During the period studied, the data showed a trend toward a decrease in the death rate of ELBW infants, although this trend was not significant. Mild forms of BPD affected approximately 30% of the preterm infants during the study, whereas the incidence of severe forms of BPD declined, and the BPD-free survival rate increased from 58% (1997–2000) to 75% (2001–2009).
Chorioamnionitis and patent ductus arteriosus have been diagnosed more frequently in recent years. This increase in diagnosis may be due to an improvement in the accuracy of amniotic liquid analysis or heart ultrasound techniques, respectively. Extubation was performed earlier in recent years than it had been in the past, and PDA was more frequent. However, this was not followed by an increase in the diagnosis of BPD throughout the study period; in fact, the opposite trend was observed.
A change in the delivery room respiratory resuscitation strategy was introduced in 2001. With the increased use of CPAP since 2001, the need for endotracheal intubation and ventilation in the delivery room has diminished. The duration of mechanical ventilation has also decreased. The use of mechanical ventilation in premature infants may result in barotrauma, volutrauma and BPD
. Early surfactant therapy and the initiation of nasal CPAP in these infants significantly reduce the need for mechanical ventilation and the incidence of BPD
. In the COIN study
, which included data from centers with a relatively recent history of using CPAP, a trend toward a lower rate of BPD was found in the CPAP group compared with the MV group. Many observational studies that compared primary CPAP and MV support found a decreased risk of developing BPD when CPAP was used as the primary means of ventilator support
[14, 15]. Together, these studies support a strong correlation between the use of MV and the development of BPD. The use of nasal CPAP appears to be a successful strategy for avoiding the need for mechanical ventilation in some infants, with the presumptive benefit of decreasing the risk of BPD
. The Columbian approach of using nasal CPAP in the delivery room in premature infants has resulted in a significant reduction in BPD. The recommended approach for ELBW infants with respiratory distress is to start CPAP in the delivery room immediately after stabilization, with intubation performed only for surfactant administration. In addition, adjustment of the supplemental oxygen intake is recommended to maintain pulse oximetry saturations between 85% and 93% in infants with a gestational age of less than 32 weeks
[17–20]. In the SUPPORT trial, which involved ELBW infants, there was no significant difference between a strategy involving early CPAP and limited ventilation compared to one involving early intubation and surfactant administration within one hour after birth with respect to the rate of the composite primary outcome of death or BPD
[21, 22]. In secondary analyses, the CPAP strategy resulted in a lower rate of intubation than early surfactant treatment, both in the delivery room and in the NICU, which is similar to our findings. These data support the consideration of CPAP as an alternative to routine intubation and surfactant administration in preterm infants
Other strategies that may be effective in reducing lung injury and subsequent BPD include the prevention of infection, early implementation of aggressive nutrition and treatment of a patent ductus arteriosus
. We began a policy of aggressive nutrition in 2001, with a significant decrease in the duration of parenteral nutrition and an increase in the amount of mother’s milk administered. These facts could have influenced the reduction of BPD incidence and length of stay with low weight at discharge, although the higher weight gain observed throughout the hospital stay did not represent a significant difference with low weight gain. However, Wilson
 reported that sick VLBW infants allocated to an aggressive nutritional regimen exhibited better growth but similar survival and a similar incidence of BPD compared with a control group.
In 2006, we initiated a new mode of ventilation, namely, volume-guarantee (VG) ventilation, which reduces large tidal volumes, decreases the incidence of inadvertent hyperventilation, reduces the duration of mechanical ventilation and pneumothorax
, and reduces proinflammatory cytokine levels
. Furthermore, VG decreases the expression of early inflammatory markers to a greater extent than high-frequency oscillatory ventilation
. Therefore, VG may decrease the incidence of BPD; however, in our study, there was no reduction in the BPD rate after 2006, although the duration of mechanical ventilation remained low.
Cesarean section was associated with elective preterm delivery, and vaginal delivery was associated with emergency deliveries and chorioamnionitis. For this reason, preterms born by cesarean section have better prognoses and typically do not require aggressive prenatal support
This study has some limitations. The data were collected from a database but were introduced prospectively during the study period. The most important changes during this period were the introduction of respiratory assistance in the delivery room, the initiation of a protocol of aggressive nutrition and the practice of VG ventilation. However, other changes could have influenced the neonatal prognosis. The strength of the study was the use of a large number of ELBW infants (415) who were born at the same hospital, thus yielding similar baseline characteristics.