Respiratory distress syndrome, infant

Synonyms

7

Overview

Respiratory distress syndrome in infant is a syndrome in premature infants caused by developmental insufficiency of surfactant production and structural immaturity in the lungs. It can also be a consequence of neonatal infection. It can also result from a genetic problem with the production of surfactant associated proteins. IRDS affects about 1% of newborn infants and is the leading cause of death in preterm infants. The incidence decreases with advancing gestational age, from about 50% in babies born at 26–28 weeks, to about 25% at 30–31 weeks. The syndrome is more frequent in infants of diabetic mothers and in the second born of premature twins. IRDS is distinct from pulmonary hypoplasia, another leading cause of neonatal death that involves respiratory distress.

Symptoms

This disease begins shortly after birth and is manifest by:

  • fast breathing
  • fast heart rate
  • chest wall retractions (recession)
  • expiratory grunting
  • nasal flaring
  • blue discoloration of the skin during breathing efforts

As the disease progresses, the baby may develop:

  • ventilatory failure (rising carbon dioxide concentrations in the blood)
  • prolonged cessations of breathing ("apnea")


Whether treated or not, the clinical course for the acute disease lasts about 2 to 3 days. During the first day the patient worsens and requires more support. During the second day the baby may be remarkably stable on adequate support and resolution is noted during the third day, heralded by a prompt diuresis. Despite huge advances in care, it remains the most common single cause of death in the first month of life in the developed world. Complications include metabolic disorders (acidosis, low blood sugar), patent ductus arteriosus, low blood pressure, chronic lung changes, and bleeding in the brain. The disease is frequently complicated by prematurity and its additional defects in other organ function.

Causes

This disease occurs when there is not enough of a substance in the lungs called surfactant. Surfactant is made by the cells in the airways and consists of phospholipids and protein. It begins to be produced in the fetus at about 24 to 28 weeks of pregnancy, and is found in amniotic fluid between 28 and 32 weeks. By about 35 weeks gestation, most babies have developed adequate amounts of surfactant.

Prevention

Most cases of infant respiratory distress syndrome can be ameliorated or prevented if mothers who are about to deliver prematurely can be given glucocorticoids, one group of hormones. This speeds the production of surfactant. For very premature deliveries, a glucocorticoid is given without testing the fetal lung maturity. The American College of Obstetricians and Gynecologists (ACOG), Royal College of Medicine, and other major organizations have recommended antenatal glucocorticoid treatment for women at risk for preterm delivery prior to 34 weeks of gestation. Multiple courses of glucocorticoid administration, compared with a single course, does not seem to increase or decrease the risk of death or neurodevelopmental disorders of the child.

In pregnancies of greater than 30 weeks, the fetal lung maturity may be tested by sampling the amount of surfactant in the amniotic fluid by amniocentesis, wherein a needle is inserted through the mother's abdomen and uterus. Several tests are available that correlate with the production of surfactant. These include the lecithin-sphingomyelin ratio ("L/S ratio"), the presence of phosphatidylglycerol (PG), and more recently, the surfactant/albumin (S/A) ratio. For the L/S ratio, if the result is less than 2:1, the fetal lungs may be surfactant deficient. The presence of PG usually indicates fetal lung maturity. For the S/A ratio, the result is given as mg of surfactant per gm of protein. An S/A ratio <35 indicates immature lungs, between 35-55 is indeterminate, and >55 indicates mature surfactant production(correlates with an L/S ratio of 2.2 or greater).

Diagnosis

It is usually diagnosed by a combination of assessments, including:

  • Appearance, color and breathing efforts (these signs indicate your baby's need for oxygen)
  • X-rays of lungs – x-rays are electromagnetic energy used to produce images of bones and internal organs onto film. In HMD, they often show a unique "ground glass" appearance called a reticulogranular pattern.
  • Blood gases (tests for oxygen, carbon dioxide and acid in arterial blood) - often show lowered amounts of oxygen and increased carbon dioxide.
  • Echocardiography (EKG) – may be used to rule out heart problems that could cause symptoms similar to HMD. An electrocardiogram is a test that records the electrical activity of the heart, shows arrhythmias (abnormal rhythms) and detects damage to the heart muscle.

Prognosis

If not treated, can be fatal.

Treatment

Treatment may include:

  • Placing an endotracheal tube (breathing tube, also called an ET) into your baby's windpipe
  • Mechanical breathing machine (to do the work of breathing for your baby)
  • Supplemental oxygen (extra amounts of oxygen)
  • Continuous positive airway pressure (CPAP) - a mechanical breathing machine that pushes a continuous flow of air or oxygen to the airways to help keep tiny air passages in the lungs open
  • Surfactant replacement with artificial surfactant – this treatment has been shown to reduce the severity of HMD, and is most effective if started in the first six hours of birth. It may be given as preventive treatment for babies at very high risk for HMD, or used as a "rescue" method. The drug comes as a powder that is mixed with sterile water and given through the ET tube. This treatment is usually administered in several doses.
  • medications (to help sedate and ease your baby's pain during treatment)

 

  • Approved therapies:
    • Pulmonary surfactant replacement, porcine (Curosurf) - FDA-approved indication: Treatment (rescue) of respiratory distress syndrome in premature infants. 
    • Colfosceril palmitate, cetyl alcohol, tyloxapol (Exosurf Neonatal for Intratracheal Suspension) -FDA-approved indication: Treatment of established hyaline membrane disease at all gestational ages. 
    • Surface active extract of saline lavage of bovine lungs (Infasurf) - FDA-approved indication: Treatment and prevention of respiratory failure due to pulmonary surfactant deficiency in preterm infants. 
    • Beractant (Survanta intratracheal suspension) - FDA-approved indication: Treatment of ("rescue") of premature infants with RDS confirmed by x-ray and requiring mechanical ventilation.

Resources

Refer to research Publications.