As many as 10 percent of newborn infants require some degree of active resuscitation to stimulate breathing. When infants become asphyxiated, either before or after birth, they demonstrate a well-defined sequence of events, leading to primary or secondary apnea (Figure 89-1). Initial oxygen deprivation results in a transient period of rapid breathing. If such deprivation persists, breathing movements cease and the infant enters a stage of apnea known as primary apnea. This is accompanied by a decrease in heart rate and loss of neuromuscular tone. Simple stimulation and exposure to oxygen will reverse primary apnea. If oxygen deprivation and asphyxia persist, the infant will develop deep gasping respirations, followed by secondary apnea. This is associated with a further decline in heart rate, falling blood pressure, and loss of neuromuscular tone. Infants in secondary apnea will not respond to stimulation and will not spontaneously resume respiratory efforts. Unless ventilation is assisted, death will occur. Clinically, primary and secondary apnea are indistinguishable. For this reason, secondary apnea must be assumed, and resuscitation of the apneic infant must be started immediately.
FIGURE 89-1 Physiological changes associated with primary and secondary apnea in the newborn. (Adapted from Kattwinkel J: Textbook of Neonatal Resuscitation. 4th ed. Elk Grove Village, IL: American Academy of Pediatrics and American Heart Association, 2000.)
The protocol for neonatal resuscitation shown in Figure 89-2 is recommended by the International Liaison Committee on Resuscitation (2006) and endorsed by the American College of Obstetricians and Gynecologists.
FIGURE 89-2 Algorithm for resuscitation of the newborn infant. HR, heart rate. (Reproduced, with permission, from Cunningham FG, Leveno KJ, Bloom SL, et al (eds). Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010.)
1. Prevent heat loss. Place the infant in a radiant warmer.
2. Clear the airway. The airway is opened by suctioning the mouth and nares if no meconium is present. If meconium is present, the trachea may require direct suctioning (Figure 89-3).
FIGURE 89-3 Protocol for dealing with meconium in the newborn. (From Kattwinkel J: Textbook of Neonatal Resuscitation. 5th ed. Elk Grove Village, IL: American Academy of Pediatrics and American Heart Association, 2006, with permission.)
3. Dry, stimulate, and reposition.
4. Evaluate the infant. Observe for respirations, heart rate, and color to determine what further steps are necessary. If the infant is breathing, the heart rate is greater than 100 beats/min, and the skin of the central portion of the body and mucus membranes is pink, then routine supportive care is provided. These initial steps should be performed within 30 seconds or less.
The presence of apnea, gasping respirations, or bradycardia beyond 30 seconds after delivery should prompt administration of positive-pressure ventilation. The resuscitator, using an appropriate ventilation bag attached to the tracheal tube, should deliver puffs of oxygen-rich air into the tube at 1- to 2-second intervals with a force adequate to gently lift the chest wall. Pressures of 25- to 35-cm H2O typically will expand the alveoli without causing a pneumothorax or pneumomediastinum.
If the heart rate remains below 60 beats/min despite adequate ventilation with 100-percent oxygen for 30 seconds, chest compressions are initiated. Compressions are delivered on the lower third of the sternum at a depth sufficient to generate a palpable pulse. A 3:1 ratio of compressions to ventilations is recommended, with 90 compressions and 30 breaths to achieve approximately 120 events each minute. The heart rate is reassessed every 30 seconds, and chest compressions are continued until the spontaneous heart rate is at least 60 beats/min.
Medications and Volume Expansion
Administration of epinephrine is indicated when the heart rate remains below 60 beats/min after a minimum of 30 seconds of adequate ventilation and chest compressions. The recommended intravenous or endotracheal dose is 0.1 to 0.3 mL/kg of a 1:10,000 solution. This is repeated every 3 to 5 minutes as indicated.
Volume expansion should be considered when blood loss is suspected, the infant appears to be in shock, or the response to resuscitative measures is inadequate. An isotonic crystalloid solution, such as normal saline or lactated Ringer’s, is recommended. Symptomatic anemia may require transfusion of red blood cells. The initial dose of either type of volume expander is 10 mL/kg given by slow intravenous push over 5 to 10 minutes.
The routine use of sodium bicarbonate during neonatal resuscitation is controversial and should be administered only after establishment of adequate ventilation and circulation.
Naloxone is a narcotic antagonist indicated for reversal of respiratory depression in a newborn infant whose mother received narcotics within 4 hours of delivery. Adequate ventilation should always be established prior to naloxone administration. The recommended dose of naloxone is 0.1 mg/kg of a 1.0-mg/mL solution.
If bag-and-mask ventilation is ineffective or prolonged, endotracheal intubation should be performed. Other indications include the need for chest compressions or tracheal administration of medications or special circumstances such as extremely low birth weight or congenital diaphragmatic hernia.
TECHNIQUE OF INTUBATION
Use of the laryngoscope for tracheal intubation is shown in Figure 89-4. The head of the supine infant is kept level. The laryngoscope is introduced into the right side of the mouth and then directed posteriorly toward the oropharynx. The laryngoscope is next gently moved into the space between the base of the tongue and the epiglottis. Gentle elevation of the tip of the laryngoscope will pick up the epiglottis and expose the glottis and the vocal cords. The endotracheal tube is introduced through the right side of the mouth and is inserted through the vocal cords until the shoulder of the tube reaches the glottis. It is essential that the appropriate-sized endotracheal tube be used (Table 89-1). Steps are taken to ensure that the tube is in the trachea and not the esophagus by listening for breath sounds or a gurgling sound if air is introduced into the stomach. Any foreign material encountered in the tracheal tube is immediately removed by suction. Meconium, blood, mucus, and particulate debris in amnionic fluid or in the birth canal may have been inhaled in utero or while passing through the birth canal.
FIGURE 89-4 A. Use of laryngoscope to insert a tracheal tube under direct vision. B. Sagittal view during intubation. The laryngoscope blade is inserted between the tongue base and epiglottis. Upward tilting of the tongue also lifts the epiglottis. C. The endotracheal tube is then threaded below the epiglottis and between the vocal cords to enter the trachea. (Reproduced, with permission, from Cunningham FG, Leveno KJ, Bloom SL, et al (eds). Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010.)
TABLE 89-1. Suggested Endotracheal Tube Size and Depth of Insertion
Using an appropriate ventilation bag attached to the tracheal tube, puffs of oxygen-rich air are delivered into the tube at 1- to 2-second intervals with a force adequate to lift the chest wall gently. Pressures of 25 to 35 cm H2O are desired to expand the alveoli yet not cause pneumothorax or pneumomediastinum. If the stomach expands, the tube is almost certainly in the esophagus rather than in the trachea. Once adequate spontaneous respirations have been established, the tube can usually be removed safely.
For further reading in Williams Obstetrics, 23rd ed.,
see Chapter 28, “The Newborn Infant.”