True about mapleson D circuit is
Expiratory valve is away from the patient end in mapleson D circuit. 3 times minute ventilation is required for spontaneous ventilation.
Mapleson A is the preferred circuit for spontaneous ventilation.
FGF for spontaneous ventilation is equal to minute ventilation
Expiratory valve is closer to patient
1.8 times the minute ventilation is required gas flow for controlled ventilation.
Preferred circuit for spontaneous ventilation.