Bronchopulmonary dysplasia in ventilated neonates :incidence and risk factors

ABSTRACT

Bronchopulmonary dysplasia occurs in neonates who need supplemental oxygen at 36 weeks gestational age and those born at >/= 32 weeks gestation who need additional oxygen after 28 postnatal days. Mechanical ventilation is an invasive life support procedure that may cause lung injury through a combination of oxygen toxicity, barotrauma, and volutrauma. Alveolar development is interrupted and parenchyma destroyed leading to emphysematous changes, decreased lung compliance, and impaired gas exchange. There is a positive correlation between ventilator settings, duration of assisted ventilation and development of BPD. The aim of the study was evaluation of the incidence of bronchopulmonary dysplasia among ventilated neonates and determination of associated risk factors. A retrospective study conducted in the Neonatal Intensive Care Unit Cairo University over the period from January 2007 to December 2008. It included 633 ventilated neonates out of 3321 total admissions [19.06%]. All data were collected from patient's records. Patients were diagnosed to have bronchopulmonary dysplasia if they needed supplemental oxygen at 36 weeks gestational age or those born at >/= 32 weeks gestation who need additional oxygen after 28 postnatal days. Patients were classified to 2 groups BPD group and non BPD group. Bronchopulmonary dysplasia [BPD] developed in 221633 ventilated neonates [3.48%]. Twenty of them had gestational age between [28 - 32] weeks [90.90%],14/22 were males [63.63%], 13/22 were delivered by CS [59.09%], BPD developed in 18/290 [6.2%] neonates ventilated by SIMV from start, 3/178 ventilated by NCPAP followed by SIMV [1.7%], 1/165 ventilated by NCPAP only [0.61%], with P-value 0.002 [significant]. Eleven neonates out of 22 BPD cases [50%] were discharged. Twenty one out of 285 neonates diagnosed as respiratory distress syndrome [7.4%] developed BPD. In BPD group, Mean Fraction of inspired oxygen was 60.68 +/- 16.90, compared to 33.24 +/- 21.57 in non BPD group P value < 0.001 Highly Significant [HS]. Mean PIP in BPD group was 21.94 +/- 4.22 and 21.32 +/- 5.26 non BPD group, P Value 0.63. Mean PEEP was3.94 +/- 0.24 in BPD group and3.79 +/- 0.45 in non BPD group, P value 0.17. Mean Rate was 39.29 +/- 8.27 in BPD group compared to 36.23 +/- 12.10 in non BPD group, P value 0.32. Mean Flow was 7.83 +/- 0.71 in BPD group and 7.66 +/- 0.57 in non BPD group, P Value 0.25. Mean I/E Ratio was 0.40 +/- 0.02 in BPD group and 0.38 +/- 0.03 in non BPD group, P value 0.04 [significant]. Mean birth weight in BPD group was 1.22 +/- 0.21 compared to 2.27 +/- 0.80 in non BPD group, P value <0.001 [H.S.]. Mean duration of ventilation was 35.77 +/- 4.07 days in BPD group compared to 6.36 +/- 4.07days in non BPD group, P value<0.001 [H.S]. Mean length of hospital stay was 39.36 +/- 4.58 days in BPD group compared to 8.12 +/- 5.68 days in non BPD group, P value <0.001. In conclusion; The use of NCPAP is associated with a lower incidence of BPD compared to SIMV. The least required oxygen should be delivered to minimize oxygen toxicity and reduce the incidence of chronic lung disease