Respiratory Distress
Syndrome
Resident Lecture Series
Soo Hyun Kwon, MD
Neonatal-Perinatal Fellow
Overview
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Definition
Epidemiology
Lung Development
Pathophysiology
Risk Factors
Clinical Manifestations
DDx
Diagnosis
Treatment
Objectives
• Define respiratory distress syndrome (RDS).
• Discuss the epidemiology, pathophysiology, and
diagnosis of RDS.
• List a differential diagnosis for respiratory distress in the
neonate.
• Describe the treatments for RDS.
• Discuss ventilation strategies that can be used in the
infant who has RDS.
• Describe long-term complications of RDS and its
treatments.
Definition
• Formerly known as hyaline membrane
disease
• Deficiency of pulmonary surfactant in an
immature lung
• Disease of prematurity
Epidemiology
• Major cause of morbidity and mortality in preterm
infants
• 20,000-30,000 newborn infants each year
• Incidence and severity of RDS are related inversely to
gestational age of newborn infant
• 26-28 weeks' gestation : 50%
• 30-31 weeks' gestation : <30%
• Overall incidence in 501-1500 grams: 42%
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501-750 grams: 71%
751-1000 grams: 54%
1001-1250 grams: 36%
1251-1500 grams: 22%
Phases of Lung Development
Lung Development
Surfactant
• Complex lipoprotein
• Composed of 6
phospholipids and 4
apoproteins
• 70-80%
phospholipids, 8-10%
protein, and 10%
neutral lipids
Surfactant Metabolism
Assessment of Fetal Lung
Maturity
• Lecithin/sphingomyelin (L/S) ratio
• Lamellar body counts
• Phosphatidylglycerol
• After 35 weeks gestation
L/S Ratio
Pathophysiology
Etiology
• Preterm delivery
• Mutations in genes encoding surfactant
proteins
• SP-B
• SP-C
• ATP-binding cassette (ABC) transporter A3
(ABCA3)
Lung Compliance
Normal Lung
Hyaline Membranes
Risk Factors
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Prematurity
Maternal diabetes
C-section delivery
Asphyxia
Surfactant Inactivation
• Meconium and blood can inactivate
surfactant activity (Full-term > Preterm)
• Proteinaceous edema and inflammatory
products increase conversion rate of
surfactant into its inactive vesicular form
• Oxidant and mechanical stress associated
with mechanical ventilation that uses large TV
Clinical Manifestations
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Tachypnea
Nasal flaring
Grunting
Intercostal, subxiphoid, and subcostal
retractions
• Cyanosis
Differential Diagnosis
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TTN
MAS
Pneumonia
Cyanotic Congenital Heart Disease
Pneumomediastinum, pneumothorax
Hypoglycemia
Metabolic problems
Hematologic problems
• Anemia, polycythemia
• Congenital anomalies of the lungs
Diagnosis
• Onset of progressive respiratory failure
shortly after birth
• Characteristic chest radiograph
• ABG
• Hypoxia
• Hypercarbia
CXR
Prevention
• Antenatal glucocorticoids
• Enhances maturational changes in lung architecture
and inducing enzymes
• Stimulate phospholipid synthesis and release of
surfactant
• All pregnant mothers at risk for preterm delivery at or
below 34 weeks gestation should receive ACS
Treatment
• Surfactant Therapy
• Assisted Ventilation Techniques
• Supportive Care
• Thermoregulation
• Fluid Management
• Nutrition
References
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Jobe AH. Why Surfactant Works for Respiratory Distress Syndrome.
NeoReviews. 2006; 7: 95-106.
Pramanik AK, et al. Respiratory distress syndrome.
http://emedicine.medscape.com/article/976034-overview.
Saker F, Martin R. Pathophysiology and clinical manifestations of
respiratory distress syndrome in the newborn. Uptodate.
http://www.utdol.com
Warren JB, Andersen JM. Respiratory distress syndrome. Neoreviews.
2009; 7: 351-361.
Questions or Comments?