Surfactant Deficiency

by Brian Alverson, MD

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    00:01 Let’s switch a little bit to surfactant deficiency as this is a subset of those patients with chronic lung disease, but it’s an important subset.

    00:09 So these are infants who are born with an inadequate amount of surfactant in their lungs.

    00:17 Let’s pause for a moment.

    00:18 What is surfactant? As you recall from you basic pulmonary physiology, surfactant is a soap-like molecule with a hydrophilic end and a lipophilic end, usually a long series of carbons.

    00:32 That hydrophilic end likes to stick together and the lipophilic end likes to stick together.

    00:38 So inside the lung, you will see this stuff accumulating such that the fatty ends are facing up and the hydrophilic ends are against the wall.

    00:49 What this allows is it allows patients to easily inflate and expand their lungs.

    00:57 A deficiency of surfactant can result in anything from mild to severe respiratory distress as these infants are less able to expand their lungs.

    01:07 So decreased surfactant will result in increased surface tension, which results in atelectasis and areas of lung collapse as it is harder to keep that lung inflated.

    01:24 In infants with surfactant deficiency, they are usually in respiratory distress within minutes of birth.

    01:31 Breath sounds sound normal, decreased, or they may have crackles.

    01:37 A blood gas will show a decreased PaO2, and later an increased respiratory acidosis, a PaCO2, and, because of poor oxygenation in the distal tissues, a metabolic acidosis as well.

    01:54 The differential diagnosis for these patients is broad.

    01:58 This could be something as simple as transient tachypnea of the newborn, which is simply an inadequate clearance of amniotic fluid from the lungs in a child usually who underwent a cesarean section as opposed to vaginal birth.

    02:14 However, this could be something serious, like sepsis, or maybe the patient has pulmonary hypoplasia, a lack of development of some area of the lung.

    02:23 The child might have aspirated meconium.

    02:26 This usually happens in infants with distress during the birthing period and they will reflectively defecate and aspirate that defecation while still inside the mother.

    02:38 Alternatively, this child might have congenital heart disease and really is needing prostaglandins to keep their duct open that this really isn’t a surfactant problem or, alternatively, this child may have a congenital abnormality of the lung.

    02:52 So there are many possible things going on that might be causing this child’s respiratory distress.

    02:59 So how do we make a diagnosis of surfactant deficiency? There is a classic X-ray appearance in these children, which is called a ground glass appearance.

    03:09 As you can see on this X-ray on this slide, these patients will have a clouded, diffuse lung field, which looks almost like you’re looking at ground glass.

    03:21 The margins of the heart are appropriate There are no masses, there are no other problems.

    03:25 This a classic picture of surfactant deficiency.

    03:30 If these patients have it, we can prevent it before it even happens.

    03:36 One way to prevent anything like this is to give a mother who is about to deliver a premature infant corticosteroids.

    03:44 So mothers who are about to deliver infants who are premature will often be given a course of steroids.

    03:52 What the steroids do inside the mother is they travel into the fetus, into the baby, and they promote both surfactant production and lung maturation in the infant before the child is born.

    04:07 So children who are exposed to steroids given to mom have a better outcome from a respiratory standpoint.

    04:15 Premature babies, after birth, where there is surfactant deficiency, will often get artificial surfactant.

    04:24 This is provided through intubating the baby and then blowing the surfactant down into their lungs.

    04:29 This artificial surfactant takes the place of the deficiency of their own surfactant and allows those lungs inflate.

    04:37 They will often get positive airway pressure to help blow open those lungs and relieve the atelectasis.

    About the Lecture

    The lecture Surfactant Deficiency by Brian Alverson, MD is from the course Pediatric Pulmonology.

    Included Quiz Questions

    1. Corticosteroids
    2. Surfactant
    3. Rituximab
    4. Magnesium
    5. Terbutaline

    Author of lecture Surfactant Deficiency

     Brian Alverson, MD

    Brian Alverson, MD

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    Excellent lecture
    By Jalil Z. on 29. October 2020 for Surfactant Deficiency

    I particularly liked the differential diagnosis. I would have preferred to see them organised by ethology (infectious, etc.) and to have an explanation for the surface tension. I understand the concept but I think it's worth more details. That being said excellent lecture. Thank you!