Respiratory distress syndrome

Definition

A respiratory condition seen in premature infants, due to lack of surfactant production and immature lung structures. Similar to Acute Respiratory Distress Syndrome seen in adults.

Epidemiology

The more preterm the infants, the higher the chance of them getting it. A birth at 39 weeks will usually be okay, whereas the 26 week baby will almost certainly have it.

Pathophysiology

Being a premature baby with RDS is a little like trying to breathe into a blancmange. But not very much so.

Surfactant is a liquid, similar to washing up liquid, produced by type II pneumocytes in the lungs. It descreases the surface tension within the lungs, meaning that the lungs can fill fairly equally and easily, rather than being like trying to fill a blancmange with air. In RDS, the lungs aren't ready to produce surfactant, and so a lot more forced is required to keep the lungs open.

Also, the lungs are not fully developed, leading to thickened cell walls, and thus poor gas exchange. This makes the problem worse, since the little air the infant is getting inside isn't being utilised properly.

This has a ground glass appearance. It kind of looks fuzzy. To be honest, xrays always look fuzzy, so it's not something I would find very useful, and I'd certainly not make a diagnosis on the basis of it.

Risk Factors

• Being born prematurely.
• Low birth weight
• Mum not given glucocorticoids.

That's about it.

Clinical Features

Within 4 hours of birth, neonates develop;

• Tachypnoea
• Recession
• Expiratory grunting (trying to maintain open airways)
• Tachycardia
• Cyanosis

Investigations

Xray will show a distinctive "ground glass" appearance, where the heart border is also indistinct. I think that's the main investigation.

Management

Glucocorticoids given to the mother, if a preterm birth is expected, are shown to stimulate foetal surfactant production.