TY - JOUR T1 - Bench Assessment of Expiratory Valve Resistance of Current ICU Ventilators in Dynamic Conditions JF - Respiratory Care SP - 610 LP - 618 DO - 10.4187/respcare.08098 VL - 66 IS - 4 AU - Alexandre Pinède AU - Martin Cour AU - Florian Degivry AU - Bruno Louis AU - Laurent Argaud AU - Claude Guérin Y1 - 2021/04/01 UR - http://rc.rcjournal.com/content/66/4/610.abstract N2 - BACKGROUND: We hypothesized that the lack of benefit of setting a low versus a high PEEP in patients with ARDS may be due in part to differences in the dynamic behavior of the expiratory valve in ventilators. We tested this hypothesis by conducting a bench comparison of the dynamic behavior of expiratory valves on ICU ventilators currently in use.METHODS: We attached 7 ICU ventilators (C5, C6, Carescape, PB980, ServoU, V500, and V680) to the ASL 5000 lung model (passive condition with compliance 20 mL/cm H2O and resistance 5 cm H2O/L/s) and set in volume controlled mode (tidal volume 0.8 L, breathing frequency 10 breaths/min). Flow and pressure were measured just before the exhalation valve. At PEEP of 5, 10, and 15 cm H2O, the median instantaneous expiratory resistance, the time to valve opening, and the pressure time products above or below the values of PEEP (expressed in cm H2O × s) were determined.RESULTS: Median instantaneous expiratory resistance values differed between the ventilators and PEEP settings with a significant interaction: at PEEP 5 cm H2O, the median (interquartile range) expiratory resistance values were 3.9 (3.5–4.7), 3.0 (3.0–3.1), 20.9 (15.8–24.9), 27.4 (26.5–43.2), 13.8 (13.6–13.9), 4.4 (4.0–4.6), and 34.3 (33.7–33.8) cm H2O/L/s, for the C5, C6, Carescape, PB980, ServoU, V500, and V680, respectively. For all the PEEP settings, the corresponding times to valve opening were 0.080 (0.077–0.082), 0.082 (0.080–0.085), 0.110 (0.105–0.110), 0.100 (0.085–1.05), 0.072 (0.062–0.072), 0.145 (0.115–0.150), and 0.075 (0.070–0.080) s, respectively, and pressure-time products were 2.8 (2.1–7.4), 6.8 (6.7–7.3), 2.4 (2.1–2.4), 3.5 (2.7–3.6), 1.8 (1.8–2.1), 2.8 (2.7–2.9), and 5.7 (5.4–5.9) cm H2O × s, respectively.CONCLUSIONS: The resistance of active expiratory valves differed significantly between the 7 ICU ventilators tested. ER -