Breathing Systems Flashcards
Which is the most efficient Mapleson system for spontaneously breathing patients?
Mapleson A (magill)
What % of minute volume does the Mapleson A require of FGF for spontaneous ventilation?
It will work with minimal re-breathing at FGF of 70% of minute volume in spontaneous ventilation
Is scavenging of exhaled gases easy in the Mapleson A?
No.
Scavenging requires an appropriate system to be connected to the APL valve but this is not particularly more or less easy to achieve for the Mapleson A than other systems.
What is the coaxial version of the Mapleson A?
Lack system
Is the Mapleson A efficient for controlled ventilation?
No
Can the Jackson-Rees modification to Mapleson E (making it mapleson F) be used with a normal reservoir 0.5L bag?
The Jackson-Rees modification to the Mapelson E (making it a Mapelson F) includes a specialised reservoir bag with an opening at the end to allow a controlled leak and variable PEEP
Do reservoir bags prevent wastage of FGF during the expiratory pause?
Yes
Can reservoir bags provide a rough visual assessment of the volume of ventilation?
Yes
Why are reservoir bags required?
Because the anaesthetic machine can not provide the peak inspiratory flow required in normal respiration
Are the D, E and F systems all T pieces?
Yes
When is the Magill system most efficient?
For spontaneously breathing patient at a FGF of 70% of minute ventilation
What FGF does the Bain require to prevent rebreathing?
The Bain system (a Mapelson D variant) requires a FGF 2-3x minute ventilation to prevent rebreathing.
What does the rate of change of vapour concentration in the circle system depend on?
Circle system volume
FGF rate
Net gas uptake
Why is the Magill inefficient during controlled ventilation?
Because much of the gases are vented via pop-off valve
What is the size of soda lime granules?
4-8 mesh
What does baralyme contain?
Calcium hydroxide plus barium hydroxide
What will make soda lime produce more compound A?
Low FGF
Does dry soda lime absorb more CO2?
No. Water is generated by the overall reaction of CO2 with soda lime but it’s presence or absence does not influence performance of the compound.
What does carbon dioxide react with first in soda lime?
Sodium and potassium hydroxide first
Can re-breathing be prevented in the Mapleson D during controlled ventilation?
Re-breathing can be prevented from occurring in controlled ventilation with the Mapelson D but this is dependent on adequate fresh gas flow
Can volatile concentration in the breathing system be higher than the dial setting of the vaporiser at steady state?
The delivered volatile concentration is, in practice, rarely the same as the dial setting but it cannot exceed it except in the few moments after the vapouriser is dramatically turned down or switched off and the system is re-equilibrating.
In the circle system with a FGF <1L (N2O:O2 = 66:34), what happens to FiO2 in the circle over time?
In low flow operation of the circle, particularly where the oxygen volume supplied falls towards or below metabolic requirements, the FiO2 will steadily fall and the circle will empty; N2O rapidly equilibrates and so uptake of N2O will not exceed that of oxygen so increase in oxygen concentration does not result.
What FGF does the bain need to prevent re-breathing in spontaneous ventilation?
3 x minute volume
What happens to dead space gas in the Magill system during spontaneous ventilation?
It is preserved
