Ventilators and Breathing circuits Flashcards
What are the 5 tasks of O2 in the anesthesia machine?
- Powers the ventilator driving gas
- The flush valve
- Powers the oxygen pressure failure alarm
- Powers the oxygen pressure Sensor shut off valve (fail safe valve)
- Powers O2 to flowmetes
also plays a role in the proportioning system in the hypoxic guard system, maintaining correct proportions of O2:N2O
Non-rebreathing Mapleson circuits highly dependent on what? in regards to the amount of rebreathing
Highly dependent on dilution of expirations with high FGF
What is the Bain circuit?
A coaxial Mapleson D system–and works by FGF runs coaxially in corrugated tube–ends at the point where FG supply wou
Which Mapleson system is most efficient for the spontaneously breathing patient?
Mapleson A system
What are the 4 types of breathing circuits?
- Open
- Semi-open
- Semi-closed
- Closed
Which breathing circuit is the most common? Subcategories?
Circle system which can be categorized as:
1. Semi open
2. Semi closed
3. Closed
In a circle system subcategories, what are the main features in regards to rebreathing?
- Semi-open: No Rebreathing, Reservoir bag , High FGF with circle system or have non rebreathing system
- Semi-closed: Yes, Partial Rebreathing, Reservoir bag , low FGF with circle system
- Closed: Yes, Complete Rebreathing, Reservoir bag, circle system with the APL valve closed
Hazards of the Bain system
Detachment of connectors at either end-develops a leak at the machine end, Fresh gas supply becomes kinked or twisted, the system is INCORRECTLY Assembled; defect in the metal head so that fresh gas + exhaled gas mix–increasing dead space
Where is there mechanical dead space on the breathing circuits?
- The mouth to the breathing circuit
- The elbow on the breathing circuit
- Any connector used between the end of the tube and the breathing circuit
- The Y piece at the end of a Y circuit
What must occur to overcome mechanical dead space?
The fresh gas flow must be greater than the tidal volume that the patient breathes. Otherwise, there will be CO2 build-up and the difference between tidal volume and fresh gas flow will essentially be additional dead space.
Where is the CO2 absorbent best located on the Circle system?
The preferred location for the CO2 absorbent in a circle system is on the inspiratory limb (Quadrant A)
Has two ports—connection to breathing tube and fresh gas inlet
Which Mapleson system is most efficient for controlled ventilation?
Mapleson D system
What is the Mapleson F (Jackson-Rees or Rees) good for?
Pediatric because it offers slightly less work of breathing ; has low resistance and minimal dead space
What are 2 ways CO2 can be eliminated in a breathing circuit?
- Washout with adequate fresh gas flow
- Soda lime absorption
How are Breathing circuits classified (2)?
- Presence of a reservoir bag
- Presence of rebreathing
A term for Non-Rebreathing system
Mapleson
A term for Rebreathing system
Circle
CO2 Absorption
Allows rebreathing of exhaled volume of gas and FGF determines the degree of rebreathing
What is compound A?
Soda Lime converts Sevoflurane to CF2=C(CF3)OCH2F, a vinyl ether called “Compound A,
Name an alkali-free absorbent used in CO2 absorption
Calcium Hydroxide
What does a hardener do in a CO2 Absorption?
A hardener is added to CO2 absorbent b/c some granules within are fine and fragment easily creating dust which can cause system to malfunction
What is the ideal granule size of CO2 absorbent?
The ideal size is 2.5 mm or 4-8 mesh
What does an indicator do in the CO2 Absorbent?
It will indicate a color change when the soda lime is exhaused..b/c the pH granules change; ethyl violet is an indicator and changes to purple when exhausted
Show me the chemistry of Soda Lime
Chemistry of Soda Lime
CO2 + H2O ↔ H2CO3
H2CO3 + NaOH ↔ Na2CO3 + H2O + energy
Na2CO3 + Ca(OH) 2 → CaCO3 + NaOH
