Resuscitation in the Delivery Room
Steven A. Ringer
I. GENERAL PRINCIPLES.
A person skilled in basic neonatal resuscitation, whose primary responsibility is the newly born baby, should be present at every birth. Delivery of all high-risk infants should be ideally attended by personnel who possess the skills required to perform a complete resuscitation.
The highest standard of care requires the following: (i) knowledge of perinatal physiology and principles of resuscitation; (ii) mastery of the technical skills required; and (iii) a clear understanding of the roles of other team members and coordination among team members. This allows anticipation of each person’s reactions in a specific instance and helps ensure that care is timely and comprehensive. Completion of the Newborn Resuscitation Program (NRP) of the American Academy of Pediatrics/American Heart Association by every caregiver helps ensure a consistent approach to resuscitations and team-based training. NRP provides an approach to resuscitation that is successful in a very high percentage of cases and aids clinicians in more rapidly identifying those unusual cases in which specialized interventions may be required.
Perinatal physiology. Resuscitation efforts at delivery are designed to help the newborn make the respiratory and circulatory transitions that must be accomplished immediately after birth: the lungs expand, fetal lung fluid is cleared, effective air exchange is established, and the right-to-left circulatory shunts terminate. The critical period for these physiologic changes is during the first several breaths, which result in lung expansion and elevation of the partial pressure of oxygen (PO2) in both the alveoli and the arterial circulation. Elevation of the PO2 from the fetal level of approximately 25 mm Hg to values of 50 to 70 mm Hg is associated with (i) decrease in pulmonary vascular resistance, (ii) decrease in right-toleft shunting through the ductus arteriosus, (iii) increase in venous return to the left atrium, (iv) rise in left atrial pressure, and (v) cessation of right-to-left shunt through the foramen ovale. The end result is conversion from fetal to transitional to neonatal circulatory pattern. Adequate systemic arterial oxygenation results from perfusion of well-expanded, well-ventilated lungs and adequate circulation.
Conditions at delivery may compromise the fetus’s ability to make the necessary transitions. Alterations in tissue perfusion and oxygenation ultimately result in depression of cardiac function, but human fetuses initially respond to hypoxia by becoming apneic. Even a relatively brief period of oxygen deprivation may result in this primary apnea. Rapid recovery from this state is generally accomplished with appropriate stimulation and oxygen exposure. If the period of hypoxia continues, the fetus will irregularly gasp and lapse into secondary apnea. This state may occur remote from birth or in the peripartum period. Infants born during this period require resuscitation with assisted ventilation and oxygen (see III.D.).
Goals of resuscitation are the following:
Minimizing immediate heat loss by drying and providing warmth, thereby decreasing oxygen consumption by the neonate.
Establishing normal respiration and lung expansion by clearing the upper airway and using positive-pressure ventilation if necessary.
Increasing arterial PO2 by providing adequate alveolar ventilation. The routine use of added oxygen is not warranted, but this therapy may be necessary in some situations.
Supporting adequate cardiac output.
II. PREPARATION.
Anticipation is key to ensuring that adequate preparations have been made for a neonate likely to require resuscitation at birth. It is estimated that as many as 10% of neonates require some assistance at birth for normal transition, while less than 1% require extensive resuscitative measures.
Perinatal conditions associated with high-risk deliveries. Ideally, the obstetrician should notify the pediatrician well in advance of the actual birth. The pediatrician may then review the obstetric history and events leading to the high-risk delivery and prepare for the specific problems that may be anticipated. If time permits, the problems should be discussed with the parent(s). The following antepartum and intrapartum events warrant the presence of a resuscitation team at delivery:
Evidence of nonreassuring fetal status
Category III fetal tracing, including either sinusoidal pattern or absent fetal heart rate variability and any of the following: late decelerations, recurrent variable decelerations or bradycardia.
History of an acute perinatal event (e.g., placental abruption, cord prolapse or abnormal fetal testing, or a scalp pH of 7.20 or less).
History of decreased fetal movement, dimunition in growth, or abnormalites of umbilical vessel Doppler flow studies.
Evidence of fetal disease or potentially serious conditions (see Chap. 1)
Meconium staining of the amniotic fluid and/or other evidence of possible fetal compromise (see Chap. 35)
Prematurity (<37 weeks), postmaturity (>42 weeks), anticipated low birth weight (<2.0 kg), or high birth weight (>4.5 kg)
Major congenital anomalies diagnosed prenatally
Hydrops fetalis
Multiple gestation (see Chap. 11)
Labor and delivery conditions
Significant vaginal bleeding
Abnormal fetal presentation
Prolonged or unusual labor
Concern about a possible shoulder dystocia
The following conditions do not require a pediatric team to be present, but personnel should be available for assessment and triage:
Neonatal conditions
Unexpected congenital anomalies
Respiratory distress
Unanticipated neonatal depression, for example, Apgar score of <6 at 5 minutes
Maternal conditions
Signs of maternal infection
Maternal fever
Membranes ruptured for >24 hours
Foul-smelling amniotic fluid
History of sexually transmitted disease
Maternal illness or other conditions
Diabetes mellitus
Rh or other isoimmunization without evidence of hydrops fetalis
Chronic hypertension or pregnancy-induced hypertension
Renal, endocrine, pulmonary, or cardiac disease
Alcohol or other substance abuse
Mode of delivery
In the absence of other antenatal risk factors, delivery via cesarean section done using regional anesthesia at 37 to 39 weeks’ gestation does not increase the likelihood of a baby requiring endotracheal (ET) intubation, compared to vaginal delivery at term.
Necessary equipment must be present and operating properly. Each delivery room should be equipped with the following:
Radiant warmer with procedure table or bed. The warmer should be turned on and checked before delivery. For a very low birth weight (VLBW) infant, additional warming techniques should be available, which might include prewarming the delivery room to 26°C, covering the baby with a plastic wrap or using an exothermic mattress. When used in combination, care should be taken to avoid hyperthermia.
A blended oxygen source (adjustable between 21% and 100%) with adjustable flowmeter and adequate length of tubing. A humidifier and heater may be desirable.
Pulse oximeter available for use when oxygen therapy is anticipated.
Flow-inflating bag with adjustable pop-off valve or self-inflating bag with reservoir. The bag must be appropriately sized for neonates (generally about 750 mL) and capable of delivering 100% oxygen.
Face mask(s) of appropriate size for the anticipated infant.
A bulb syringe for suctioning.
Stethoscope with infant- or premature-sized head.
Equipped emergency box or cart
Laryngoscope with no. 0 and no. 1 blades. For extremely low birth weight infants, a no. 00 blade may be preferred.
Extra batteries.
Uniform diameter ET tubes (2.5-, 3.0-, and 3.5-mm internal diameters), two of each.
Drugs, including epinephrine (1:10, 000) and NaCl 0.9%. Sodium bicarbonate (0.50 mEq/mL) or other buffers and naloxone are rarely useful.
Umbilical catheterization tray with 3.5 and 5F catheters.
Syringes (1.0, 3.0, 5.0, 10.0, and 20.0 mL), needles (18-25 gauge), T-connectors, and stopcocks.
Transport incubator with battery-operated heat source and portable-blended oxygen supply should be available if delivery room is not close to the nursery.
The utility of equipment for continuous monitoring of cardiopulmonary status in the delivery room is hampered by difficulty in effectively applying monitor leads. Pulse oximetry can be applied right after birth and successfully used to provide information on oxygen saturation and heart rate, and should be available when oxygen use is anticipated or possible.
End-tidal CO2 monitor/indicator to confirm ET tube position after intubation.
Preparation of equipment. Upon arrival in the delivery room, check that the transport incubator is plugged in and warm, and has a full oxygen tank. The specialist should introduce himself or herself to the obstetrician and anesthesiologist, the mother (if she is awake), and the father (if he is present). While the history or an update is obtained, the following should be done:
Ensure that the radiant warmer is on, and that dry, warm blankets are available.
Turn on the oxygen source or air—oxygen blend and adjust the flow from 5 to 8 L/minute. Adjust the oxygen concentration to the desired initial level.
Test the flow-inflating bag (if used) for pop-off control and adequate flow. Be sure the proper-sized mask is present.
Make sure the laryngoscope light is bright and has an appropriate blade (no. 1 for full-term neonates, no. 0 for premature neonates, and no. 00 for extremely low birth weight neonates).
Set out an appropriate ET tube for the expected birth weight (3.5 mm for fullterm infants, 3.0 mm for premature infants >1,250 g, and 2.5 mm for smaller infants). The NRP recommends a 4.0-mm tube for larger babies, but this is rarely necessary. For all babies, the tube should be 13 cm long. An intubation stylet may be used if the tip is kept at least 0.5 cm from the distal end of the ET tube.
If the clinical situation suggests that extensive resuscitation may be needed, the following actions may be required:
Set up an umbilical catheterization tray for venous catheterization.
Draw up 1:10,000 epinephrine and isotonic saline for catheter flush solution and volume replacement.
Check that other potentially necessary drugs are present and ready for administration.
Universal precautions. Exposure to blood or other body fluids is inevitable in the delivery room. Universal precautions must be practiced by wearing caps, goggles or glasses, gloves, and impervious gowns until the cord is cut and the newborn is dried and wrapped.
III. DURING DELIVERY
the team should be aware of the type and duration of anesthesia, extent of maternal bleeding, and newly recognized problems such as a nuchal cord or meconium in the amniotic fluid.
Immediately following delivery, begin a process of evaluation, decision, and action (resuscitation)
Place the newborn on the warming table.
Dry the infant completely and discard the wet linens, including those upon which the infant is lying. Drying should be thorough but gentle; avoid
vigorous rubbing or attempts to clean all blood or vernix from the baby. Make sure the infant is warm. Extremely small infants may require extra warming techniques such as wrapping the body and extremities in a plastic wrap or bag or with the use of an exothermic mattress.
Place the infant with head in midline position, with slight neck extension.
Suction the mouth, oropharynx, and nares thoroughly with a suction bulb if there is obvious obstruction or if the baby requires positive pressure ventilation. Deep pharyngeal stimulation with a suction catheter may cause arrhythmias that are probably of vagal origin, and this should be avoided. If meconiumstained amniotic fluid is present and the infant is not vigorous, suction the oropharynx and trachea as quickly as possible (see IV.A. and Chap. 35).
Assessment of the need for supplemental oxygen. In the normal fetal environment, oxygen saturation levels are well below those necessary during extrauterine life. These levels do not completely rise to the normal postnatal range for about 10 minutes after birth, and oxygen saturation levels of 70% to 80% are normal for several minutes. During this time, the baby may appear cyanotic, although clinical assessment of cyanosis has been shown to be an unreliable indicator of actual oxyhemoglobin saturation. However, either insufficient or excessive oxygenation can be harmful to the newborn.
Pulse oximetry. Several studies have examined the change in oxygen saturation levels in the minutes following birth and have defined percentile ranges for uncompromised babies born at full term. The best-defined data have been obtained using readings made at a “preductal” site (i.e., the right upper extremity) in order to avoid the potentially confounding effect of shunting during the transition to an adult-type circulation. Probes specifically designed for neonates can provide reliable readings within 1 to 2 minutes or less; however, oxygen saturation measurements may be unreliable when cardiac output and skin perfusion are poor. It is recommended that oximetry be available for use in the delivery room so that it will be available when:
Resuscitation can be anticipated, as noted previously.
Positive pressure ventilation is used for more than a few breaths.
Cyanosis is persistent despite interventions.
Supplemental oxygen is administered.
The concentration of oxygen used to begin resuscitation remains an area of debate. Several trials have shown that survival is improved when resuscitation is initiated with room air compared with 100% oxygen in full-term infants, although there are no studies evaluating other oxygen concentrations. A single study of preterm infants showed that the use of a blended air—oxygen mixture as the initial gas resulted in less hypoxemia or hyperoxemia than did the use of room air or 100% oxygen, but the ideal starting concentration has not been defined. Once oxygen use is started, the concentration should be adjusted so that the measured preductal oxygen saturation value lies within a specified minute-specific reference range (Table 5.1) as advocated by the NRP program. The best available reference is the interquartile range of saturations measured in healthy term babies following vaginal birth at sea level. Different ranges have not been determined for preterm babies or those born via cesarean or vaginal routes.
Since when using these guidelines the administered oxygen concentration is guided by the measured oxygen saturation, the choice of initial concentration is
discretionary, but a uniform approach makes sense. We use room air as the initial concentration for term babies, and 60% oxygen for premature babies less than 32 weeks’ gestation.
Table 5.1 Target Preductal SpO2 during the First 10 Minutes After Birth
1 minute
60%-65%
2 minutes
65%-70%
3 minutes
70%-75%
4 minutes
75%-80%
5 minutes
80%-85%
10 minutes
85%-95%
Air should be used if blended oxygen is not available.
Oxygen concentration should be increased to 100% if bradycardia (HR < 60 beats per minute [bpm]) does not improve after 90 seconds of resuscitation while employing a lower oxygen concentration.
Sequence of intervention.
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