Respiratory Distress Syndrome, Infant
Synonyms of Respiratory Distress Syndrome, Infant
- Hyaline Membrane Disease
- Infantile Respiratory Distress Syndrome
- surfactant protein-B deficiency
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.
Symptoms of the following disorders can be similar to those of infant respiratory distress syndrome, although they tend to affect older children or adults:
Adult respiratory distress syndrome is a lung disorder caused by direct injury to the lungs or acute illness. It often occurs in conjunction with other illnesses and is characterized by the inability to breathe properly. Mechanical ventilation, surgical insertion of a breathing tube (tracheotomy) or positive end-expiratory pressure (PEEP) is usually necessary to aid in breathing. Secondary complications may occur resulting in pneumonia, blood poisoning (sepsis) or other infections. Chronic lung disease, multiple organ system failure and irreversible respiratory dysfunction may also occur. (For more information on this disorder, choose "adult respiratory distress syndrome" as your search term in the Rare Disease Database.)
Pulmonary alveolar proteinosis is a rare lung disorder characterized by breathing difficulty that gradually becomes more severe, especially following exertion. The air sacs in the lungs (alveoli) are filled with a granular material (phospholipid) consisting mostly of protein and fat. Certain cells called macrophages, that usually swallow inhaled particles in the lung alveoli, can be found in the phospholipid material. This disorder may spread throughout the lungs or be confined to a small area. It may progress, remain stable, or spontaneously clear. (For more information on this disorder, choose "pulmonary alveolar proteinosis" as your search term in the Rare Disease Database.)
Pneumonia is marked by excessive accumulation of fluid in the lungs due to an infection. Symptoms such as fever, cough, large amounts of mucous production (sputum), fluid in surrounding the lungs (pleurisy) and/or chills occur. Chest pain, headache, diarrhea, sore throat and fever blisters may also develop. Shortness of breath, difficulty in breathing, decreased exercise tolerance and night sweats are characteristic. Pneumonia occurs frequently in middle-aged to older adults with various underlying diseases. It can occur in persons of all ages, statistically most often in winter and early spring. Pneumonia can be caused by various bacteria, viruses, and fungi.
Bronchial asthma is a common respiratory disease due to many different causes, airway irritability of unknown causes, and airway inflammation. Most of these problems are treatable. Asthma affects 2 to 6 percent of the U. S. population. It usually begins before the age of ten in about one-half of all patients and occurs twice as often in males as in females.
Emphysema is characterized by abnormal difficulty in breathing upon exertion. As the disease advances it becomes more and more difficult for the patients to breathe. In advanced stages, breathing even at rest is difficult. The patient becomes thin and malnourished-appearing with a barrel-shaped chest, and appears to be in respiratory distress even during mild exertion as indicated by noisy expulsion of air. Lack of elasticity in lung tissue obstructs the airflow during exhalation. There is loss of lung tissue with abnormally enlarged air spaces. The causes of emphysema may include air pollution, smoking, occupational exposure to mineral dust, vegetable dusts and fibers. Regularly inhaled fumes and gases, infection and heredity may also play an important part in the development of emphysema. The disease may progress even with intensive treatment and after stopping smoking. However, one hereditary type of emphysema (alpha-1-antitrypsin deficiency) is treatable with the orphan drug Prolastin. (For more information on this disorder, choose "alpha-1-antitrypsin" as your search term in the Rare Disease Database.)
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.
Organizations related to Respiratory Distress Syndrome, Infant
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Cole FS. Surfactant protein B: unambiguously necessary for adult pulmonary function. Am J Physiol Lung Cell Mol Physiol. 2003 Sep;285(3);L540-2. Review.
Nogee LM. Abnormal expression of surfactant protein C and lung disease. Am J Respir Cell Mol Biol. 2002;Jun 26(6):641-4.
Merchak A, Janssen DJ, Bohlin K, et al. Endogenous pulmonary surfactant metabolism is not affected by mode of ventilation in premature infants with respiratory distress syndrome. J Pediatr. 2002 Jun;140(6);693-8.
Lopez-Herce J, et al., Surfactant treatment for acute respiratory distress syndrome. Arch Dis Child. 1999;80:248-52.
van Helden HP, et al., Efficacy of Curosurf in a rat model of acute respiratory distress syndrome. Eur Respir J. 1998;12:533-9.
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Gitlin JD, et al., Randomized controlled trial of exogenous surfactant for the treatment of hyaline membrane disease. Pediatrics. 1987;79:31-7.
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