Background Synchronized noninvasive ventilation (sNIPPV) might be superior to fixed time-cycled modes. Several body-surface respiratory signals have been suggested for noninvasive synchronization. However, the quality and utility of such signals have not been evaluated comprehensively.

Methods Respiratory signals in spontaneously breathing preterm infants (n=9) were recorded simultaneously (i) respiratory impedance plethysmography (RIPabd & RIPchest), (ii) Graseby Capsule (GC), (iii) a strapless piezo sensor (Piezo), and (iv) a fluid-filled esophageal pressure catheter (Pes). A total of 5813 breaths were evaluated. Subsequently, periods of good-quality signals on all recorded channels were analyzed with regard to signal availability, time lag relative to Pes, and variability of signals.

Results In all breaths studied 38 % of breaths showed valid signals in all channels without movement artefacts. Of all signals, RIPabd indicated the onset of inspiration earliest in time relative to the onset of inspiration detected by Pes (–52±160ms). RIPabd-signal was followed by GC-signal (+10±177ms). Both signals had a reasonable variability. The Piezo-signal was very sensitive and prone to large variations (+70±1372ms compared to Pes). RIPchest indicated inspiration later than RIPabd (+104±212ms).

Conclusion These data indicate that both RIPabd and Graseby Capsule are suitable surface sensors for non-invasive synchronization of NIPPV whereas a Piezo sensor exhibited large variability. Signals from all studied sensors were only suitable for a limited amount of time.