Mike: Hello, I’m Mike Clarke, podcast editor for the Cochrane Library Podcast. I'm pleased to welcome you to this podcast for a crucial topic in the care of preterm babies: the use of surfactant therapy guided by tests of their lung function. Practice is evolving in this area, and we're here to discuss the latest evidence. Three guests are joining me today, Greta Sibrecht and Franek Borys, authors of the October 2023 Cochrane review, and, later, Anna Lavizzari, lead investigator for one of the ongoing studies. Thank you for being here.

Greta: Thank you for having us.

Franek: It's great to be here.

Mike: Let’s start with the basics. Greta, please could you explain why surfactant therapy is so important for preterm infants with respiratory distress syndrome?

Greta: Sure. Firstly, respiratory distress syndrome, known as RDS, is common in preterm infants. It occurs when a baby's lungs aren't fully developed, making it difficult for them to breathe. This is often due to a lack of a substance called surfactant, which helps to keep the lungs open and prevents them from collapsing when the infant breathes out. Without sufficient surfactant, the lungs can collapse, and surfactant therapy involves using this substance to reduce the risk of RDS.

Mike: That makes sense. So, let’s move on to the importance of the timing and the method of administering surfactant. Franek, can you tell us more about how tests for lung maturity come into play here?

Franek: Absolutely. Traditionally, surfactant is given either as a prophylactic treatment to high-risk infants before symptoms of RDS develop, or as a therapeutic treatment after RDS is diagnosed using clinical signs and radiology. However, some researchers have suggested that rapid tests of lung maturity might help identify infants who would benefit most from surfactant therapy, potentially optimizing the timing of their intervention.

Mike: Interesting. So, what exactly are these tests for lung maturity, and how do they work?

Greta: Tests for lung maturity, such as the click test, lamellar body counts, and the stable microbubble test, measure pulmonary surfactant in the amniotic fluid or the first fluid taken from the baby’s stomach or windpipe after birth. The tests aim to quickly assess whether the lungs are likely to be surfactant deficient. The goal is to avoid unnecessary treatment, while ensuring that those infants who need surfactant are given it promptly.

Mike: And what does the evidence say? What did your review find out about surfactant therapy guided by these rapid tests?

Franek: We were able to include three studies involving 562 preterm infants in the review. These studies compared surfactant therapy guided by rapid tests for surfactant deficiency to therapy based on clinical and radiologic criteria. However, based on this evidence, it’s uncertain whether using these tests significantly impacts the likelihood of death before hospital discharge. Moreover, the evidence suggests that there may be little to no difference in the rates of chronic lung disease of prematurity, the need for surfactant treatment, or the incidence of pneumothorax, which is a collapsed lung.

Mike: Given that there’s still some uncertainty, are there any ongoing studies that might provide more clarity?

Greta: Yes, two large studies are underway. One on the use of lung ultrasound and the other evaluating lung function together with clinical assessments. And I’m pleased that Dr Anna Lavizzari, the lead researcher of the REMEDIES trial, is able to join us today.

Mike: Thanks Greta and hello to Anna. Anna, please could you tell us more about your study and what you hope to discover?

Anna: Hello Mike, thanks for inviting me. REMEDIES is a randomised trial of two different techniques for deciding whether to administer surfactant to preterm infants: the standard oxygenation-based criteria and criteria based on respiratory oscillatory mechanics. Respiratory oscillatory mechanics, which is also called FOT (standing for Forced Oscillation Technique) is a noninvasive technique that assesses the mechanical properties of the respiratory system, in particular lung reactance, which is a reliable marker of lung recruitment and correlates with lung compliance.

Mike: That sounds fascinating. What potential advantages do you see in using oscillatory mechanics over the traditional methods?

Anna: Our hope is that respiratory mechanics may predict the need for surfactant earlier and with better accuracy. This would help because some infants require extra oxygen for reasons other than a lack of surfactant, such as hemodynamics. On the other hand, some compensate for lung “de-recruitment” by increasing their work of breathing, but this might lead to lung inflammation, muscle exhaustion, late intubation and sometimes even air-leaks.

Mike: When do you expect to have findings from your trial?

Anna: We hope to be able to share our results in a couple of years. Because this is a new approach, the design and optimization of the application have taken some time, and training centers in the trial in the new technique also requires time and energy.

Mike: Thank you, Anna, for sharing information about your trial, and thanks also to Greta and Franek for joining us today to talk about the Cochrane Review. If listeners want to dive deeper into this subject, the full review can be found at CochraneLibrary.com, with a search for "surfactant therapy guided by lung maturity tests".