Let it flow?

There are now accumulating a few trials of the use of high flow nasal cannulae (HFNC) as a means of respiratory support in the newborn Collins CL, Holberton JR, Barfield C, Davis PG: A randomized controlled trial to compare heated humidified high-flow nasal cannulae with nasal continuous positive airway pressure postextubation in premature infants. J Pediatr 2012. . This new trial is an RCT of 132 infants under 32 weeks gestation who were enrolled when they were extubated, and given either CPAP or HFNC. They had objective criteria for extubation failure, which occurred in 15 (22%) of the HFNC group compared with 22 (34%) of the NCPAP babies. Which was consistent with a chance effect, but they did have much lower nasal trauma score 3.1 (SD 7.2) with HFNC compared to NCPAP 11.8 (SD 10.7), P < .001. The study was designed to show if HFNC were better than NCPAP, and it seems to show that there probably wasn’t a real difference. This study used the Vapotherm system, starting at 8 litres per minute or CPAP at either 7 or 8 depending on the FIO2.

It is reassuring that there certainly did not seem to be a substantially worse outcome with the HFNC. Despite the fact that, as reviewed by Carlo Dani and his associates, HFNC deliver “continuous distending pressure (CDP) in patients with closed mouth, whose value is proportional to the delivered flow only in smaller infants; the CDP delivered by HFNC is unpredictable and present large inter-patient and intra-patient variability” so maybe as long as there is some CPAP after extubation it doesn’t matter very much how high the pressure is, or maybe the improved comfort outweighs the fact that some babies might have lower pressures delivered.

The only previous RCT post-extubation that I am aware of showed higher extubation failure with the HFNC, but that was a non-heated system, used at flow rates between 1.4 and 1.7 litres a minute, with a sample size of only 30 babies.

The evidence is still not very strong to use HFNC post-extubation, but it does seem that it may turn out to be a reasonable alternative, but you probably need a heated system with very high flows.

About Keith Barrington

I am a neonatologist and clinical researcher at Sainte Justine University Health Center in Montréal
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