Iowa Neonatology Handbook: Pulmonary

Care of the Infant with the Meconium Aspiration Syndrome

Jonathan M. Klein, MD
Peer Review Status: Internally Peer Reviewed

 Meconium staining of amniotic fluid occurs in 11-22% of all deliveries. Meconium aspiration syndrome occurs in approximately 2% of these deliveries (1). Release of meconium into the amniotic fluid is usually the result of in utero hypoxia and/or fetal distress. If meconium is passed more than 4 hours before delivery, the infant's skin will be meconium stained. The distressed fetus will make reflex gasping movements and aspirate meconium stained fluid into the tracheo-bronchial tree. After the first breath, the infant will deposit the aspirated meconium stained fluid further down the bronchial tree and therefore cause a mechanical blockage of alveoli and small airways with a resultant ball-valve type obstruction. An infant born via breech presentation will often pass meconium prior to delivery, even without fetal distress. 

I. Treatment in the delivery room:

A. Thin Meconium -

1. The infant's oro- and nasopharynx should be suctioned by the obstetrician prior to delivery of the shoulders. 

2. In a clinically well-appearing newborn, visualization of the larynx and intubation should not be necessary. 

3. In a depressed newborn, intubate and suction first, then proceed with the resuscitation.

B. Thick Meconium - 

1. The infant's oro- and nasopharynx should be suctioned by the obstetrician prior to delivery of the shoulders. 

2. Following suctioning of the oro- and nasopharynx by the obstetrician, the infant's oro- and nasopharynx should be immediately suctioned by the pediatrician followed by endotracheal intubation and suctioning of any meconium that is present below the cords. In a clinically well-appearing, vigorously crying newborn without meconium at the level of the vocal cords, intubation may not be necessary.

3. Visualize the cords via direct laryngoscopy and remove as much of the meconium from below the cords as possible. Do not apply suction to the tube by your mouth. Use an adapter connecting the endotracheal tube directly to wall suction, with the pressure set at 40 to 60 TORR. Repeat the intubation as often as necessary to clear the lower airway of meconium, even if the infant has cried. 

4. Following suctioning, ventilate the infant as necessary. 

5. Keep the infant warm and dry to prevent hypothermia and shunting. Continue to monitor the infant's heart and respiratory rates. 

6. After the infant has been stable for a least five minutes, the stomach can be aspirated to remove as much of the meconium-stained fluid as possible. 

7. If warranted by the clinical history (fetal distress, depressed infant, etc.), intubation should be performed even if meconium is not seen on the cords. 

II. Treatment in the nursery:

A. The infant should be monitored and observed carefully for signs of respiratory distress, i.e., cyanosis, tachypnea, retractions, and grunting. 

B. Arterial blood gases and pH should be monitored for evidence of either metabolic or respiratory acidosis. 

C. Obtain a chest x-ray to rule out air leak (pneumothorax, pneumomediastinum, or pneumopericardium), secondary to air trapping from ball-valve obstruction. 

D. An infant with a history of meconium aspiration who develops respiratory distressshould be placed in a hood to maintain O2 saturations greater or equal to 99% to prevent episodes of hypoxia and shunting. 

E. Postural drainage should be done as clinically indicated. 

F. Consider intubation and suctioning below the cords in the nursery, since meconium can be removed from the upper airways even after the infant has initiated spontaneous respirations.

G. If the infant experiences persistent respiratory distress after one-half hour of life, antibiotics should be started after first obtaining blood, tracheal aspirate, and CSF cultures. Urine, for Group B Strep Latex, should also be obtained, but antibiotics should not be withheld while waiting for urine. 

H. Monitor the infant for pulmonary hypertension with evidence of right-to-left shunting (See protocol for Treatment of Pulmonary Hypertension). 

Reference:

Holtzman R.B., et al. Perinatal management of meconium staining of the amniotic fluid. Clin Perinatol, 1989;16:825-838.

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