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Respiratory Disorders of the Newborn

Respiratory distress is a common problem during the first few days of life. Respiratory distress may present with tachypnea, nasal flaring, sternal and intercostal retractions, cyanosis, and apnea, RDS, TTN, BPD. The most common respiratory disorders of the newborn are respiratory distress syndrome, chronic lung disease, and transient tachypnea of the newborn.

Transient Tachypnea of the Newborn

Transient tachypnea of the newborn (TTN) usually presents as early respiratory distress in term or preterm infants. It is caused by delayed reabsorption of fetal lung fluid.

TTN is a very common, and it is often seen following cesarean section because, compared with those born vaginally, babies born by cesarean section have delayed reabsorption of fetal lung fluid.

Symptoms of TTN include tachypnea, retractions, nasal flaring, grunting, and cyanosis.

Arterial blood gas reveals respiratory acidosis and mild to moderate hypoxemia.

Chest x-ray often reveals fluid in the interlobar fissures and perihilar streaking, which sometimes obscures the heart borders. Hyperaeration of the lungs and mild cardiomegaly may be seen; alveolar edema may appear as coarse, fluffy densities.

Delayed reabsorption of fetal lung fluid is seen in term or near-term infants as well as in small, preterm infants who may have respiratory distress syndrome (RDS). TTN initially may be difficult to distinguish from RDS or group B streptococcal pneumonia.

TTN usually resolves within12-24 hours. The chest radiograph appears normal in 2-3 days. The symptoms rarely last more than 72 hours.

Treatment of TTN consists of oxygen therapy. Infants will usually recover fully, without long-term pulmonary sequelae.

Respiratory Distress Syndrome

RDS is a lung disease caused by pulmonary surfactant deficiency. It occurs almost always in preterm infants who are born before the lungs are able to produce adequate amounts of surfactant.

Surfactant is produced by pneumocytes in the lung. It lowers the surface tension of the alveolus. The preterm neonate whose lungs are deficient in surfactant will develop diffuse atelectasis because of decreased lung compliance (stiff lungs).

Respiratory distress usually begins at, or soon after, delivery and tends to worsen over time. Infants will have tachypnea, nasal flaring, intercostal and sternal retractions, and expiratory grunting. Tiny preterm infants who lack pulmonary surfactant may fail to initiate ventilation in the delivery room and rapidly become hypoxic and apneic.

Chest radiography shows diffuse atelectasis, which appears as reduced lung volume, with homogeneous haziness or the "ground glass" appearance of lung fields, and air bronchograms. Positive pressure ventilation can reverse the radiographic findings of atelectasis.

RDS is diagnosed when a premature infant has respiratory distress and a characteristic chest radiograph. The differential diagnosis includes pneumo nia, often caused by group B streptococci, which is more common in preterm infants and can mimic RDS, both clinically and radiographically.

Ventilatory Management

Continuous positive airway pressure (CPAP) improves oxygenation and survival. CPAP (about 5-7 cm H2O pressure) is applied via nasal prongs, nasopharyngeal tube, or endotracheal tube. In some infants with milder disease, CPAP may prevent the need for mechanical ventilation.

For infants exhibiting respiratory acidosis, hypoxemia or apnea, intermittent positive pressure ventilation.