Authors: Nestor E Vain, Edguardo G Szyld, Luis M Prudent, Thomas E Wiswell, Adrianna M Aguilar, Norma I Vivas.

Introduction: Meconium Aspiration Syndrome is an important complication in newborns born through meconium-stained amniotic fluid. Some limited data have led to the practice of intrapartum suctioning of the oropharyngeuml and nasopharyngeum in infants when there is meconium-stained amniotic fluid. Other data do not support this approach. The international liaison committees on resuscitation, American Academy of Pediatrics, and ACOG have recommended the procedure, although it is not advocated in the UK newborn life-support guidelines. Until this study, there were no other randomized controlled studies to evaluate the effectiveness of intrapartum oropharyngeal and nasopharyngeal suctioning in the presence of MSAF to prevent meconium aspiration syndrome.

The aim of this study was to interpret prevention of meconium aspiration syndrome by routine intrapartum oropharyngeal and nasopharyngeal suctioning of term infants born through meconium-stained amniotic fluid.

Method: This study was designed in a randomized controlled trial, which included twelve centers, eleven in Argentina, and one in the US. The trial sites included six public hospitals and six private hospitals. Patients were enrolled between March 13, 2000 and October 1, 2001.

There were 2514 patients with MSAF of any consistency, gestational age at least 37 weeks, and cephalic presentation. The patients were randomly assigned to suctioning, and no suctioning groups. In the suctioning group the number was 1263 and the no suctioning had 1251. The primary outcome was Meconium Aspiration Syndrome. Exclusion criteria were major congenital malformations, inability to randomize before delivery, and refusal by the obstetrician to allow their patients to participate. Patients were in enrolled in a no informed consent.

Procedure: Infants were randomly divided to either suctioning or no suctioning groups in blocks of four. (See Table 1). Computer generated random numbers were assigned to these groups. Sealed envelopes were opened before attending a delivery that was complicated my meconium staining. Envelopes were opened by the neonatologist in charge of resuscitation. Clinicians and investigators who cared for the infant outside of the delivery room were unaware of individual treatment group assignments. The infants who were suctioned, a suction catheter of 10 French to 13 French was connected to a negative pressure of 150 mm Hg. The oropharynx was suctioned first followed by the nasopharynx. After that, care was given according to the guidelines of Neonatal Resuscitation Program of the American Academy of Pediatrics and the American Heart Association, which recommended tracheal suction followed by positive pressure ventilation in the case of non-vigorous infants. Chest X-rays were taken for infants who had respiratory distress or infants who required oxygen. Some infants required mechanical ventilation.

The primary outcome was the incidence of Meconium Aspiration Syndrome. The definition of meconium aspiration syndrome was:

1. Respiratory distress which included tachypnea, retraction, or grunting.
2. Need for supplemental oxygen to maintain 92 percentile Oxygen saturation.
3. Oxygen requirements during the 1 st two hours of life and lasting for more than 12 hours.
4. Absence of congenital malformations of lung or heart.

Major secondary outcome variables were:

Mortality

1. Incidence of severe MAS
2. Air leaks

Occurrence of other disorders causing respiratory distress, low apgar scores, need for positive pressure ventilation, pneumothorax, and other respiratory disorders.

Statistical Analysis: The sample size was based on the assumption of the incidence of MAS to be 7%, obtained from a retrospective review of the population. The data was analyzed on an intention to treat for continuous variables. They used analysis of variance and x 2

Findings: no significant difference between treatment groups was seen in the incidence of MAS (52 [4%] suction vs. 47 [4%] no suction; relative risk 0.9, 95% CI 0.6-1 .3), need for mechanical ventilation for MAS (24 [2%] vs. 18 [1%]; 0 .8, 0 .4-1 .4), mortality (9 [1%] vs. 4 [0 .3%]; 0 .4, 0 .1-1 .5), or in the duration of ventilation, oxygen treatment, and hospital care.

Result: Routine intrapartum oropharyngeal and nasopharygeal suctioning of term-gestation infants born through MSAF does not prevent MAS. Consideration should be given to revision of present recommendations.

Discussion: the conclusion of this study was that intrapartum suctioning did not decrease the risk of MAS.

This trial showed that infants were at highest risk of MAS who were born through thick meconium of the amniotic fluid, with fetal distress, or delivered through C-section. These infants did not seem to benefit from intrapartum suctioning. This study was not powered for the assessment of this subgroup. The similarity in the incidences in both groups and the narrow confidence interval suggest that prenatal suctioning does not have any effect. The use of suction catheter has its potential risks such as apnea and cardiac arrhythmia, which can be triggered by pharyngeal stimulation.

A study done by Carson and colleagues, a cohort of 273 meconium stained infants who were managed by intrapartum suctioning and larygyngoscopy and intubation when mec. was detected at the level of vocal cords compared with a control group in which no intrapartum suctioning had been done. That study showed that in the combined approach infants were less likely to develop MAS 0.4% vs. 1.9% in infants that were not suctioned. Although these differences are not significant, intrapartum suctioning has become the common practice. Another study done by Falcigila and colleagues a perspective non randomized observational study, showed higher incidence of MAS in the suction group 10% vs. 7% in the non suction group.

The study was adequately powered, we see that there is a narrow confidence interval. The study concluded that routine intrapartum suctioning does not prevent MAS and consideration should be given to revise the present recommendation.