Altered anatomy and physiology of the neonate

The birth of a neonate initiates the transition period between intrauterine to extra-uterine life. This can be a complex process involving major organ and metabolic changes such as the change from foetal to newborn circulation and alteration to the haemodynamics of the cardiovascular system as well as the hepatic, renal and endocrine functions (see Chapter 1). The neonate must assume the role of the ‘producer’ from being a ‘consumer’ and take on the functions of the placenta in terms of oxygen transport through the establishment of breathing as well as maintaining glucose and thermal homeostasis. Gestation and other external factors such as the mode of delivery, use of analgesics or anaesthetics, timing of cord clamping, and availability of oxygen, glucose and warmth can have an impact on this process of transition. The successful adaptation from foetal to neonatal life has a large influence on well-being at birth. Any problems encountered at birth or even as late as 24–48 hours post birth due to failure of normal adaptive processes (Hillman et al, 2012; Michel and Lowe, 2017) may lead to problems that require hospital admission. This chapter provides an insight into what happens when normal adaptation at birth is compromised (Figure 7.1) and common conditions presenting in a neonatal unit using a multisystem approach (Table 7.1). Prematurity and respiratory distress syndrome are two commonly seen situations, the focus of Table 7.2 and Figure 7.2, respectively, as examples of specific pathophysiology and related care.