Respiratory Distress Syndrome Resident Lecture Series Soo Hyun Kwon, MD Neonatal-Perinatal Fellow.

Respiratory Distress Syndrome

Resident Lecture Series

Soo Hyun Kwon, MDNeonatal-Perinatal Fellow

Overview

• 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%• 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

• 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

• Tachypnea• Nasal flaring• Grunting• Intercostal, subxiphoid, and

subcostal retractions • Cyanosis

Differential Diagnosis

• 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

• 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?