NEWBORN

INITIATION OF AIR BREATHING
Immediately following birth, the infant must promptly convert to air breathing as the fluid-filled alveoli expand with air and pulmonary perfusion is established. The newborn begins to breathe and cry almost immediately after birth, which indicates establishment of active respiration. Some factors that appear to influence the first breath include: • Physical stimulation—examples include handling the neonate during delivery. • Oxygen deprivation and carbon dioxide accumulation—these serve to increase the frequency and magnitude of breathing movements both before and after birth (Dawes, 1974). • Thoracic compression—this occurs during pelvic descent, following which vaginal birth forces fluid from the respiratory tract in volume equivalent to approximately a fourth of the ultimate functional residual capacity (Saunders, 1978). • Aeration of the newborn lung does not involve the inflation of a collapsed structure, but instead, the rapid replacement of bronchial and alveolar fluid by air. After delivery, the residual alveolar fluid is cleared through the pulmonary circulation and to a lesser degree, through the pulmonary lymphatics (Chernick, 1978). Delay in fluid removal from the alveoli probably contributes to the syndrome of transient tachypnea of the newborn (TTN) (Guglani, 2008). As fluid is replaced by air, compression of the pulmonary vasculature is reduced considerably, and in turn, resistance to blood flow is lowered. With the fall in pulmonary arterial blood pressure, the ductus arteriosus normally closes (Fig. 7-8, p. 136). High negative intrathoracic pressures are required to bring about the initial entry of air into the fluid-filled alveoli. Normally, from the first breath after birth, progressively more residual air accumulates in the lung, and with each successive breath, lower pulmonary opening pressure is required. In the normal mature newborn, by approximately the fifth breath, pressure-volume changes achieved with each respiration are very similar to those of the adult. Thus, the breathing pattern shifts from the shallow episodic inspirations characteristic of the fetus to regular, deeper inhalations (Chap. 17, p. 337). Surfactant, which is synthesized by type II pneumocytes and already present in the alveoli, lowers alveolar surface tension and thereby prevents lung collapse. Insufficient surfactant, common in preterm infants, leads promptly to respiratory distress syndrome, which is described in Chapter 34 (p. 653).

CARE IN THE DELIVERY ROOM
 Personnel designated for infant support are responsible for immediate care and for acute resuscitation initiation if needed.
 Immediate Care
 Before and during delivery, careful consideration must be given to several determinants of neonatal well-being including: (1) maternal health status; (2) prenatal complications, including any suspected fetal malformations; (3) gestational age; (4) labor complications; (5) duration of labor and ruptured membranes; (6) type and duration of anesthesia; (7) difficulty with delivery; and (8) medications given during labor and their dosages, administration routes, and timing relative to delivery.
 Newborn Resuscitation
The International Liaison Committee on Resuscitation (ILCOR) updated its guidelines for neonatal resuscitation that are sanctioned by the American Academy of Pediatrics and the American Heart Association (Biban, 2011; Perlman, 2010). These substantially revised guidelines are incorporated into the following sections. Approximately 10 percent of newborns require some degree of active resuscitation to stimulate breathing, and 1 percent require extensive resuscitation. It is perhaps not coincidental that there is a two- to threefold risk of death for newborns delivered at home compared with those delivered in hospitals (American College of Obstetricians and Gynecologists, 2013b). When deprived of oxygen, either before or after birth, neonates demonstrate a well-defined sequence of events leading to apnea (Fig. 32-1). With oxygen deprivation, there is a transient period of rapid breathing, and if it persists, breathing stops, which is termed primary apnea. This stage is accompanied by a fall in heart rate and loss of neuromuscular tone. Simple stimulation and exposure to oxygen will usually reverse primary apnea. If oxygen deprivation and asphyxia persist, however, the newborn will develop deep gasping respirations, followed by secondary apnea. This latter stage is associated with a further decline in heart rate, falling blood pressure, and loss of neuromuscular tone. Neonates in secondary apnea will not respond to stimulation and will not spontaneously resume respiratory efforts. Unless ventilation is assisted, death follows. Clinically, primary and secondary apneas are indistinguishable. Thus, secondary apnea must be assumed and resuscitation of the apneic newborn must be started immediately.


Resuscitation Protocol
 The updated algorithm for newborn resuscitation recommended by ILCOR and the International Consensus on Cardiopulmonary Resuscitation is shown in Figure 32-2. Many of its tenets follow below.
Basic Measures
 The vigorous newborn is first placed in a warm environment to minimize heat loss, the airway is cleared, and the infant dried. Routine gastric aspiration has been shown to be nonbeneficial and even harmful (Kiremitci, 2011). And although previously recommended, there is no evidence that bulb suctioning for clear or meconium-stained fluid is beneficial, even if the newborn is depressed (Chap. 33, p. 638). With stimulation, the healthy newborn will take a breath within a few seconds of birth and cry within half a minute, after which routine supportive care is provided.
Assessment at 30 Seconds of Life. Apnea, gasping respirations, or heart rate < 100 bpm beyond 30 seconds after delivery should prompt administration of positive-pressure ventilation with room air (Fig. 32-3). Assisted ventilation rates of 30 to 60 breaths per minute are commonly employed, and the percent of oxygen saturation is monitored by pulse oximetry. At this point, supplemental oxygen can be given in graduated increasing percentages to maintain oxygen saturation (Spo2) values within a normal range (Vento, 2011). Adequate ventilation is indicated by improved heart rate. ventilation. The head should be in a sniffing position with the tip of the nose pointing to the ceiling. The neck should not be hyperextended. Assessment at 60 Seconds of Life. If the heart rate remains < 100 bpm, then ventilation is inadequate. The head position should be checked as shown in Figure 32-3, secretions cleared, and if necessary, inflation pressure increased. If the heart rate persists below 100 bpm beyond 60 seconds, tracheal intubation is considered. A number of conditions may be the cause of inadequate response, including the following: • Hypoxemia or acidosis from any cause • Drugs administered to the mother before delivery • Immaturity • Upper airway obstruction • Pneumothorax • Lung abnormalities • Meconium aspiration • Central nervous system developmental abnormality • Sepsis syndrome. Tracheal Intubation If bag-and-mask ventilation is ineffective or prolonged, tracheal intubation is then performed. Other indications include the need for chest compressions or tracheal administration of medications, or special circumstances such as extremely low birthweight or a congenital diaphragmatic hernia. A laryngoscope with a straight blade—size 0 for a preterm infant and size 1 for a term neonate—is introduced at the side of the mouth and then directed posteriorly toward the oropharynx as shown in Figure 32-4. The laryngoscope is next moved gently into the vallecula—the space between the base of the tongue and the epiglottis. Gentle elevation of the laryngoscope tip will raise the epiglottis and expose the glottis and the vocal cords. The tube is then introduced through the vocal cords. Gentle cricoid pressure may be useful. Tube sizes vary from 3.5 to 4.0 mm for term infants down to 2.5 mm for those < 28 weeks or < 1000 g.