AMIR SALAH
MODERN ANAESTHETIC
MACHINE
2 of 4
CLASSIFICATION OF BS
I. MODE OF RESPIRATION
1. Spontaneous : patient use his own muscles of
respiration ; this needs neuronal and muscle power
2.Controlled :This needs no resistance to ventilation
which can be achieved by means of : MR, central
inhibition (anaesth,opioid,illness) or adaptation or
cooperation in ICU patients.
II.RATE OF FGF
1. Low FGF : < ½ MV or < alveolar v.
2. High FGF := or > MV
III.REBREATHING
1.Total rebreathing.
2.Partial rebreathing.
3.No rebreathing.
IV. OPEN OR CLOSED
1. Open : Insufflation ?
2. Semi-open : Open-drop ansth.?
3. Semi-closed :Mapleson ?
4. Closed.
V. VALVES AND RESERVOIR PRESENCE
1. No valve or reservoir bag
2. Single adjustable spill valve and reservoir
bag
3. In addition one or more unidirectional
valves ,this group can be categorized into :
With CO2
Without CO2
V. MAPLESON’S CIRCUITS
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In 1954 Mapleson described and analyzed five
different semi-closed anaesthetic systems and
are designated A,B,C,D,E. Willis and co-workers
added the F system to the five original in 1975
In this systems there is a steady flow of FGF
supplying a variable and cyclical tidal flow,in
order to reach NO REBREATHING
by alternating its components. Which are ?
Components of Mapleson’s
1. Breathing tubes.
2. Fresh Gas Inlet.
3. Adjustable Pressure-Limiting Valve (APL)
Pressure Relief Valve ;Pop-Off Valve
4.Reservoir Bag (Breathing Bag).
1.Breathing tubes
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Corrugated black (elephant tubing) BT made of
rubber (reused) or plastic (disposable) with large
diameter (22mm) creates a low resistance
pathway which maintains its internal lumen
patent when angled acutely.
BT volume must be more than peak inspiratory
flow(30L/min) or in combination with bag.
2.Fresh Gas Inlet
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The relative position of FGI is a key
differentiating factor in Mapelson’s
performance.
FGI is in the beginning of “A” and in the
end of others.
3.Adjustable pressure-limiting valve
APL valve present near patient in Mapleson’s A,B,C
and on the other end in D,E,F.
If the gas flow is greater than the combined uptake of
the patient and circuit compliance ,so the excess gas
must be allowed to go out through APL valve
controlling the pressure buildup.
The exiting gas enter the operating room or preferably
a scavenging system.
The APL valve should be fully open during spontaneous
respiration. Assisted and controlled ventilation require
positive pressure during inspiration to expand lungs.
Partial closure of the APL valve limits gas exit,
permitting positive pressure during bag compression
APL VALVE
Unidirectional Valve
AMBU
4.Reservoir Bag
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It presents in the beginning of “A” and at the end of
the rest except “E” without.
RB has elastic characteristics up to 5 K pascal(60
cmH2O).It is designed to increase in compliance as
volume increase .Three distinct phases are recognized
in RB filling
1. full of 3 L capacity 2.Pressure rises to a peak press.
3.Plateau pressure
This ceiling effect helps to protect the lungs if APL
valve is left in close position.
A danger of RB is the possibility of bag material to be
sucked across inlet to prevent this a metal or a plastic
basket is fitted into the connector.
function of RB
1. It allows BS to meet peak inspiratory
flows that are greater than FGF.
2. It allows manual artificial ventilation.
3. monitors respiration in spontaneous vent
4. It allows testing for FGF and circuit leak
5. Increases compliance of system if there is an
obstruction to the outflow.