Risk factors of meconium aspiration syndrome developing into persistent pulmonary hypertension of newborn.

Clinical experience indicates that persistent pulmonary hypertension of the newborn (PPHN) is one of the major causes of death in infants with meconium aspiration syndrome (MAS). We aimed to investigate the risk factors associated with MAS which lead to PPHN in order to search for ways to reduce the mortality associated with MAS. From 1995 to 2003, we conducted a retrospective study of infants with MAS at the China Medical University Hospital. We compared the risk factors associated with MAS, including pattern of fetal heart beat, mode of delivery, apgar score, sex, gestational age, birth body weight, in born or out born infants, resuscitation before admission, first pH at admission, asphyxia, surfactant usage, pneumothorax, pulmonary hemorrhage and shock before the diagnosis of PPHN between PPHN and non PPHN infants. During the nine-year study, 362 infants with MAS were enrolled. There were 64 infants with (17.7%) PPHN and 298 infants without PPHN. According to univariant analysis, the significant risk factors associated with MAS which lead to PPHN were out born infant (p=0.007), change of fetal heart beat pattern (p=0.0001), resuscitation before admission (p=0.0001), low pH (p=0.002), asphyxia (p<0.0001), shock (p<0.0001), pneumothorax (p=0.0004), and pulmonary hemorrhage (p<0.0002). Based on the results of logistic regression analysis, the risk factors were pneumothorax (p=0.04, odds ratio: 2.34), change of fetal heart beat pattern (p=0.02, odds ratio: 2.37) and asphyxia (p=0.001, odds ratio: 5.48). We conclude that pneumothorax, change of fetal heart beat pattern and asphyxia are the most important risk factors associated with MAS which lead to the development of PPHN. Avoidance of asphyxia and pneumothorax might be the key to reduce the incidence of PPNH and mortality rate of MAS.