Impacto da corioamnionite na displasia broncopulmonar em recém nascidos prematuros de muito baixo peso

Abstract

The quality of pre and postnatal care and the structure of Neonatal Intensive Care Units have allowed the survival of increasingly premature infants, but have also increased morbidities such as bronchopulmonary dysplasia (BPD). Strong recent evidence has associated chorioamnionitis (CA) and systemic response with an imbalance between proinflammatory and antiinflammatory factors in the pathogenesis of this multifactorial disease. Understanding this process is vital for the development of appropriate strategies in preventing preterm delivery (PTD) and providing better neonatal care. The present prospective study aimed at assessing the incidence of BPD in very low birth weight infants (VLBW) and the impact of histologic CA in their development. Out of the initial 225 neonates and their mothers, 216 were studied after consent, and were analyzed data on prenatal care, characteristics of the neonate, resuscitation in delivery room, neonatalventilation, hemodynamic and nutritional support, placental histology, andcytokines in the cord blood. The maternal conditions most associated to PTD were PT labor (43.1%), preeclampsia (39.4%), intrauterine growth restriction (30.1%), and urinary tract infection (23.1%). Antenatal steroids (ANS) and antibiotics (AB) were used in 72% and 42.7%, respectively. Out of the 216 neonates, most (61.6%) were less than 30 weeks of age, 53.7% were females, 37% were small for gestational age (SGA). Tracheal intubation (31.6%) was preferred over bag and mask ventilation (23.7%), and mechanical ventilation (MV) was used in 78.2%, for an average of 12.7 days. Surfactant was used in 64.4%. Mortality rate was 19.9%, and in neonates weighing under 1,000g, 38.6%. Early sepsis (EOS) (positive hemoculture) occurred in 3.7% and late sepsis (LOS) in 31.5%. Moderate and severe BPD occurred in 26.0% of cases. In the univariate analysis, BPD was associated with gestational age (GA) (p<0.001), birth weight (p<0.001), CA (p=0.005), LOS (p<0.001), EOS (p=0.020), days on MV and days in oxygen therapy (both p<0.001), surfactant (p<0.001), start of enteral feeding, days of parenteral nutrition (PN) and days to reach full enteral nutrition (EN) (all p<0.001). Incidence of histologic CA was 18.5% and 32.1% among those aged less than 28weeks. CA was associated with antenatal AB (p<0.001), PT labor (p<0.001), GA, EOS (p=0.035), high levels of proinflammatory cytokines (all p<0.05), leukocytosis (p=0.019) and high band neutrophils (p<0.001). In the logistic regression model for BPD outcome, besides GA and oxygen therapy, the following variables remained significant: CA (p=0.020), LOS (p=0.002), days on PN (p=0.005) and late surfactant (p=0.030). The results reinforce the role of prematurity, oxidative injuryand inflammation (CA and sepsis) in the pathogenesis of BPD, and indicates the need for better nutritional practices, as well as better care for early respiratory impairment and ventilation support, with possible influence in the prevention of BPD.