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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Neonatal RDS is surfactant deficiency, classically in preterm infants, especially <34 weeks
- Symptoms begin soon after birth: tachypnea, grunting, nasal flaring, retractions, cyanosis, and increasing oxygen need
- Chest X-ray shows low lung volumes, diffuse reticulogranular ground-glass opacities, and air bronchograms
- Prevention: antenatal corticosteroids for threatened preterm birth; treatment: CPAP/oxygen and exogenous surfactant when indicated
- Differentiate from transient tachypnea of the newborn: term/late preterm, C-section, fluid in fissures, hyperinflation, and rapid improvement
Overview
Respiratory distress syndrome of the newborn, historically called hyaline membrane disease, results from inadequate surfactant production by type II pneumocytes. Without surfactant, alveoli collapse at end expiration, increasing work of breathing and causing ventilation-perfusion mismatch. It is primarily a disease of prematurity but can be worsened by maternal diabetes, perinatal asphyxia, and cesarean delivery without labor. USMLE questions often ask for the diagnosis based on timing, gestational age, and radiographic pattern.
Epidemiology
Risk is inversely related to gestational age and birth weight. It is common in extremely preterm infants and uncommon in term infants unless other risk factors exist. Antenatal steroids, early CPAP, and selective surfactant therapy have reduced mortality substantially. Maternal diabetes increases risk because fetal hyperinsulinemia delays surfactant production; antenatal corticosteroids accelerate fetal lung maturity.
Clinical Features
Symptoms
Tachypnea and increased work of breathing within minutes to hours of birth
Grunting, nasal flaring, intercostal/subcostal retractions
Cyanosis or need for supplemental oxygen
Apnea or respiratory failure in severe disease
History of prematurity, maternal diabetes, or lack of antenatal steroids
Signs
Preterm infant with respiratory distress shortly after delivery
Decreased breath sounds, poor air entry, and signs of atelectasis
Hypoxemia and respiratory acidosis on blood gas if severe
Persistent oxygen requirement and increased work despite initial support
Signs of complications: asymmetric breath sounds with pneumothorax or worsening shock
Investigations
First-line
Clinical diagnosisPrematurity plus early respiratory distress is highly suggestive
Chest X-rayLow lung volumes, diffuse fine reticulogranular/ground-glass pattern, and air bronchograms
Pulse oximetry and blood gasAssess hypoxemia, hypercapnia, and acidosis; guide respiratory support
Second-line
Sepsis evaluationRDS can mimic pneumonia/sepsis; evaluate if maternal risk factors, instability, or unclear diagnosis
Glucose and electrolytesHypoglycemia and metabolic abnormalities can worsen respiratory distress
EchocardiographyIf hypoxemia is disproportionate or persistent pulmonary hypertension/congenital heart disease is suspected
Specialist
NeonatologyPreterm respiratory distress, need for CPAP/ventilation, surfactant, or NICU monitoring
Respiratory therapy/NICU teamOptimize noninvasive ventilation, oxygen targets, and surfactant delivery strategy
1
Prevention before birth
- Give antenatal corticosteroids to pregnant patients at risk of preterm delivery within the recommended gestational age windows
- Maternal transfer to a center with NICU capability when very preterm birth is anticipated
- Avoid unnecessary elective early delivery
2
Initial respiratory support
- Warm, position, clear airway only if needed, and support breathing per neonatal resuscitation principles
- Early CPAP is preferred for spontaneously breathing preterm infants with respiratory distress
- Use blended oxygen and target saturations appropriate for gestational age to avoid hypoxia and oxygen toxicity
3
Surfactant and ventilation
- Administer exogenous surfactant for infants with RDS who require intubation or have significant oxygen/pressure needs despite CPAP
- Use minimally invasive or INSURE-style approaches when appropriate to reduce ventilation injury
- Mechanical ventilation is indicated for severe respiratory failure, apnea, or persistent acidosis/hypoxemia
4
Ongoing care
- Caffeine for apnea of prematurity when indicated
- Monitor for pneumothorax, pulmonary hemorrhage, patent ductus arteriosus, and bronchopulmonary dysplasia
- Nutrition, thermoregulation, infection prevention, and careful fluid management support recovery
Complications
- Air leak syndromes: Pneumothorax and pulmonary interstitial emphysema can occur from fragile lungs and positive pressure
- Bronchopulmonary dysplasia: Chronic lung disease from prematurity, oxygen exposure, inflammation, and ventilation injury
- Patent ductus arteriosus: Common in preterm infants and can worsen respiratory status
- Intraventricular hemorrhage: Prematurity and cardiorespiratory instability increase risk
- Retinopathy of prematurity: Associated with prematurity and oxygen exposure
USMLE Step 2 CK Exam Tips
- 1Preterm infant + respiratory distress immediately after birth + low lung volumes/ground-glass = RDS
- 2RDS is surfactant deficiency from immature type II pneumocytes
- 3Maternal diabetes increases RDS risk because fetal hyperinsulinemia delays surfactant production
- 4Antenatal corticosteroids prevent RDS by accelerating lung maturity
- 5Transient tachypnea has hyperinflation and fluid in fissures; RDS has low lung volumes
- 6Exogenous surfactant is given when significant RDS requires intubation or escalating respiratory support
- 7Sudden deterioration with asymmetric breath sounds in ventilated preterm infant = pneumothorax
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