Triggering delay time and work of breathing in three paediatric patient-triggered ventilators

To compare the effectiveness of three patient-triggered ventilators by evaluating triggering delay time and pressure-volume loops during initiation of inspiration.

In a two-part study, a model lung was used in part 1 and 20 children, after tracheal intubation, in part 2. Triggering delay time and work of breathing (WOB) during pressure support ventilation using three patient-triggered ventilators: Servo Ventilator 300, VIP Bird, and SLE 2000 Neonatal Ventilator. Triggering delay time was from the beginning of negative deflection in the oesophageal pressure trace, to the onset of inspiration. The WOB was estimated directly by measuring the oesophageal pressure-volume loop.

The Servo demonstrated superior triggering delay time and reduced WOB in the model study. The VIP Bird demonstrated shorter triggering delay and reduced WOB in the clinical component of the study. In the model lung, triggering delay time in the Servo 300 [62 +/- 6 msec (mean +/- SD)] was shorter than that in the VIP Bird (76 +/- 7 msec) (P < 0.05), and WOB with the SLE 2000 (202 +/- 37 g.cm) was greater than with other ventilators, (Servo 300, 112 +/- 32 g.cm and VIP Bird 72 +/- 41 g.cm) (P < 0.05). In the clinical study, triggering delay time in the VIP Bird (52 +/- 19 msec) was shorter than in the other ventilators, Servo 300 (66 +/- 14 msec), SLE 2000 (68 +/- 65 msec) (P < 0.05). The Servo 300 (56 +/- 34 g.cm) required higher WOB than the other ventilators: VIP Bird (22 +/- 12 g.cm), SLE 2000 (14 +/- 3 g.cm) (P < 0.05).

Comparative model lung performance of these ventilators does not correspond with their clinical performance. In our clinical evaluation, the VIP Bird ventilator demonstrated superior performance with shorter triggering delay time, low WOB needed to initiate inspiration, and little air leak.