Respiratory distress syndrome (RDS) is a life-threatening problem in the newborn that has decreased in frequency due to improved scientific understanding of the problem and implementation of new therapies. RDS is characterized by breathing difficulties due to immaturity of multiple coordinated systems that prepare the newborn for air breathing after delivery. These include delays in the 1) production of surfactant, a substance made by lung cells, which is needed to decrease the work of opening the lungs, 2) clearance of fetal lung fluid, and 3) growth of the lung surface so that transfer of oxygen into the blood can occur.

The risk of RDS increases the more premature the baby as these systems haven't had a chance to fully develop. Many scientific advances in the past 30 years that NHLBI has supported have contributed to the tremendous decline in deaths due to RDS, from 5,498 in 1979 to 860 in 2005. As a result of investigations demonstrating that premature infants have insufficient surfactant production at birth, surfactant is the single most important therapy for RDS.

NHLBI supports a strong scientific program in the basic and clinical research in lung development. Examples of research advances include: identification of gene mutations that cause surfactant deficiency and can predict prognosis of infants with RDS, discovery of genes that program the lung to form its complex structure, mechanisms of clearance of fluid from the lung so that the baby can take the first breath, the interaction between the cells that form blood vessels with the cells that form the airways and air sacs so that a healthy lung can develop normally, and use of inhaled nitric oxide to reduce breathing difficulties of the premature newborn. In addition, scientists have determined that the premature lung is especially vulnerable to injury from oxygen and ventilator pressures that are used to support premature newborns. This has led to modifications of clinical practice that have minimized the adverse effects of life saving therapies.

Despite the significant success of surfactant replacement and changes in oxygen and ventilator use at improving survival of premature newborns with RDS, many go on to develop chronic lung disease (CLD) that can persist into adulthood. It is estimated that 5-10,000 newborns develop the most common form of CLD, bronchopulmonary dysplasia (BPD) each year, with an incidence of up to 85% in preterms of very low birth weight (500-699 g). Preterm infants with and without BPD have life-long increased risk of death, rehospitalization, and chronic and acute respiratory symptoms requiring therapy compared to term infants.

Given the high prevalence of respiratory symptoms in premature infants after discharge home, continued research to evaluate newborns at risk of low lung function is needed. Strategies to help understand these infants may include evaluating airway obstruction and low lung volumes using infant pulmonary function tests and /or imaging, exercise capacity (by oral feeding success), pulmonary hypertension by echocardiography, abnormalities of breathing (obstructive, central, and mixed apnea) using polysomnography, and responses to conventional medical treatments.

This article was published in the Fall 2008 issue of the ALA Lung Health Magazine.