A bench study of intensive-care-unit ventilators: new versus old and turbine-based versus compressed gas-based ventilators.
OBJECTIVE
To compare 13 commercially available, new-generation, intensive-care-unit (ICU) ventilators in terms of trigger function, pressurization capacity during pressure-support ventilation (PSV), accuracy of pressure measurements, and expiratory resistance.


METHODS
Bench study at a research laboratory in a university hospital.


METHODS
Four turbine-based ventilators and nine conventional servo-valve compressed-gas ventilators were tested using a two-compartment lung model. Three levels of effort were simulated. Each ventilator was evaluated at four PSV levels (5, 10, 15, and 20 cm H2O), with and without positive end-expiratory pressure (5 cm H2O). Trigger function was assessed as the time from effort onset to detectable pressurization. Pressurization capacity was evaluated using the airway pressure-time product computed as the net area under the pressure-time curve over the first 0.3 s after inspiratory effort onset. Expiratory resistance was evaluated by measuring trapped volume in controlled ventilation.


RESULTS
Significant differences were found across the ventilators, with a range of triggering delays from 42 to 88 ms for all conditions averaged (P < 0.001). Under difficult conditions, the triggering delay was longer than 100 ms and the pressurization was poor for five ventilators at PSV5 and three at PSV10, suggesting an inability to unload patient's effort. On average, turbine-based ventilators performed better than conventional ventilators, which showed no improvement compared to a bench comparison in 2000.


CONCLUSIONS
Technical performance of trigger function, pressurization capacity, and expiratory resistance differs considerably across new-generation ICU ventilators. ICU ventilators seem to have reached a technical ceiling in recent years, and some ventilators still perform inadequately.
Medical Intensive Care Unit, AP-HP, Centre Hospitalier Albert Chenevier-Henri Mondor Hospital, 51 Avenue du Maréchal de Lattre de Tassigny, 94010 Creteil, France. arnaud.thille@hmn.aphp.fr
Arnaud W
AW
Thille
Aissam
A
Lyazidi
Jean-Christophe M
JC
Richard
Fabrice
F
Galia
Laurent
L
Brochard
D004867:Equipment Design; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D008954:Models, Biological; D012121:Respiration, Artificial / Q000295:instrumentation* / Q000592:standards*; D014939:Work of Breathing / Q000502:physiology