Meconium Aspiration Syndrome

What Causes Meconium Aspiration Syndrome?

Many believe that MAS is related to some stress during the labor and delivery process.

Some examples of conditions that may lead the infant to become stressed before birth include:

• A mother who is a heavy cigarette smoker or who has diabetes, high blood pressure or other medical condition
• Poor growth of the baby while in the womb
• A prolonged or difficult delivery
• An infant who is significantly past his due date
• Complications with the umbilical cord or placenta
• Infection

Note: MAS is very rare in babies born before 34 weeks.

How Is Meconium Aspiration Syndrome Diagnosed?

If the doctor believes the baby has aspirated meconium, treatment will begin during delivery. After the baby's head is delivered, the physician will suction the baby's mouth and nose to clear any meconium present.

Immediately after birth, the doctor will evaluate the baby's activity and breathing. If the baby is limp or slow to begin breathing, the doctor may then insert a tube into the baby's trachea to remove any meconium that might be present before stimulating the child to breathe.

If the baby shows signs of breathing problems the doctor or a neonatologist, a pediatrician trained in the care of sick newborns, will continue to support the infant and admit the baby to a special care or Neonatal Intensive Care Unit (NICU). In the NICU, careful examinations and laboratory tests such as chest x-rays and blood tests will help determine the presence of MAS.

What Are the Symptoms of Meconium Aspiration Syndrome?

• Evidence of meconium (dark green streaks) in the amniotic fluid and on the baby's skin
• Breathing problems such as rapid breathing, labored breathing or periods of not breathing immediately after birth
• The baby's lips and mouth may be bluish (low blood oxygen)
• Limpness in the infant at birth or low Apgar scores (a system to evaluate the condition of the newborn immediately after birth)

How Is Meconium Aspiration Syndrome Treated?

If the baby is suspected of meconium aspiration but generally appears well, the health care team may simply observe the baby for symptoms such as increased respiratory rate, grunting or cyanosis.

However, if an infant has aspirated meconium and appears ill, the first priority is to ensure the baby is well oxygenated by supplying extra oxygen and supporting his breathing. Further treatments may include:

• Breathing support through nasal cannula or mechanical ventilation
• Fluid and nutrition through an intravenous catheter (IV)
• IV antibiotics
• Obtaining blood routinely to assess the baby's oxygenation and ventilation

Alternative Treatment

If the above therapies (or a combination of them) do not work, there is another alternative. Extracorporeal membrane oxygenation (ECMO) is a form of cardiopulmonary bypass, in which an artificial heart and lung machine temporarily takes over to supply blood to the baby's body.

Babies who have severe aspiration and require mechanical ventilation are at increased risk for the following conditions:

• Pneumothorax–a collapsed lung, treated by inserting a tube into the collapsed lung, allowing the lung to gradually re-expand
• Aspiration pneumonia–an infectious complication is treated with antibiotics
• Bronchopulmonary dysplasia–a chronic lung condition be treated with medication or oxygen
• Pulmonary hypertension (PHN)

In severe cases, MAS may lead the infant to revert to the blood circulation pattern found in the womb. This pattern of blood flow bypasses the lungs, which makes newborn infant's blood be severely low in oxygen. This condition may be treated with several medical interventions including a medical gas called nitric oxide (NO). Nitric oxide is a medicine that is breathed in, causing the lung blood vessels to dilate, which allows more blood to reach the lungs and raise the level of oxygen in the baby's blood.

What Are the Long-Term Effects of Meconium Aspiration Syndrome?

Most babies with uncomplicated MAS improve within a few days or weeks, depending on the severity of the aspiration. Although a baby's rapid breathing may continue for days after birth, usually there is no severe permanent lung damage. Some studies, however, suggest that those born with MAS are at a higher risk of having more sensitive lungs, which may lead to an asthmatic-like condition.

Severely affected babies have a much more guarded prognosis; they may develop chronic lung disease, developmental abnormalities and hearing loss. Sometimes very severe cases of MAS can be fatal. Studies suggest that deaths from MAS have decreased significantly through prompt and thorough suctioning and reducing the number of births that go beyond 40 weeks.