Dr. David Lyness
Breathing systems can usually
be classified into two groups:
Semi-open systems include those in the Mapleson classification; they rely on their gas dynamics to ensure that CO2 is washed out and not rebreathed.
An open system includes the Schimmelbusch mask and chloroform.
A closed system is one like a circle system used with intubated patients.
The efficiency of a breathing system is defined by the lowest fresh gas flow that prevents the patient rebreathing CO2.
Co-axial version of D, with FGF
down the centre surrounded by
an expiratory limb
The co-axial version of Magill where
the expiratory limb is in the centre
1. Systems with CO2 washout (open and semi-open)
2. Systems with CO2 absorption (closed and semi-closed)
FGF = Fresh Gas Flow
IPPV = Intermittent Positive Pressure Ventilation
SV = Spontaneous Ventilation
MV = Minute Volume
PEEP = Peak End Expiratory Pressure
Co-Axial - One tube within another tube
The key is figuring out where the APL valve is and how the system is used to effectively rid the system of exhaled gases.
The most commonly used: A (Magill) for SV and D (Bain) for IPPV - then C for resus.
EFFICIENCY OF SV
A > D,E > C > B
EFFICIENCY OF IPPV
D,E > B > C > A
Bain's is useful where the patient is not accessible such as in the MRI suite
Most now are BAIN type and FGF enters at machine end