There are two types of heel prick: the screening shot for all babies on the one hand, and the diagnostic shot for premature babies on the other. If it is up to adjunct professor Nienke Bosschaart of the Department of Biomedical Photonic Imaging, the diagnostic heel prick for premature babies will be a thing of the past in a few years.
With her team of PhD candidates and students, she is working on a non-invasive, photonic scanning method for blood vessels. This allows blood from premature babies to be examined for the amount of haemoglobin and bilirubin, among other things. With a Veni grant in her pocket, she brought her research to UT in 2015.
Haemoglobin and bilirubin
'Haemoglobin causes the red colouring in red blood cells. It transports oxygen through the body to the organs. A deficiency of it can lead to organ or brain damage. Bilirubin is a breakdown product of haemoglobin and is often present in elevated concentrations in newborns. Too much bilirubin can lead to jaundice and, in the most severe cases, brain damage,' Bosschaart explains.
Gold standard
Measuring this early on is crucial, in other words. Especially in children who are born much too early. At the moment, the traditional heel prick is still the gold standard for this. Blood is taken from the heel of the newborn. Bosschaart explains why that is far from ideal. 'First of all, it hurts, especially for a newborn child. Secondly, there is a risk of infection, which is extra dangerous if the baby is premature.' She also mentions costs and relatively long time needed for taking and analysing blood.
One of the reasons for the heel prick is research into anaemia. 'While the heel prick can actually contribute to that. You may be causing what you want to prevent.'
Espresso cup of blood
Then there is another point: 'If a child weighs only 500 grams, it has a total blood supply of about 50 millilitres. That fits in an espresso cup,' Bosschaart describes it visually. Every drop taken for research therefore constitutes significant blood loss.
Light measurements
The method used by Bosschaart and her team involves a broadband light source, which consists of reflecting light rays of multiple wavelengths. Bosschaart: 'This allows us to shine on a skin surface of one square millimetre, in several blood vessels. We also use a reference light beam that does not shine into the blood vessel. When the two come together, you get an interference signal. This allows us to create a 3D image of the blood vessels and different layers of skin at a microscopic level. If we then analyse the signal further, we can determine the haemoglobin value in each blood vessel.'
Plaster
The advantage of this method is that it does not hurt, and is relatively cheaper and faster. In addition, it can be incorporated into small sensors, making it even easier to use. 'We are not that far yet, but the technology could be incorporated into a simple plaster in the future, for example.'
Although the technique is ultimately intended for premature babies, adults also benefit from it. 'Adults can endure a tiny sting, but if you don't have to, a quick light test at the GP’s is more pleasant.'
Men and women
Last year, the team conducted the first pilot study among adults with the new technique, which was published just last month. A striking additional discovery by postdoctoral researcher Carlos Cuartas is that there is a standard difference in values between women and men. 'On average, women have higher haemoglobin levels than men. This may be due to the influence of hormones such as oestrogen.'
According to Bosschaart, who is also a member of the TechMed research pillar of Women's Health, this confirms once again that it is important to take into account the differences between men and women, in order to avoid bias. 'At the same time, it nicely shows how sensitive our technology is.'
Now it is important to investigate further whether this difference also exists in newborns.
Working product?
In the near future, Bosschaart wants to expand the tests to haemoglobin patients and eventually, of course, to babies. 'It will probably produce even better results in babies than in adults, because they have thinner skin and the blood vessels lie much closer to the surface. But before there is a working product and it becomes the new gold standard, it will take years of validation, certification and acceptance. Moreover, it depends on whether we can get subsidies for further research.'
