Case Study: Meconium Aspiration Syndrome

• Aspiration of meconium (the neonate’s first feces) into the lungs.
• Typically occur with the first breath or while the neonate is in utero.
• Thick, sticky, and greenish black substance; may be seen in the amniotic fluid after 34 weeks gestation.

Pathophysiology

• Asphyxia in utero leads to increased fetal peristalsis, relaxation of the anal sphincter, passage of meconium into the amniotic fluid, and reflex gasping of amniotic fluid into the lungs.
• Neonates with meconium aspiration syndrome (MAS) increase respiratory efforts to create greater negative intrathoractic pressures and improve air flow to the lungs.
• Hyperinflation, hypoxemia, and academia cause increased peripheral vascular resistance.
• Right-to-left shunting commonly follows.
• Meconium creates a ball-valve effect, trapping air in the alveolus and preventing adequate gas exchange.
• Chemical pneumonitis results, causing the alveolar walls and interstitial tissues to thicken, again preventing adequate gas exchange.
• Cardiac efficiency can be compromised from pulmonary hypertension.

Causes

• Commonly related to fetal distress during labor.
• Advance gestational age (greater than 40 weeks)
  
  • Difficult delivery
  • Fetal distress
  • Intrauterine hypoxia
  • Maternal diabetes
  • Maternal hypertension
  • Poor intrauterine growth
  • Risk factors for MAS:
  
  

Assessment Findings

• Fetal hypoxia as indicated by altered fetal activity and heart rate.
• Dark greenish staining or streaking of the amniotic fluid noted on rupture of membranes.
• Obvious presence of meconium in the amniotic fluid
• Greenish staining of the neonate’s skin (if the meconium was passed long before delivery) or placenta.
• Signs of distress at delivery, such as the neonate appearing limp, an Apgar score below 6, pallor, cyanosis, and respiratory distress.
• Coarse crackles when auscultating the neonate’s lungs.

Test Results

• Arterial blood gas analysis shows hypoxemia and decreased pH.
• Chest X-ray may show patches or streaks of meconium in the lungs, air trapping, or hyperinflation.

Treatment

• Respiratory assistance via mechanical ventilation
• Maintenance of a neutral thermal environment
• Administration of surfactant and an antibiotic
• Extracorporeal membrane oxygenation (in severe cases).

Nursing Interventions

• During labor, continuously monitor the fetus for signs and symptoms of distress.
• Immediately inspect any fluid passed with rupture of the membrane.
• Assist with immediate endotracheal suctioning before the first breaths, as indicated.
• Monitor lung status closely, including breath sounds and respiratory rate and character.
• Frequently assess the neonate’s vital signs.
• Administer treatment modalities, such as oxygen and respiratory support as ordered.
• Institute measures to maintain a neutral thermal environment.
• Provide the family with emotional support and guidance.