ORIGINAL ARTICLE Lung protective ventilatory strategies in very low birth weight infants R Ramanathan and S Sardesai Division of Neonatal Medicine, Department of Pediatrics, Women’s and Children’s Hospital and Childrens Hospital Los Angeles, Keck School of Medicine University of Southern California, Los Angeles, CA, USA Respiratory distress syndrome (RDS) is the most common respiratory diagnosis in preterm infants. Surfactant therapy and mechanical ventilation using conventional or high-frequency ventilation have been the standard of care in the management of RDS. Bronchopulmonary dysplasia (BPD) continues to remain as a major morbidity in very low birth weight infants despite these treatments. There is no significant difference in pulmonary outcome when an optimal lung volume strategy is used with conventional or high-frequency ventilation. Lung injury is directly related to the duration of invasive ventilation via the endotracheal tube. Studies using noninvasive ventilation, such as nasal continuous positive airway pressure and noninvasive positive pressure ventilation, have shown to decrease postextubation failures as well as a trend toward reduced risk of BPD. Lung protective ventilatory strategy may involve noninvasive ventilation as a primary therapy or following surfactant administration in very preterm infants with RDS. Initial steps in the management of preterm infants may also include sustained inflation to establish functional residual capacity, followed by noninvasive ventilation to minimize lung injury and subsequent development of BPD. Journal of Perinatology (2008) 28, S41–S46; doi:10.1038/jp.2008.49 Keywords: respiratory distress syndrome; surfactant; non-invasive ventilation; high frequency ventilation; bronchopulmonary dysplasia; nasal continuous positive airway pressure Introduction Bronchopulmonary dysplasia (BPD) continues to be a major morbidity among preterm infants treated for respiratory distress syndrome (RDS). Application of positive pressure ventilation via the endotracheal tube (ET) and the duration of mechanical ventilation have a direct effect on the incidence of BPD. However, the incidence of BPD varies among different centers. One reason for this variation is the lack of a standard definition for BPD. To standardize BPD incidence, Walsh et al. 1 proposed the term ‘physiological BPD’, based on a timed room-air challenge at 36 ± 1 weeks postmenstrual age in preterm infants. Preterm infants on mechanical ventilation or requiring >30% oxygen to maintain oxygen saturation between 90 and 96% were considered to have ‘physiological BPD’. Infants receiving p30% oxygen or effective oxygen >30% with saturations >96% were given room-air challenge for 30 min. Infants in whom saturations decreased to <90% were considered to have ‘physiological BPD’. However, differences in BPD incidence remain, even with the use of this standardized definition of BPD. BPD is a multifactorial disease. Mechanical ventilation via the ET is a major contributing factor for BPD. Significant improvements have been made in the use of ventilatory strategies in very low birth weight (VLBW) infants. Both tidal ventilation using conventional mechanical ventilators and nontidal ventilation using high-frequency ventilators have been extensively studied. High-frequency ventilators deliver smaller tidal volumes at supraphysiological rates. Nontidal ventilation using high-frequency oscillatory ventilation (HFOV), high-frequency flow interruption (HIFI) and high-frequency jet ventilation (HFJV) have all been studied in the management of RDS before and after surfactant therapy became available and in comparison with intermittent mandatory ventilation (IMV) as well as synchronized IMV (SIMV). 2 Among the six trials 3–8 published during the presurfactant era, Clark et al. 6 reported a decrease in BPD with HFOV when compared to IMV (Table 1). However, the incidence of severe intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL) was significantly higher in one of the HIFI trials published in 1989. 3 Three trials 9–11 were conducted after surfactants became available for treatment of RDS (Table 1). Two of these studies 9,10 reported lower BPD incidence among infants randomized to high-frequency ventilation (HFV) when compared to IMV, while Wiswell et al. 11 had to stop their study because of increase in IVH or PVL among infants randomized to HFJV. Among the eight HFV trials 12–19 published between 1998 and 2003, when Correspondence: Professor R Ramanathan, Division of Neonatal Medicine, Department of Pediatrics, Women’s and Children’s Hospital and Childrens Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, 1240, N. Mission Rd, Room L-919, CA, USA. E-mail: ramanath@usc.edu Journal of Perinatology (2008) 28, S41–S46 r 2008 Nature Publishing Group All rights reserved. 0743-8346/08 $30 www.nature.com/jp