Meconium aspiration syndrome in term neonates with normal acid-base statusat delivery: Is it different?

OBJECTIVE: Our aim was to compare the clinical characteristics of meconium aspiration syndrome in cases with pH greater than or equal to7.20 and in th ose with pH <7.20. STUDY DESIGN: Medical records of diagnostic codes from the International Cl assification of Diseases, Ninth Revision, were used to identify neonates wi th severe meconium aspiration syndrome who had been delivered at our instit ution from 1994 through 1998. Severe meconium aspiration syndrome was defin ed as a mechanical ventilator requirement of > 48 hours. Clinical data incl uding neonatal outcomes of cases of meconium aspiration syndrome associated with umbilical pH greater than or equal to7.20 at delivery were compared w ith data on outcomes of cases with pH <7.20. RESULTS: During this 4-year study period, 4985 singleton term neonates were delivered through meconium-stained amniotic fluid. Forty-eight cases met a ll study criteria, and pH values at delivery were as follows: pH greater th an or equal to7.20, n = 29, and pH <7.20, n = 19. There were no differences between groups in the incidence of clinical chorioamnionitis, in the prese nce of meconium below the vocal cords, or in birth weight. Neonates with me conium aspiration syndrome and umbilical pH greater than or equal to7.20 at delivery developed seizures as often as those with pH <7.20 (20.1% vs 21.1 %; P = 1.0). CONCLUSION: Normal acid-base status at delivery is present in many cases of severe meconium aspiration syndrome, which suggests that either a preexist ing injury or a nonhypoxic mechanism is often involved.