Gestational age: an important influence on the success of patient triggered ventilation.

We have evaluated a new patient triggered (PT) ventilator which has been produced as suitable for neonatal use. This ventilator, the Draeger Babylog 8000, is triggered by airflow changes detected by a hot wire anemometer. Laboratory assessment demonstrated maintenance of tidal volume and absence of inadvertent PEEP at flow rates up to 20 l min-1 and rates of 120 breaths min-1. The ventilator was then used in both conventional and trigger mode in 14 pre-term infants. The results were compared with PT ventilation delivered by the SLE ventilator. At all inflation times studied, using the Draeger ventilator 100% of respiratory efforts were detected in the majority of infants. The trigger delay varied from a median of 80-100 ms and was significantly shorter than the trigger delay of the SLE system (P less than 0.05). Oxygenation improved on Draeger PT compared with conventional ventilation, however, only in infants more mature than 27 weeks gestation. We conclude the Draeger Babylog 8000 is an important advance in patient triggered ventilation, particularly at fast frequencies, but PT ventilation should still be restricted to relatively mature infants.