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About 10% of neonates require some respiratory assistance at birth. Less than 1% need extensive resuscitation. Causes are numerous (see Table: Problems in the Neonate That May Require Resuscitation), but most involve asphyxia or respiratory depression. Incidence rises significantly if birth weight is < 1500 g.
Problems in the Neonate That May Require Resuscitation
The Apgar score is used at birth to evaluate a newborn's condition and possible need for resuscitation; it was not initially intended to determine long-term neurologic prognosis. The Apgar score assigns 0 to 2 points for each of 5 measures of neonatal health (Appearance, Pulse, Grimace, Activity, Respiration—see Table: Apgar Score). Scores depend on physiologic maturity, maternal perinatal therapy, and fetal cardiorespiratory and neurologic conditions. A score of 7 to 10 at 5 min is considered normal; 4 to 6, intermediate; and 0 to 3, low. A low Apgar score is not by itself diagnostic of perinatal asphyxia but is associated with a risk of long-term neurologic dysfunction. A persistently low Apgar score (0 to 3 at 5 min) is associated with increased neonatal mortality.
The earliest sign of asphyxia is cyanosis, followed by decreases in respiration, muscle tone, reflex response, and heart rate. Effective resuscitation leads initially to increased heart rate, followed by improved reflex response, color, respiration, and muscle tone. Evidence of intrapartum fetal distress, persistence of an Apgar score of 0 to 3 for > 5 min; an umbilical arterial blood pH < 7; and a sustained neonatal neurologic syndrome that includes hypotonia, coma, seizures, and evidence of multiorgan dysfunction are manifestations of hypoxic ischemic encephalopathy. The severity and prognosis of posthypoxic encephalopathy can be estimated with the Sarnat classification (see Table: Clinical Staging of Posthypoxic Encephalopathy) in conjunction with EEG, neuroradiologic imaging, and brain stem auditory and cortical evoked responses.
Clinical Staging of Posthypoxic Encephalopathy
Initial measures for all neonates include providing warmth, drying, and stimulating breathing (eg, flicking the soles of the feet, rubbing the back). If there is obvious obstruction to spontaneous breathing, the airway is cleared using bulb suction or a suction catheter. Suctioning has not proved beneficial in infants without obvious obstruction, even if amniotic fluid was stained with meconium (suctioning was previously recommended in such infants). If deep suctioning is required, appropriately sized catheters and pressure limits of 100 mm Hg (136 cm H2O) must be used. Infants not responding with appropriate respirations and heart rate may require positive pressure ventilation (PPV), O2 therapy, and, less commonly, chest compressions.
The infant is quickly dried and placed supine under a preheated overhead warmer in the delivery room. The neck is supported in the neutral position (sniffing position) to maintain an open airway.
If spontaneous respirations are absent, the infant is gasping, or heart rate is < 100 beats/min, respirations are assisted with PPV via mask, or sometimes laryngeal mask airway or endotracheal tube. Note that infants with a sunken, convex (scaphoid) abdomen may have a congenital diaphragmatic hernia, in which case ventilation using a mask can be dangerous; if such infants require ventilatory assistance, they should undergo endotracheal intubation. O2 saturation is monitored using a pulse oximeter placed to measure preductal saturation (typically on the right hand or wrist). Resuscitation should be started with room air or a blend of O2 and air and titrated to achieve O2 saturations within the target range, which increases over the first 10 min of life (see Table: Neonatal Oxygen Saturation Targets). Inspiratory and end-expiratory pressures should be monitored and kept at the lowest level necessary to maintain heart rate > 100 beats/min. It is particularly important to keep pressures low in extremely premature and/or extremely low-birth-weight infants, whose lungs are easily injured by PPV.
Bradycardia (heart rate < 60) in a distressed child is a sign of impending cardiac arrest; neonates tend to develop bradycardia with hypoxemia. If bradycardia persists > 90 sec, O2 concentration is increased to 100% until recovery. If heart rate is < 60 despite adequate ventilation for 30 sec, begin chest compressions using a 3:1 compression:ventilation ratio (see Figure: Algorithm for resuscitation of neonates.). Advanced resuscitation techniques, including endotracheal intubation, and selection of equipment size, drugs and dosages, and CPR parameters are discussed elsewhere (see page Cardiopulmonary Resuscitation in Infants and Children).
Algorithm for resuscitation of neonates.
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