The relationship between lung ultrasound imaging and oxygenation during alveolar recruitment manoeuvres in neonates receiving high frequency oscillatory ventilation.

Babies often require help to breath from a breathing machine (mechanical ventilation with a ventilator). While this keeps babies alive, it may damage their lungs. To minimise this damage, we use gentle methods of mechanical ventilation. High frequency oscillatory ventilation (HFOV) is an alternative type of mechanical ventilation thought to cause less lung damage. To use this type of breathing support safely, a baby’s lungs need to be properly inflated. We usually find out this information by using x-rays of a baby’s lungs, oxygen levels, and measurements we get from the ventilator. Babies whose lungs are not fully inflated need more pressure from the ventilator to open up their lungs, but it can be hard to know when we have given enough pressure. Lung x-rays give us some information about how well inflated the lungs are, but they use radiation and only provide a picture at one point in time. As a result, we rely on a baby’s oxygen levels and measurements from the ventilator to guide how we open the lungs with pressure. These are not very accurate. Ultrasound and electrical impedance tomography (EIT) are forms of imaging that do not use radiation. Ultrasound uses reflected sound to create an image of different parts of the body. EIT uses changes in electrical resistance to create images of the lung. Both are safe, painless and can be used to assess lung inflation over a period of minutes rather than a single time point like x-rays do. We are exploring whether a lung ultrasound performed during a procedure to inflate the lungs called a “recruitment manoeuvre” can help us find the best pressure to use to keep the lungs properly inflated. In this study, we will perform ultrasounds of a baby’s lungs at each step during a recruitment manoeuvre. We will compare the lung ultrasound findings to the usual ways we measure the lung inflation and also to measurements of lung inflation from EIT. These findings may help us better use HFOV in the future.