Respiratory Distress Syndrome (RDS)

Why is this topic important?

Respiratory Distress Syndrome (RDS) is one of the commonest causes of respiratory distress in preterm infants and one of the highest-yield neonatal topics in MRCPCH examinations.

Candidates should be able to:

Recognise risk factors
Understand surfactant deficiency
Interpret chest X-rays
Understand surfactant therapy
Manage respiratory support
Recognise complications

RDS frequently appears in FOP, TAS and AKP examinations.

Definition

Respiratory Distress Syndrome is a condition caused by pulmonary surfactant deficiency leading to alveolar collapse, impaired gas exchange and respiratory failure.

Previously known as:

Hyaline Membrane Disease

Key MRCPCH Facts

Most common in preterm infants.
Incidence increases as gestational age decreases.
Caused by surfactant deficiency.
Antenatal steroids reduce risk.
Surfactant replacement improves outcomes.
Chest X-ray classically shows a "ground-glass" appearance.
Major cause of neonatal respiratory morbidity.

Normal Surfactant Physiology

Surfactant is produced by:

Type II Pneumocytes

Functions:

Reduces alveolar surface tension
Prevents alveolar collapse
Improves lung compliance
Reduces work of breathing

Production increases significantly after:

32–34 weeks gestation

Pathophysiology

Surfactant deficiency causes:

Alveolar Collapse

↓

Reduced lung compliance

↓

Atelectasis

↓

Ventilation-perfusion mismatch

↓

Hypoxaemia

↓

Respiratory distress

Risk Factors

Prematurity

Most important risk factor.

Risk increases dramatically below:

32 weeks gestation

Maternal Diabetes

Delayed fetal lung maturation.

Male Sex

Slightly higher risk.

Elective Caesarean Section

Without labour increases risk.

Perinatal Asphyxia

May worsen respiratory adaptation.

Clinical Features

Symptoms usually begin shortly after birth.

Tachypnoea

Respiratory rate >60/min

Grunting

Attempts to maintain functional residual capacity.

Recession

Intercostal
Subcostal
Sternal

Nasal Flaring

Cyanosis

Severe disease.

Examination Findings

Increased Work of Breathing

Reduced Air Entry

Oxygen Requirement

Respiratory Failure

In severe disease.

Differential Diagnosis

Transient Tachypnoea of the Newborn

Usually term infants.

Neonatal Pneumonia

May mimic RDS.

Meconium Aspiration Syndrome

Usually term or post-term infants.

Pneumothorax

Sudden deterioration.

Congenital Heart Disease

Consider if severe cyanosis.

Investigations

Blood Gas

May show:

Hypoxaemia
Hypercapnia
Acidosis

Chest X-Ray

Classic findings:

Ground-Glass Appearance

Air Bronchograms

Low Lung Volumes

This is a favourite MRCPCH image question.

Sepsis Screen

If infection suspected.

Management

Antenatal Steroids

Given to mothers at risk of preterm delivery.

Benefits:

Reduce RDS
Reduce IVH
Reduce neonatal mortality

Important MRCPCH fact.

Continuous Positive Airway Pressure (CPAP)

Often first-line respiratory support.

Benefits:

Prevents alveolar collapse
Improves oxygenation

Surfactant Therapy

Main treatment.

Examples:

Poractant alfa
Beractant

Can be given via:

INSURE

Intubate → Surfactant → Extubate

LISA

Less Invasive Surfactant Administration

Increasingly used in modern neonatal practice.

Mechanical Ventilation

Required if:

Severe respiratory failure
Persistent apnoea
Rising carbon dioxide

Supportive Care

Thermoregulation
Fluids
Nutrition
Infection surveillance

Complications

Air Leak Syndromes

Pneumothorax

Most common.

Bronchopulmonary Dysplasia (BPD)

Associated with prolonged ventilation.

Intraventricular Haemorrhage

More common in extremely preterm infants.

Retinopathy of Prematurity

Related to prematurity and oxygen exposure.

Prevention

Antenatal Steroids

Most effective preventive strategy.

Avoid Unnecessary Prematurity

Early CPAP

Reduces need for ventilation.

Common Exam Traps

Trap 1

RDS = Surfactant deficiency.

Trap 2

Prematurity is the strongest risk factor.

Trap 3

Ground-glass appearance on chest X-ray.

Trap 4

Antenatal steroids reduce incidence.

Trap 5

Surfactant therapy treats the underlying problem.

Trap 6

Do not confuse RDS with TTN.

TTN usually occurs in:

Term infants
Elective Caesarean deliveries

One Minute Revision

Surfactant deficiency causes RDS.
Prematurity is the major risk factor.
Presents with grunting, recession and tachypnoea.
Ground-glass chest X-ray.
Antenatal steroids reduce risk.
CPAP often first-line support.
Surfactant replacement improves outcomes.
Watch for pneumothorax and BPD.

Suggested References

Rennie & Roberton's Textbook of Neonatology
Nelson Textbook of Pediatrics
European Consensus Guidelines on RDS
BNF for Children
NICE Preterm Labour and Birth Guideline
Neonatal Life Support (NLS) Manual

Disclaimer

These notes are intended for MRCPCH revision and educational purposes only. They do not replace local, national or institutional guidelines. Clinical decisions should always be based on current guidance, senior advice and individual patient circumstances.

Mobile - Navigation Menu

Guide to MRCPCH