A newborn that has a surfactant deficiency will have which assessment noted on a physical exam?

Physiologic stress at the time of labor and delivery (eg, due to hypoxia and/or acidosis caused by umbilical cord compression or placental insufficiency or caused by infection) may cause the fetus to pass meconium into the amniotic fluid before delivery. Meconium passage also may be normal before birth, particularly in term or postterm infants; meconium passage is noted in about 10 to 15% of births. However, it is never normal for meconium to be noted at the delivery of a premature infant. During delivery, perhaps 5% of neonates with meconium passage aspirate the meconium, triggering lung injury and respiratory distress, termed meconium aspiration syndrome. Although the pneumonitis caused by the meconium contributes to respiratory compromise in these infants after delivery, the persistent pulmonary hypertension Persistent Pulmonary Hypertension of the Newborn Persistent pulmonary hypertension of the newborn is the persistence of or reversion to pulmonary arteriolar constriction, causing a severe reduction in pulmonary blood flow and right-to-left... read more (PPH) caused by the prenatal and postnatal acidosis and/or hypoxia is equally or even more compromising.

The mechanisms by which aspiration induces the clinical syndrome probably include

• Nonspecific cytokine release

• Airway obstruction

• Decreased surfactant production and surfactant inactivation

• Chemical pneumonitis

Neonates also may aspirate vernix caseosa, amniotic fluid, or blood of maternal or fetal origin during delivery, all of which can cause respiratory distress and signs of aspiration pneumonia on chest x-ray.

• Meconium passage

• Respiratory distress

• Characteristic x-ray findings

Diagnosis of meconium aspiration syndrome is suspected when a neonate shows respiratory distress in the setting of meconium-containing amniotic fluid.

Because meconium may enhance bacterial growth and meconium aspiration syndrome is difficult to distinguish from bacterial pneumonia, cultures of blood also should be taken.

Prognosis is generally good, although it varies with the underlying physiologic stressors; overall mortality is increased. Infants with meconium aspiration syndrome may be at greater risk of asthma in later life.

• Endotracheal intubation and mechanical ventilation as needed

• Supplemental oxygen as needed to keep PaO2 high to relax pulmonary vasculature in cases with PPH

• Surfactant

• IV antibiotics

• Inhaled nitric oxide in severe cases of PPH

• Extracorporeal membrane oxygenation (ECMO) if unresponsive to above therapies

Routine deep suctioning (ie, intubating to suction below the cords) of neonates delivered with meconium-stained fluid has not been shown to improve outcome. However, if the neonate's breathing appears obstructed, suctioning is done with an endotracheal tube attached to a meconium aspirator. Intubation or nasal continuous positive airway pressure ( CPAP Continuous Positive Airway Pressure (CPAP) Initial stabilization maneuvers include mild tactile stimulation, head positioning, and suctioning of the mouth and nose followed as needed by Supplemental oxygen Continuous positive airway... read more ) are indicated for respiratory distress, followed by mechanical ventilation Mechanical Ventilation Initial stabilization maneuvers include mild tactile stimulation, head positioning, and suctioning of the mouth and nose followed as needed by Supplemental oxygen Continuous positive airway... read more and admission to the neonatal intensive care unit as needed. Because positive pressure ventilation enhances risk of a pulmonary air-leak syndrome, regular evaluation (including physical examination and chest x-ray) is important to detect this complication, which should be sought immediately in any intubated neonate whose blood pressure, perfusion, or oxygen saturation suddenly worsens. See Pulmonary Air-Leak Syndromes Pulmonary Air-Leak Syndromes Pulmonary air-leak syndromes involve dissection of air out of the normal pulmonary airspaces. (See also Overview of Perinatal Respiratory Disorders.) Extensive physiologic changes accompany... read more for treatment of air-leak syndromes.

• About 5% of neonates with meconium passage aspirate the meconium, triggering lung injury and respiratory distress or have prenatal and postnatal physiology that predisposes them to persistent pulmonary hypertension, which can complicate meconium aspiration syndrome.

• Neonates may have tachypnea, nasal flaring, retractions, cyanosis or desaturation, rales, rhonchi, and visible meconium staining in the oropharynx.

• Suspect the diagnosis when respiratory distress occurs in neonates who had meconium-containing amniotic fluid.

• Do chest x-ray and cultures of blood to exclude pneumonia and bacterial sepsis.

• After delivery, if infants have signs of obstructed breathing, suction them using an endotracheal tube attached to a meconium aspirator.

• Severe cases require mechanical ventilation and sometimes antibiotics, inhaled nitric oxide, or extracorporeal membrane oxygenation (ECMO).

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