Comparison of work of breathing using drawover and continuous flow anaesthetic breathing systems in children*

We compared the work of breathing under general anaesthesia in children using drawover and continuous flow anaesthetic systems. A pilot study was conducted in four children weighing > 20 kg in whom it would usually be considered appropriate to use breathing systems designed for adult anaesthesia. The pilot study compared work of breathing using the Mapleson D breathing system and the Triservice Anaesthetic Apparatus (TSAA). Work of breathing was calculated using the modified Campbell technique that calculates work using a pressure volume loop derived from oesophageal pressure and airway gas volume measurements. We found no difference in the work of breathing when comparing the Mapleson D and the TSAA in children > 20 kg. Following completion of the pilot study, we conducted a study on 10 children weighing between 10 and 20 kg comparing work of breathing using the Mapleson F breathing system and the TSAA. We found no significant difference in the work of breathing between the Mapleson F and the TSAA for these children. The TSAA can therefore be recommended for use down to a lower weight limit of 10 kg.