Subject-ventilator synchrony during neural versus pneumatically triggered non-invasive helmet ventilation

Intensive Care Med. 2008 Sep;34(9):1615-23. doi: 10.1007/s00134-008-1163-z. Epub 2008 May 30.


Objective: Patient-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.

Design: Randomized, single-blinded, experimental study.

Setting: University Hospital. PARTICIPANTS AND SUBJECTS: Seven healthy human volunteers.

Interventions: Pneumatic triggering and cycling-off were compared to neural triggering and cycling-off during NIV delivered with the helmet.

Measurements and results: Triggering 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).

Conclusions: The 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Equipment Design
  • Female
  • Head Protective Devices*
  • Humans
  • Male
  • Patient Satisfaction*
  • Positive-Pressure Respiration / instrumentation*
  • Positive-Pressure Respiration / methods
  • Respiration
  • Single-Blind Method