Paediatrics: Respiratory distress syndrome

Respiratory distress syndrome

RDS refers to lung disease caused by surfactant deficiency. The disease is largely seen in preterm infants. RDS is rare >32wks gestation.

Causes

Surfactant deficiency causes alveolar collapse, increased work of breathing and hypoxia (due to intrapulmonary shunting of blood). Increased risk of RDS is associated with CS delivery; hypothermia; perinatal hypoxia; me-conium aspiration; congenital pneumonia; maternal diabetes mellitus; past family history.

Presentation

Cyanosis, tachypnoea, chest in drawing, grunting within 4hr of birth. If untreated, the disease worsens over 48–72hr and then (depending on severity) resolves over 5–7 days.

Investigations

•   CXR: bilateral, diffuse ‘ground-glass’ appearance (generalized atelectasis), airway bronchograms, reduced lung volume (see Fig, 6.3).

•   SpO₂ monitoring and blood gases.

Management

•   Good delivery room resuscitation. This may involve intubation and administration of surfactant (extremely preterm) or nasal CPAP.

•   Respiratory support will depend on the severity. May need O₂, nasal CPAP, or ventilation.

•   Surfactant (Curosurf ^® or Survanta^®) requires intubation and ventilation, and should be considered in all extremely preterm (<27/40) infants and when oxygen requirement exceeds 30–40%.

given as bolus down ETT;

give 2nd dose if oxygen requirement remains high (FiO₂>0.3);

•   further doses are sometimes required.

•   Antibiotics: e.g. penicillin and gentamicin, until congenital pneumonia has been excluded, as it can mimic or coexist with RDS.

•   Nutrition: use IV fluids until the baby is stable. Then start gastric tube feeds with minimal volumes and slowly increase as tolerated. If unstable, start parenteral nutrition after 24–48hr.

Prognosis

The majority have a good recovery. Mortality is 5–10% and depends on severity and gestation. Bronchopulmonary dysplasia may develop (715% of cases, inversely proportional to gestational age).

Prevention

•   Corticosteroids (betamethasone/dexamethasone, 2 doses, 12-hourly) given to mother 1–7 days before birth decreases incidence and mortality by 40%. Maximum benefit 24hr after first dose and lasts 7 days.

•   Treat co-existing morbidities that inhibit surfactant production developing, e.g. hypothermia, acidosis, infection.