Meconium aspiration syndrome is a respiratory distress in infants born through meconium-stained amniotic fluid. Risk factors include maternal health problems, post-term pregnancy, and fetal stress. Meconium obstructs airways, causes chemical pneumonitis, and inactivates surfactant. Affected infants have respiratory distress, and chest X-rays show hyperinflated lungs. Management includes suctioning meconium during delivery, pulmonary toilet, oxygen therapy, ventilation if needed, antibiotics, and treatments for pulmonary hypertension. Complications are common and outcomes range from full recovery to long-term issues like cerebral palsy.

1. Dr Sheikh Aasif Rasool(intern)
Dept: paediatrics & Neonatology
(Tmmc&h)

2. TOPIC ;MECONIUM ASPIRATION
SYNDROME

3. Definition
Meconium aspiration syndrome is a
respiratory distress of an infant
born through meconium stained
amniotic fluid
Meconium found below vocal cord

4. Meconium
pH of meconium : 5.5-7
A sterile, viscous, dark green, odorless substance
Component :
- 75-80% water
- desquamated cells from the intestine and epithelial
cell
- Lanugo hair
- Fatty material from vernix caseosa
- Mucus
- Bile
Description :
Light - amniotic fluid thinly stained
Moderate - opaque without patricles
Thick - pea soup particles

5. Physiology
Meconium 1st found in the fetal ileum between the 10th
and 16th week of gestation
In utero passage of meconium uncommon due to :
- lack of strong peristalsis (low motilin level)
- good anal sphinter
- a cap of viscious meconium in the rectum
Meconium passage uncommon before 36 weeks but
occurs more than 30% beyond 42 weeks due to :
- Fetal maturation post term (high motilin level).
- In utero stress (hypoxia, acidosis) producing
relaxation of anal sphincter.

6. Risk factors for MAS
Maternal HPT
Maternal DM
Maternal heavy cigarette smoking
Maternal chronic respiratory or
cardiovascular disease
Post date pregnancy
Pre-eclampsia/eclampsia
Oligohydromnions
IUGR
Abnormal fetal HR pattern

7. Pathophysiology
1. Mechanical obstruction of airways
Thick and viscous meconium lead to complete or partial
airway obstruction.
With onset of respiration- meconium migrates from central to
peripheral airways
Complete obstruction -> atelectasis
Partial Obstruction -> ball valve -air trapping (risk of
penumothorax 15-33%)
2. Chemical pneumonitis
Distal progressing of meconium chemical pneumonitis ->
bronchiolar edema and narrowing of the small airway.

8. 3. Surfactant inactivation
Bilirubin, fatty acid, triglycerides, cholestrol
content of meconium inhibit surfactant
function and inactivation.
4. Pulmonary hypertension
Meconium in lung stimulate - >
proinflammatory cytokines and vasoactive
substance which cause pulmonary
vasoconstriction
Hypoxia, acidosis, hyperinflation ->
pulmonary hypertension

15. CLINICAL FEATURES
History
Infant with MAS must have a history of MSAF
Often are term or post-term
IUGR
Many are depressed at birth
Physical Examination
Evidence of postmaturity ; peeling skin, long fingernails, reduced
vernix
Vernix, umbilical cord and nails may be meconium-stained,
depending how long the infant has been exposed in utero
Generally
nails stained after 6 hrs
vernix after 12-14 hrs
umbilical cord staining thick 15 min, thin 1 hour

16. Respiratory distress with marked tachypnea and cyanosis
Use of accessory muscles of respiration (ICR, SCR and abdominal
breathing) , grunting and nasal flaring.
Chest : appears barreal shape with increase AP diameter due to
overinflation
Auscultation : rhonchi immmediately after birth
Sign of cerebral irritation from cerebral edema or hypoxia :
jitteriness, seizures
Some patient are asymptomatic at birth and develop worsening
signs of respiratory distress as the meconium moves from large
airways into the lower tracheobronchial tree.
Meconium found below vocal cord defines MAS

17. Differential diagnosis
Perinatal Asphyxia
Bacterial Pneumonia
Respiratory Distress Syndrome
Transient Tachypnea Of Newborn
Congenital Heart Disease

19. Lab Investigations
Arterial blood gas (Acid-base status)
- Metabolic acidosis
- Hypoxia
- Hypercarbia
Chest radiograph
- hyperinflated lung and flatten diapghram
- B/L diffuse grossly irregular patchy infiltrates
- Pneumothorax and pneumomediastinum
- Small pleural effusion
- No air bronchogram

20. Air trapping and
hyperexpansion due to
airway obstruction
Diffuse, asymmetric patchy
infiltrates
Areas of concolidation
Hyperinflation

21. a
Atelectasis

22. Diffuse chemical pneumonitis

25. MANAGEMENT
Prenatal
1. Identification of high risk pregnancies
- recognition of predisposing maternal factors
- post dates pregnancy inductions as early as 41
weeks
2. Monitoring
- careful observation and fetal monitoring during labour
- corrective measures should be undertaken to
identifiy
compromised fetus.
3. Amnioinfusion
- relieved umbilical cord compression during labor ->
reducing occurrence of variable fetal heart rate
decelerations
- efficiency not well demonstrated.

26. Delivery room management
Anticipate the worst….
Be
prepared…

27. American Academy of
Paediatric NRP guidelines:
If the baby is not vigorous :
- direct suction immediately after delivery
- suction for no longer than 5 sec
- If no meconium retrieved, do not repeat
intubation and suction
- If meconium is retrieved and no bradycardia
present, re-intubate and suction.
- If HR low, administer IPPV and consider
suctioning again later.
If baby is vigorous :
- Clear secretions and meconium from the
mouth and nose with a bulb syringe or a large
bore suction catheter.

28. Management of newborn with MAS
1. General management
Maintain a neutral thermal environment
Minimal handling protocol to avoid agitation
Maintain adequate BP and perfusion
Correct any abnormalities
Sedation
2. Respiratory management
Pulmonary toilet - from the ETT + chest physiotherapy
every 30 min to 1 hr
Arterial blood gas level - to assess infant ventilatory
compromise
Frequent blood taking -> UAC + UVC
3. Oxygen monitoring
Severity of infant’s respiratory status and to prevent
hypoxemia
Compare pre ductal and post ductal o2 saturation
identifies infant with right to left ductal shunting secondary
to MAS associated pulmonary hypertension

29. 4. Antibiotic coverage
Start on broad spectrum antibiotic
5. Supplemental Oxygen
To prevent episodes of alveolar hypoxia leading to
hypoxic pulmonary vasoconstriction and PPHN.
maintain arterial oxygen tension 80-90mmHg
6. CPAP
7.Mechanical ventilation
In MAS with impending respiratory failure with
hypercapnia and persistent hypoxemia
Volume targeted ventilation decreased lung
overdistention
Use of relatively short inspiratory time limit potential air
trapping
Requires high pressure and faster rate

30. 8. Surfactant
infant with severe MAS
who require mechanical ventilation
and radiologic findings of parenchymal
lung disease benefit from early
surfactant therapy
9. Inhaled nitric oxide
MAS with pulmonary hypertension

32. Prognosis
Complications are common and
associated with significant mortality
Neurodevelopmental sequelae
including , CP, and autism -long
term follow up

34. • ROAMS BY VD AGARWAL 13TH ED
• ESSENCE OF PAEDIATRICS BY PROFF
DR M R KHAN

36. •THANK YOU
FOR
YOUR ATTENTION