3. What is meconium aspiration?
Meconium is the first intestinal discharge of the newborn
Epithelial cells, fetal hair, mucus, bile
Intrauterine stress may cause in utero passage of
meconium
Aspirated by the fetus when fetal gasping or deep
breathing occurs stimulated by hypoxia and hypercarbia
Warning sign of fetal distress
4. Meconium: The Stats
Frequency of Mec stained amniotic fluid = 10-25%
OF MEC stained infants:
30 % depressed at birth
10 % meconium aspiration syndrome (range 2-36 %)
OF infants with MEC aspiration syndrome
17 % deliver through thin meconium (range 7-35 %)
35 % need mechanical ventilation (range 25-60 %)
12 % die (range 5-37 %)
5. OHSU Experience: Inborn + Transfers
# Mec DR MAS MAS ECMO Died
passed intub + vent
1992-94 146 88 44 28 4 3*
1995-97 154 92 39 25 1 1*
Total 300 180 83 53 5 4
MAS = Meconium aspiration syndrome as primary pulmonary diagnosis
No pulmonary hypoplasia or major congenital anomalies
MAS+ vent = ventilated with pulmonary diagnosis of MAS or PPHN
ECMO = MAS infants transferred for ECMO
Died : * 1 infant in each of the years died with a diagnosis of severe HIE
7. Meconium in Amniotic Fluid
Intrapartum suctioning of mouth,
nose, pharynx
Infant Depressed
Infant Active
Intubate and suction
Observe
trachea
Other resuscitation as indicated
8. Meconium Aspiration
Syndrome
Pathophysiology
Airway obstruction of large and small airways
Inflammation and edema
Protein leak
Inflammatory Mediators
Direct toxicity of meconium constituents = chemical
pneumonitis
Surfactant dysfunction or inactivation
Effects of in utero hypoxemia and acidosis
Altered pulmonary vasoreactivity (PPHN)
9. Meconium Aspiration
Syndrome
Diagnosis
Known exposure to meconium stained amniotic fluid
Respiratory symptoms not explained by other cause
R/O pneumonia, RDS, spontaneous air leak
CXR changes - diffuse, patchy infiltrates, consolidation,
atelectasis, air leaks, hyperinflation
10.
11. Meconium Aspiration Syndrome
Treatment
Ventilation strategies
Avoid air leak, check CXR with acute
deterioration
Prevent pulmonary hypertension - generous O2
HFOV if unable to maintain on conventional vent
Steroids (no human data, controversial)
ROS, Antibiotics (ampicillin, gentamicin)
Surfactant
Inhaled Nitric Oxide
ECMO
12. Other Things to Watch For
Hypoxia
Acidosis
Hypoglycemia
Hypocalcemia
End-organ damage due to perinatal
asphyxia
13. Meconium Aspiration Syndrome
Outcome
High incidence long term pulmonary problems
At 6 months - 23% MAS with regular bronchodilator
therapy*
FRC was higher in symptomatic infants
IPPV and O2 were not predictors of problems
Increased risk of poor neurologic outcome due
to perinatal insult - seizures, CP, mental
retardation
*Yuksel et al. Pediatric Pulmonology 16:358, 1993
14. Meconium Aspiration Syndrome
Surfactant Treatment
Methods
< 6 hours old with MAS
20 infants randomized to receive 150 mg/kg surfactant
by 20 minute infusion, q6h x4 doses maximum
On ventilator - FiO2 > 50%, MAP > 7, a:A PO2 < 0.22
Endpoint = improvement in OI and a:A PO2
No difference in groups
Findlay et al. Pediatrics 97 (1): 48, 1996.
15. Meconium Aspiration Syndrome
Surfactant Treatment
Results
No infant received more than 3 doses
Significant improvement in OI, MAP, FiO2
within 3-6 hours after 2nd dose of surfactant
Significant improvement in a:A PO2 within 1
hour of 1st dose of surfactant
Findlay et al. Pediatrics 97 (1): 48, 1996.
16. Meconium Aspiration Syndrome
Surfactant Treatment
Control Surf P value
Air leak 5 0 0.024
ECMO 6 1 0.037
Days MV 11 (1) 8 (1) 0.047
Days O2 20 (3) 13 (1) 0.031
LOS (days) 24 (2) 16 (1) 0.003
D/C on O2 8 6 NS
Mortality (< 28 d) 0 0 NS
Findlay et al. Pediatrics 97 (1): 48, 1996.
