Meconium aspiration syndrome is a common cause of respiratory failure in term and post-term infants caused by inhalation of meconium-stained amniotic fluid before, during, or after birth. It can range from mild respiratory issues to severe forms that can lead to death. Risk factors include fetal distress, umbilical cord compression, post-term birth, and breech presentation. Clinically, affected infants may experience tachypnea, retractions, grunting, and decreased breath sounds. Chest x-rays can show infiltrates, atelectasis, and pneumothorax. Management involves respiratory support, antibiotics, surfactant therapy, and measures to maintain temperature and oxygen levels.

1. RAKHI DAS
I YR MSc NURSING, JMCON, THRISSUR

2. Introduction
• Meconium aspiration syndrome (MAS) is one of the
most common causes of severe respiratory failure in
term and post term infants caused by inhalation of
meconium before, during or immediately after
delivery. It may be present with varying degrees of
severity, ranging from mild respiratory compromise
to severe forms that may result in perinatal death.

3. Incidence
• In western countries, MSAF incidence rate is
reported to range from 5.6 to 24.6% and MAS
develops in 35.8% infants born through MSAF
• An Indian study from Maharashtra 2000, found MSAF
16.5 with MAS developing in 18.7% live birth.
• Other studies reported evident increase in the
incidence.

4. Definition
Cleary & Wiswell;
• Respiratory distress in infant born through
meconium stained amniotic fluid whose symptoms
cannot be otherwise explained.
National neonatal- perinatal database of India;
MAS should be diagnosed if any two of the following
three criteria are present
• Meconium staining of liquor or straining of umbilical
cord or skin or nails
• Respiratory distress soon after birth within one hour
• Radiological evidence of aspiration pneumonitis

5. Meconium pathogenesis
• Meconium is a viscous, dark green substance which
has bile, lanugo, shed intestinal epithelial cells and
water.
• Intrauterine distress causes passage of meconium
into amniotic fluid.
• Liquor can be aspirated into the lungs during labour
and delivery.

6. Presence of meconium under the vocal cord confirms for meconium aspiration
syndrome
Enzymes, bile salts and fat in the meconium irritate the Airway and parenchyma
causing diffuse inflammation
Complete or partial obstruction of small Airways resulting in air trapping and atelectasis due to ball valve
effect
Chemical pneumonitis
Secondary surfactant deficiency due to destruction of surfactant
areas of atelectasis and Pneumothorax
Ventilation perfusion mismatch and
respiratory failure

7. Mechanism of passage of meconium
• There are two controls operating the fetal meconium
passage:
– Hormonal control dependent upon " motilin"-
intestinal peptide responsible for bowel peristalsis and
defecation
– Neural control dependent upon maturation and
myelination of neural plexus of gastrointestinal tract
• In utero passage of meconium is commonly not occurring
before 34 weeks of gestation because of
– Relative lack of strong peristalsis
– Good anal sphincter tone
– Present of a "cap" of particularly viscous meconium in
rectum

8. Risk factors
• Fetal distress associated with fetal asphyxia and
decreased umbilical venous blood PO2
• Compression of umbilical cord eg: Olivgohydramnias
• Gut maturation in post term neonates
• Breech presentation and pressure over buttocks
• Listeriosis (representing fetal diarrhoea)

9. Classification of meconium passage• Based on timing
– Early - noted on rupture of fetal membranes prior
to, or during active stage of labour
– Late - MSAF passed in second stage of labour after
clear fluid noted previously
• Based on content consistency
– Light meconium - lightly stained amniotic fluid,
yellow or greenish colour
– Heavy meconium - darkly stained amniotic fluid,
dark green or black in colour, usually thick and
tenacious

10. Clinical features
General appearance
• Baby usually term for post term
• Classic signs of postmaturity include dry and loose or
peeling skin, overgrown nails, abundant scalp hair,
visible palmar and sole crease, minimal fat deposits,
green/ brown/ yellow colouring of skin from
meconium staining

11. Clinical features contd…Respiratory features
• Tachypnea more than 120 beats per minute
• Marked sternal retraction
• Intercostal and subcostal recession
• Use of accessory muscles and flaring of nostrils
• Expiratory grunting maybe present
• Widespread crepitus and ronchi
• Air trapping due to Ball - valve effect
• Overdistension of chest with increased AP diameter
• Apnea in neurological involvement

12. Clinical features contd…
Cardiovascular features
• In absence of asphyxial damage to myocardium, no
specific cardiovascular features
• Myocardial damage manifest as hypotension or CHF
• If persistant pulmonary hypertension (PPHN), s2 may
remain single along with Murmur of tricuspid
Incompetence

13. Clinical features contd…
Abdominal features
• Downward displacement of the diagram due to air
trapping resulting in palpable liver and spleen
• In severe cases bowel sounds are absent and no
further meconium may be passed
• If neurological involvement is there urinary retention
makes bladder palpable

14. Clinical features contd…
Central nervous system features
• Baby may be normal neurologically or may have
features of Birth asphyxia which may vary from stage
I to III hypoxemic ischemic encephalopathy (HIE)

15. Diagnostic evaluation
History collection
• (antenatal history, gestational score, obstructive history,
onset of labour, correct date of expected delivery,
previous history in the family)
Physical findings
• (meconium stained amniotic fluid during first stage of
labour, fetal distress or decrease movement at term,
radiological changes and presence of meconium in
trachea, staining of skin, nails or umbilical cord
immediately after birth

16. Investigations - hematological changes
• (increased WBC, thrombocytopenia in PPHN, DIC
secondary to severe birth asphyxia
Chemical changes (decreased PO2, increased PCO2, pH
changes)
Urine analysis - usually normal output unless renal
failure develops, greenish brown colour of urine due
to absorbed meconium pigments across pulmonary
epithelium and excretion

17. Electrocardiography or echocardiography
• Normal in uncomplicated cases, sub-endocardial
ischemia in severe intrapartum asphyxia, reduced cardiac
contractility
Chest X Ray
• Helps in determining extent of intrathoracic Pathology
• Identify areas of atelectasis or air block syndromes
• Patchy infiltrate, coarse streaking of lung field, increased
AP diameter, atelectasis, flat diaphragm, plural effusion,
pneumothorax, pneumonitis

18. Management
• Initial management
• Observe closely for respiratory distress
• Monitor oxygen saturation
• Immediate neonatal resuscitation
• Avoid hypoxemia

19. Routine care
• Maintain hydration
• High flow oxygen to prevent hypoxia
• Peripheral perfusion to be maintained with ionotopic
agents
• Chest physiotherapy and oropharyngeal suctioning
as-needed
• Correction of metabolic acidosis monitoring of renal
function
• of chemical pneumonitis and potential benefits
• Broad spectrum Antibiotics

20. Thermal environment
• Conservation of heat, warmer care
• Cling wrap to prevent heat loss to environment
• Minimal handling and disturbance to baby and
provide sensory comfort
Acid-base hemostasis
• Maintenance of PaO2 and PaCO2
• monitor O2 saturation and provide adequate
concentration of warmed humidified oxygen 80 to
90%

21. Ventilatory support
• Continuous positive Airway pressure (CPAP)
• Intermittent positive pressure ventilation (IPPV) rate
of 60 to 80 per minute and low levels of PEEP
Drug therapy
• Glucocorticoid - for treatment
• Broad spectrum antibiotics

23. Surfactant replacement therapy
• Intratracheal administration of surfactant (Colfosceril
Palmitate 108mg as lyphilised powder and supply
with cetyl alcohol, tyloxapol and sodium chloride
• 5ml/kg body weight; no more than 3 doses
• Rescue treatment should be administered in two
doses. Initial dose as soon as possible after diagnosis
of respiratory distress syndrome.
• Saline lavage of surfactant Replacement and
surfactant lavage with or without subsequent bolus
to 'wash out' meconium in the Airways

25. Other management
• High frequency ventilation of high frequency nasal
cannula (HFNC)
• Extracorporeal membrane oxygenation(ECMO)