American Review of Respiratory Disease

We studied the response time (RT) and reliability of three neonatal patient-triggered ventilator (PTV) systems: the Draeger Babylog® 8000, the Bear Cub® enhancement module (CEM), and the Infrasonics Star Sync.® In 10 adult rabbits, airway flow and pressure recordings showed the RT of the Star Sync to be shorter than that of the Bear CEM (53 ± 13 versus 65 ± 15 ms, p < 0.05), and both were shorter than that of the Babylog (95 ± 24 ms, p < 0.01) by ANOVA. The RT of the Bear CEM and the Babylog increased significantly at decreased trigger sensitivity settings. All ventilators triggered successfully on assist-control (A/C). However, the Babylog had a higher rate of asynchrony on SIMV (30 ± 25%) than the Bear CEM (1.1 ± 0.3%) and the Star Sync (1.2 ± 0.4%), p < 0.01. In 10 infants with respiratory failure, recordings of airway flow and pressure were made at ventilator inspiratory time (Ti) settings of 0.3, 0.4, and 0.5 s on assist-control and on SIMV at rates of 15, 30, 45, and 60 breaths/min. The Star Sync and Bear CEM triggered successfully on A/C (100%) and had low rates of asynchrony on SIMV (1 to 3%). The Babylog had a lower success rate on A/C (70 ± 12%) and a higher rate of asynchrony on SIMV (29 ± 30%) than the other two ventilators; p < 0.01. The lower reliability of the Babylog was due to its variable refractory period (0.2 to 0.5 s, to equal the set Ti). At Ti ⩾ 0.4 s, this caused missed ventilator triggering on alternate spontaneous breaths, which resulted in phase locking in asynchrony on SIMV at rates of 45 and 60 breaths/min. The Star Sync and Bear CEM had shorter RT than previously reported neonatal PTV systems, and the Babylog had a unique but potentially correctable design feature that adversely affected its reliability.

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