A model lung with the capacity for simulated spontaneous breathing.

A model lung is described which can be ventilated artificially but which also has the capacity to breathe spontaneously at pre-determined rate and depth. It appears particularly suitable for studying the performance of ventilators which interact with the patient, including those with the facility for triggering, synchronization and mandatory minute ventilation. An additional facility is the blocking of a simulated spontaneous inspiration during an artificial inflation (" Hering -Breuer reflex").