• Onnen Moerer, Jennifer Beck, Lukas Brander, Roberta Costa, Michael Quintel, Arthur S Slutsky, Fabrice Brunet, and Christer Sinderby.
• Interdepartmental Division of Critical Care, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada.
• Intensive Care Med. 2008 Sep 1; 34 (9): 161516231615-23.

ObjectivePatient-ventilator synchrony during non-invasive pressure support ventilation with the helmet device is often compromised when conventional pneumatic triggering and cycling-off were used. A possible solution to this shortcoming is to replace the pneumatic triggering with neural triggering and cycling-off-using the diaphragm electrical activity (EA(di)). This signal is insensitive to leaks and to the compliance of the ventilator circuit.DesignRandomized, single-blinded, experimental study.SettingUniversity Hospital. PARTICIPANTS AND SUBJECTS: Seven healthy human volunteers.InterventionsPneumatic triggering and cycling-off were compared to neural triggering and cycling-off during NIV delivered with the helmet.Measurements And ResultsTriggering and cycling-off delays, wasted efforts, and breathing comfort were determined during restricted breathing efforts (<20% of voluntary maximum EA(di)) with various combinations of pressure support (PSV) (5, 10, 20 cm H(2)O) and respiratory rates (10, 20, 30 breath/min). During pneumatic triggering and cycling-off, the subject-ventilator synchrony was progressively more impaired with increasing respiratory rate and levels of PSV (p < 0.001). During neural triggering and cycling-off, effect of increasing respiratory rate and levels of PSV on subject-ventilator synchrony was minimal. Breathing comfort was higher during neural triggering than during pneumatic triggering (p < 0.001).ConclusionsThe present study demonstrates in healthy subjects that subject-ventilator synchrony, trigger effort, and breathing comfort with a helmet interface are considerably less impaired during increasing levels of PSV and respiratory rates with neural triggering and cycling-off, compared to conventional pneumatic triggering and cycling-off.

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