Lung-protective ventilatory strategies in intubated preterm neonates with RDS

Summary

This article provides a narrative review of lung-protective ventilatory strategies (LPVS) in intubated preterm infants with RDS. A description of strategies is followed by results on short-and long-term respiratory and neurodevelopmental outcomes. Strategies will include patient-triggered or synchronized ventilation, volume targeted ventilation, the technique of intubation, surfactant administration and rapid extubation to NCPAP (INSURE), the open lung concept, strategies of high-frequency ventilation, and permissive hypercapnia. Based on this review single recommendations on optimal LPVS cannot be made. Combinations of several strategies, individually applied, most probably minimize or avoid potential serious respiratory and cerebral complications like bronchopulmonary dysplasia and cerebral palsy.

Introduction

There is an increasing interest for avoiding endotracheal intubation by increased use of non-invasive ventilation (NIV) [1], [2], [3], [4], including nasal continuous positive airway pressure (NCPAP), nasal intermittent positive airway pressure (NIPPV), nasal high frequency ventilation (nHFO), and high flow nasal cannula (HFNC) for respiratory support in preterm infants. Nevertheless, endotracheal intubation and mechanical ventilation (MV) is a lifesaving therapy and is commonly required, either in the delivery room (DR) or neonatal intensive care unit (NICU). Failure of NIV may be as high as 60%, depending on gestational age, birth weight, disease severity, mode of NIV and other perinatal variables [5], [6]. However, early and even short MV with high intrathoracic airway pressures and tidal volumes (TV) may cause injury to the lungs and other organs like the brain due to hemodynamic disturbances and/or inflammatory mediator-induced systemic responses [7], [8]. Acute and chronic pulmonary ventilator- induced/or associated lung injury (VILI) are pulmonary air leaks such as pneumothorax or pulmonary interstitial emphysema (PIE) and bronchopulmonary dysplasia (BPD), a form of chronic lung disease (CLD). BPD, regardless of diagnostic criteria [either continued oxygen requirement at 28 days of life or at 36 weeks postmenstrual age (BPD 36wks)], is the most common short-term adverse outcome in very preterm infants and may be associated with impairments in respiratory and neurological long-term outcomes [9], [10], [11], [12]. Although the “classical, old” picture of BPD changed in the last decade [9], with the increased survival of infants with extremely low gestational age (< 28 weeks) and birth weight (< 1000 g, ELBWI) the overall BPD incidence has not changed and continues to be a challenging problem in neonatology [1]. Therefore, various lung-protective ventilatory strategies (LPVS) were introduced to minimize lung injury associated with MV. These are the different modes of patient triggered or synchronized ventilation (PTV, High Frequency Positive Pressure Ventilation with short inspiratory times and ventilator rates > 60/min (HFPPV)), volume targeted ventilation (VTV), INSURE strategy (INtube, SURfactant- Extubate to NCPAP), High Frequency Ventilation (HFV) (including High Frequency Oscillatory Ventilation (HFOV) and High Frequency Jet Ventilation (HFJV) and permissive hypercapnia (PH). Furthermore, one may add lung recruitment with the “open lung” concept, and the manual or automatic control of oxygen to facilitate appropriate targeting of peripheral oxygen saturation (SpO₂). The main goals of LPVS are avoidance of volutrauma, atelectotrauma, and oxygen toxicity. The aim of this narrative review article is to provide an update of LPVS during MV including the evaluation of long-term effects on pulmonary and neurodevelopmental outcomes in preterm infants with respiratory distress syndrome (RDS). For SpO₂ monitoring and the option of automated oxygen control we refer to other recently published articles in the literature [13], [14], [15], [16], [17].