Figure 3

Modification of a previously described bench model of positive-pressure ventilation with an unprotected airway [3,33]. The upper airway was provided by a new intubation manikin head. The tracheal outlet of the manikin head was connected to a mechanical test lung (lung compliance 50 ml/cmH₂O; airway resistance 16 cmH₂O/l per s). The oesophageal outlet of the manikin head was connected to an adjustable PEEP valve, which represented lower oesophageal sphincter pressure. A second outlet from the PEEP valve was connected to a paediatric pneumotachometer in order to record oesophageal peak pressure and gastric inflation. A flow sensor was inserted between the self-inflating bag and the airway device under investigation; another flow sensor was inserted into the simulated trachea. The flow sensors were connected to respiratory monitors in order to measure ventilation variables.