Guide — Neonatal & Pediatric
Neonatal Respiratory Distress Syndrome (RDS)
Surfactant-deficient lung disease of the premature newborn — why RDS happens, how it looks on exam and X-ray, and the modern management ladder of antenatal steroids, early CPAP, and surfactant (INSURE and LISA). This guide ties the pathophysiology to the bedside so the findings and the interventions make sense together.
10 min read · Neonatal & Pediatric
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Overview
RDS (formerly hyaline membrane disease) is the most common respiratory disease of premature infants, caused by a deficiency of pulmonary surfactant. Risk is inversely related to gestational age and is greatest below about 28–32 weeks. Surfactant — produced by Type II pneumocytes and adequate by roughly 35 weeks — lowers alveolar surface tension; without enough of it, alveoli collapse (Laplace’s law), producing diffuse atelectasis, low compliance, high work of breathing, V/Q mismatch and intrapulmonary shunting, and hypoxemia.
Key Concepts
- The core defect. Surfactant deficiency raises surface tension, causing progressive atelectasis, a low functional residual capacity, stiff lungs, and right-to-left intrapulmonary shunting.
- Risk factors. Prematurity (the dominant factor), male sex, maternal diabetes, cesarean delivery without labor, perinatal asphyxia, and being the second-born twin. Factors that accelerate lung maturity (and lower risk): antenatal corticosteroids, chronic intrauterine stress (maternal hypertension, IUGR), and prolonged rupture of membranes.
- Time course.Onset within minutes to hours of birth, worsening over the first 48–72 hours, then improving as endogenous surfactant production rises.
- Chest X-ray.A diffuse, fine reticulogranular “ground-glass” pattern with air bronchograms and low lung volumes.
- Lung maturity testing. A lecithin-to-sphingomyelin (L/S) ratio of 2:1 or higher indicates maturity.
Assessment & Findings
The infant presents with signs of increased work of breathing. The Silverman-Andersen score grades the degree of distress. Expiratory grunting is the classic finding — the infant generates auto-PEEP against a partly closed glottis to defend FRC.
| Sign | Detail | What It Reflects |
|---|---|---|
| Tachypnea | Respiratory rate over 60/min | Compensation for low compliance and high work of breathing |
| Expiratory grunting | Auto-PEEP against a partly closed glottis | Infant defending a falling FRC |
| Nasal flaring | Widening of the nares with each breath | Effort to reduce airway resistance |
| Retractions | Intercostal, subcostal, substernal | High negative intrathoracic pressure against stiff lungs |
| Cyanosis | Central, worsening with disease | Hypoxemia from shunt and V/Q mismatch |
Arterial blood gas shows hypoxemia and, as the disease worsens, hypercapnia with a combined respiratory and metabolic acidosis.
RT Priorities & Interventions
- Antenatal corticosteroids. Betamethasone or dexamethasone given to mothers at risk of preterm delivery are the single most effective prevention, accelerating fetal surfactant production.
- Early nasal CPAP.About 5–6 cmH₂O, started in the delivery room, recruits and maintains FRC and is first-line for the spontaneously breathing preterm infant; it reduces the need for intubation.
- Surfactant replacement. Given through the airway. Minimally invasive strategies are now preferred: INSURE (INtubate, give SURfactant, Extubate back to CPAP) and LISA/MIST (Less Invasive Surfactant Administration through a thin catheter while the infant stays on CPAP). Treat established RDS or a rising FiO₂.
- Gentle ventilation if CPAP fails. Use targeted tidal volumes to avoid volutrauma; volume-targeted modes are favored.
- Oxygen targeting.Keep SpO₂ in a band (about 90–95%) — avoid hyperoxia (retinopathy of prematurity, oxidative lung injury) and hypoxia. Caffeine treats apnea of prematurity.
Common Pitfalls
- Over-oxygenating the preterm infant, driving retinopathy of prematurity and lung injury — target the saturation band rather than 100%.
- Delaying CPAP or surfactant in a deteriorating infant.
- Aggressive ventilation causing volutrauma and contributing to bronchopulmonary dysplasia.
Board Exam Pearls
- Surfactant is made by Type II pneumocytes; it is usually adequate by about 35 weeks; an L/S ratio of 2:1 or more signals maturity.
- Grunting is physiologic auto-PEEP (expiration against a partially closed glottis).
- Antenatal corticosteroids are the best prevention; early CPAP is first-line; surfactant treats established disease.
- Chest X-ray shows ground-glass opacification with air bronchograms and low lung volumes.
- Target SpO₂ around 90–95% to avoid both ROP and BPD.
FAQ
Why do babies with RDS grunt?
Grunting is expiration against a partially closed glottis, which generates auto-PEEP to keep alveoli from collapsing at end-expiration and defends the low FRC of surfactant-deficient lungs. It is a sign of significant distress, not a benign noise.
CPAP or surfactant first?
For a spontaneously breathing preterm infant, early nasal CPAP comes first to establish FRC. Surfactant is added for established RDS or rising oxygen needs, increasingly through minimally invasive routes (INSURE or LISA) so the infant can remain on CPAP.
Why not target SpO₂ 100% in a premature infant?
Hyperoxia in premature infants drives retinopathy of prematurity and oxidative lung injury that contributes to bronchopulmonary dysplasia. Target a saturation band of roughly 90-95% rather than the highest possible number.
What is the single best way to prevent RDS?
Antenatal corticosteroids given to mothers at risk of preterm delivery. They accelerate fetal surfactant production and substantially reduce the severity of RDS and neonatal mortality.
Put it to work
A sick neonate produces a messy gas. Practice reading the acid-base and oxygenation picture step by step.
Open the ABG Interpreter →Related Resources
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Neonatal and pediatric respiratory care chapters.
- Sweet DG, Carnielli VP, Greisen G, et al. European Consensus Guidelines on the Management of Respiratory Distress Syndrome: 2022 Update. Neonatology. 2023;120(1):3-23.