For humans, the most profound pulmonary adaptation occurs at birth. This process includes

Inflation of the lung with air, the release of surfactant, the establishment of functional residual capacity, the reabsorption of lung liquid, increase.s in pulmonary blood flow and establishment of a regular respiratory pattern are necessary for successful postnatal adaptation.1

Understanding this adaptive process and complications that ensue secondary to illness, delayed transition, pulmonary hypertension, or prematurity offers a glimpse of the varied respiratory issues discussed in this special series of Advances of Neonatal Care.

Amazing strides have been made over the past several decades with regard to both understanding and treatment of neonatal respiratory complications. Respiratory distress syndrome (RDS) continues to be the leading cause of admissions to the neonatal intensive care unit (NICU). It is estimated that 29% of late preterm and nearly 100% of extremely low birth-weight infants suffer from complications related to RDS.2

Respiratory distress is a global term that is used to describe any neonatal condition that leads to a progressive state of hypoventilation and/or hypoxia.3 This condition typically presents with one or more physical symptoms that include tachypnea, grunting, retractions, nasal flaring, and cyanosis.4 Respiratory distress syndrome is a specific term that refers to a surfactant deficient state that is most commonly linked to prematurity. Term infants who suffer from RDS classically have surfactant inactivation typically linked to maternal diabetes, neonatal infection, asphyxia, or meconium aspiration.

As neonatal care providers, we have long understood the relationship between acute care treatment of neonatal pulmonary compromise and bronchopulmonary pulmonary dysplasia (BPD). Bronchopulmonary pulmonary dysplasia also known as "chronic lung disease" remains a major morbidity among the extremely low birth-weight infants. Although BPD is clearly multifactorial, recent and compelling evidence points to a clear relationship between BPD and negative short- and/or long-term pulmonary and nonpulmonary outcomes.5 Increases of the neonatal inflammatory response have been measured in neonates who have received positive pressure ventilation in the delivery room for less than 5 minutes, and progressive, sustained inflammation secondary to mechanical ventilation has been correlated with negative outcomes including neurodevelopmental compromise.6

Understanding pulmonary mechanics and the basic concepts that guide mechanical ventilation will provide the neonatal care provider the tools to support invasive strategies when needed. Conventional and high-frequency ventilators with various modes remain essential in the treatment of respiratory compromise and failure. Recent evidence supports newer methods of noninvasive respiratory management of the neonate. These protective ventilatory strategies include noninvasive modalities supporting gentle ventilation while managing the symptoms of RDS. Modalities include noninvasive positive pressure ventilation, continuous positive airway pressure, neutrally adjusted ventilatory assist, and specialized nasal cannulas to best support the functional residual capacity and reduce barotrauma, volutrauma, and ventilation-induced lung injury.7 These methods often utilized as the primary mode of ventilation or used to support ventilation following surfactant administration have demonstrated improved outcomes in the preterm infant.4 Research is still needed to explore and refine current noninvasive practices and weaning recommendations.

Additional exploration will likely provide a better understanding of the relationships between respiratory issues and prenatal, antenatal, and postnatal events. For example, we are just beginning to understand the importance of the neonatal microbiome.8 The relationship between method of birth (vaginal or cesarean delivery), maternal and/or neonatal antibiotic history, and the departure of the neonate from mother to the NICU environment has been shown to alter the infant's microbiome.9 These alterations may influence the development of the neonate's immune system altering the systemic inflammatory response. We understand from previous research the negative implications that widespread inflammation may have on neonatal neurologic, gastrointestinal, and pulmonary system.10 Through increasing research surrounding the microbiome, we hope to unravel the implications and develop strategies to improve health.

This conversation ties directly into the support for use of human milk, which clearly has global impact on the neonate's immune system. Protection from oral care utilizing human milk has been associated with a reduction in ventilator-associated pneumonia and needs to be a routine practice in the NICU.11 This exciting area of research has implications for both the pulmonary and gastrointestinal systems.

Genomic sequencing describes an organism's complete DNA, which has been used to identify certain genetic variations and mutations that may play a role in susceptibility to disease state. Currently, a small study has been conducted examining relationships between RDS and certain gene types. Pulmonary surfactant has been shown to be more or less effective in those neonates with certain genotypes.12 Although early, the implication for this research on neonatal pulmonary implications may be promising.

In this and the next issue, we have highlighted various pulmonary conditions of the neonate, examining specific treatment modalities supported by current scientific evidence. This collection of 4 articles focuses on various aspects of respiratory issues of the neonate, keeping in mind the mantra "Breath is life and nowhere is that more true than in the NICU.

The article, "Bronchopulmonary dysplasia (BPD) beyond the neonatal unit" published by Jayesh Bhatt, MD, and his colleagues, provides an overview of the specialized care of the patient with BPD. This manuscript provides the reader with evidence that supports pathophysiological understanding of BPD as well as the long-term treatment of this complicated disease. Dr Bhatt highlights the importance of nutrition, medications, and pulmonary testing useful in the management of these children.

The contribution submitted by Jan Hau Lee and colleagues pertains to neurodevelopment outcomes following neonatal extracorporeal membrane oxygenation (ECMO). This informative manuscript provides insight to the nursing care during ECMO, strategies during and following ECMO to ensure best practices. Long-term following up requirements are highlighted. The contribution submitted by Dr Flanagan describes various methods of noninvasive respiratory modalities and strategies to best support infants receiving this type of respiratory support.

Finally, Lozano and Newnam present a comprehensive overview regarding the mechanical ventilation strategies volume targeted versus pressure-limited. This manuscript provides the reader with a basic explanation of pulmonary dynamics and compares these different methods of ventilation to provide clinicians a better understanding of these modalities, highlighting key considerations during therapy. Evidence supporting recommendations for these mechanical ventilation modalities is provided for preterm and term neonates.

Through the exploration and understanding of emerging scientific knowledge related to respiratory complications and treatment modalities, we will be uniquely prepared to provide the most appropriate intervention and improve short- and long-term neonatal outcomes. I would like to thank the coeditors of Advances in Neonatal Care for dedicating this special series to the topic of neonatal respiratory care. I hope that the readership find this small collection of 4 articles interesting, educational, and relevant to the care that you provide to NICU infants and their families.

References