Circuits

Clark Venable, M.D.

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  • A: McGill

  • B

  • C
  • D: Bain is modified D
  • E:
  • F: Jackson-Rees modification of Ayres T-piece

Possibility of rebreathing during spontaneous ventilation from least to most:

  • All Dogs Can Bite (spontaneous event)

Possibility of rebreathing during controlled ventilation from least to most:

  • Dog Bites Can Ache (after situation controlled)

 

Advantages of:

Open systems-like open drop ether

  • lightweight, portable
  • no complex equipment needed
  • usefull in situations of extreme need

    • Semi-open systems-like the Mapleson's

  • lightweight, portable
  • no valves, so resistance is low

    • Semi-closed- generic circle system used in OR every day

  • rebreathing is possible, therefore heat is conserved
  • CO2 absorber is employed so CO2 rebreathing is avoided, even at low flow rates

    • Closed Systems-APL valve closed

  • heat and anesthetic agents are conserved
  • saves money
  • good teaching guide for teaching uptake and distribution

    • What is the difference between semi-closed and semi-open systems?

    In the semi-closed system, there is partial rebreathing of carbon dioxide. If soda lime is not present in the semiclosed system, CO2 builds up.

     

    Summary table of anesthetic breathing systems

     System Reservoir Bag  Rebreathing  CO2 Absorber  Valves  Gas Inflow Rate 
     Open          
     Insufflation  No  No  No None  Unknown
     Open Drop  No  No  No  None  Unknown
     Semiopen          
     Mapleson A, B, C, D Yes No  No   One  >6 L/min
     Bain Yes No  No  One  >6 L/min
     Mapleson E No   No No   None  >6 L/min
     Jackson-Rees Yes No No   One  >6 L/min
     Semiclosed          
     Circle Yes  Partial  Yes  Three 3-6 L/min 
     Closed Yes  Total  Yes  Three 0.3-0.5 L/min 

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