Slow Flow

I have worked in a couple of NICUs in the past where infants were placed on low flow room air by nasal cannulae. The idea, I was told, was that a bit of flow would help the babies to inhale. Now this never seemed to have any possible physiologic basis to me, and now two recent studies, both from Dublin, confirm that there are no detectable clinical effects.

The first is by O’Donnell and collaborators at the Coombe hospital, with colleagues from a second hospital in Prague. They randomized 78 babies <1500g birth weight to either get 1 liter per minute of air by nasal cannulae or no flow when they were coming off CPAP. The babies were followed for 120 hours to see if they failed weaning from CPAP and had to go back on CPAP or not. There were no benefits of any kind detected.

The second is from Hensey and others at the National Maternity Hospital just down the road. Their study was a short term crossover study to look at whether breathing patterns and apnea were different between getting a little air in the cannulae, (at 0.1 l/min), getting nothing in the cannulae, (they were left in place but disconnected), or getting a little oxygen in the cannulae (100% oxygen at 0.1 l/min). 3 hour intervals were recorded to see the number of desaturations. They basically showed in 14 babies less than 33 weeks gestation that low flow air did nothing to desaturations, that low flow oxygen reduces desaturations but many of the infants spent time over 95% saturation. Even on very low flow oxygen you do need to have your high saturation alarms switched on.

Low flow air does nothing, which I think is what they expected to find!

About Keith Barrington

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