Trigger performance of mid-level ICU mechanical ventilators during assisted ventilation: a bench study.
OBJECTIVE
To compare the triggering performance of mid-level ICU mechanical ventilators with a standard ICU mechanical ventilator.


METHODS
Experimental bench study.


METHODS
The respiratory care laboratory of a university-affiliated teaching hospital.


METHODS
A computerized mechanical lung model, the IngMar ASL5000.


METHODS
Ten mid-level ICU ventilators were compared to an ICU ventilator at two levels of lung model effort, three combinations of respiratory mechanics (normal, COPD and ARDS) and two modes of ventilation, volume and pressure assist/control. A total of 12 conditions were compared.


RESULTS
Performance varied widely among ventilators. Mean inspiratory trigger time was <100 ms for only half of the tested ventilators. The mean inspiratory delay time (time from initiation of the breath to return of airway pressure to baseline) was longer than that for the ICU ventilator for all tested ventilators except one. The pressure drop during triggering (Ptrig) was comparable with that of the ICU ventilator for only two ventilators. Expiratory Settling Time (time for pressure to return to baseline) had the greatest variability among ventilators.


CONCLUSIONS
Triggering differences among these mid-level ICU ventilators and with the ICU ventilator were identified. Some of these ventilators had a much poorer triggering response with high inspiratory effort than the ICU ventilator. These ventilators do not perform as well as ICU ventilators in patients with high ventilatory demand.
Ferreira
Juliana C
JC
Departments of Respiratory Care and Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA 02114, USA.
Chipman
Daniel W
DW
Kacmarek
Robert M
RM
D004867:Equipment Design; D007362:Intensive Care Units; D008954:Models, Biological; D012122:Ventilators, Mechanical / Q000145:classification*