Pediatric Respiratory Physiology

Abstract

This chapter provides information about structural and biochemical lung development, which starts as early as the fifth week of gestational age but can last up to 4 years postnatally. During the intrauterine period, fetal breathing movements and lung fluid are essential factors for regular lung maturation and growth. Transition from intrauterine to extrauterine life is a critical phase, during which clearance of lung fluid and lung expansion due to air filling on the one hand and establishment of pulmonary blood flow due to a marked reduction of pulmonary vascular resistance on the other hand are the key features of this process. In contrast to older infants and adults, respiratory physiology of neonates is characterized by a relatively small airway diameter enhancing airway resistance, a higher chest wall compliance, and weakness of respiratory muscles, making the newborn much more vulnerable to respiratory failure. Dysfunctional transition may result in respiratory distress and persistent pulmonary hypertension, both of them still being important causes of morbidity and mortality. Their present-day management includes prenatal steroid treatment, intratracheal surfactant application, mechanical ventilation, and a differentiated medical therapy.