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Respiratory distress syndrome in the newborn (discussed in detail
in Chapter 54) is the most frequent problem
that results in neonatal intensive care unit admission. It is essential
to recognize, evaluate, and differentiate between the many possible
causes of respiratory distress, including those that do not primarily
involve the lung. The presenting symptoms and severity of these
symptoms may alert the physician in a life-threatening situation.
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One or more of the following may characterize respiratory distress
in the newborn: tachypnea, grunting, nasal flaring, and chest retractions.
A newborn normally breathes at a rate of 30 to 60 breaths per minute.
A newborn with tachypnea may breathe at a faster rate to maintain
adequate ventilation and may attempt to decrease airway resistance
by flaring the nares. The infant may try to maintain lung volume
by partially closing the glottis during expiration, thereby producing
grunting sounds. Chest retractions may occur with parenchymal lung
disease or an obstructed airway. Additional signs such as cyanosis,
gasping, apnea, stridor, or choking should alert the physician of
a more severe respiratory problem. Respiratory distress in the newborn
is a common presentation for a wide variety of disorders shown in Table 50-1.
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Transient tachypnea of the newborn (TTN) is a self-limited, usually
benign disease, affecting the term infant and late-preterm infant
soon after birth. Avery and coworkers described the clinical and
radiographic features of this condition in 1966 and attributed it
to a delayed absorption of fetal lung fluid.1 More
recently, Bland2,3 described TTN as a persistent
postnatal pulmonary edema, since some of the fluid may enter the
lungs from the pulmonary circulation postnatally. TTN occurs in
approximately 11 infants per 1000 live births and is more common
in males. It is associated with cesarean section delivery,4 the
use of maternal labor analgesia or anesthesia, gestational diabetes,
and perinatal asphyxia.
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Fetal lung fluid is essential for normal lung development, is
a secretion intrinsic to the lung, and is ...