Brett Manley from Melbourne is now the person in the world with the greatest trial experience in the use of high flow nasal cannulae in the newborn. He has been the HIPSTER, and is now the HUNTER, I can’t find an acronym for his first, post-extubation trial, but it was probably the HEXmasTER or something cleverer than that. This study is the latest (and he assures me the last) in his series of multicentre trials of high flow nasal cannula use.
***UPDATE: Brett tells me that the post-extubation trial was called HIPERSPACE, which maybe he can un-acronym for us one day and explain…. or not, lets just leave it ineffable***
In this study (acronym HUNTER) infants in what I would call level 2 units (that is they don’t plan to deliver kids less than 32 weeks, and don’t keep kids who need more than transient invasive ventilation) who had respiratory distress, were randomized, as initial method for respiratory support, to receive either standard CPAP, at 6 cmH2O, or high flow cannulae at 6 liters per minute. The study was registered as ACTRN12614001203640 and the protocol published here.
Infants in level 2 centers were randomized if they were less than 24 hours old, were over 31 weeks gestation, and needed respiratory support. If they had CPAP for more than 2 hours they were excluded. This was a non-inferiority trial, which means that they thought that high-flow had some advantages (ease of use and comfort), but those advantages were only of interest if there was no inferiority in respiratory outcomes.
The primary outcome of the trial was “treatment failure”, which was defined as needing progressive increases in support up to 8 (litres or cmH2O) and any of the following within 72 hours: FiO2 of more than 0.4, respiratory acidosis (pH<7.2 with pCO2>60), severe apnea (more than 1 an hour), needing intubation, or needing transport to a level 3 NICU.
The high-flow group had more failures and was inferior to CPAP, just over 20% of the high-flow group failed as opposed to 10% of the CPAP babies. Babies needed to be on respiratory support for a longer duration (median 20 vs 15 hours) if they were started on high flow.
On the other hand, as all hospitals had to have CPAP available in order to be part of the trial; when they failed high-flow the babies could be switched to CPAP, and they were therefore not much more likely to be intubated (8.1% of high-flow vs 6.4% CPAP) or transferred to tertiary care (10.2% vs 8.6%). Duration of hospital stay was the same in each group.
I guess this means that if you are in a level 2 nursery with CPAP available, you could try high-flow first if you wished, and then switch to CPAP if it is not working well, without the babies coming to any harm. You will on average have to give the babies respiratory support for longer, but they will get home to their families at about the same time.
This is the kind of patient centered research that we need in neonatology. Thanks Brett, and all the other Hunters. (Except those with guns).
**I just updated my previous post after receiving the full text of the previous publication that I mentioned, which now looks like a separate study comparing the outcomes of 2 cohorts**