Breathing Circuits

Anesthetic Breathing Circuits

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22Mapleson Systems

A three-way T-tube is connected to the fresh gas outlet (F), a breathing bag (B) and a
reservoir tube (R). The other end of the reservoir tube is connected to the patient (P) and a spring-loaded expiratory valve (V).

22"A four-way block is attached to the fresh gas outlet (F). This block is connected to an outer reservoir tube (R) attached to the patient (P), an inner exhaust tube (E), a breathing bag (B) and a spring-loaded expiratory valve (V). Very similar in appearance to the modified Bain, except that the inner exhaust tube has a greater diameter than the fresh gas supply tube in the modified Bain"  One of the problems associated with the Magill (Mapleson A)  system has to do with waste gas scavenging. The Lack circuit noted above with its repositioning of the popoff valve facilitates scavenging of expired gases. Note the animation below:

30One of the problems associated with the Magill (Mapleson A)  system has to do with waste gas scavenging. The Lack circuit noted above with its repositioning of the popoff valve facilitates scavenging of expired gases.  22"The Lack circuit is essentially similar in function to the Magill, except that the expiratory valve is located at the machine-end of the circuit, being connected to the patient adapter by the inner coaxial tube." -"Inspiration -The valve closes and the patient inspires fresh gas from the outer reservoir tube. Expiration - The patient expires into the reservoir tube. Toward the end of expiration, the bag fills and positive pressure opens the valve, allowing expired gas to escape via the inner exhaust tube. Expiratory pause - Fresh gas washes the expired gas out of the reservoir tube, filling it with fresh gas for the next inspiration."

22Inspiration -The patient inspires fresh gas from the reservoir tube. Expiration - The patient expires into the reservoir tube. Although fresh gas is still flowing into the system at this time, it is wasted as it is contaminated by expired gas. Expiratory pause - Fresh gas washes the expired gas out of the reservoir tube, filling it with fresh gas for the next inspiration.

38, 29Mapleson Type F: Spontaneous Ventilation (left); Controlled Ventilation (right): "Gas Disposition at End Expiration"

 

38, 29Mapleson Type D: Spontaneous Ventilation (left); Controlled Ventilation (right): "Gas Disposition at End Expiration"

 

Mapelson D (Left) and as coaxially modified (Bain Circuit) (Right)

Mapleson System Summary

"Gas Disposition at end-expiration during spontaneous (left) and controlled (right) ventilation in circuits A-F, FEF, fresh gas flow"29

 

 

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