Infant respiratory distress syndrome is a lung disorder that tends to affect premature infants. Major symptoms include difficulty in breathing and collapsed lungs, potentially requiring mechanical ventilation or positive end-expiratory pressure (PEEP).
Infant respiratory distress syndrome is characterized by diminished oxygen intake in the premature newborn. A clear membrane is found lining the alveolar (air cell) ducts in the lungs and is associated with reduced amounts of lung wetting agents or emulsifier (surfactant). The surfactant is a lipoprotein based on lecithin that stabilizes alveolar membranes. When this surfactant is missing, breathing is difficult and may lead to collapse of a lung. The affected infant must be placed on some type of ventilation, either mechanical or physical, in order to continue breathing.
Infant respiratory distress syndrome is caused by the absence of a natural lung wetting agent (surfactant) in the immature lungs of infants. Since surfactant normally develops late in prenatal life it usually is not present in the very premature infant of about 26-36 weeks of gestational age. This can result in improper functioning of the alveoli (air cells) of the lungs causing breathing difficulties and collapsed lungs.
Surfactant protein-B (SP-B) deficiency is a rare type of infant respiratory distress syndrome caused by an abnormal pulmonary surfactant B gene. This type of infant respiratory distress syndrome follows autosomal recessive inheritance.
Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.
Infant respiratory distress syndrome affects male and female premature infants in equal numbers. Among approximately 250,000 infants born prematurely each year in the United States, up to 50,000 will have IRDS which will kill approximately 5,000 of them. Due in large part to the use of surfactants beginning in 1989, infant mortality rates in the United States have dropped from 9.7 per 1,000 births in 1989 to 8.9 per 1,000 births in 1991. Infants with surfactant protein-B deficiency do not respond to surfactant replacement therapy.
Treatment of infant respiratory distress syndrome consists of mechanical or physical breathing assistance such as positive end expiratory pressure (PEEP). Other treatment is symptomatic and supportive.
Exosurf Neonatal (colfosceril palmitate) is a synthetic lung surfactant that was approved for use in August of 1990 by the Food and Drug Administration (FDA) for treatment of infant respiratory distress syndrome. The treatment consists of a single dose given 30 minutes after birth to high-risk infants. Surfactants are surface-cleaning agents that are used to wash out (lavage) the lungs and its air passages (bronchopulmonary area). This synthetic form of lung surfactant is manufactured by Burroughs Wellcome.
Survanta (beractant) developed by Abbott Labs is another pediatric surfactant and is derived from bovine tissues. There is also great improvement in the infants treated with this product.
Surfactant TA and Human Surf have both been approved by the FDA for treatment of infant respiratory distress syndrome.
The FDA has also approved Dey Lab's lung surfactant, Curosurf Intratracheal Suspension (poractant alpha) for the treatment of infant respiratory distress syndrome.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.
For information about clinical trials being conducted at the National Institutes of Health (NIH) Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
New drugs are being developed to replace the missing surfactant in the lungs of infants with respiratory distress syndrome. At the present time, there are several different pulmonary surfactants that have been designated for the treatment of infantile respiratory distress syndrome.
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