Letting a Baby's Own Breathing Signal Guide the Ventilator After Diaphragmatic Hernia Surgery

What a small London study by Shetty and colleagues found when babies recovering from diaphragmatic hernia repair tried a breathing-machine setting called NAVA (European Journal of Pediatrics, 2026)

After surgery for a congenital diaphragmatic hernia, most babies need a breathing machine while their small lungs recover; in a small London study, nine such babies each spent four hours on the usual setting and four hours on NAVA, a setting that follows the baby's own breathing signal. All nine had a better oxygen score on NAVA, with gentler machine pressures. The study was too short to show whether NAVA helps babies come off the ventilator sooner.

If your baby has been diagnosed with a diaphragmatic hernia, you have probably already heard a great deal about lungs, oxygen and breathing machines. This article explains one particular question that doctors have been asking: can the way the ventilator gives each breath be made kinder to a baby's lungs after surgery? It describes what the new study, published in 2026 by Shetty and colleagues, did, what it found, and what it does and does not mean for your baby [1].

What a diaphragmatic hernia does to a baby's lungs

The diaphragm is the dome-shaped sheet of muscle under the lungs that we use to breathe. In congenital diaphragmatic hernia, often shortened to CDH, a hole in this muscle forms before birth. Organs from the belly, such as the intestines and sometimes the liver, move up into the chest and take up the space the lungs need to grow. As a result, the lungs are smaller than usual, and the blood vessels inside them are thicker and tighter than normal, which makes it hard for blood to flow through and pick up oxygen; doctors call this pulmonary hypertension [2].

Babies with CDH have an operation to close the hole, sometimes using a patch. Afterwards, most still need a ventilator, a machine that helps them breathe through a tube in the windpipe. Doctors across Europe follow shared guidance on caring for these babies, which recommends a standard type of ventilator support to start with and sets out how much oxygen and carbon dioxide in the blood is acceptable [3]. This careful, gentle approach exists because a ventilator, while life-saving, can also strain and injure delicate lungs if it pushes too hard or too much [4][5].

How doctors have tried to make the ventilator follow the baby

On the usual setting, called assist-control ventilation, the machine senses when the baby starts to breathe in and then gives a breath at a fixed pressure chosen by the medical team. A newer setting, neurally adjusted ventilatory assist, or NAVA, works differently. A thin, soft tube, very like the feeding tubes many babies already have, is passed through the nose into the stomach. Small sensors on the tube pick up the electrical signal that the brain sends to the diaphragm each time the baby wants to breathe. The machine then gives a breath in time with that signal, and more or less help depending on how strong it is [6][7].

The idea is appealing: the baby leads, and the machine follows. A study of ten older babies, about four months old on average, showed that NAVA matched the machine to the baby's own breathing better than older settings [8], and the same London team had earlier found better oxygen use on NAVA in very premature babies with long-term lung disease [9]. But a careful review of all the evidence found that nobody yet knew for certain whether NAVA was better overall for newborns [7].

For babies with CDH there was an extra worry. NAVA relies on a signal from the diaphragm, and in these babies the diaphragm is the very muscle that formed incompletely and has been repaired, sometimes with a patch of artificial material. For years, many doctors simply assumed it would not work [10]. Then hospitals in Italy, Finland and the United States began trying it. In one Italian hospital, NAVA worked in most babies, including most of those who had a patch, but not in two babies who were missing almost all of one side of their diaphragm [11]. Other teams reported that NAVA helped babies come off the ventilator after surgery [12][13], and one American hospital found lower machine pressures and less need for pain-relief and calming medicines while 16 babies were on NAVA [14]. Most of these were looks back at babies' records, though, and none was a fair, side-by-side test. One team said plainly that a proper trial was needed [13].

How the new study was done

That trial is the Neurally adjusted ventilatory Assist for Neonates with Congenital diaphragmatic hernias study, known as NAN-C [15]. It took place in the newborn intensive care units of two London hospitals, St George's and King's College Hospital, and its results were reported by Shetty and colleagues [1].

The researchers invited parents of babies who had already had their CDH operation and were stable on the ventilator. Babies who needed a lot of extra oxygen, or a special gas called nitric oxide that relaxes the lung blood vessels, were not included [1]. Each baby spent four hours on the usual setting and four hours on NAVA, with a short 20-minute settling-in break between the two. A process similar to drawing lots decided which setting came first. Because each baby was compared with themselves, differences between babies were largely taken out of the comparison.

The main thing the team measured was the oxygenation index. This is a single number that combines how much oxygen the baby is breathing, how hard the machine is pushing, and how much oxygen reaches the blood. A lower number means the baby is getting enough oxygen with less effort from the machine [1].

What the researchers found

Eleven babies started the study. In two of them the diaphragm signal stayed too weak for NAVA to use, so they could not continue in the study. Both had a very severe form of CDH in which most of the diaphragm on one side was missing, very similar to the two Italian babies described earlier [1][11]. Nine babies completed both parts of the study.

All nine babies had a lower oxygenation index on NAVA. On average it was 3.9 on NAVA compared with 5.9 on the usual setting, about a third lower [1]. The machine also pushed less hard: the highest pressure during each breath was on average 17 on NAVA compared with 22 on the usual setting (measured in centimetres of water, the unit used for breathing pressures). The amount of extra oxygen the babies needed was about the same on both, and so was their oxygen saturation, the reading from the small light sensor taped to the skin. The diaphragm signal was lower on NAVA, which the researchers think may mean the babies' breathing muscle was working less hard, though the study was not designed to prove this [1]. Which setting came first made no difference to the results.

The team checked the results halfway through, as planned. The difference was already so clear that the study stopped after nine babies instead of the 18 originally planned [1].

What this means for your baby

The simplest way to put it is that, for these nine babies, NAVA gave the same oxygen levels with gentler help from the machine. That matters because gentler ventilation is generally thought to be kinder to fragile lungs [5]. It is encouraging news.

It is important, though, to be clear about what the study could not tell us. Four hours is a very short time, and the researchers did not follow the babies to see whether NAVA helped them come off the ventilator sooner, go home earlier or have healthier lungs later on [1]. A study that stops early because results look good can sometimes make a benefit look larger than it really is, and the authors themselves point this out. The babies in the study were stable; the findings may not apply to the sickest babies, or to the time before surgery. In an earlier study of premature babies, those whose lung blood vessels were very tight did not cope well with NAVA in the early, most unwell phase of their illness [16]. And NAVA will not work for every baby: if most of the diaphragm is missing, there may simply be no signal to follow.

If your baby's team suggests NAVA, it is reasonable to ask how they will know the signal is strong enough, what happens if it drops (the machine automatically switches to backup breaths), and how they will judge whether it is helping. If they prefer the usual setting, that is also a sound choice, because it remains the standard approach and the evidence for NAVA is still early. You may also find our article on how doctors assess CDH severity before birth helpful.

What researchers are working on next

The NAN-C team says that larger studies, across many hospitals, are needed to find out whether the gentler pressures seen over a few hours lead to real benefits such as less time on the ventilator or fewer long-term lung problems [1]. Another team has already used NAVA without a breathing tube, once the tube was out [10]. Families who are offered a place in such a study can ask the team any questions they have before deciding.

In summary

This small, careful study from London is the first fair, side-by-side test of NAVA in babies recovering from diaphragmatic hernia surgery. In every one of the nine babies who completed it, NAVA kept oxygen levels steady while the machine pushed less hard. It is a promising first step, but not yet proof that NAVA leads to better recoveries, and it does not suit every baby.

References

  1. Shetty S, Jenkinson A, Poole G, et al. Randomised crossover trial of neurally adjusted ventilatory assist (NAVA) for neonates with congenital diaphragmatic hernias: the NAN-C study. Eur J Pediatr. 2026;185(5):246. doi:10.1007/s00431-026-06888-5 ↩
  2. Montalva L, Antounians L, Zani A. Pulmonary hypertension secondary to congenital diaphragmatic hernia: factors and pathways involved in pulmonary vascular remodeling. Pediatr Res. 2019;85(6):754-768. doi:10.1038/s41390-019-0345-4 ↩
  3. Snoek KG, Reiss IK, Greenough A, et al. Standardized Postnatal Management of Infants with Congenital Diaphragmatic Hernia in Europe: The CDH EURO Consortium Consensus - 2015 Update. Neonatology. 2016;110(1):66-74. doi:10.1159/000444210 ↩
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