Air bronchogram in chest x-ray

Which of the following will favour the diagnosis RDS in newborn?

  1. Reciept of antenatal steroids
  2. Air bronchogram in chest x-ray
  3. Manifests after 6 hours
  4. Occurs after term gestation

Explanation

Respiratory distress syndrome (Hyaline membrane disease)

Incidence

Its incidence is inversely related to gestational age and birth weight. It occurs in 60-80% of infants <28 wk of gestational age, in 15-30% of those between 32 and 36 wk, and rarely in those >37 wk.

Etiology and Pathophysiology

Surfactant deficiency (decreased production and secretion) is the primary cause of RDS. The major constituents of surfactant are dipalmitoyl phosphatidyl choline (lecithin), phosphatidyl glycerol, apoproteins (surfactant proteins SPA, SP-B, SP-C, SD-D), and cholesterol. These phospholipids are synthesized and stored in type II alveolar cells. They are released into alveoli, where they reduce surface tension and help prevent collapse of small air spaces at end expiration.

Abnormalities in surfactant protein B and C genes are associated with severe and often lethal familial respiratory disease called neonatal alveolar proteinosis.

Diagnosis

Age of onset: Presents usually within minutes of birth.

Chest X-ray Features of RDS

Bilateral diffuse reticulo granular opacities in the pulmonary parenchyma.

  "Prominent air bronchograms" (aerated bronchioles superimposed on a background of collapsed alveoli)

Conditions Associated with air Bronchogram

• Pneumonia

• ARDS

• HMD (Hyaline membrane disease)

• Pulmonary consolidation

• Alveolar proteinosis

• Sarcoidosis

• Lymphoma

Prevention

Administration of antenatal corticosteroids reduces the incidence of RDS, IVH, NEC, early onset sepsis and developmental delay.

Drug Regimens

• Inj. Betamethasone 12 mg/ 1/m every 24 hours 2 doses (preferred)

• Inj. Dexamethasone 6 mg 1/m every 12 hours, 4 doses.

• Maximum effect is seen between 24 hours - 7days

Treatment

CPAP indication: If oxygen saturation cannot be kept >85% at inspired oxygen concentrations of 40-70% or greater.

Mechanical Ventilation Indication

  1. Persistent apnea

  2. Respiratory failure

    a. Arterial blood PH <7.2

    b. Arterial blood PCO2 ≥ 60mm Hg

    c. Oxygen saturation <85% at oxygen concentrations of 40-70% and CPAP 5-10 mm H2O.

Surfactant Indications

i. Moderate to severe RDS-Rescue treatment

ii. All neonates less than 29 weeks irrespective of presence or absence of RDS - Prophylactic treatment.