The Study On Risk Factors And Levels Of Serum Cortisol In Preterm Infants With Patent Ductus Arteriosus

Objective To identify the risk factors for patent ductus arteriosus(PDA) and to determine the relationship between the levels of serum cortisol and PDA in preterm infants.Methods A Case-Control Study was conducted on 751 preterm infants hospitalized in NICU of Fujian Maternity & Children Hospital during January to December,2008 for identifying their risk factors using simple and multivariate Logistic regression.One hundred thirty three cases underwent cardioechogram examination and clinical information was compared between forty-eight cases with PDA and eighty-five infants without PDA.Next,a 1:1 matched nested case-cotrol study was conducted.38 pair of preterm infants were selected from January to December,2009.38 preterm infants were develop PDA.And we also close 38 non-PDA preterm infants as the controls,who had the correspond gestational age and same exposure to antenatal steroids.The serum cortisol concentrations of these infants were measure twice by chemiluminesence immunoassay.All data was analyzed via SPSS13.0.Results In the first sudy,single factor analysis showed that PDA in preterm infants was significantly associated with gestational age (OR=2.636),birth weight(OR=2.755),antenatal steroids(OR=0.311),fetal distress(OR=12),oxygen inhalation(OR=0.431),birth asphyxia(OR= 3.692),respiratory failure(OR=3.038),hyaline membrane disease(OR=7.085),septicemia(OR=2.282),fluid intake(OR=1.026) and echocardiography detection time(OR=0.474).The logistic regression analysis showed small gestational age(OR=2.517),low birth weight(OR=2.957),birth asphyxia(OR=13.770),and septicemia(OR=3.493)were main risk factors for PDA in preterm infants, while antenatal steroids(OR=0.208) and oxygen inhalation(OR=0.127) were protective factors.The next study showed there were no significant differences between the PDA and control groups in demographic characteristics and influence factors for serum cortisol.The first mean levels of serum cortisol in PDA group was 9.49±8.32μg/dl,which was significantly lower than control group(13.76±8.56μg/dl)(P=0.031).The logistic regression analysisshowed low serum cortisol concentrations at birth was risk factor for PDA in preterm infants(OR=0.916).The second adjusted mean levels and 95% confidence interval of serum cortisol in PDA and control group were 10.87μg/dl(8.42～13.31μg/dl),9.55μg/dl(7.11～2.0μg/dl),respectively.There was no significant difference between two groups(P=0.466).Conclusion Multiple factors contribute to PDA during perinatal period.Small gestational age,low birth weight, birth asphyxia,septicemia and low serum cortisol concentrations at birth are main risk factors for PDA in preterm infants, while antenatal steroids and oxygen inhalation are protective factors.The serum cortisol value may not affected by PDA.It is an effective way to reduce incidence of PDA in preterm infants that all measures for perinatal health care should be relevant to its risk factors.