Introduction
Modern neonatal paediatrics started in the 1970s with the introduction of assisted ventilation. Before that time, respiratory distress syndrome, also known as hyaline membrane disease, was the commonest cause of death in preterm infants. Respiratory distress syndrome is caused by a lack of pulmonary surfactant to reduce surface tension at the air–liquid interface in the lung. Fetal surfactant production increases at 34–35 weeks' gestation, and surfactant deficiency is rare in infants born after that time.
Preterm infants born with insufficient pulmonary surfactant have respiratory distress that manifests clinically by laboured, rapid breathing, grunting, and central cyanosis. Respiratory distress typically becomes more severe during the first few days after birth as the airways progressively collapse because of increased surface tension. If infants survive the first few days, the lungs start to produce surfactant; the respiratory distress stabilises and then abates as the lungs reinflate. Before the 1970s, effective treatment for respiratory distress syndrome was limited to supplemental oxygen therapy.
The first attempts to mechanically assist breathing in these infants were often a desperate final attempt to avoid death and relied on the use of adult ventilators, but these early attempts were not very successful. Not until infant ventilators were developed and assistance could be provided earlier in the course of the disease did survival rates increase. Survival chances in infants weighing less than 1000 g at birth increased from less than 10% in the late 1960s (before assisted ventilation)1 to about 35% by the mid-1970s, when ventilation was widespread.1 However, morbidities improved at a slow pace; many extremely preterm infants who survive have neurodevelopmental disabilities or develop bronchopulmonary dysplasia—the so-called chronic lung disease of prematurity.
Other advances that improved survival of preterm infants included use of antenatal corticosteroids, first reported in 19722 and more widely used from the late-1970s onwards, and exogenous surfactant, which became available from the early 1990s. Another important advance leading to improved survival was a change in attitude, such that more of the most immature infants were offered active medical care.3
In this Series paper, we examine landmark developments in neonatal respiratory care. We describe the history of preterm respiratory support, the move towards gentler, non-invasive support, and the long-term effects of respiratory support given following preterm birth. We assess the lessons learned and areas for future research, focusing in particular on neonatal respiratory care provided in high-income countries.
Key messages
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Oxygen is vital to life, but how much oxygen to give and how to accurately monitor oxygen saturation in preterm infants is controversial
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Exogenous surfactant improves survival and morbidity in preterm infants, but more research on when and how it is administered is needed
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Neonatal respiratory care is rapidly evolving; clinicians are moving away from routine intubation and ventilation and developing new modes of non-invasive support
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Postnatal corticosteroids have a limited role in infants with evolving bronchopulmonary dysplasia
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Despite many advances in neonatal intensive care, including widespread use of antenatal corticosteroids, exogenous surfactant, and gentler techniques for assisted ventilation, bronchopulmonary dysplasia remains a major problem in neonatal care