Clinical Analysis Of Neonatal Respiratory Distress Syndrome Among Different Gestational Ages And Different Grades

Background and purposeWith the rapid development of perinatal medicine, the neonatal survival rate has been significantly improved. However, more and more clinical studies have demonstrated that the prevalence of premature infants and neonatal respiratory distress syndrome (RDS) was also increasing year by year. The ratio of RDS was especially high in term or near term infants, which has been reported to be closely connected with cesarean section. Lacking sufficient pulmonary surfactant (PS) because of immature lung is the main reason for RDS in preterm infants, whereas deficiency of PS caused by various factors is intimately related to the RDS in term or near term infants, whose lung is almost mature. Despite of different risk factors, clinical manifestations and treatment between preterm infants RDS and term/near term infants RDS, systemic comparison was rarely reported. Moreover, since different risk factors will lead to different clinic presentation in preterm infants RDS, it is necessary to elucidate the relationship between them.This study was designed to compare cases according to different gestational ages and different grades so as to achieve these objectives:1) To provide a new basis for clinical theraphy through investigate the different clinical characteristics and incidence of early preterm infants, late preterm infants and full term infants with RDS; 2) To understand the relevance between different risk factors and serious degree of RDS by comparing the perinatal conditions of different classifications of preterm RDS infants to provides the basis for assessing the curative effect and prognosis.Materials and methods1 Objects and groupingA total of 963 RDS infants were recruited from the neonatal intensive care unit of the Third Affiliated Hospital of Zhengzhou University between January,2006 and December,2010. Cases were divided into three groups:early preterm infants group (gestational age<34 weeks,679 cases), late preterm infants group (gestational age 34-<37 weeks,204 cases), and full-term infants group (gestational age$=37 weeks, 80 cases). Among these cases,667 subjects had chest x-ray radiograph within 24 hours after birth, and the degree of RDS were classified into 4 groups according to the chest X-ray:RDS grade 1 (217cases), RDS grade 2 (225cases), RDS grade 3 (126cases), RDS grade 4 (99 cases).2 MethodsAll of the 963 RDS cases with different gestational ages were analyzed by the following aspects:(1) incidence:the percentage of RDS cases in all NICU patients, the constituent ratio of RDS infants with different gestational age in each year; (2)general situation:including gender, Apgar score, and the condition of using corticosteroids before delivery; (3) risk factors:elective cesarean section, intrauterine distress, birth asphyxia, premature rupture of membranes, abnormal of placenta, diseases of mother in pregnancy; (4) treatment:the time window of diagnosing RDS, duration and frequency of using pulmonary surfactant, situation of using CPAP and mechanical ventilation; (5) prognosis and complications:including treatment outcome and pulmonary infection, sepsis, pneumothorax, pulmonary edema, and bronchial lung dysplasia.667 preterm with different RDS grades were analyzed by the following three aspects:(1) the Prenatal situation:mother’s age, conception type, pregnancy-induced hypertension syndrome, premature rupture of membranes, abruptio placentae, condition of using corticosteroids before delivery, delivery mode; (2) the general situation:gestational age, birth weight, sex, whether twins or the small one, perinatal asphyxia; (3) the prognosis analysis:use PS, therapeutic outcome, coincide infection, etc.3 Statistics analysisAll statistical data were analyzed by SPSS 17.0 software, quantitative data were presented as mean±standard deviation (x±s). One-way analysis of variance was used to compare the means during groups and LSD-t test was used between groups. Qualitative data were presented as rate(%) and compared with Chi-square test. P< 0.05 was considered as statistically significant.Results1 Comparisons among groups of different gestational ageRDS mainly occurred in the preterm infants. There was an increasing tendency regarding the proportion of RDS infants in all hospital patients during the recent five years, and the percentage was 3.7%,7.0%,9.2%,12.0%, and 14.3% respectively. The prevalence of RDS in late preterm infants and term infants was increasing with statistically significant. The proportion of RDS in male was higher than that in females, especially when the gestational ages and weight are greater. The risk factors of preterm RDS were closely relevant to the rupture of membranes, placental abnormality, women with pregnancy-induced hypertension and so on, while the full-term newborns with RDS were mainly related to selective cesarean section. The diagnosis of the full-term RDS was later than that of the preterm RDS. The treatment with mechanical ventilation and the clinical cure rate in full-term RDS infants was significantly higher than that in the preterm infants, but with more pneumothorax occured. Early preterm infants with RDS had a higher proportion of pulmonary hemorrhage and abandonment rate. No significant differences were found in other complications and mortality between groups.2 Comparisons among groups of different gradesThere were no significant differences in the maternal age, the percentage of using antenatal corticosteroids, premature rupture of membranes, placental abruption, the delivery mode, male, and twins among preterm RDS infants with different chest X-ray radiograph grades. However, the higher the grades were, the smaller the gestational age and the birth weight was. The percentage of the infants with Apgar score less than 7 and maternal pregnancy-induced hypertension increased as the severity of grade increased. In addition, the cure rate decreased with more death and infection, the percentage of using PS increased, and the hospitalization time increased when the grades increased.Conclusions1 Neonatal RDS predominantly occurred in the preterm infants and the proportion of RDS in hospital patients was increasing year by year. There was an increasing tendency of prevalence of RDS in late preterm infants and term infants.2 Due to the fact that the risk factors, the clinical presentations, the treatment and the complications are different among the early preterm RDS, late preterm RDS infants and term RDS, gestational ages should be considered when making diagnosis and providing treatment for RDS.3 The full-term RDS characterized by relatively late onset and complication of pneumothorax has a close relation to selective cesarean section and infection, which should be paid more attention in the future.4 The grades of infants RDS is mainly related to gestational age, birth weight and high risk factor like perinatal asphyxia during the perinatal period. The higher the grade is, the worse the treatment effect and prognosis will be.