Meconium Aspiration
Syndrome
Kamala devi budha
Roll no. 13
MN 1st year
INTRODUCTION
Meconium is thick , pasty, greenish- black substance that is
present in the fetal bowel, which is first stool passed by new
born.
• Meconium is typically passed for 2-3 days after birth.
• The detection of meconium stained amniotic fluid during
labour often causes anxiety in the delivery room because of its
association with increased perinatal mortality and morbidity.
Introduction cont….
• Meconium is composed of :
– Small dried amniotic fluid debris
– Bile pigment
– The residue from intestinal secretions.
• It is a sterile compound made up primarily of
water (75 %), with mucous glycoproteins, lipids and
proteases.
Introduction cont’d…
• Although meconium is sterile, its passage into
amniotic fluid is important because of the risk
of the muconium aspiration syndrome (MAS)
and its sequelae.
Introduction cont’d….
• Infants delivered though meconium –stained
amniotic fluid are more likely to be depressed
at birth and to require resuscitation neonatal
intensive care.
Introduction cont’d…
• Neonates born to mother with thick or thin muconium
stained liqor can aspirate the meconium into the lungs
and develop respiratory distress.
• This is known as aspiratory meconium aspiration
syndrome (MAS).
• Aspiration of meconium can occur in utero, during
birth or immediately after birth.
Introduction cont’d…
• Thin meconium can cause chemical
pneumonitis.
• Thick meconium aspiration can block the large
and small airway causing areas of atelectasis
and emphysema which can progress to develop
air leak syndromes like pneumothorax
INCIDENCE
• Muconium-stained liquor is rare in premature
infants
• Passage of meconium is increasingly common in infants more
than 37 weeks and occurs in up to 50% of post mature infants
• Muconium staining liquor occur in 10- 14 % of pregnency
where as 5% cases develop MAS.
• 30% required mechanical ventilation and 3-5% are
mortality.
Causes
• Placental insufficiency. When a mother has placental
insufficiency, there is a lack of adequate blood flow to the
baby, which can cause fetal distress, leading to the
untimely passage of meconium.
• Preeclampsia.
• Maternal infection/chorioamnionitis.
• Fetal hypoxia. Fetal hypoxia leads to passage of
meconium from neural stimulation of a
maturing gastrointestinal system.
RISK OF DEVELOPING MAS
• Lack of antenatal care
• Abnormal fetal heart rate monitoring
• Thick meconium
• Oligohydramnios
• The presence of meconium in the trachea
RISK FACTORSCONT……
• Machanism of passage of meconium in utero is unclear
• The fetal bowel has little peristaltic action and the anal
sphincter is contracted.
• It is thought that hypoxia cause the anal sphincter to
relax, while at the same time increasing the production
of motilin which promots peristalsis.
PATHOPHYSIOLOGY
• Muconium aspiration syndrome is a disease of term and
post term infants and its severity is linked to fetal
asphyxia.
• Aspiration of meconium into the distal airways can occur
either antenatally or postnatally.
• Meconium has been found in the lungs of infants without
evidance of fetal distress.
Fig. shows meconium in lungs
PATHOPHYSIOLOGY CONT…..
• Postnatal inhalation can occur late in the
second stage or immediately after delivery if
the infant gasps or makes breathing movements
while the oropharynx, nasopharynx,or trachea
contains meconium-stained liquor.
Pathphysiology cont’d…
• Muconium has a number of adverse effects on
the neonatal lung, which may ultimately lead
to the respiratory failure, characterizes MAS.
PATHOPHYSIOLOGY CONT…..
MECONIUM :
• Causes mechanical blockage of the airway,
• Acts as a chemical irritant causing pneumonitis,
alveolar collapse and cell necrosis
• Although initially sterile, predisposes to
secondary bacterial infection
CLINICAL MANIFESTATION
• Infants are stained from green meconium stools
• Tachypnia
• Hypoxia
• Respiratory grunting
• Nasal flaring
• Cyanotic or pale
• Severe MAS progress rapidly to respiratory failure
• Barrel chest(increased anteroposterior diameter due to
presence of air trapping
• Auscultated rales and rhonchi (in some cases)
• Yellow green staining of finger nail , umbilical cord and
skin may be observed
• Grunting
• Arterial PO2 may be low
• If hypoxia metabolic acidosis is present
• Pulmonary edema
DIAGNOSTIC EVALUATION
• Before birth the fetal monitor may show bradycardia
• During delivery or at birth ,meconium can be seen in the
amniotic fluid and on the infant.
• Low APGAR score after birth
• Physical examination : lungs sound (coarse, crackly
sound)
• Blood gas analysis :low blood acidity ,decreased oxygen
and increased carbon dioxide.
• Chest x-ray may show patchy or streaky areas in lungs
• Urine color may appear dark brown
MANAGEMENT OF INFANT DELIVERED
THROUGH MECONIUM-STAINED FLUID
• INITIAL ASSESSMENT
– At a delivery complicated by MSAF determine
whether the infant is vigorous..
– demonstrated by:
• heart rate more than 100 beats/min
• spontaneous respiration
• good tone(spontaneous movement or some degree of
flexion).
If the infant appears vigorous, routine care should be
provided, regardless of the consistency of the
meconium
• Initiate suctioning as soon as the baby is delivered.
• If the baby has continuous breathing problem, continue suctioning
using laryngoscope
• The infant should be placed on a radiant warmer and given free flow
oxygen. -Delay drying and stimulation and postpone emptying of
any gastric contents until the infant has stabilized.
• Intubation should be done under direct laryngoscopy before
inspiratory efforts have been initiated .
• Avoid positive pressure ventilation if possible until tracheal
suctioning is accomplished.
• Do NOT perform the following harmful techniques in an
attempt to prevent aspiration of meconium-stained
amniotic fluid:
• Squeezing the chest of the baby
• Inserting a finger into the mouth of the baby
Meconium in amniotic fluid
Suction of mouth , nose and pharynx
Infant active Infant depressed
Intubated and suction
Observed trachea
Other resuscitation as
indicated
General management
• A.Observation:Baby born with meconium stained
liquor requires close observation for the assessment of
respiratory distress.
• A chest radiograph may be helpful to determine signs of
respiratory distress.
• Monitoring of oxygen during this period helps to assess
severity of infant’s condition and avoids hypoxemia.
• B.Routine care: neutral thermal environment should be
maintained with minimum of tactile stimulation.
• Blood glucose and calcium level should be monitored
and corrected if necessary.
• Fluid should be restricted as far as possible to prevent
cerebral and pulmonary edema. Special therapy for
hypotension and poor cardiac output is required including
cardiotonic medicines such as dopamine.
• Circulatory support with normal saline or packed
red blood cells should be provided in patients
with marginal oxygenation.(Hb above 15g and
haematocrit above 40% should be maintained)
• Renal function should be continuously monitored
• C. Oxygen therapy : Hypoxia should be managed by
increasing inspired oxygen concerntration and
monitoring of blood gases and PH.
• D. Asissted Ventilation:
1. Continuous Positive Airway Pressure(CPAP)
2. Mechanical ventilation
• E.Medications:
1. Antibiotics(ampicillin, gentamicin).
2. Surfactants
3. Corticosteroids
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 oxygen and respiratory support as
ordered.
– Warm and humidify oxygen
– Institute measures to maintain a neutral thermal
environment
• Provide the family with emotional support and
guidance.
• Interventions for thermo regulation
– Place warm blankets on scales, x-ray plates, or
other surfaces in contact with the baby
– Warm blankets and clothing before use
– Preheat incubators, radiant warmers, heat shield
– Maintain room temperature at levels adequate to
provide a safe thermal environment for neonate
Prevention Of MAS
• ANTEPARTUM PERIOD
– Women should be carefully monitored during pregnancy and
should be encouraged for hospital delivery.
• INTRAPARTUM PERIOD
– Fetal heart rate should be monitored every half an hourly to
determined the sign of fetal distress
– Babies born to mother with meconium stained liquor should
have oropharyngeal suction before the delivery of shoulder.
• AMNIOINFUSION
• TIMING AND MODE OF DELIVERY
– Pregnancy that crosses the date should be induced
as early as 41weeks which helps to prevent MAS
by avoiding passage of meconium .Delivery mode
does not appear to significantly impact the risk of
aspiration.
PROGNOSIS
• Recovery usually occurs within 3-5days but tachypnea may
persist for a longer period
• Mortality rate is as high as 50%if PPHN(Persistant Pulmonary
Hypertension of neonates) is present.
• Residual problem is rare but cough, wheezing and persistent
hyperinflation may extend upto 5-10years.
• 50%of MAS cases require mechanical ventilation out of which
60- 70% neonate survive.
• Its mortality rate is 3-5%.
Complication
• Pneumothorax(15-33%)
• Massive atelectasis
• Pneumopericardium
• Pneumomediastinum(15-33%)
• Persistent pulmonary hypertension in neonates.
• If prolonged assisted ventilation , bronchopulmonary
dysplasia
• Meconium aspiration pneumonia 5%.
