Q

Circle System

A
  • Components are arranged in a circle
  • Can be used as a semi-open, semi-closed, or closed system
    • Depends on the adjustment of the APL valve
    • Depends on Fresh gas flow rate
  • Prevents re-breathing of CO2 by chemical neutralization
  • Allows re-breathing of other exhaled gases
31
Q

7 Components of a Circle System

A
  1. Fresh gas flow source
  2. Inspiratory and expiratory unidirectional valves
  3. Inspiratory and expiratory limbs/ corrugated tubing
  4. Y-piece connector
  5. Adjustable pressure-limiting valve (APL valve, over-flow valve, or Pop-off valve )
  6. Reservoir bag
  7. CO2 absorber
32
Q

Picture

A
33
Q

Picture

A
34
Q

Gas Flow on Inspiration

A
35
Q

Gas Flow: Expiration

A
36
Q

Rules of the Circle System

A
  1. A unidirectional valve must be located between the patient and the reservoir bag on both the inspiratory and expiratory limbs of the circuit; unidirectional valves should be close to patient to prevent backflow into the inspiratory limb if a circuit leak develops; however, unidirectional valves should not be placed in the breathing Y-piece, since that makes it difficult to confirm proper orientation and intraoperative function.
  2. The FGF inflow cannot enter the circuit between the expiratory valve and the patient; should be placed between the absorber and the inspiratory valve; positioning FGF downstream from the inspiratory valve would allow FGF to bypass the patient during exhalation and be wasted; FGF introduced between the expiratory valve and the absorber would be diluted by recirculating gas (furthermore, inhaled anesthetics may be absorbed or released by soda lime granules in CO2 absorber, thus slowing induction and emergence)
  3. The over-flow pop-off valve (APL) cannot be located between the patient and the inspiratory valve. It should not be placed immediately before the CO2 absorber to conserve absorption capacity of the granules and to minimize venting of FGF.
  4. Resistance to exhalation is decreased by locating the breathing bag in the expiratory limb; bag compression during controlled ventilation will vent alveolar gas through a pressure relief valve (APL), conserving absorbent.
37
Q

How does gas flow through the circle system?

A
38
Q

Unidirectional Valves

A
  • Gas flowing into the valve raises the disc from its seat, then passes through the valve.
  • Reversing the gas flow causes the disc to contact its seat, stopping further retrograde flow.
  • The guide (cage) prevents lateral or vertical displacement of the disc.
  • The transparent dome allows observation of disc movement.
39
Q

Reservoir Bag and Functions

A
  • AKA: Breathing bag, Respiratory bag
  • Made of neoprene or rubber
  • Neck – 22 mm female fitting to male system
  • Tail – end opposite neck

Functions:
- accumulation of gas during exhalation
- assist/control ventilation
- visual/tactile monitor to observe spontaneous respirations
- protects against excessive pressure
reservoir of gas

40
Q

Breathing Tubes and Functions

A
  • Large bore, non rigid corrugated tubing
  • Rubber or clear plastic
  • 22 mm female fitting w/machine
  • Patient end – T piece 22 mm male, 15 mm female coaxial fitting

Functions:

  • Flexible, low resistance, lightweight connection
  • Reservoir
41
Q

APL Valve

A
  • AKA: pressure relief, pop-off, safety-relief valve
  • Releases gases to scavenge or atmosphere exhaust port
  • User-adjustable: clockwise – closes valve & increases pressure within system
  • Provides control of pressure in system – pressure gauge on absorber
42
Q

APL Valve Ventilations

A
  • *Spontaneous Respiration:**
  • valve fully open
  • close partially only if reservoir bag collapses
  • *Assisted Ventilation:**
  • valve partially open
  • bag squeezed on inspiration
  • careful & frequent adjustments necessary
  • *Mechanical Ventilation** – valve closed (if machine not equipped w/switch)
43
Q

Dead Space in Circle System

A

If the unidirectional valves are working properly, the only dead space in the circle system is between the Y piece and the patient.

44
Q

Oxygen Flush

A

The pathway of gas flow through the absorber during oxygen flush.

45
Q

Semi-Open Circle System

A
  • Not used often- occasionally for sedation (mask placed over face to increase FiO2)
  • No re-breathing occurs; very high flow of fresh gas flows (10-15L/min) are used and eliminates rebreathing of gases
  • No conservation of wastes gases and heat
  • APL valve is open all the way or ventilator in use
46
Q

Semi-closed Circle System

A
  • Most commonly used breathing system in U.S. practice
  • Allows for some re-breathing of agents and exhaled gases (minus CO2 due to CO2 absorption)
  • Uses low flow rates (1-3L/min)
  • Conserves some heat and gases
  • APL valve is partially closed and adjusted as needed; or ventilator is in use
47
Q

Closed Circle System

A
  • Used often in long surgical cases and third world countries
  • Inflow gas exactly matches metabolic needs/ O2 consumption of the patient using very low flows (O2 flow rate = @ 200 mL/min)
  • Total re-breathing of all exhaled gases after absorption of CO2
  • APL valve is CLOSED or ventilator is in use
48
Q

O2 Consumption

A

O2 Consumption (VO2) = 10 x kg3/4

In a 70kg patient: 10 x 703/4
10 x 24.2 = 242 mL O2/min

49
Q

Advantages of the Circle System

A
  • Relative stability of concentration of inspired gases
  • Conservation of moisture and heat
  • 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
50
Q

Disadvantages of the Circle System

A
  • 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
  • Increased resistance to breathing
  • Less portable and convenient than the Mapleson systems due to its bulkiness
51
Q

Circle System Check

A
  • 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
      • This test does not assess integrity of unidirectional valves
  • Flow Test
    • Attach breathing bag to Y- piece, turn on ventilator, and assess integrity of unidirectional valves

Intro to Anesthesia Summer 18 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions