ABSTRACT
This chapter focuses on the physiological features of the surgical neonate in the postoperative period. Neonates have little functional respiratory reserve, which means they have a limited capacity to compensate for changes in respiratory demand. Respiratory muscle fatigue occurs rapidly, due to reduced lung compliance, relative immaturity of the bronchioles and alveoli, and a compliant chest wall. Synchronized patient-triggered ventilation reduces the requirement for sedation and neuromuscular medications as the infant coordinates his/her breathing with pressure assist. The chapter discusses some relevant features of high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV). Neonates may present shortly after delivery with hypoxic respiratory failure. Cardiac causes must be excluded quickly. The most common cause is persistent pulmonary hypertension of the newborn (PPHN). PHN may develop rapidly if the reactive pulmonary vascular bed is exposed to acidosis or hypoxia. Vasoactive medications produce vasodilation or vasoconstriction. Some medications also produce an increase in contractility due to direct action on the cardiac myocyte.
