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Neonatal Necrotizing Enterocolitis

Summary Necrotizing enterocolitis (NEC) is a devastating disease of the gastrointestinal tract that affects mostly premature infants. It is the most significant contributor of gastrointestinal morbidity and mortality in preterm infants. NEC was first described over 60 years ago but despite significant research efforts, its pathogenesis remains poorly understood. A general lack of reliable and specific early clinical or laboratory signs affects the ability to promptly…

Selected Gastrointestinal Anomalies in the Neonate

Thoracic Anomalies Esophageal Atresia and Tracheoesophageal Fistula Combined anomalies of the esophagus and trachea are regular occurrences in most tertiary neonatal units caring for high-risk infants. The spectrum of recognized deformities comprises a variety of combinations involving esophageal atresia (EA) and tracheoesophageal fistula (TEF). These malformations are well-recognized entities, yet they continue to stimulate a great deal of interest for a variety of reasons, and almost…

Disorders of Digestion in the Neonate

Chronic and prolonged diarrhea is a symptom complex with a variety of underlying etiologies. This chapter focuses on the approach to infants with protracted diarrhea and is a review of recent literature on infantile diarrheal illnesses. Intractable diarrhea is a term developed many years ago by Avery to describe chronic, unexplained diarrhea in young children. This phrase describes a symptom complex rather than a discrete disease…

Gastrointestinal Reflux and Motility in the Neonate

Definitions Gastroesophageal reflux (GER) is the physiologic retrograde passage of fluid from the stomach to the esophagus. Gastroesophageal reflux events occur in healthy infants multiple times per day. Gastroesophageal reflux disease (GERD) is the pathologic condition wherein such retrograde flow into the esophagus causes medical complications. Regurgitation and vomiting are common and often nonpathologic complications of GER. A definitive determination of GERD in infants is often…

Development of the Neonatal Gastrointestinal Tract

The human gastrointestinal (GI) tract is a complex combination of organs whose primary function is to digest and absorb nutrients. Many important secondary functions are also performed, such as the endocrine function of the pancreas. In fact, what was once considered a simple system of digestion and absorption is now recognized as something much more complex and dynamic. Furthermore, as with the respiratory system, to perform…

Blood Component Therapy for the Neonate

Special Considerations for Transfusion Therapy in the Neonate Neonates constitute one of the most heavily transfused patient groups in the hospital. In a Canadian study, over 50% of infants at less than 30 weeks’ gestation and more than 80% of infants with a birth weight of less than 1000 grams received at least one red blood cell (RBC) transfusion during their initial hospitalization. Neonatal transfusion practices…

Hematologic and Oncologic Problems in the Fetus and Neonate

Human Hematopoietic Development Hematopoietic Stem Cells Blood cells arise from the differentiating embryonic mesoderm. Human erythroid and macrophage progenitor cells have been observed in the yolk sac by days 16-19 and at day 19 in the aortic-gonad-mesonephros (AGM). After the development of the circulatory system on day 21, pluripotent hematopoietic cells localize in the AGM, placenta, and liver by days 24-28. Myeloid, lymphoid, and megakaryocytic precursors…

Neonatal Management of Congenital Heart Disease

Introduction Neonates with congenital heart disease require a well-integrated and multidisciplinary team approach to achieve optimal outcomes. The complexity of managing a critically ill newborn is compounded greatly when the cardiovascular physiology and/or anatomy are significantly altered. Many of the important management principles routinely followed by neonatologists can be applied to critically ill newborn cardiac patients, including thermal regulation, prematurity issues, nutritional strategies, and ventilator support.…

Disorders of Cardiac Rhythm and Conduction in Newborns

Neonates experience a variety of cardiac arrhythmias, varying from benign and asymptomatic to life threatening. In this chapter we will discusses the normal and abnormal variations in cardiac rate and rhythms that are frequently encountered in the newborn period. Normal Sinus Rhythm and Sinus Node Dysfunction Normal Sinus Rhythm and Its Variations The initiation of cardiac electrical activity typically begins in the sinus node, a small,…

Cardiovascular Problems of the Neonate

Cardiac Malposition and Abnormalities of Abdominal Situs Bodily Arrangement and Situs The development of morphologically right-sided structures on one side of the body, and morphologically left-sided structures on the other side, is termed lateralization or situs . The normal arrangement, in which right-sided structures are on the right side of the body and vice versa, is known as situs solitus . The term visceroatrial situs is…

Congenital Defects of the Cardiovascular System

Summary Congenital heart defects are the most common type of birth defect in infants worldwide. The following chapter provides an overview of the anatomy, physiology, clinical presentation, diagnostic evaluation, and management strategies for a wide range of congenital heart disease encountered in neonates and infants. While the information herein is detailed, it is important to keep in mind that many different anatomic and physiologic variants are…

Patent Ductus Arteriosus

In utero, the ductus arteriosus provides a connection between the pulmonary artery and descending aorta through which deoxygenated blood returning to the right heart is diverted to the placenta for reoxygenation. Although essential to normal fetal physiology, it normally constricts, closes, and becomes a fibrous remnant after birth. Failure of those processes, resulting in persistent ductal patency into childhood or adulthood, has been recognized as a…

Prenatal Diagnosis of Congenital Heart Disease

Introduction Congenital heart disease (CHD) affects 6-8 per 1000 live births. However, only 20% of babies with congenital heart disease would be identified if the examination of the fetal heart were confined to traditional high-risk groups such as increased nuchal translucency, family history of CHD, and teratogen exposure. The current American Society of Echocardiography guidelines suggest the optimal timing for performance of a comprehensive transabdominal fetal…

Pulmonary Vascular Development

Normal development of pulmonary vascular structure and function through prenatal and early postnatal life prepares the lung to perform its basic physiologic function of gas exchange across a thin blood–gas interface. Survival of the newborn is dependent upon rapid adaptation of the fetal cardiopulmonary system to the demands of extrauterine life. As development continues, normal lung function and growth depends on sustained low pulmonary vascular resistance.…

Cardiac Embryology

Introduction Congenital heart defects (CHDs) affect about 1% of all live births around the world, with variations in reporting depending on birth rates and access to medical care. The care of children with CHDs has increasingly become a neonatal specialty, aided by prenatal detection. The fetal diagnosis of critical CHDs decreases postsurgical morbidity and mortality, and reparative or palliative cardiovascular surgery is commonplace in the first…

Therapy for Cardiorespiratory Failure in the Neonate

Assisted ventilation and oxygen therapy remain the standard of care for neonatal respiratory failure. A few term and late preterm infants with a wide range of diagnoses develop intractable cardiorespiratory failure despite maximal ventilatory support. In these patients, severe pulmonary hypertension often contributes to persistent hypoxemia. Two unique therapies for such patients are presented in this section: extracorporeal membrane oxygenation (ECMO), which is now well established…

Bronchopulmonary Dysplasia in the Neonate

The introduction of mechanical ventilation for the management of premature infants with severe respiratory distress syndrome (RDS) in the 1960s changed the natural course of the disease, resulting in increased survival of smaller and sicker infants, many of whom had severe chronic lung damage. Northway and associates were the first to describe this condition in 1967 and introduced the term bronchopulmonary dysplasia (BPD). All these infants…

Upper Airway Lesions in the Neonate

A spectrum of pathologic conditions can affect the neonatal upper airway, resulting in respiratory distress at birth or within the first few weeks of life. The clinical presentations of these disorders, however, are often quite similar. The most common symptom is stridor; other signs and symptoms include cyanosis, apnea, dyspnea, retractions, hypercapnia, difficulty feeding, abnormal cry, and cough. The physician's ability to arrive at a diagnosis…

Neonatal Apnea and the Foundation of Respiratory Control

Breathing results in the exchange of oxygen and carbon dioxide between the lungs and the environment while maintaining homeostasis and control of blood pH. Energy-consuming breathing movements do occur in utero. Maturation of breathing is a continuous process that bridges fetal and neonatal life. Especially for premature infants, immature fetal breathing responses result in irregular respiratory effort, apnea, bradycardia, and hypoxemia. Fetal Breathing Fetal breathing activity…

Neonatal Respiratory Disorders

Multiple pathophysiologic mechanisms can present with pulmonary manifestations in term and preterm infants. The clinical picture is most commonly dominated by respiratory distress, which presents as tachypnea, grunting, flaring, retractions, cyanosis, and hypoxemia. However, apnea and hypoventilation are also common. In preterm infants, these manifestations are commonly associated with respiratory distress syndrome (RDS) as discussed in Chapter 64 . Nonpulmonary etiologies of respiratory distress include thermal…