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NPR Instructor Update 
Vol. 7 . No. 3 . October 1998

Easy Steps to a Safer Pregnancy - View e-book or Download PDF - FREE!
An interactive resource for moms on easy steps they can take to reduce exposure to chemical toxins during pregnancy.

Other excellent resources about avoiding toxins during pregnancy

These are easy to read and understand and are beautifully presented.

Delivery Room Management of the Apparently Vigorous Meconium-Stained Neonate:
Results of the Multicenter, International Collaborative Trial

by Thomas Wiswell, MD, FAAP

A common occurrence faced by health care providers is the neonate born through meconium-stained amniotic fluid. These infants make up approximately 13% of all deliveries.  The meconium-aspiration syndrome (MAS) occurs in approximately 6% of meconium-stained babies. (1, 2)  Between 25% and 60% of children with MAS need mechanical ventilation, while death occurs in 5%-12% of those with the disorder.  In the mid-1970s appeared the anecdotal reports of Gregory and colleagues (3) and that of Ting and Brady, (4) in which intubation and suctioning of meconium-stained infants appeared to be beneficial in preventing MAS. Neither of these studies was a randomized, prospective investigation. Nonetheless, following their publication, intubation of all meconium-stained babies became routine management. During the 15 years following these reports the incidence of MAS, as well as deaths due to the disorder, significantly declined. (5)

The 1988 study of Linder et al. (6) questioned the necessity of intubating the apparently vigorous meconium-stained newborn. Although this study had numerous problems in it design, its publication prompted many care providers to adopt a "selective" approach to intubation of meconium-stained infants. Since there was a lack of appropriate supportive research for both approaches (universal vs. selective intubation) we designed an investigation with two objectives.

1) to assess whether intubation and suctioning of the apparently vigorous meconium-stained neonate would reduce the incidence of MAS; and

2) to determine the frequency of complications from delivery room intubation and suctioning of such infants.

We hypothesized that intratracheal suctioning, compared to expectant management of apparently vigorous meconium-stained infants, would decrease the incidence of MAS from 3% to 1%. In order to demonstrate such a difference, at an alpha of 0.05 with 80% power, a minimum of 605 infants were needed in each group (1,210 total). Twelve centers participated in the prospective, randomized, controlled trial. The study was supported by grants from the Neonatal Resuscitation Program and the American Pediatric Society/Society for Pediatric Research (APS/SPR) Multicenter Trials Initiative.

Inclusion criteria specified a gestational age of greater than or equal to 37 weeks, birth through meconium-stained amniotic fluid of any consistency, and apparent vigor in the delivery room immediately after birth, as defined by a heart rate above 100, any spontaneous respiration, and reasonable tone. The degree of vigor was generally assessed within the first 10-15 seconds after delivery.  Randomization occurred immediately prior to delivery. If an infant did not meet the definition of vigorous, he or she was not included. Babies randomized to the intubation group were intubated with appropriate-size endotracheal tubes. A standard suction device (Neotech Meconium Aspirator) was used, and negative pressure from wall suction was set at -80 to -120 mm Hg. Suction was applied continuously for 1 to 5 seconds and as the endotracheal tube was withdrawn. The procedure was repeated until no further meconium-stained fluid could be retrieved.  Infants randomized to expectant management had routine delivery room care. If at any time these babies manifested respiratory distress, the investigators could intubate and suction as clinical conditions indicated.  Extensive antenatal, intrapartum, and postnatal data were collected on a standardized form that was forwarded to a central facility and entered into the central database. For this trial, MAS was defined as respiratory distress in a meconium-stained infant who had radiographic findings consistent with MAS and in whom other possible diagnoses had been excluded. All investigators remained blinded to results until completion of the trial. A separate Data Safety and Monitoring committee assessed data 1/3 and 2/3 of the way through enrollment to evaluate for possible overwhelming imbalances in adverse experiences in one group or the other.

Enrollment occurred between July 1995 and September 1997. A total of 2,094 infants were enrolled: 1,051 in the intubation group and 1,043 in the expectant management group, Six of the centers each enrolled between 200 and 408 infants, while the remaining six sites enrolled a total of 227 infants The mothers were similar in age, gravidity and parity, and in the proportion of vaginal versus cesarean delivery. The consistency of the meconium-stained amniotic fluid was similar in both groups: thin, 43%; moderately thick, 29%; and thick, 28%. There were no differences in racial background. Gender distribution was similar in the two groups. One-minute Apgar scores were significantly lower in the incubation group, a finding attributable to the intubation procedure. Approximately 7% of infants in both groups subsequently developed respiratory distress. There were no significant differences in the occurrence of MAS.  The disorder occurred in 3.2% of the intubation group and 2.7% management group. The other types of respiratory illnesses that were diagnosed included transient tachypnea, delayed transition, sepsis/pneumonia, persistent pulmonary hypertension, tachypnea due to hypovolemia, and blood aspiration. In both groups, as the consistency of meconium-stained amniotic fluid increased, the occurrence of MAS and of other respiratory disorders increased. The frequency of respiratory distress was similar at all participating sites. Thirty-nine percent of the babies with MAS required mechanical ventilation. Seventeen (1.5%) of the 1,051 babies in the intubation group were not intubated due to several reasons (provider arriving after 1-3 minutes of age, intubation too difficult, etc). Sixty-four (6..1%) of the 1,043 babies in the expectant management group were intubated in the delivery room because of subsequent poor respiratory effort or the development of respiratory distress. Of the 1,098 total intubated infants, 42 (3.8%) had a total of 51 complications from the procedure including bradycardia, hoarseness/stridor, laryngospasm, apnea, bleeding at the vocal cords, and cyanosis. All of these complications were transient.

We conclude that approximately 7% of apparently vigorous meconium-stained infants will subsequently develop some form of respiratory illness. The thicker the consistency of meconium-stained amniotic fluid, the more likely the occurrence of respiratory distress. The complication rate of intubation is relatively low and complications are transient. Intubation of the apparently vigorous meconium-stained neonate does not result in a decreased incidence of MAS or other respiratory distress compared to expectant management. 

This Web page is referenced from another page containing related information about Meconium


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