Respiratory distress syndrome
Respiratory distress syndrome (RDS) is a relatively common condition resulting from insufficient production of surfactant that occurs in preterm neonates.
On imaging, the condition generally presents as bilateral and relatively symmetric diffuse ground glass lungs with low volumes and a bell-shaped thorax.
RDS is also known as hyaline membrane disease (not favoured as reflects non-specific histological findings), neonatal respiratory distress syndrome, lung disease of prematurity (both non-specific terms), or as some authors prefer surfactant deficiency disorder 2.
The incidence is estimated at 6 per 1000 births 2.
Respiratory distress presents in the first few hours of life in a premature baby. Symptoms include tachypnoea, expiratory grunting, nasal flaring. The infant may or may not be cyanosed. Substernal and intercostal retractions may be evident.
Risk factors include maternal diabetes, greater prematurity, prenatal asphyxia and multiple gestations.
Associated abnormalities are those that can occur in prematurity: germinal matrix haemorrhage, necrotising enterocolitis, patent ductus arteriosus, delayed developmental milestones, hypothermia and hypoglycaemia.
Immature type II pneumocytes cannot produce surfactant. The lack of surfactant increases the surface tension in alveoli causing collapse. Patients have a decreased lecithin: sphingomyelin ratio. Damaged cells, necrotic cells, and mucus line the alveoli.
- typically gives diffuse ground glass lungs with low volumes and a bell-shaped thorax
- often tends to be bilateral and symmetrical
- air bronchograms may be evident
- hyperinflation (in a non-ventilated patient) excludes the diagnosis
- radiographs may show hyperinflation if the patient is intubated
RDS can be safely excluded if the neonate has a normal chest radiograph at six hours after birth.
If treated with surfactant therapy there may be a symmetric improvement.
Treatment and prognosis
Exogenous surfactant administration. Supportive oxygen therapy.
- persistent patent ductus arteriosus (PDA) due to reduced oxygen stimulus
- pulmonary interstitial emphysema (from treatment)
- oxygen toxicity (from treatment)
- pulmonary haemorrhage (can also be included in the differential diagnosis)
- congenital heart disease
- group B Strep pneumonia
- pulmonary haemorrhage
- pulmonary oedema / pulmonary venous congestion
- neonatal pneumonia
- transient tachypnea of the newborn: lung volumes are normal to slightly hyperinflated in TTN and are decreased in RDS
- neonatal lines and tubes
- neonatal respiratory distress (causes)
- neonatal chest x-ray (an approach)
- neonatal chest pathology
- 1. Blickman JG, Parker BR, Barnes PD. Pediatric radiology, the requisites. Mosby Inc. (2009) ISBN:0323031250. Read it at Google Books - Find it at Amazon
- 2. Agrons GA, Courtney SE, Stocker JT et-al. From the archives of the AFIP: Lung disease in premature neonates: radiologic-pathologic correlation. Radiographics. 25 (4): 1047-73. doi:10.1148/rg.254055019 - Pubmed citation
- 3. Donnelly LF, Frush DP. Localized radiolucent chest lesions in neonates: causes and differentiation. AJR Am J Roentgenol. 1999;172 (6): 1651-8. AJR Am J Roentgenol (citation) - Pubmed citation
- 4. Swischuk LE, John SD. Immature lung problems: can our nomenclature be more specific? AJR Am J Roentgenol. 1996;166 (4): 917-8. AJR Am J Roentgenol (abstract) - Pubmed citation