Meconium Aspiration Syndrome

Meconium aspiration syndrome (MAS) is characterized by early onset of respiratory distress and hypoxemia in a meconium stained term infant.

Post maturity

3

Ans. is c i.e. HMD

Ans. is ‘b’ i.e., Obstructive emphysema

Meconium aspiration syndrome

o Meconium is the first stool of an infant, composed of materials ingested during the time the infant spends in uterus, i.e. intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile and water.

o Meconium aspiration syndrome (MAS) occurs when infants take meconium into their lungs during or before delivery.

o It is more common in post-tern: neonates but may also occur in term neonates.

Consequences of meconium aspiration

o Three main problems occur due to meconium aspiration ‑

i)        Obstructive emphysema or atelectasis —> when aspirated material blocks the airways.

ii)     Pneumonitis and chemical pneumonia because of irritant property of meconium.

iii)    Defective gas exchange.

Clinical manifestations

o Respiratory distress within 1st hour with tachypnea, retraction, grunting and cyanosis.

• Overdistention of the chest.

Complications

Respiratory distress syndrome         

o Pneumothorax 

o Persistent pulmonary hypertension

Ans. is ‘b’ i.e., Meconium aspiration syndrome

o Meconium stained liquor (amniotic fluid) with respiratory distress soon after birth suggests the diagnosis of meconium aspiration syndrome.

o The important clues in this question are

i) Baby is full term —-> MAS occurs in term or post term neonates.

ii) Respiratory distress soon after birth —> MAS presents like this

iii) Liquor is meconium stained —> supports the diagnosis of MAS

o In transient tachypnea of newborn and hyaline membrane disease (.surfactant production) amniotic fluid will not be stained with meconium.

Radiographic picture of MAS

o Hyperventilated lungs with patchy infiltration.                    

o Flattening of diaphragm.

o Increased anteroposterior diameter of chest.

Ans. is ‘b’ i.e., Hyaline membrane disease

Respiratory distress in a preterm infant and X-rays showing ground glass appearance with air bronchogram suggest the diagnosis of neonatal respiratory distress syndrome (RDS) also called hyaline membrane disease. “Hyaline membrane disease is the commonest cause of respiratory distress in a preterm neonate”.  Ghai About other options

o Meconium aspiration syndrome usually occurs in full-term or post-term newborn.

o ARDS is adult respiratory distress syndrome.

Ans. is ‘d’ i.e., Trikling of sole

To solve this question, one should know the resuscitation protocol of newborn.

Resuscitation protocol

o As soon as the baby is delivered, five signs are assessed ‑

1. Clearance of meconium
2. Active breathing or crying
3. Good muscle tone (flexed posture and active movement of baby).
4. Pink color (look at tougue and lips)
5. Term gestation (delivery between 37-42 weeks of pregnancy).

o If all signs are positive no active resuscitation is required.

o If any of the 5 signs is absent, baby requires resuscitation.

o The baby should be placed under the heat source (radiant warmer) and subjected to a set of intervention known as initial steps.

Initial steps of resuscitation

1. Positioning

The neonate should be placed on her back or side with the neck slightly extended.

This can be achieved by putting a rolled blanket or towel under the shoulders, elevating them ³/4 or 1 inch off the mattress.

2. Suctioning

The mouth and nose should be suctioned

The mouth is suctioned first to ensure that there is nothing for the infant to aspirate when the nose is suctioned.

One should not insert the catheter very deep in mouth or nose for suction -4 Stimulation of posterior pharynx during the first few minutes after birth can produce a vagal responce, causing severe bradycardia or apnea.

3. Dry, stimulate and reposition

After suctioning, the baby should be dried by using pre-warmed linen to prevent heat loss.

A brief tactile stimulation in the form of flicking the soles or rubbing the back ma^y be provided in case of non-establishment of good respiratory efforts.

4. Free flow of oxygen

 If the baby continues to be depressed, provide free flow of oxygen using a facemask.

• After providing initial steps, the baby should be evaluated for three signs ‑

Respiration

1. Heart rate (HR)
2. Color

• If baby has good breathing, HR >100 and pink color, he should be given supportive care.
• If the baby is not breathing well or HR <100 then bag and mask ventilation is needed.

o After the infant has received 30 seconds of ventilation with 100% oxygen by bag and mask, evaluation of heart rate should be done –

HR >100        —->           Discontinue ventilation if spontaneous respiration is present

HR 60 to 100  —>            Continue ventilation

Below 60         —>          Continue ventilation + chest compressions

• After 30 seconds of chest compressions, the heart rate is checked.

HR <60                           Continue chest compression and bag & mask ventilation + initiate medications.

HR> 60                          Discontinue chest compression but continue bag & mask ventilation until the heart rate is above 100.

Ans. is ‘b’ i.e., Colour

Resuscitation of neonate born through meconium-stained liquer (MSL)

o When baby passes meconium in utero, there is a chance that the mecomium will be aspirated into infant’s mouth and potentially into the trachea and lungs.

o Appropriate steps must be taken immediately after delivery to reduce the risk of serious consequences resulting from aspiration of meconium.

o Intrapartum nasopharyngeal suctioning just after the delivery of head is no longer recommended as it does not reduce the risk of meconium aspiration syndrome and, on rare occasions, may cause nasopharyngeal trauma or a cardiac arrhythmia.

The first step after delivery is to identify whether the newborn is vigrous or non-vigrous : ‑

A) Vigrous newborn

               A newborn is classified as vigrous, if he has all the three signs are present : ‑

1)    Strong respiratory effort

2)    Good muscle tone

3)    Heart rate greater than 100

LI The vigrous child does not require any tracheal suctioning and the usual initial steps of resuscitation are provided, i.e., provide warmith, positioning, suctioning of mouth and nose (not tracheal suctioning), Dry, stimulate and 02 if necessary.

B) Non-vigrous newborn

              If any of the above three signs is present, the newborn is classified as non-vigrous.

               For non-vigrous child, the initial steps are modified :

Place the baby under radiant warmer and postpone suctioning to prevent stimulation of posterior pharyngeal wall that can cause bradycardia.

ii)       Residual meconium in the mouth and posterior pharynx should be removed by suctioning under direct vision using a laryngoscope.

iii)    The trachea should then be intubated and mechonium suctioned from the lower airway. Tracheal suctioning is best done by applying suction directly to the endotracheal tube.

               After providing initial steps, the further management is same as with resucitation for other conditions (See previous explanation).

Ans. is ‘b’ i.e., Meconium aspiration

o Most common cause of respiratory distress in a term or post-term neonate -4 Meconium aspiration. o Most common cause of respiratory distress in a preterm infant –> hyaline membrane disease.

Ans. is ‘a’ i.e., Transient tachypnea of newborn

o Respiratory distress, which resolves within 24 hours without any respiratory support and fluid in interlobar fissure on chest X-ray suggest the diagnosis of TTN.

Ans. is ‘b’ i.e., Bacterial flora

Meconium contains –

i)           Intestinal epithelial cells           iii) Mucus                           v) Bile

ii)          Lanugo                                   iv) Amniotic fluid                 vi) Water

Ans. is ‘d’ i.e., Low birth weight

Retrolental Fibroplasia

• Retinopathy of prematurity (Previously called as retrolental fibroplasia) is a characterized by abnormal proliferation of small retinal blood vessels due to a variety of causes.

The complication is related to high oxygen tension in the arterial blood rather than the concentration of oxygen in the inspired air.

o The condition is limited to preterm babies with a birth weight of less than 1500 gm or gestational age of less than 32 weeks.

“Retrolental fibroplasia (retinopathy of prematurity) is generally noted some weeks after birth in premature infants who have been given high concentration of oxygen, and is usually confined to those under 1.7 Kg in weight at birth.”

Ans is ‘d’ ie diaphragmatic hernia

• Bag & mask ventilation is contraindicated in diaphragmatic hernia.
• Reason – In diaphragmatic hernia the abdominal contents have herniated into the thoracic cavity and are compressing the lung. By using bag and mask ventilation air will also move into the GIT along with the lung. More air in the stomach and intestines will cause more compression on the already compressed lung.

Answer is C (Neonatal pulmonary alveolar proteinosis):

Ans. C: Corticosteroids

Antibiotic coverage is needed as meconium invites infection