U01.16.004 Neonatal Respiratory Distress Syndrome (NRDS)

Neonatal Respiratory Distress Syndrome (NRDS) is a serious condition primarily affecting premature infants, caused by a deficiency of surfactant in the lungs. Surfactant is a substance that reduces surface tension, preventing alveolar collapse. Without sufficient surfactant, the lungs cannot expand properly, leading to breathing difficulties and the characteristic “ground-glass” appearance on lung X-rays.

Risk Factors for NRDS

Prematurity: Infants born before 37 weeks are at higher risk due to underdeveloped lungs.
Maternal Diabetes: High fetal insulin levels associated with maternal diabetes can inhibit surfactant production.
Cesarean Section Delivery: C-section delivery may reduce the release of fetal glucocorticoids, which are important for lung maturation, as it is less stressful than vaginal delivery.

Diagnosis and Screening

Screening Tests for Fetal Lung Maturity:

Lecithin-Sphingomyelin (L/S) Ratio: A ratio of ≥ 2 in amniotic fluid indicates mature lungs, while a ratio < 1.5 suggests a high risk of NRDS.
Foam Stability Index: Assesses the stability of surfactants.
Surfactant-Albumin Ratio: Measures the concentration of surfactant relative to albumin in amniotic fluid.

Management and Treatment

Maternal Steroids: Administered before birth to accelerate lung maturation and surfactant production.
Exogenous Surfactant: Given to the infant after birth to replace the deficient surfactant and improve lung function.

Complications of Therapeutic Oxygen (O2) Supplementation:

Retinopathy of Prematurity: Abnormal blood vessel growth in the retina, which can lead to blindness.
Intraventricular Hemorrhage: Bleeding into the brain’s ventricular system, common in premature infants.
Bronchopulmonary Dysplasia (BPD): Chronic lung disease caused by prolonged oxygen therapy or mechanical ventilation.

Table: L/S Ratio and Gestational Age

Gestational Age (Weeks)	L/S Ratio	Maturity Status
< 32	< 1.5	Immature
32 – 34	1.5 – 2.0	Transitional
> 34	≥ 2.0	Mature

Table: L/S Ratio and Gestational Age

Points to Remember

NRDS is primarily due to a surfactant deficiency, leading to alveolar collapse.
Prematurity is the most significant risk factor for NRDS.
Early detection through screening tests like the L/S ratio can guide preventive and therapeutic interventions.
Supplemental oxygen therapy, while necessary, carries risks of serious complications.

Reference Links

MedlinePlus – Respiratory Distress Syndrome
American Lung Association – Neonatal Respiratory Distress Syndrome
National Institutes of Health – Surfactant Deficiency

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USMLE Step 1 Review Series

Curriculum

U01.16.004 Neonatal Respiratory Distress Syndrome (NRDS)

Risk Factors for NRDS

Diagnosis and Screening

Management and Treatment

Table: L/S Ratio and Gestational Age

Points to Remember

Reference Links

Your voice matters – comment below!Cancel reply

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