Perinatal Transition and Newborn Resuscitation

Key Points

Preparation prior to delivery helps ensure timely and effective newborn resuscitation.
Delayed umbilical cord clamping following delivery may have a significant impact on newborn outcomes.
Establishing adequate ventilation is key to the perinatal transition.
The laryngeal mask airway is an alternative to intubation in newborns at ≥34 weeks’ gestation and > 2000 g.
Devices such as carbon dioxide detectors, pulse oximetry, electrocardiography, and respiratory function monitors can be helpful during resuscitation.
Postresuscitation care is critical to ensure optimal outcomes after newborn resuscitation.

The transition from fetal to neonatal life is a dramatic and complex process. Individuals who care for newborns must monitor the progress of this transition and be prepared to intervene when necessary. In most births, the perinatal transition occurs without the need for assistance. However, when assistance is needed, the presence of healthcare providers skilled in neonatal resuscitation can be lifesaving. Globally, 2.9 million neonates die every year. Approximately 1 million of those babies die on the day they are born. While newborn resuscitation cannot eliminate all early neonatal deaths, properly performed newborn resuscitation can save lives and reduce subsequent morbidities.

Attempts to revive nonbreathing newborns have been described throughout recorded time. In the past 50 years, significant attention has been focused on improving the scientific evidence behind the process of newborn resuscitation. Although the sophistication of resuscitation efforts has changed over time, the basic goal of inflating the newborn’s lungs and initiating spontaneous breathing has remained constant. With collaboration between the American Heart Association (AHA) and the American Academy of Pediatrics, the Neonatal Resuscitation Program (NRP) was started in 1987 to address the specific needs of the newborn. The goal of the NRP is to teach healthcare providers the cognitive, technical, and behavioral skills needed for newborn resuscitation.

To ensure that resuscitation methods taught in resuscitation training programs are based on the best available scientific evidence, the International Liaison Committee on Resuscitation (ILCOR) was formed. ILCOR meets on a regular basis to review the world’s literature on resuscitation. The findings form ILCOR reviews are translated into AHA Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Major changes to resuscitation guidelines generally occur every 5 years. The 2020 AHA guidelines on neonatal resuscitation and the content of the 2021, 8th edition, Textbook of Neonatal Resuscitation are referenced throughout this chapter.

Transition from Fetal to Extrauterine Life

The fetus exists in the protected environment of the uterus, where temperature is closely controlled, the lungs are filled with fluid, continuous fetal breathing is not essential, and the gas exchange organ is the placenta. The transition that occurs at birth requires the newborn to increase heat production, initiate continuous breathing, replace lung fluid with air/oxygen, and significantly increase pulmonary blood flow so that gas exchange can occur in the lungs. Understanding this transitional process and knowing how to effectively assist the process helps guide the practice of newborn resuscitation. The key elements necessary for a successful transition to extrauterine life involve changes in thermoregulation, respiration, and circulation.

In utero, the fetal core temperature is approximately 0.5°C greater than the mother’s temperature. Heat is produced by metabolic processes and is lost through the placenta and skin. After birth, the temperature gradient between the newborn and the environment becomes much greater, and heat is rapidly lost through radiation, convection, conduction, and evaporation. To adapt to the increased heat loss, the newborn must produce heat through other mechanisms, such as lipolysis of brown adipose tissue. If heat is lost faster than it is produced, the newborn will become hypothermic. Preterm newborns are at particular risk of increased heat loss because of immature skin, a greater surface area to body weight ratio, and decreased brown adipose tissue stores.

The fetus lives in a fluid-filled environment, and the developing alveolar spaces are filled with lung fluid. Lung fluid production decreases in the days before delivery, and the remainder of lung fluid is reabsorbed into the pulmonary interstitial spaces after delivery. As the newborn takes its first breaths after birth, a negative intrathoracic pressure of approximately 50 cm H ₂ O is generated. The alveoli become filled with air, and with the help of pulmonary surfactant, the lungs retain a small amount of air at the end of exhalation that is known as the functional residual capacity (FRC). Although the fetus makes breathing movements in utero, these intermittent efforts mobilize fluid in physiologic dead space and are not required for fetal gas exchange. Continuous spontaneous breathing is maintained after birth by several mechanisms, including the activation of chemoreceptors, decrease in hormones that inhibit respirations, and the presence of natural environmental stimulation.

Spontaneous breathing can be suppressed at birth for several reasons, most critical being the presence of acidosis due to fetal hypoxia. Dawes described the fetal breathing response to acidosis in different animal species. The physiologic effects that occur with worsening acidosis are shown in Fig. 15.1 . When the pH is decreased, animals have a relatively short period of apnea followed by gasping. The gasping rate then increases until breathing ceases again for a second period of apnea. The first apnea period (e.g., “primary apnea”) can be reversed with tactile stimulation. The second apnea period (e.g., “secondary apnea”) requires assisted ventilation to establish spontaneous breathing. At birth, the timing of the onset of acidosis is unknown, and therefore apnea in the newborn could be either primary or secondary. Therefore, tactile stimulation should be attempted in the presence of apnea at birth to resolve primary apnea, but if it is not quickly successful, assisted ventilation should be started to resolve secondary apnea. In the absence of acidosis, a newborn can develop apnea because of exposure to respiratory-suppressing medications such as maternal anesthetics, narcotics, and magnesium.

Fig. 15.1, The sequence of cardiopulmonary changes with asphyxia and resuscitation. Time is on the horizontal axis. Asphyxia progresses from left to right; resuscitation proceeds from right to left. Units of time are not given. If there is complete interruption of respiratory gas exchange, the entire process of asphyxia from extreme left to right could occur in approximately 10 minutes. It could take much longer with an asphyxiating process that only partly interrupts gas exchange or does so completely but only for repeated brief periods. With resuscitation, the process reverses, beginning at the point to which asphyxia has proceeded. The blue dotted line is the reversal of asphyxia with resuscitation.

The fetal circulation is unique because gas exchange occurs in the placenta. Fig. 15.2 outlines the changes from fetal to neonatal circulation around the time of birth. Fetal channels, including the ductus arteriosus and foramen ovale, allow most of the blood flow to bypass the lungs. In the fetus, pulmonary blood flow is approximately 8% of the total cardiac output. With the closure of the ductus arteriosus and foramen ovale after birth, the neonatal lungs receive 100% of the cardiac output. When the low-resistance placental circulation is removed after birth, the newborn’s systemic vascular resistance rises, while the pulmonary vascular resistance falls because of lung expansion, increased arterial and alveolar oxygen tension, and the release of local vasodilators.

Fig. 15.2, The fetal circulation at term: (A) before birth and (B) after birth. (A) The path of oxygenated blood returning from the placenta is shown in orange . It mixes with deoxygenated blood returning from the fetal systemic veins shown in light blue . There is intracardiac mixing of blood as shown. The upper body receives a higher oxygen content than the lower body, as deoxygenated blood enters the descending aorta via right to left flow at the ductus arteriosus. After birth, the pulmonary and systemic circulations are completely separated as shown in (B).

The average fetal oxyhemoglobin saturation averages around 50% with a range between 20% to 80% at different points in the fetal circulation. After birth, the oxyhemoglobin saturation rises gradually over the first 5 to 15 minutes of life to 90% or greater as the air spaces are cleared of fluid. In cases of disordered transition secondary to asphyxia, meconium aspiration, pneumonia, or extreme prematurity, the lungs may not be able to develop efficient gas exchange, and thus the oxygen saturation may not increase as expected. Also, in some situations the normal drop in pulmonary vascular resistance may not fully occur, resulting in decreased pulmonary blood flow, and continued right to left shunting through the aforementioned fetal channels, a phenomenon known as persistent pulmonary hypertension of the newborn.

Birth Environment and Preparation for the Delivery

The birth environment should facilitate the transition to neonatal life and accommodate the needs of a newborn resuscitation. Hospitals and birthing centers differ in their physical layouts of the birth environment and the procedures used to prepare for delivery. Wherever the resuscitation is performed, a few key elements must be considered. The room should be warm enough to prevent excessive newborn heat loss, bright enough for assessment of the newborn’s clinical status, and large enough to accommodate the necessary personnel and equipment to care for the baby. When a preterm birth is expected, the temperature in the birth environment should be set to approximately 23°C to 25°C (74°F to 77°F).

In most cases, it is possible to use perinatal risk factors to predict which newborns will need resuscitation. According to the Textbook of Neonatal Resuscitation, every birth should be attended by at least one qualified provider skilled in the initial steps of newborn care and positive pressure ventilation (PPV), whose only responsibility is managing the newborn. If risk factors are present, at least two qualified people should be present to manage the newborn. If the need for extensive resuscitation is anticipated, then a qualified team capable of performing endotracheal intubation, chest compressions, emergency vascular access, and medication administration should be present at the time of birth. Table 15.1 lists several risk factors associated with the need for mask ventilation or intubation. Using these risk factors can guide delivery attendance decisions and may improve resource utilization.

Table 15.1

Risk Factors Associated With the Need for Mask Ventilation or Intubation ^a

Adapted from Sawyer T, Lee HC, Aziz K. Anticipation and preparation for every delivery room resuscitation. Semin Fetal Neonatal Med . 2018 Oct;23(5):312–320.

	High-Risk Deliveries ^b	Very High-Risk Deliveries ^c
Preterm delivery	34–37 weeks’ gestational age	<34 weeks’ gestational age
Birth weight	2.0–2.5 kg	<2 kg
Antepartum factors	Intrauterine growth restriction Fetal anemia or isoimmunization Polyhydramnios Gestational diabetes	Fetal hydrops Other major fetal anomalies Conditions that compromise respiratory transition
Intrapartum factors	Chorioamnionitis/maternal fever Maternal general anesthesia Emergency cesarean section Intrapartum hemorrhage Placental abruption Meconium-stained amniotic fluid Fetal heart rate trace concerns Forceps or vacuum delivery Breech presentation Shoulder dystocia	Fetal bradycardia Cord prolapse Uterine rupture Acute or severe complication of labor

a There is insufficient data to determine risk factors for chest compressions or medication administration; however, the same risk factors likely apply.

b Odds ratio less than 5 as compared to term controls.

c Odds ratio ≥5 as compared to term controls.

Institutions can improve newborn resuscitation team readiness in several ways. These include simulation-based training, encouraging task-oriented role assignment, reviewing resuscitation videos, using delivery room checklists, and debriefing after resuscitations. A systematic review of simulation-based team training in neonatal resuscitation found improved team performance and technical performance in simulation-based evaluations 3 to 6 months later. Task-oriented role assignments include specific role(s), list of tasks, and the location where each newborn resuscitation team member should stand. Task-oriented role assignment training has been associated with improved behavioral skills during simulated neonatal resuscitation. Many institutions regularly review videos of newborn resuscitations as a quality improvement process to identify areas of resuscitation performance that need improvement. Current neonatal resuscitation guidelines recommend the use of a standardized checklist before every birth. An example of a checklist is shown in Fig. 15.3 . Checklist use during neonatal resuscitation has been found to be helpful in improving overall communication and rapidly identifying issues to be addressed by institutional leaders. A performance-based postresuscitation debriefing should be completed after every resuscitation. The debriefing is a critical opportunity for teams to identify what went well, what could be improved, and what issues require follow-up.

Fig. 15.3, Delivery room resuscitation checklist. DR , Delivery room; ET , endotracheal; FiO 2 , oxygen concentration; MD , medical doctor; NICO ET , NICO Monitor (Philips-Respironics, Inc.; Wallingford, CT); PIP , peak inspiratory pressure; RN , registered nurse; RT , respiratory therapist.

Umbilical Cord Management

After birth, blood flow in the umbilical arteries and vein usually continues for a few minutes. The additional blood volume transferred to the baby during this time is known as a placental transfusion. During the first 30 seconds after birth, the newborn’s blood volume can increase by at least 12 mL/kg because of placental transfusion. The timing of umbilical cord clamping influences the amount of placental transfusion and subsequent plasma and red blood cell volume of the newborn.

The benefits and risks of delayed cord clamping (longer than 30 seconds) at birth have been closely examined. Cord clamping within 30 seconds may interfere with normal transition because it leaves fetal blood in the placenta that could have gone to the newborn. Delayed cord clamping is associated with higher hematocrit after birth and better iron levels in infancy. Although developmental outcomes after delayed cord clamping have not been comprehensively assessed, iron deficiency is associated with impaired motor and cognitive development. Based on the perceived benefits, the American College of Obstetricians and Gynecologists recommends delayed cord clamping for at least 30 to 60 seconds after birth in vigorous term and preterm infants. For uncomplicated term or late preterm births, neonatal resuscitation guidelines include deferring cord clamping until after the newborn is placed on the mother and assessed for breathing and activity. Delaying cord clamping may also be reasonable in preterm newborns because it reduces the need for blood pressure support, blood transfusions, and may improve survival. Early cord clamping should be considered in cases when placental transfusion is unlikely to occur, such as maternal hemodynamic instability/hemorrhage, placental abruption, or placenta previa. There is insufficient data at this time to make a recommendation on delayed cord clamping for newborns requiring PPV after birth, but this is an area of active research.

Cord milking is an alternative to delayed cord clamping and can be used when the cord must be cut immediately after birth for medical reasons. Cord milking is performed by gently squeezing a short segment of the cord with the thumb and forefingers and slowly pushing the blood within the cord towards the newborn’s abdomen three to four times. Cord milking may be helpful for full-term newborns born by cesarean delivery, where there is a concern that delayed cord clamping may not provide an adequate placental transfusion. Compared with delayed cord clamping, cord milking results in greater blood flow to and from the heart, higher hemoglobin levels, and higher blood pressure in neonates born by cesarean delivery. Studies are ongoing to investigate the risks and benefits of umbilical cord milking in preterm newborns and in newborns requiring resuscitation. At the time of this writing, cord milking should be avoided in babies less than 28 weeks’ gestational age, because it has been associated with brain injury.

Newborn Resuscitation

Fig. 15.4 shows the neonatal resuscitation algorithm from the 8th edition (2021) Textbook of Neonatal Resuscitation. Here, we examine several concepts and interventions in the practice of neonatal resuscitation and review the evidence that supports the current neonatal resuscitation guidelines.

Fig. 15.4, 2020 Neonatal Resuscitation Algorithm.

Initial Steps

Preparing for the birth includes antenatal counseling, a team briefing, and an equipment check using a checklist. Before delivery, the following four “prebirth questions” should be asked of the obstetric team.

What is the gestational age?
Is the amniotic fluid clear?
Are there any additional risk factors?
What is the plan for umbilical cord management?

After the birth, an initial assessment includes a visual inspection of the newborn to determine if it is term gestation, has good muscle tone, and if it is breathing or crying. If the newborn is preterm, has poor muscle tone, or is not breathing or crying, it should be moved to the radiant warmer and the initial steps of newborn resuscitation should begin.

The initial steps of newborn resuscitation include warming, drying, tactile stimulation, and positioning the airway. Radiant warmers are used to maintain the newborn’s body temperature between 36.5°C and 37.5°C. For preterm and low-birth-weight newborns, warming adjuncts including plastic wraps or bags, hats, exothermic mattresses, and warmed humidified inspired gases may reduce the risk of hypothermia. Drying the newborn is done by placing the baby on a warm towel or blanket and gently drying fluid on the skin. Drying is not necessary for newborns less than 32 weeks’ gestation. Preterm infants less than 32 weeks’ gestation should be immediately covered in plastic or their torso and extremities placed inside a plastic bag to reduce evaporative heat loss. Tactile stimulation should be limited to drying and rubbing the back and soles of the feet. Appropriate positioning of the airway includes placing the newborn supine with the head in a neutral or “sniffing” position to facilitate maintenance of an open airway.

Routine suction of the airway is not indicated in newborns that are vigorous or crying. Avoiding unnecessary suctioning helps prevent reflex bradycardia resulting from laryngeal stimulation. The mouth and nose may be suctioned with a standard bulb syringe if there is visible fluid obstructing the airway, if the baby is having difficulty clearing their secretions, or if there is concern for obstructed breathing. Suctioning of secretions from the airway should be performed if the baby is not breathing, is gasping, has poor tone, and before PPV is given.

Neonates born through meconium-stained amniotic fluid are at risk of aspirating meconium and developing meconium aspiration syndrome. For many years, routine management of nonvigorous newborns with meconium-stained amniotic fluid included endotracheal intubation and tracheal suctioning to remove meconium from the trachea in hopes of preventing meconium aspiration syndrome. In 2015, after careful deliberation, the neonatal resuscitation guidelines were changed to eliminate routine tracheal intubation and suctioning due to insufficient evidence of clinical benefit and concern for possible harm. A specific concern with routine tracheal suctioning was that it delayed the start of PPV in nonvigorous newborns. Neonatal resuscitation guidelines continue to recommend against routine direct laryngoscopy and tracheal suctioning for nonvigorous newborns born through meconium-stained fluids. However, tracheal suction with a meconium aspirator can be beneficial in newborns who have evidence of airway obstruction while receiving PPV.

Positive Pressure Ventilation

Assisted ventilation with PPV is the most important step in newborn resuscitation. Approximately 3% to 5% of newborns require PPV to initiate spontaneous respirations at birth. The need for PPV is more common in preterm newborns than term newborns. The indications for PPV include apnea, gasping, and bradycardia (heart rate less than 100 bpm). A PPV rate of 40 to 60/min is recommended in newborns. PPV can be delivered noninvasively with a pressure delivery device and face mask or with a laryngeal mask airway (LMA). PPV can be delivered invasively using an endotracheal tube (ET). Pressure delivery devices used for newborn resuscitation include self-inflating bags, flow-inflating (e.g., anesthesia) bags, and T-piece resuscitators. Each device has its advantages and disadvantages. Currently, there is insufficient evidence to recommend one type of PPV device over another.

Proficiency is needed to perform effective PPV with a face mask. This is especially true when administering PPV to extremely low birth weight newborns. It is important to maintain an open airway for pressure to be transmitted to the lungs. This is done by keeping the head in a neutral position and lifting the jaw towards the mask, as opposed to pushing the mask down onto the face. The mask must make a good seal on the face for air to pass to the lungs. Leakage around the mask and airway obstruction from suboptimal airway positioning are common issues with face mask PPV. Signs that the airway is open and the face mask is well-sealed include visible chest rise with each breath and, most importantly, improvement in the newborn’s heart rate.

It is important to provide adequate pressure for ventilation; however, excessive pressure can contribute to lung injury. Initial inflation pressures of 20 to 25 cm H ₂ O are recommended. If there is no visible chest rise or improvement in the newborn’s heart rate at the initial inflation pressures, the pressures can be increased in 5 to 10 cm H ₂ O increments. In term newborns, a peak inflation pressures of 30 cm H ₂ O is usually sufficient to inflate the lungs. In preterm newborns, peak inflation pressures of 20 to 25 cm H ₂ O are usually sufficient. In some cases, however, higher inflation pressures are required. The Textbook of Neonatal Resuscitation recommends a maximum peak inspiratory pressure (PIP) of 40 cm H ₂ O.

Immaturity and surfactant deficiency result in lung collapse in preterm newborns. In animal studies, positive end expiratory pressure (PEEP) has been shown to maintain FRC during PPV and thus improve lung function and oxygenation. PEEP may be beneficial during neonatal resuscitation; however, the evidence from human studies is limited. In clinical practice, PEEP is commonly used when providing PPV to both term and preterm newborns with either a flow-inflating bag or T-piece resuscitator. The optimal PEEP has not been determined. All current human studies have used a PEEP of 5 cm H2O.

Continuous Positive Airway Pressure (CPAP)

Both term and preterm newborns need to establish a FRC as part of the transition from fetal to extrauterine life. The use of continuous pressure throughout the breathing cycle is helpful in establishing FRC and improves surfactant function. Continuous positive airway pressure (CPAP) is a form of continuous pressure that helps newborns keep their lungs open and lessens breathing difficulty in preterm infants. CPAP should only be used in spontaneously breathing newborns. CPAP is not appropriate in newborns that are apneic, gasping, or have a heart rate less than 100 bpm. CPAP is administered during resuscitation using a face mask attached to either a T-piece resuscitator or a flow-inflating bag. CPAP cannot be administered with a self-inflating bag. The desired CPAP level is achieved by adjusting the PEEP dial on the cap of the T-piece resuscitator or the flow-control valve on the flow-inflating bag. If CPAP is administered for a prolonged period, the interface can change to nasal prongs or a nasal mask attached to a CPAP device or a mechanical ventilator.

Studies comparing initial respiratory management with CPAP to endotracheal ventilation report a reduction in death and bronchopulmonary dysplasia in preterm infants < 30 weeks’ gestation. Thus, it is reasonable to use CPAP rather than intubation in spontaneously breathing preterm newborns who require respiratory support at birth. The recommended level of CPAP is 5 to 6 cm H ₂ O.

Sustained Inflation

CPAP is one method to establish FRC. Another method is to use sustained inflation. Sustained inflation is performed using either a T-piece resuscitator or a flow-inflating bag to deliver a prolonged PIP at a level of 20 to 25 cm H ₂ O for 15 to 20 seconds. Animal studies suggest that a sustained inflation may be beneficial for short term respiratory outcomes. However, a 2020 ILCOR systematic review and metaanalysis on sustained lung inflations during neonatal resuscitation at birth did not find benefit in using sustained inflations. In that analysis, sustained inflations were associated with an increased risk of death before discharge in newborns < 28 weeks’ gestation. A 2020 Cochrane systematic review examining sustained versus standard inflations during neonatal resuscitation also found no evidence to support the use of sustained inflation. The current newborn resuscitation guidelines recommend against the routine use of sustained inflations in the delivery room.

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