[Frequency, severity and risk factors for bronchopulmonary dysplasia among very low birth weight premature infants admitted in the NICU of the University Obstetrics and Gynecology Hospital, Sofia].

BACKGROUND: The progress in the perinatology improved the survival rate of the infants with extremely low birth weight and gestational age. Among the most immature of them the frequency of bronchopulmonary dysplasia (BPD) remains high.. The use of different diagnostic criteria for BPD makes comparing the results difficult.

AIM: To evaluate the frequency of BPD by birth weight and gestational age according to the new diagnostic criteria, and to identify the risk factors for development the disease.

METHODS: 563 very low birth weight infants (<1500 g) were admitted to NICU from 01.01.2008 to 30.06.2010. 485 survived more than 28 days and were included in this study. BPD was diagnosed if supplemental 02 for the first 28 days was necessary. 02-requirements at 36 gestational weeks (gw) determine the severity level.

RESULTS: 26,8% from the infants were with supplemental 02 in the first 28 d of life, but only the half of them 13,6% were with 02 > 21% at 36 gw (the classical diagnostic criteria for BPD). 10,9% were with moderate BPD, 2,7% - with severe BPD. The frequency of BPD decreased progressively from almost 100% at 23 gw or birth weight < 600 g to single cases after the 31 gw and birth weight > 1200 g. Mild or moderate BPD was more likely if gestational age was > 27 gw. The need for ventilatory support increased from 1,5 (+2,8) days (no-BPD group) to 50,2 (+/-20,1) days (severe BPD), p<0.05. Significant postnatal risk factors for developing BPD were patent ductus arteriosus - diagnosed in 25,4%; pneumothorax - in 3% of the BPD infants, compared with 1,7% and 0,5% among the infants without BPD respectively, p<0. 05. Sepsis and pulmonary hemorrhage were found slightly more frequently in the BPD group too (p>0, 05). The use of antenatal steroids was found to be a protective factor - 45% of the BPD infants had received antenatal steroids compared with 55% of those without BPD (p=0.05).

CONCLUSION: According to the new diagnostic criteria, the frequency of BPD was about 2 times higher compared to the classical definition. Main risk factors were found to be ELBW, ELGA; additional risk carried the need for prolonged ventilatory support, patent ductus arteriosus and air leak syndrome.