We mentioned in a previous post the study that Vicky had been doing to try and help make better decisions about what help children on the paediatric (children’s) intensive care unit, or PICU, need with their breathing. The study had two parts: one where we measured lots of children who were very poorly and needed a machine (‘ventilator’) to help them breathe, and the second part where we gave some healthy children help with their breathing. In both parts, we measured how hard the breathing muscles were working. We hope that, in future, measuring the breathing muscles might be able to tell us when sick children are ready to breathe on their own without the help from the machine. All together, we used measurements from 25 children on PICU and 16 healthy children.
When people are very sick, having help from a ventilator can be really important in helping them to get better, but it’s important for them to go back to breathing on their own again as soon as possible to stop them getting any other problems, like infections or damage to their throat from the breathing tube. If we take the ventilator away before children are able to breathe properly on their own, they can end up having very severe breathing problems, which can be dangerous and very frightening for children and their families. What we are looking for is a test that can tell us exactly the right time to take the ventilator away. While it might seem a bit strange to compare measurements from children who are really healthy to children who are so sick that they can’t even breathe on their own, it’s really important for us to know what happens in “normal” lungs so that we can understand exactly how much of what we see in sick children is just due to their illness. Children on PICU can have a lot of different things happening in their bodies that can make their breathing muscles work in different ways, so looking for patterns can be quite tricky.
In the PICU part of the study, we measured the breathing muscles while the children were having help from the ventilator, and then again after we had turned the help down so that the children were having to breathe for themselves (a setting called CPAP). We saw that the breathing muscles worked harder when the children were on CPAP, which was what we had expected to see. We also noticed that in some children breathing muscle activity went up a lot while in others, not very much (see the graphs below). When we first started working on the project, we wanted to test whether these increases in breathing muscle activity would tell us whether children were ready to come off the ventilator. When we saw how different the changes in breathing muscle activity could be in different children, we wanted to know whether this was normal or whether it was related to how sick the PICU children were.
The way we can give breathing support to healthy children is a bit different to the way it is given on PICU: the photo shows the face-mask we used rather than the breathing tube in children’s windpipes used on PICU. Whether the support is given through a tube or a face-mask, it works in the same way – either full support, blowing air into the lungs every time the child takes a breath in, or CPAP, where only a bit of extra air is given to keep the lungs open. Although the muscles in the PICU children were working harder because they were so poorly, when we measured the healthy children both on supported breathing and on CPAP, we saw that the variation in how much and in what way their breathing muscle activity changed was quite similar (you can see that some lines on both graphs go up or down a lot, and some are quite flat).
Seeing this same pattern in both groups of children told us that the amount of change in breathing muscle activity was probably not related to whether the PICU children were ready to come off the ventilator or not. We did find, however, that the amount of breathing muscle activity while on CPAP (together with how much air moved into the lungs with each effort) was the thing that best told us whether the children were going to manage to breathe when they came off the ventilator. Having a good test to see if children are ready to come off the ventilator could make a big difference to children on PICU, as they could spend less time on a ventilator and be less likely to get the extra problems mentioned above.
Although we would need to do a much bigger study, with at least 120 children on PICU, to decide for certain whether measuring the breathing muscles would be the best thing to use when deciding when to take a child off a ventilator, the results from this study are really exciting and suggest that it would be worth trying to do a bigger study. We have to apply to places like charities and the government to get the money to do our research projects, and having results like this from a small (or ‘pilot’) study is really important when we write our applications to get money as it shows that we are on the right track – we are writing applications to do the bigger PICU study right now.
We would like to thank all of the children who took part in this study, as well as their parents and carers, for their help with this project. We would also like to thank the Guy’s and St Thomas’ Charity and the Rosetrees Trust, who provided the money to allow us to do the study. We’ve obtained really useful data and we are very grateful, especially as we know that not all of the children found the study easy (wearing the face-mask can feel quite funny, and we had some quite young children being really brave in order to help us). We have also written a full report of the study and will send it to a scientific magazine, called a journal. We hope, before long, to say that it has been published.