Transient Tachypnea of the Newborn
(Neonatal Wet Lung Syndrome)
Transient tachypnea of the newborn is transient respiratory distress caused by delayed resorption of fetal lung fluid.
Transient tachypnea of the newborn affects premature infants, term infants delivered by elective cesarean delivery without labor, and infants born with respiratory depression, all of whom have delayed clearance of fetal lung fluid. Part of the cause is immaturity of the Na channels in lung epithelial cells; these channels are responsible for absorbing Na (and thus water) from the alveoli. (Mechanisms for normal resorption of fetal lung fluid are Perinatal Physiology : Neonatal pulmonary function.) Other risk factors include macrosomia, maternal diabetes and/or asthma, lower gestational age, and male sex.
Transient tachypnea of the newborn is suspected when the infant develops respiratory distress shortly after birth. Symptoms include tachypnea, intracostal and subcostal retractions, grunting, nasal flaring, and possible cyanosis.
Pneumonia, respiratory distress syndrome, and sepsis may have similar manifestations, so chest x-ray, CBC, and blood cultures usually are done. Chest x-ray shows hyperinflated lungs with streaky perihilar markings, giving the appearance of a shaggy heart border while the periphery of the lungs is clear. Fluid is often seen in the lung fissures. If initial findings are indeterminate or suggest infection, antibiotics (eg, ampicillin, gentamicin) are given while awaiting culture results.
Recovery usually occurs within 2 to 3 days. Treatment is supportive and involves giving O2 by hood and monitoring ABGs or pulse oximetry. Rarely, extremely premature infants, those with neurologic depression at birth, or both require continuous positive airway pressure and occasionally even mechanical ventilation.