RT Journal Article
SR Electronic
T1 Maintenance of airway pressure during filter exchange via autotrigging of mechanical ventilator
JF Respiratory Care
FD American Association for Respiratory Care
SP respcare.02892
DO 10.4187/respcare.02892
A1 Joakim Engström
A1 Henrik Reinius
A1 Camilla Fröjd
A1 Hans Jonsson
A1 Göran Hedenstierna
A1 Anders Larsson
YR 2013
UL http://rc.rcjournal.com/content/early/2013/11/26/respcare.02892.abstract
AB INTRODUCTION. Daily routine ventilator-filter exchange interrupts the integrity of the ventilator circuit. We hypothesized that this might reduce positive airway pressure in mechanically ventilated ICU patients, inducing alveolar collapse and causing impaired oxygenation and compliance of the respiratory system (CRS). METHODS. 40 consecutive ICU patients (PaO2/FIO2 ratio ≤ 300 mm Hg), mechanically ventilated with pressure regulated volume control or pressure support and PEEP ≥ 5 cm H2O. Before the filter exchange (baseline) tidal volume, respiratory rate, end-inspiratory plateau pressure and PEEP were registered. CRS was calculated, FIO2, blood pressure and pulse rate were registered and PaO2, PaCO2, pH and base excess were measured. Measurements were repeated 15 and 60 min after the filter exchange. In addition, a bench test was performed with a precision test lung with similar compliance and resistance as in the clinical study. RESULTS. The exchange of the filter took 3.5 ± 1.2 s (mean±SD). There was no significant change in PaO2 (89 ± 16 mm Hg at baseline vs. 86 ± 16 mm Hg at 15 min and 88 ± 18 mm Hg at 60 min, P = .24) or in CRS (41 ± 11 mL/cm H2O at baseline vs. 40 ± 12 mL/cm H2O at 15 min and 40 ± 12 mL/cm H2O at 60 min, P = .32). The bench study showed that auto-triggering by the ventilator at disconnecting from the expiratory circuit kept the tracheal pressure above PEEP for at least 3 s with pressure controlled ventilation. CONCLUSIONS. This study showed that a short disconnection of the expiratory ventilator circuit from the ventilator during filter exchange was not associated with any significant deterioration in lung function 15 and 60 min later. This result may be explained by auto-triggering of the ventilator with high inspiratory flows during the filter exchange, maintaining the airway pressure.