Meconium Aspiration Syndrome

1. CONTENT
UNIT 15.2 MAJOR PROBLEMS OF NEWBORN
MECONIUM ASPIRATION SYNDROME
Definition: Meconium aspiration syndrome (MAS) refers to a serious condition of aspiration of
meconium stained liquor into lungs that occurs when a fetus has been suspected to fetal asphyxia or
other intrauterine stress that causes relaxing of the anal sphincter and passage of meconium into the
amniotic fluid.
The majority of meconium aspiration occurs with the first breath. But severely compromised fetus
may aspirate in utero.
Prevalence
Meconium aspiration syndrome occurs in an about of 5-20% of all births and more common in
postdated births.
Risk Factors for Meconium Passage :
1. Post term babies
2. Preeclampsia and eclampsia
3. Maternal diabetes mellitus
4. Oligohydraminous
5. Maternal drug abuse i.e. tobacco and cocaine
6. Maternal infection i.e. chorioamnionitis
7. Abnormal biophysical profile
Pathophysiology
Meconium which comprises of gastrointestinal,hepatic and pancreatic secretions , cellular debris,
swallowed amniotic fluid, lanugo , vernix caseosa begins to appear in the fetal intestines by the 10th
week of life and gradually increasing in amount to reach 200gms at birth. However due to lack of
strong peristalsis, good anal sphincter tone, low levels of motilin and a cap of viscous meconium in
the rectum ,in utero passage is uncommon till term. In utero hypoxia and acidosis lead to a vagal
response with the resultant increased peristalsis and a relaxed anal sphincter leading to meconium
passage. Integrity of parasympathetic system therefore appears to be pre requisite for meconium
passage making it a maturational event and rare before term.

2. Meconium aspiration
Large plugs-upper airway obstruction Small particles-diffuse spread
Acute hypoxia lower airway obstruction
Mechanical obstruction Chemical inflammation Infection
Displaces surfactant &
Incomplete Complete damage type II pneumocytes
Ball valve obstruction Atelectasis
Respiratory distress
Air leaks Right to left shunts
Increased PaCO2 Decrease PaO2
Hypoxemia , Hypercapnia , Acidosis
Persistent pulmonary hypertension of newborn(PPHN)
Clinical Features
 Infant who have released meconium in utero for some time before birth are stained from green
meconium. Umbilicus and nails will be greenish rather than white or yellowish.
 Those babies develop respiratory distress within first hours of life which is featured as
expiratory grunting, nasal flaring and retractions.
 They may be initially cyanotic ( circumoral cyanosis) or pale as well as tachypneic and they
may demonstrate the classic barrel shaped chest from hyperinflammation.
 On auscultation for lung sounds, abnormal lung sounds especially coarse crackles are heard.
 Severe meconium aspiration progresses very rapidly to respiratory failure. These infants exhibit
profound respiratory distress with gasping, ineffective ventilations , marked cyanosis, pallor
and hypothermia.

3. Diagnosis
 On inspection , amniotic fluid appears to be stained from green meconium.
 At birth, baby appears to be stained green from meconium. Nails and umbilicus appears
greenish.
 At birth, meconium can often be visualized by laryngoscopy in the respiratory passage and
vocal cord.
 Signs of respiratory distress can be observed.
 On auscultation for lung sounds, abnormal lung sounds especially coarse crackles are heard.
 Blood gas analysis shows low blood pH (acidosis due to decreased PaO2 and increased PaCO2).
 Chest radiograph shows uneven distribution of patchy infiltrates, air trapping, hyper expansion
and atelectasis.
 Echocardiography shows the diagnosis of right to left shunt.
Management
A. Immediate management
The American Academy of Paediatrics Neonatal resuscitation programme steering guidelines are as
follows:
 If baby is vigorous
 Don't electively intubate.
 Clear suction and meconium from mouth and nose with a bulb syringe or a large bore
suction catheter.
 If baby is not vigorous
 Suction trachea immediately after delivery.
 Suction for no longer than 5 seconds.
 If meconium is not retrieved, don’t repeat intubation and suction.
 If meconium is retrieved and no brady is present, reintubate and suction.
 If heart rate is low, administer positive pressure ventilation and consider suctioning again
later.
 Dry, stimulate reposition and administer oxygen as necessary.
 Transfer ill newborn with respiratory distress to NICU.
B. General Management
 Most babies born through meconium stained liquor do not require any resuscitation at birth
and remain well. Infants with meconium stained amniotic fluid who are born in good condition

4. and are free of respiratory distress and have no other perinatal risk should receive routine
postnatal care.
 Close observation and monitoring of oxygen saturation, heart rate and respiratory rate.
 Maintainance of optimal thermal environment and minimal handling because the infants are
agitated easily and become hypoxemic and acidotic quickly.
 Adequate warm and humidified O2 in high concentration to maintain arterial PO2 between 50-
90 mm of Hg is given. If oxygen saturation of blood cannot maintained at a satisfactory level
and carbon dioxide level rises , infant will required ventilator support.
 Tapping on the chest can be done to loosen the secretions.
 Insert the nasogastric tube and keep the baby nil per orally. Because moderate amount of
meconium may remain is stomach and be aspirated later, it is advisable to perform gastric
lavage after the baby has been stabilized.
 Use of intravenous fluids until the respiratory difficulty diminishes. It is advisable to start
intravenous infusion in all newborn babies with respiratory distress because the oral feeding
may not be possible with the baby as oral feeding has the risk of aspiration. Intravenous
administration of 10% glucose in amount of 60 ml/kg body weight per day may be given to a
term baby on the first day through a catheter inserted into peripheral or umbilical vein.
 But if there are no signs of respiratory distress, just do suctioning and initiate breastfeeding but
monitor the baby's condition closely for development of severe respiratory distress.
 Monitoring of blood glucose as the infant may be at increased risk of hypoglycaemia after a
hypoxic-ischemic insult. If hypoglycaemia exist then glucose infusion, 2 ml/kg of 10%
glucose, through an intravenous line is given over 2–3 minutes. Glucose infusion is continued at
a rate of 4-6 mg/kg/min or 60 ml/kg/day. Blood glucose should be maintained at 70–100 mg/dl.
The infusion may be stopped after hypoglycaemia is corrected.
 Monitoring of PaCO2 to detect worsening respiratory acidosis. If respiratory acidosis exists
then intravenous administration of sodium bicarbonate 7.5% sodium bicarbonate in dose of 3-8
meq/kg in 24 hours in 1:1 dilution with distilled water is required.
 Systemic vasopressors i.e.nor epinephrine are critical in maintaining systemic blood pressure
greater than pulmonary blood pressure, thereby reducing right to left shunt through patent
ductus arteriosus. IV dose of nor epinephrine is 0.1-0.3 ml/kg of a 1:10,000 solution which is
given via umbilical vein.
 Amnioinfusion
The infusion of warm isotonic fluid transcervically during labour complicated by meconium stained
liquor has been considered beneficial in reducing MAS either by diluting thick meconium or by
providing support to the umbilical cord and so reducing the risk of hypoxic-ischemia due to cord

5. obstruction. Recommendations for infusion may vary according to the institution. The most
common protocol starts along with an initial bolus of 250ml infused over 20-30 minutes. The rate is
then adjusted according to the severity of decelerations but usually at a rate of 10 to 20 ml per
minute up to 600ml. An additional 250ml beyond the volume at which decelerations resolve is
administered then the infusion is terminated, unless decelerations resume. The infusion is
considered failure if infusion of 800-1000ml of saline doesn't result in termination of deceleration.
In patients with thick meconium fluid, an infusion of 250 to 500 mL over 30 minutes, followed by a
constant infusion at 60 to 180 mL per hour, is the accepted protocol. The fetal heart rate and resting
tone(<15 mm Hg) are assessed continuously during the intervention.
 Ventilatory support
One third of infants with MAS require ventilator support. Because air leaks are a major problem in
this condition, high concentration of oxygen are necessary initially. Continuous positive airway
pressure (CPAP) could be beneficial if air trapping is not a major problem. If CPAP does not
suffice , mechanical ventilation with low inspiratory pressure, short inspiratory and long expiratory
times and rapid rates is required to maintain blood gas within normal limits.
 Surfactant Therapy
Surfactant deficiency in MAS is a consequence of altered function rather than a deficiency state.
Meconium displaces surfactant from the alveolar surface and inhibits its surface tension lowering
function. In high concentrations, it has a direct cytotoxic effect on the type 2 pneumocytes. Dose -
100mg/kg body weight of phospholipid in 2-4 divided doses at 6-12 hrs apart .Depending upon the
baby’s condition, repeated dose of surfactant need to be administered.
 Broncho-alveolar lavage
There is a high efficacy of lung lavage by bronchoscopy in removing large quantities of meconium
and improving lung function while the patient is on ventilator. Surfactant is more effective than
saline as a lavage fluid. An alternative to surfactant is to use lavage with relatively large volumes of
diluted surfactant to facilitate removal of meconium from the lungs, whilst maintaining sufficient
surfactant production.
 Inhaled nitric oxide
Inhaled nitric oxide is considered the most effective therapy in the management of PPHN. Inhaled
nitric oxide is a pulmonary vasodilator that plays a major role in maintaining vascular tone. INO
therapy may be used in conjunction with surfactant replacement therapy, high-frequency
ventilation, or ECMO.
The recommended dose of inhaled nitric oxide is 20 PPM with gradual reduction of the dose
following improvement of oxygenation, usually after 4-6 hours. Then, iNO can usually be weaned
from 20 to 5 ppm in decrements of 5 ppm every 1 to 2 hours. After that, wean by 1 ppm every 1 to
2 hours. Reduction of iNO from 1 to 0 ppm must be done with care as hypoxemia may result .

6. iNO has a high affinity for haemoglobin. Once bound it forms methaemoglobin.Methaemoglobin
cannot bind with oxygen and transport it to the tissues. For the first 24 hours methaemoglobin
blood levels should be checked every 12 hours. This may be reduced to 24 hourly once the infant is
stable.
 Corticosteroid therapy
Meconium in the airway evokes an inflammatory response characterised by the presence of
elevated cell counts and pro inflammatory cytokines i.e. IL-1B,IL-6,IL-8,IL-13. Steroids through
intravenous supresses the inflammatory response and thus improves pulmonary function in babies
with MAS. They can stabilize the blood pressure, particularly in infants who suffer from
intrauterine hypoxia and adrenal insufficiency, they can inhibit inflammation and decrease
cytokine-induced vasoconstriction and therefore, may be beneficial for infants who have PPHN
and dexamethasone can increase cardiac stroke volume and improve overall cardiopulmonary
function.
 Antibiotic therapy
Meconium is always sterile, yet it produces chemical pneumonitis with segmental atelectasis
mimicking bacterial pneumonitis. In vitro enhancement of bacterial growth by meconium suggests
the increased risk of superimposed bacterial infection in MAS. Broad spectrum antibiotics are
preferred.
 Extracorporeal membrane oxygenation
It is an extracorporeal technique of providing prolonged cardiac and respiratory supports to those
whose heart and lungs are unable to provide an adequate amount of gas exchange or perfusion to
sustain life. It works by removing the carbon dioxide and oxygenating red blood cells. This therapy
involves a modified heart–lung machine, although in ECMO the heart is not stopped and blood
does not entirely bypass the lungs. Blood is shunted from a catheter in the right atrium or right
internal jugular vein by gravity to a servo-regulated roller pump, pumped through a membrane lung
where it is oxygenated and through a small heat exchanger and then returned to the systemic
circulation via a major artery such as the carotid artery to the aortic arch. ECMO provides oxygen
to the circulation; allows the lungs to “rest”; and decreases pulmonary hypertension and hypoxemia
in such conditions as persistent pulmonary hypertension of the newborn, congenital diaphragmatic
hernia, sepsis, meconium aspiration, and severe pneumonia. It is generally continued until the
underlying cardiac and lung problem is improved or resolved.
C. Nursing Considerations:
1. Assessment of fetus : The assessment of fetal condition is a major priority of all birth
attendants.Several studies have shown the relationship between CTG abnormality, MSAF,
umbilical cord pH and apgar score.
2. Assessment of neonate: Monitor and maintain temperature and monitor vital signs for change
in condition or status such as decreased cardiac output (poor perfusion, mottling, deteriorating
ventilation status). Closely monitor for deviations from desired breathing pattern—pulse
oximetry, arterial blood gases, clinical signs of poor oxygenation, grunting, nasal flaring,
apnea, tachypnea, retractions, and cyanosis.

7. 3. Airway clearance : Suctioning should be performed only when necessary and should be based
on individual neonate assessment, which includes auscultation of the chest, evidence of
decreased oxygenation, excess moisture in the ET tube, or increased infant irritability. When
nasopharyngeal passages, the trachea, or the ET tube is being suctioned, the catheter should be
inserted gently but quickly; intermittent suction is applied as the catheter is withdrawn.
Suctioning should not be done for more than 5 seconds , as it causes vagal stimulation and then
bradycardia and continuous suction removes air from the lungs along with the mucus.
4. Maintainance of respiration: The most advantageous positions for facilitating an infant’s open
airway are on the side with the head supported in alignment by a small folded blanket or, when
on the back, positioned to keep the neck slightly extended. With the head in the “sniffing”
position, the trachea is opened at its maximum; hyperextension reduces the tracheal diameter in
neonates. Facilitate proper oxygenation by implementing appropriate therapy such as
supplemental oxygen, mechanical ventilation, or change of position.
5. Inspection of the skin is part of routine neonate assessment. Position changes and the use of
water pillows are helpful in guarding against skin breakdown.
6. Mouth care is especially important when infants are receiving NPO, and the problem is often
aggravated by the drying effect of oxygen therapy. Drying and cracking can be prevented by
good oral hygiene using sterile water. Irritation to the nares or mouth that occurs from
appliances used to administer oxygen (e.g., nasal CPAP) may be reduced by the use of a water-
soluble ointment. Routine oral hygiene care in intubated neonate has been shown to decrease
the incidence of ventilator-associated pneumonia.
7. Chest physiotherapy : Perform gentle chest percussion, vibration, and postural drainage based
on assessed need and neonate's tolerance.
8. Carry out treatment protocol.
9. Maintain nutrition: IV infusion ,breast feeding ,expressed breast milk.
10. Watch for signs of complications such as fever, vomiting, seizures, breathing difficulties etc.
11. Parental support: Parents need reassurance concerning their infant’s progress. All the
procedures are explained to familiarize them with the benefits and risks. It is imperative that
nurses remain sensitive to parents’ feelings and information needs during this process; an
important nursing intervention is assessment of the parents’ understanding of the treatment
involved and clarification of the nature of the treatment.
Prognosis
The mortality rate of meconium-stained infants is considerably higher than that of non-stained
infants. Residual lung problems are rare but include symptomatic cough, wheezing, and persistent
hyperinflation for up to five to ten years. The ultimate prognosis depends on the extent of CNS
injury from asphyxia and the presence of associated problems such as pulmonary hypertension.

8. Complications:
1. Brain damage
2. Parenchymal lung disease
3. Persistent pulmonary hypertension of a newborn
4. Air block syndrome
5. Pneumothorax, pneumomediastinum,pneumopericardium
6. Pulmonary interstitial emphysema
Summary
Meconium aspiration syndrome (MAS) refers to a serious condition of aspiration of meconium
stained liquor into lungs that occurs when a fetus has been suspected to fetal asphyxia or other
intrauterine stress that causes relaxing of the anal sphincter and passage of meconium into the
amniotic fluid. There are many risk factors for MAS like post dated pregnancy, pre eclampsia,
eclampsia and maternal diabetesIt is characterised by signs of respiratory distress. Most babies born
through meconium stained liquor do not require any resuscitation at birth and remain well. Infants
with meconium stained amniotic fluid who are born in good condition and are free of respiratory
distress and have no other perinatal risk should receive routine postnatal care. Those who develop
respiratory distress require further management with admission to neonatal unit

9. References
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,Baneshwor, Kathmandu,Nepal (pp:248-250).
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ed.).Akshav Publication , kathmandu,Nepal (pp:
98-99).
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ed.).Jaypee Brothers Medical
Publishers,New Delhi,India(pp:550-551).
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Delhi, India(pp: 170).
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Delhi,India( pp:222-223).
 Hockenberry,M. & Wilson, D.(2013). Wong's Essential of Pediatric Nursing(9th
ed.). Library of
Congress, United States of America (pp:267-279)
 Thakur, L .(2012).Advanced child health nursing (3rd ed.).Ultimate Marketing ,Lazimpat
,Kathmandu,Nepal (pp: 77-79).
 Air Cmde U Raju, Maj V Sondhi, Maj SK Patnaik.Meconium Aspiration Syndrome: An Insight. MJAFI
2010;66:152-157.
 Benjamin J Stenson, Allan D Jackson.Management of Meconium Aspiration Syndrome.pediatrics and
child health 2008;19: 174-176.
 Managing newborn problems.(2003).Geneva: Department of reproductive health and research,WHO.

10. SAMPLE QUESTION
Subject : Midwifery II Total Hour :30 min
Course no : BSN19 Total Mark :10
Pass Mark : 4
Candidates are required to give answers in their own words as far as practicable.
The figures in the margin indicates full marks.
Attempt all questions.
Objective Type of Question
1. Choose the best alternatives. 1X2=2
A. Meconium begins to appear in fetal intestines by
a. 10th week of life b. 8th week of life
c. 12th week of life d. 14th week of life
B. The recommended dose of inhaled nitric oxide is
a. 5 PPM b. 10 PPM
c. 20PPM d. 15 PPM
Subjective Type of Question
Long Answer Type Question
Answer the following question.
A. Define meconium aspiration syndrome.Describe the general management of meconium
aspiration syndrome. 2+6=8