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.

Asphyxia or other stress can cause passage of meconium before the fetus is born.

Meconium aspiration syndrome occurs when the meconium stained amniotic fluid is aspirated by the fetus before or after delivery.

Aspiration of meconium in utero can cause chemical pneumonitis.

Meconium is present in the fetal bowel as early as 10 weeks’ gestation.

An infant with hypoxia in utero experiences a vagal reflex relaxation of the rectal sphincter, which releases meconium into the amniotic fluid.

Babies born breech may expel meconium into the amniotic fluid from pressure in the buttocks.

In both instances, the appearance of the fluid at birth is green to greenish black from the staining.

Meconium staining occurs in approximately 10% to 12% of all pregnancies.

It does not tend to occur in extremely-low-birthweight infants because the substance has not passed far enough in the bowel for it to be at the rectum in these infants.

An infant may aspirate meconium either in utero or with the first breath after breath.

Meconium can cause severe respiratory distress in three ways:1. it causes inflammation of bronchioles because it is a

foreign substance2. it can block small bronchioles by mechanical plugging3. it can cause a decrease in surfactant production through

lung cell trauma. Hypoxemia, carbon dioxide retention, and

intrapulmonary and extrapulmonary shunting occur.A secondary infection of injured tissue may lead to pneumonia.

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 deliveryFetal distress Intrauterine hypoxiaMaternal diabetesMaternal hypertensionPoor intrauterine growth

COMPLICATIONS

1. Air leak

2. Pulmonary interstitial emphysema

3. Pulmonary hemorrhage

4. Pulmonary hypertension

5. Pneumonia

6. Infection

7. Thrombocytopenia

8. Asphyxia

SIGNS AND SYMPTOMS

1. Air trapping, mechanical obstruction by particles of meconium

2. Chemical pneumonitis caused by irritation of the alveoli by meconium

3. Signs of infection as meconium is a good medium of bacterial growth in the lungs

4. Diagnostic tests: Chest x-ray Complete blood count (CBC) C-reactive protein Blood cultures

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.

MANAGEMENT

1. Suctioning after head is delivered

2. Oxygenation and ventilation

3. Administer prescribed Antibiotic therapy Bicarbonate for acidosis

4. Monitoring of blood gases

5. Watch out for seizures, GIT bleeding and renal failure

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.