6) Breathing Circuits Flashcards
(33 cards)
Why do we use the circle system in the OR
- more economical and efficient
- retains heat and humidity
- prevents OR pollution
Basic functions of breathing circuit
- interface between anesthesia machine and patient
- delivers O2 and other gases
- eliminates CO2 (FGF or absorber)
- 3 essential components
3 essential components for breathing system
- low resistance (corrugated tubing)
- reservoir for gas that meets inspiratory flow demand
- expiratory port or valve to vent excess gas
What can we add on breathing circuits?
- HME
- nebulizers
- filters
- pressure gauges
- spirometer
- add weight, dead space, resistance
Requirements of breathing circuit
- deliver gases from machine to alveoli is the same concentration set in shortest possible time
- allow for rapid adjustment in gas concentration
- eliminate CO2
- minimize dead space
- low resistance
Breathing System features
- economy of fresh gas
- conservation of heat/humidity
- light weight
- portable
- efficiency in SV and CV
- adaptability
- reduces environmental pollution
Open system
-no reservoir; no rebreathing; nasal cannula, open drop
Semi open system
-reservoir, no rebreathing, FGF > MV; Mapleson
Semi Closed
-reservoir, partial rebreathing, FGF
Closed system
Reservoir; complete rebreathing; scuba diver; circle system with very low FGF like 250mL/m
Steal induction
-use mask to blow by child not touching face
Insufflation
- blow by bronch port while sharing airway with ENT
- danger in O2 under drapes lead to fire
- pollutes OR
What are pros and cons of Mapleson Circuits
Pros: lightweight, portable, can change depth of anesthesia rapidly, eliminates CO2, visualize ventilation with reservoir,
Cons: use high FGF so inefficient, unable to scavenge, does not conserve heat or humidity
What Maplesons are best for SV
-A, D, C, B
What Maplesons are best for CV
-D, B, C, A
CO2 rebreathing depends on
- FGF rate in Mapleson
- I:E ratio
- mode of ventilation
- CO2 production
Describe the Bain Circuit
- modified coaxial Mapleson D
- FGF inflow tubing is within the correlated tubing
- maintains heat and humidity
- potential for disconnection
- requires Pethick test to test for disconnection
- can be used for SV/CV but more efficient in CV
Mapleson E
T piece
- no pop off valve
- reservoir is the tubing
- FGF 2-3x MV
Jackson Reese
- modified Mapleson F
- has an APL valve at the end of the reservoir bag
- popular in pediatrics
- visual cue that patient is breathing
- allows CPAP or hand ventilation
Ambu Bag
- critical piece of equipment and morning check
- contains self inflating bag and non-breathing valve
- can deliver high FiO2 with O2 reservoir
- CO2 washout depends on MV
Mapleson and Circle System Similarities and differences
Similarities: accepts FGF, supplies gas from a reservoir, eliminates CO2
Differences: Mapleson has bidirectional flow, does not use an absorber, depends on FGF to eliminate CO2, no valves
What is a circle system
- unidirectional flow via unidirectional valves
- components arranges in a circle
- can be modified to closed, semi-closed, semi-open system
- prevents rebreathing by absorber
- allows rebreathing of other gases
What are the components
-FGF inlet, inspiratory limb, inspiratory valve, y piece, expiratory limb, expiratory valve, APL valve, reservoir, and CO2 absorber
Explain FGF
-comes from CGO
-placed between CO2 absorber and unidirectional valve of inspiratory limb
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