1. Dr.P.Karunanithi Dr.Gayathri SRM Medical college & Research centre Potheri kancheepuram Breathing circuits

2. Anesthetic gas exits the anaesthesia machine (via the common gas outlet) and then enters a breathing circuit. The function of the circuit is to deliver oxygen and anaesthetic gases to the patient and to eliminate CO2. 3. Classification This most basic classification of breathing systems divides them into open, semi-open, semi-closed or closed. 4. Ideal breathing circuit Simple and safe to use Delivers the right gas mixture Allows all methods of ventilation in all age groups Efficient Pressure relief Sturdy, small and light Allows easy removal of waste gases Easy to maintain with low running costs 5. Components Fresh Gas connection Patient connection Adjustable Pressure Limiting (APL) Valve Reservoir (Bag or Bellows) Tubing Waste gas connection 6. Open method FGF Reservoir bag X APL valve X Open is the old fashioned method of dropping ether or chloroform over a gauze or lint 7. open method Later modernised by the likes of the Schimmelbusch mask. 8. The Mapleson Alphabet The F was added later to the alphabet 9. Apl valve The valve disc is held in place by a weak spring, the tension on which can be adjusted by a screw mechanism, thereby adjusting the pressure required to open the valve. 10. Types of Semi- closed Circuit Systems Mapleson A or Magill System Mapleson A or Lack System Mapleson D or Bain System Mapleson F or Ayres T Piece System Mapleson F with APL Valve Mapleson C Bagging System 11. What FGFs are needed? Mapleson Systems Uses FGF SV FGF IPPV A Magill Lack Spontaneous Gen Anaesthesia 70-100 ml/kg/min 1X MV Min 3 x MV B Very uncommon, not in use today C Resuscitation Bagging Min 15 lpm D Bain Spontaneous IPPV, Gen. Anaes 150-200 ml/kg/min 70-100 ml/kg/min E Ayres T Piece Very uncommon, not in use today F Jackson Rees Paediatric