Monday, 9 November 2015

MECONIUM ASPIRATION





Q.3) A term infant requires intubation in the delivery room after aspiration of thick meconium and is brought to the neonatal intensive care unit. Which of the following is the most likely risk factor for meconium aspiration syndrome in this infant?
(A) chromosomal anamoly
(B) congenital heart disease
(C) cystic fibrosis
(D) fetal distress
(E) tracheoesophageal fistula
Ans: D.
 Fetal distress is the major risk factor for meconium aspiration. The mechanism involves the loss of anal sphincter tone, passage of meconium into the amniotic fluid, and aspiration by the distressed, gasping infant during the process of birth. The thick meconium obstructs the airways, causing tachypnea, retractions, and grunting.

This is the type of question in which a little common sense is required. If you knew that meconium aspiration was a relatively common problem in the delivery room, you could eliminate (C) cystic fibrosis (a relatively uncommon disease) as its cause. 
(Meconium ileus, which is associated with cystic fibrosis, has nothing to do with meconium aspiration.) If you realized that aspiration of meconium can only occur before or during delivery, you also could eliminate (B) congenital heart disease and (A) neonatal meningitis, as neither of these generally cause distress during delivery. 
Finally, you should be able to figure out that a tracheoesophageal fistula with or without associated esophageal atresia, would lead to aspiration of saliva, milk, or gastric contents after birth but would not predispose to aspiration of meconium.

A severe pneumonia following meconium aspiration occurs as an in utero response to significant hypoxic or ischemic stress. Infants who have fetal distress, thick meconium, and APGAR scores of less than 7 at 1 and 5 minutes are at increased risk for meconium aspiration syndrome.

When meconium staining of amniotic fluid is noted, the appropriate approach to care of the infant according to The Neonatal Resuscitation Program (NRP) of the American Academy of Pediatrics and American Heart Association include intubation when the infant is not vigorous (defined as having poor respiratory efforts, poor muscle tone, and a heart rate less than 100 beats/minute).

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