Anaesthesia True about mapleson D circuit is A FGF for spontaneous ventilation is equal to minute ventilation B Expiratory valve is closer to patient C 1.8 times the minute ventilation is required gas flow for controlled ventilation. D Preferred circuit for spontaneous ventilation. 💡 Explanation True about mapleson D circuit is ✓ Correct Answer: C. 1.8 times the minute ventilation is required gas flow for controlled ventilation.