<prompt> Best spontaneous breathing circuit is:Mapleson AMapleson DMapleson EMapleson F  <response>: Ref: Ajay Yadav !v Short Textbook of Anaesthesia, Page 27Explanation:BREATHING CIRCUITSBreathing circuits connect patient to anaesthesia machine.They are classified into:Open systems: Obsolete technique e.g.: Schimmelbusch mask, open drop anaesthesia.Semi-open systems.Semi-closed systems: e.g.: Mapleson circuits.Closed systems: No gas escapes to atmosphere, exhaled gases after absorption of carbon dioxide can be reused, e.g.: Circle system, To and fro closed system.SEMICLOSED CIRCUITSThese circuits were described by Mapleson.Hence, known as Mapleson circuits.Divided into 5 types: A, B, C, D and E.Characteristics of Semiclosed Mapleson CircuitsCircuitFresh gas HowFeaturesSpontaneousControlledType A Magill CircuitEqual to minute volume2xminutc volume Circuit of cheque tor spontaneous ventilationType B Obsolete. No mere usedType CWater Circuit Obsolete. No more usedType DBain Circuit2.5 x minute volume1.6 x minute volume Circuit of choice for controlled ventilation Most commonly used circuit in anaesthesiaType EAvres T piece Pediatric circuit Obsolete, No more usedType F Jackson Rees Circuit3 x minute volume2 x minute volume Commonly used in Pediatric circuit 