RDS (respiratory distress syndrome)
Formerly known as hyaline membrane disease, a syndrome of respiratory difficulty in newborn infants caused by a deficiency of a molecule called surfactant.
RDS almost always occurs in newborns born before 37 weeks of gestation. The more premature the baby is, the greater is the chance of developing RDS. RDS is more likely to occur in newborns of diabetic mothers.
Surfactant, a mixture of phospholipids and lipoproteins, is secreted by lung cells. The air-fluid interface of the film of water lining the alveoli of the lung (where the exchange of oxygen and CO2 occurs) exerts large forces that cause the alveoli to close if surfactant is deficient. Lung compliance is decreased, and the work of inflating the stiff lungs is increased. The preterm newborn is further handicapped because his or her ribs are more easily deformed (compliant). Breathing efforts therefore result in deep sternal (breastbone) retractions but poor air entry if the ribs are compliant compared with the lungs. This results in diffuse atelectasis (collapse of the lungs).
Rapid, labored, grunting respirations usually develop immediately or within a few hours after delivery, with retractions above and below the breastbone and flaring of the nostrils. The extent of atelectasis (lung collapse) and the severity of respiratory failure progressively worsen.
Not all infants with RDS have signs of respiratory distress; extremely low birth weight newborns (i.e., < 1000 g) may be unable to initiate respirations at birth because their lungs are so stiff; they may fail to initiate breathing in the delivery room. The incidence of RDS can be reduced by assessment of fetal lung maturity to determine the optimal time for delivery. When a fetus must be delivered prematurely, giving betamethasone systemically to the mother for at least 24 hours before delivery induces fetal surfactant production and usually reduces the risk of RDS or decreases its severity. If untreated, severe RDS can result in multiple organ failure and death. However, if the newborn's ventilation is adequately supported, surfactant production will begin and RDS will resolve by 4 or 5 days. Recovery is hastened by treatment with pulmonary surfactant.
Read Also:
- Reabsorption
Being absorbed again. For example, the kidney selectively reabsorbs substances it has already secreted into the renal tubules, such as glucose, protein, and sodium. These reabsorbed substances are returned to the blood.
- Reaction kinetics
The rate of change in a biochemical (or other) reaction.
- Reaction, allergic
A reaction that occurs when the immune system attacks a usually harmless substance (an allergen) that gains access to the body. The immune system calls upon a protective substance called immunoglobulin E (IgE) to fight these invading allergic substances (allergens). Even though everyone has some IgE, an allergic person has an unusually large army of […]
- Reaction, chemical
A process in which one substance is transformed into another. Thousands of different types of chemical reactions occur in the body and are essential to its structure and function.
- Reaction, desmoplastic
This term refers to the growth of fibrous or connective tissue. Some tumors elicit a desmoplastic reaction, the pervasive growth of dense fibrous tissue around the tumor. Scar tissue (adhesion) within the abdomen after abdominal surgery is another type of desmoplastic reaction. “Desmo-” comes from the Greek “desmos” meaning “a fetter or band” and “-plastic” […]