1. Meconium Aspirations syndrome (MAS)
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2. What is meconium aspiration syndrome?
Meconium is a dark green fecal material produced in the intestines of a fetus before birth. After delivery, your newborn will pass meconium stools for the first few days of life.
Stress that your baby experiences before or during birth may cause your baby to pass meconium stool while still in the uterus. The meconium stool then mixes with the amniotic fluid that surrounds the fetus.
Your baby may then breathe the meconium and amniotic fluid mixture into their lungs shortly before, during, or right after birth. This is known as meconium aspiration or meconium aspiration syndrome (MAS).
Although MAS is often not life-threatening, it can cause significant health complications for your newborn. And, if MAS is severe or untreated, it can be fatal.

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Definition of MAS
Aspiration of the amniotic fluids containing meconium, in to the trachea of the newborn
Meconium is a mixture of epithelial cells and bile salt found in the fetal intestinal tract

4. Incidence
Meconium- stained amniotic fluid (MSAF) is present in 13% of all newborn.
Of these 5%-12% develop MSA.
MAS is a disease of term or postterm infants
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5. What causes MAS?
MAS may occur when your baby experiences stress. Stress often results when the amount of oxygen available to the fetus is reduced. Common causes of fetal stress include:
a pregnancy that goes past the due date (more than 40 weeks)
difficult or long labor
certain health issues experienced by the mother, including hypertension (high blood pressure) or diabetes
an infection
The fetus doesn’t begin to produce meconium until later in pregnancy, so as a pregnancy goes past its due date, the fetus has the potential to be exposed to meconium for a longer period of time.
As pregnancy progresses to term and beyond, the amount of amniotic fluid is also decreased, which concentrates the meconium. As a result, MAS is more common in overdue newborns as compared to term newborns. MAS is rare in preterm newborns.

6. Risk factors associated with in utero passage of meconium
Postterm pregnancy
IUGR/ placental insufficiency
Maternal HTN
Preeclampsia
Maternal drug abuse (tobacco, cocaine).
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7. PATHOPHYSIOLOGY
With intrauterine stress or asphyxia,(الإختناق) peristalsis is stimulated and relaxation of anal sphincter occurs, releasing meconium into the amniotic fluid.
Aspiration may occur whenever meconium passes into the amniotic fluid.
Risk increases when repeated episodes of severe asphyxia lead to gasping respirations in utero.
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8. Complete or partial airway obstruction.
Atelactasis or air trapping leads to hyperinflation.
A chemical pneumonitis develops (caused by bile salts)
It increases PVR due to asphyxia →↑RT- Lft shunting and development of PPHN.
It interferes with surfactant production and increases surface tension
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9. Airway obstruction: obstruction of large airways:
hypoventilation => hypoxemia, hypercapnea, acidosis
obstruction of small airways:
Complete  atelectasis
Partial  air trapping  hyperdistention of alveoli 
increaesed lung resistance during exhalation
pneumothorax, pneumomediastinum ,
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10. What are the symptoms of MAS?
Respiratory distress is the most prominent symptom of MAS. Your infant may breathe rapidly or grunt during breathing. Some newborns may stop breathing if their airways are blocked by meconium. Your baby may also exhibit the following symptoms:
a bluish skin color, which is called cyanosis
limpness
low blood pressure

11. Clinical presentation
Asphyxia , hypoxia which lead to PPHN
Respiratory distress range from mild to severe
RD signs are nonspecific and include tachypnea, flaring and retraction
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12. Nailbeds and skin are stained a yellow- green
Chest appear to be hyperinfated.
Expiration phase of respirations is prolonged.
Rales and rhonchi are common on ascultation.
ABGs will show the following:
Respiratory and metabolic acidosis
Low pao2 even with 100% oxygen administration
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13. Management In 2015, the ACOG revised recommendations and
recommended that “all infants with MSAF should not longer receive intrapartum suctioning.”
Intrapartum suctioning not effective in removing meconium aspirated by the fetus into the lungs prior delivery
Skilled resuscitation team should be present at all deliveries that involve MSAF.
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14. Management of MAS
In 2015, the guidelines were updated to reflect new evidence in the management of nonvigorous and vigorous newborns with meconium-stained fluid.
Routine intubation and tracheal suctioning are no longer
required.
If the infant is vigorous,
Vigorous infant has Strong resp. efforts, Good muscle tone and Heart rate >100b/m
the infant may stay with the mother to receive the initial steps
of newborn care.
Gentle clearing of meconium from the mouth and nose with a
bulb syringe may be done if necessary.
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15. bulb syringe
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16. The initial steps of resuscitation should be completed under
If the infant born through meconium-stained amniotic fluid presents and was nonvigorous (with poor muscle tone and inadequate breathing efforts),
The initial steps of resuscitation should be completed under
the radiant warmer.
Appropriate intervention to support ventilation and oxygenation should be initiated as indicated for each infant and,
if the airway is obstructed, this may include intubation and
suction.
Resuscitation should follow the same principles for infants
with meconium-stained fluid as for those with clear fluid
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17. How is MAS treated?
After emergency treatment has been provided, your newborn may be placed in a special care unit to observe their breathing. Additional treatment may be needed to avoid complications of MAS. Five common treatments include:
oxygen therapy to make sure there is enough oxygen in the blood.
the use of a radiant warmer to help your baby maintain body temperature.
antibiotics such as ampicillin and gentamicin to prevent or treat an infection.
the use of a ventilator (a breathing machine) to help your infant breathe.
extracorporeal membrane oxygenation (ECMO) if your baby isn’t responding to other treatments or has high blood pressure in the lungs (for this treatment, a pump and machine that performs the function of the lungs do the work of your newborn’s heart and lungs so that these organs can heal)

18. Treatment in NICU
Severe MAS can lead to hypoxemia that leads to acidosis, which together cause pulmonary vein constriction.
May lead to persistent pulmonary hypertension.
The resultant right-to-left shunting at the level of the ductus arteriosus causes further cyanosis and hypoxemia
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19. Management of MEC in NICU
ABGs to determine degree of respiratory compromise and type of therapy needed.
Oxygen therapy
Continuous positive airway pressure (CPAP)
or mechanical ventilation may be needed to correct hypoxemia
Supportive care needed related to severity of the aspiration and lung tissue damage
Consider a dose of surfactant within 6 hours after birth which improve oxygenation and reduced pulmonary morbidity.
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20. What complications are associated with MAS?
Most newborns with MAS won’t have any long-term health complications. However, MAS is a serious issue that can have an immediate impact on your newborn’s health. Meconium in the lungs can cause inflammation and infection.
Meconium can also block the airways, which can cause lung over expansion. If a lung over expands or inflates too much, it can rupture or collapse. Then air from inside the lung can accumulate in the chest cavity and around the lung. This condition, known as a pneumothorax, makes it difficult to reinflate the lung.
MAS increases the risk of your infant developing persistent pulmonary hypertension of the newborn (PPHN). High blood pressure in the vessels of the lungs restricts blood flow and makes it difficult for your baby to breathe properly. PPHN is a rare but life-threatening condition.
On rare occasions, severe MAS may limit oxygen to the brain. This may cause permanent brain damage.

21. Complications of MEC Pneumothorax and
pneumomediastinum due to rupture of over expanded lungs
Persistent pulmonary, hypertension
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22. Prognosis of MAS Mild cases of MAS is excellent
In severe cases, neurologic sequelae are common and death may occur.
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