Bench tests of simple, handy ventilators for pandemics: Performance, autonomy, and ergonomy

Abstract

BACKGROUND: It has been pointed out that in the wake of a virulent flu strain, patients with survivable illness will die from lack of resources unless more ventilators are made available. Numerous disaster-type ventilators are available, but few evaluations have been performed. OBJECTIVE: To compare simple, lightweight, and handy ventilators that could be used in the initial care of patients with respiratory distress. METHODS: We bench-tested 4 volume-cycled ventilators (Carevent ALS, EPV100, Pneupac VR1, and Medumat Easy) and 2 pressure-cycled ventilators (Oxylator EMX and VAR-Plus). We studied their general physical characteristics, sonometry, gas consumption, technical performance, ergonomy, and user-friendliness. With a test lung we assessed performance at FIO2 of 0.50 and 1.0, set compliance of 30, 70, and 120 mL/cm H2O, and set resistance of 5, 10, and 20 cm H2O/L/s. To study user-friendliness and ergonomy we conducted, in randomized order, 7 or 8 objective, quantitative tests and 2 subjective tests. RESULTS: Compliance and resistance strongly affected tidal volume with the pressure-cycled ventilators (from 418±49 mL to 1,377 ± 444 mL with the VAR-Plus, at the lowest pressure level), whereas the volume-cycled ventilators provided a consistent tidal volume in the face of changing test lung characteristics. CONCLUSIONS: We are concerned that the pressure-cycled ventilators did not provide a consistent tidal volume, and under certain conditions the volume delivered would be unsafe (too large or too small). Most of the volume-cycled ventilators proved to be technically efficient and reliable. Their reliability, portability, and ease of use could make them valuable in natural disasters and mass-casualty events. © 2011 Daedalus Enterprises.