Crtical Care and Shock Journal

Comparing asynchrony in two noninvasive ventilators

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Objectives: Noninvasive ventilation (NIV) is commonly used in respiratory failure as an alternative to more invasive tracheal intubation. A major challenge of NIV is synchronization between the patient’s spontaneous breathing efforts and the support of the ventilator.

Design: We compared simulator-ventilator synchrony characteristics of two ventilators during noninvasive ventilation, using an adult lung simulator under three leak configurations.

Setting: Bench test with lung simulator.

Patients and participants: Active Servo Lung with the bellavista 1000 NIV (bellavista NIV) and Respironics V60 (V60).

Interventions: Three configurations simulating different levels of unintended leak were tested for each ventilator: No Leak, Continuous Leak, and Inspiratory Leak. The recorded pressure and volume waveforms were analyzed to quantify trigger delay, triggering pressure-time product (PTPtrig), pressure-time product at 300 ms (PTP300), insufflation time excess (TI,excess), and time required to reach 63.2% (Texp,63) and 95.0% (Texp,95) of expired tidal volume (VTexp) for each ventilator in all three leak scenarios.

Measurements and results: Trigger delays for the bellavista NIV were significantly lower for all three leak conditions (p<0.0001) and it responded faster to simulated muscle activity compared to the V60. Both the bellavista NIV and V60 experienced no auto-trigger or missed trigger events. The bellavista NIV reached target pressure values more quickly as indicated by significantly higher PTP300 for all three leak conditions (p<0.0001) and had significantly shorter TI,excess (p<0.0001). The bellavista NIV experienced no delayed cycling breaths while more than 25% of V60 breaths showed delayed cycling during inspiratory leak tests.

Conclusions: The bellavista NIV showed significantly lower trigger delays for all three leak conditions, reached target pressure values more quickly (i.e., higher PTP300), and showed superior cycling performance (i.e., lower trigger delay) compared to the V60, which may improve patient-ventilator synchrony and patient comfort.

Ross C. Freebairn, Andreas D. Waldmann, Christian Remus, Michael J. Pedro

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