Meconium aspiration syndrome occurs when meconium, an infant's first stool, is present in the lungs before or during delivery. Meconium normally remains in the intestines until after birth but is sometimes expelled into the amniotic fluid in response to fetal distress. If inhaled, meconium can cause respiratory problems. Symptoms include rapid breathing, cyanosis, and crackles heard on auscultation. Treatment focuses on humidified oxygen and ventilation support, with antibiotics, surfactant, and nitric oxide used in severe cases. Complications can include persistent pulmonary hypertension and respiratory failure.

1. MECONIUM ASPIRATION SYNDROME
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‫خواجه‬ ‫طارق‬ ‫محمد‬
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3. MECONIUM ASPIRATION SYNDROME
• Its medical condition effecting newborn infant. It occur when meconium is present in their
lung during or before delivery.
• Meconium is first stool of an infant.
• Meconium first appears in the fetal ileum between 10 and 16 weeks of gestation, green
liquid composed of gastrointestinal secretions, cellular debris, bile and pancreatic juice,
mucus, blood, lanugo, vernix and approximately 72% to 80% water. The dry weight
composition consists primarily of mucopolysaccharides, with less protein and lipid.
• Meconium is normally stored in the infant’s intestine until after birth, but sometime (often
in response to fetal distress and hypoxia) it is expelled into amniotic fluid prior to birth, or
during labor. If the baby then inhaled the contaminated fluid, respiratory problems may
occur.
what makes meconium pass?
Fetal stress in near term, full term & specially (post term: the older fetus, the more the
meconium aspiration risk)

5. • Meconium aspiration can take place in utero or time of birth (neonate)
• Too much meconium can Cause mechanical obstruction atelectasis
Clinical feature
• Greenish or yellowish appearance of the amniotic fluid
• Infant skin, umbilical cord, nailbed may be stained green if the meconium was passed a
considerable amount of time before birth.
• After birth  rapid breathing, cyanosis, hypoxia, slow heartbeat, barrel-shaped chest or
Low APGAR score
• In auscultation diffused wet crackles & Rhonchi
Maternal risk factor
• Preeclampsia
• Maternal HTN
• Oligohydramnios
• Maternal infection & drugs
• Intrauterine growth restriction

6. Pathogenesis and aetiology
Meconium causes a number of anatomical and physiological problems that make lung
function worse:
• Plugging of the airways, with consequent atelectasis. It also causes a ‘ball-valve’
obstruction with hyperinflation of the lungs and a high risk of pulmonary air leaks.
• Irritation of the airways, causing a chemical pneumonitis.
• Antagonism of surfactant production.
• Possible secondary bacterial infection.
• In a proportion of babies with severe MAS there is development of marked
ventilation/perfusion inequality and right-toleft shunt due to persistent pulmonary
hypertension

8. Diagnosis
• C/F
• High risk infant  tachycardia
• At birth cachexic
• Usually progress into infant RDS within 4hrs
• CXR
• ABG samples  show decrease oxygen level

9. Radiology
Chest radiographs show hyperinflation (flat diaphragms, widening of rib spaces) with diffuse
patchy opacities throughout both lung fields, cardiomegaly. Pneumothorax or
pneumomediastinum may also be seen.

10. Prophylactic management
• Amnioinfusion therapy for thick-consistency MSAF does not reduce the risk of MAS.
• Intrapartum naso- and oropharyngeal suctioning does not reduce the incidence of MAS
and hence is not recommended.
• Routine endotracheal intubation and suctioning is of no benefit. This should, however, be
performed in infants if they are depressed, and need PPV.
• In such cases, the baby is intubated with a wide-bore suction catheter or endotracheal
tube and the trachea is suctioned clear. Suctioning is facilitated by the use of a meconium
aspirator. The stomach should be aspirated following intubation. All depressed babies who
are born through thick MSAF should be carefully assessed and regularly monitored for
signs of MAS

11. Treatment of established meconium aspiration syndrome
The treatment will be the same as for respiratory distress. Particular emphasis or consideration should
be given to the following points:
• Humidification of inspired oxygen.
• Postural drainage positioning, suctioning of airways and chest percussion are of unproven benefit.
• Antibiotics are usually given, although the efficacy has not been established.
• Both conventional and high-frequency ventilation can be used with multiple strategies to achieve
normal gaseous exchange and prevent complications such as air trapping and air leaks, which are
common in such infants.
• Exogenous surfactant has been used with success in some studies. In some centres lavage with
surfactant is practiced, but its efficacy is not fully established.
• Inhaled nitric oxide (iNO) therapy should be considered in infants with concomitant PPHN who are
not responding to conventional treatment. Other agents used in such condition are prostacyclin
and sildenafil.
• Extracorporeal membrane oxygenation (ECMO) is considered as a rescue treatment when
predicted mortality is running high. The overall success rate of ECMO in babies with MAS is over
80%.

12. Complication
• Persistent pulmonary HTN of the neonate
• Respiratory failure
• pneumothorax

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