When we performed the trial of nasal ventilation post-extubation in San Diego we used the Infantstar ventilator, synchronised to the babies’ respiratory efforts with a Graseby capsule stuck on the abdomen. Two other trials also used the same system, and one trial used a non-synchronised system, but did also show benefit. I thank that synchronisation is probably an advantage, as delivering a positive pressure breath while the infant makes an effort, and therefore probably has the glottis open, is probably more efficacious than delivering positive pressure while the infant is trying to exhale.
In this new study from Ulm (Huang L, et al. Effects of Synchronization during Noninvasive Intermittent Mandatory Ventilation in Preterm Infants with Respiratory Distress Syndrome Immediately after Extubation. Neonatology. 2015;108(2):108-14.) a crossover design was used with 2 hour periods synchronised (using a Graseby capsule) and 2 hours non-synchronised, immediately after extubation of small preterm infants. The synchronised periods showed improved gas exchange, and reduced respiratory effort (as defined by deflections in oesophageal pressure), the results are similar to others using similar systems. I don’t think there is an RCT comparing the 2 methods effects on clinical outcomes, but it seems logical to use synchronised nasal ventilation in preference as that has been most studied post-extubation, and shown to be preferable to CPAP for re-intubation rates. This study confirms some physiologic advantages.
The big problem is how to do it. The infantstar is no longer available, and we don’t have access to the Sophie ventilator used in the new study from Ulm. Some studies have reported using flow triggering, but I can’t see how that would work over any significant period of time, as leaks are huge and variable. The only available option looks like being the NAVA system, but that requires a substantial financial investment, both in ventilators and in the nasogastric tubes with the oesophageal electrodes. A comparative trial using the NAVA, to determine if any clinical outcomes are improved with synchronization, would permit us to know if that investment is worthwhile.