Chapter 24: Neonatal Resuscitation: Pathophysiology, Organization, and Survival

Each year, an estimated 23% of the 3.5 million neonatal deaths that occur worldwide are the result of birth asphyxia. In the United States, preliminary 3.9 million children are born annually, with a reported infant mortality rate of 6.11 for the year 2011.^1,2 This suggests that every year, among US children who reach 28 weeks’ gestation, over 26,000 die prior to their seventh day of life. A significant portion of those infants who succumb do so from birth asphyxia. Further, among children reaching term gestation, 2 to 3 per 1000 live term births suffer hypoxic ischemic encephalopathy (HIE), (0.3 per 1000 severe HIE). (Table 24-1) Up to 80% of infants who survive severe hypoxic-ischemic encephalopathy develop serious complications and 10% to 20% develop moderately serious disabilities. In addition, it is widely accepted that 10% of all newborns require some assistance to begin and maintain normal breathing and that 1% require aggressive resuscitation. Thus, using the national birth rate data, annually 400,000 newborns need some help during the perinatal period, 40,000 per year require expert assistance to reverse profound cardiorespiratory depression, and 1200 per year develop severe HIE. Although there is some evidence that therapeutic hypothermia is beneficial to term newborns with moderate to severe hypoxic ischemic encephalopathy, and that cooling decreases death without increasing major disability in survivors, this therapy is not available at all centers yet as further research is being compiled. (Table 24-2).

Since, for those caring for mothers and their babies, the goal with each pregnancy is to optimize short-term and long-term outcome of both patients, steady increase in rate of late preterm births (34-36 weeks’ gestational age [GA]) over past 3 decades has also become concerning. Current data clearly point out that late preterm infants are not only likely to have much higher rate of immediate morbidity and mortality but they are also at a higher risk for developmental delay, school-related, and behavioral problems compared to full-term infants. There is also an escalating concern that some late preterm births occur not for medical but logistic reasons and it must be acknowledged that if not for medical reasons, it is much more beneficial for elective deliveries to occur at full term.

You need only to relate previously listed statistics to your own practice to appreciate the frequency with which you may encounter an infant in need of neonatal resuscitation and at risk for long-term neurodevelopmental sequelae. Unfortunately, despite best efforts by care providers, this goal is often challenged by the expected, or, even more challenging, unexpected delivery of a neonate who requires urgent medical attention for a disorder(s) threatening his/her life. Obstetric providers are, by training and experience, more skilled in adult than neonatal emergency care. As a consequence, without standards in place that direct personnel, training, and equipment, an obstetric practitioner may find himself/herself ill prepared to effectively respond to a neonatal emergency. The objective of this chapter is to offer an overview of the pathophysiology, organization, and provision of emergency medical care to the newly born patient for the obstetric primary care provider.

This chapter is not meant to replace the information found in references such as the Textbook of Neonatal Resuscitation. Instead, the reader will be guided through an approach of creating an environment conducive to facilitating optimal neonatal emergency care. This will include a brief discussion of the pathophysiology of brain injury, a description of the organization of neonatal resuscitation teams and equipment, and a review of resuscitation guidelines. Readers interested in more detail will find additional resources in the selected list of suggested readings. All obstetric clinicians will find completing Neonatal Resuscitation Program (NRP) certification useful and are encouraged to do so.

The onset of an aberration in fetal well-being marked by concerning changes in vital signs, like fetal heart rate, is a common herald of a potentially deteriorating fetus. Clinicians respond to this with measures designed to improve oxygen and energy substrate (glucose) delivery to the fetus. Ominous changes in fetal heart rate and the clinician’s response to it highlight, in great measure, one of the most concerning disturbances in homeostasis occurring to the unborn child—ischemia and hypoxemia. The result of worsening oxygen and energy delivery to the fetus is the onset of a series of changes in fetal status that must be reversed to avoid an untoward neurodevelopmental outcome. The scope of this chapter is not intended to cover prepartum management, but the same sequence of events can continue into the immediate postpartum period prompting the need for infant management. A brief review of the fetal response to hypoxia is useful (Fig 24-1).

Studies in newly born animals describe the importance of both low oxygen states and decreased cerebral flow in the development of perinatal depression and, if uninhibited, HIE. The addition of absent breathing and resulting respiratory acidosis common to clinical events distinguishes the human experience from animal research. However, from limited studies in nonhuman primates, we know that complete asphyxia results in a series of fetal responses. Initially, there is an increase in muscular activity with tachypnea followed by a period of muscular quiet and apnea (primary apnea). The apnea lasts for about 1 minute, is followed by a few minutes of gasping respirations, and simple stimulation of the baby is usually adequate to restore normal breathing. During this time the fetal heart rate is less than the allowed threshold, 100 beats per minute (beats/min). After 4 to 5 minutes without resolution, secondary apnea with progressive fetal bradycardia occurs. This is unresponsive to simple stimulation. Fetal arterial blood pressure, and as a consequence, cardiac output and cerebral blood flow have also been decreasing coincident with the lowered heart rate (Fig 24-1).

As tissues receive less and less oxygen from the combination of low fetal oxygen content and decreased cardiac output (low heart rate not compensated for by an increase in stroke volume), glycolytic pathways switch from aerobic to anaerobic. This results in increasing metabolic acidosis followed by primary energy failure from inefficient glucose utilization (recall that under aerobic conditions, a unit of glucose produces 16 times more high-energy phosphate adenosine triphosphate [ATP] than under anaerobic conditions). This further inhibits the effectiveness of myocardial contractility and a positive feedback loop develops with disastrous consequences (Fig 24-2). As this sequence of events continues, the fetus or newborn infant develops a deepening derangement in vital functions and the opportunities for recovery without sequelae rapidly diminish. The key ingredients to this are depression of fetal oxygenation, impaired cardiac output, altered central nervous system and myocardial energy stores, and neural cell death. Resuscitative efforts designed to mitigate this process as it develops are discussed in Resuscitation section. The essentials needed to develop and implement the resource capabilities required to assure state-of-the-art neonatal resuscitation are shown in Table 24-3, and will form the blueprint for the remainder of this discussion.

Identification of Peripartum Risk Factors

Anticipating the specific clinical circumstances leading to the need for neonatal resuscitation in the delivery room is very helpful. Not enough can be said for the value of time to prepare for a sick newborn. In addition, while the basics of resuscitation do not vary from one patient to the next, certain clinical situations will require the resuscitation team to be prepared to provide specific medical care beyond the usual. For example, the needs of an uncomplicated 28-week premature infant delivered for worsening maternal preeclampsia will be quite different from a term infant with particulate meconium stained amniotic fluid, or a 36-week-old child with nonimmune hydrops fetalis. Table 24-4 shows many of the more common ante- and intrapartum conditions likely to result in the initiation of neonatal resuscitation. Some of the additional requirements of children presenting under these circumstances are shown in Tables 24-5 and 24-6. An unusual example of this is the ex utero intrapartum treatment (EXIT) procedure. This operating room procedure is used when a prenatal diagnosis is made of a fetus with airway anatomy likely to make endotracheal tube intubation difficult. The delivered infant’s umbilical cord blood flow is not interrupted until airway access is secured. This allows the intubation to proceed without immediate concern for asphyxia. In addition, if a tracheotomy is anticipated, the provision of anesthetic to the maternal circulation can provide the fetus with pain relief adequate for the procedure to be performed. Thus, advance preparation will optimize even the most complex and dire delivery room events.

Team Identification

In order to function properly, each member of the resuscitation team (and back up members in the event of simultaneous resuscitations, eg, multiple gestations) should be identified for each shift. All team members should respond to high-risk deliveries and to urgent calls from the delivery room. In addition, it is standard of care for the team to attend all cesarean deliveries. A recommended team composition and delineation of responsibilities are listed in Table 24-7. Note the considerable overlap of duties. The nature of a neonatal delivery room emergency requires that all team members are capable of performing multiple tasks, as the circumstance requires. Indeed, a child who needs a thoracentesis for a spontaneous pneumothorax or large pleural effusion will need the most skilled practitioner to perform this procedure. Usually, this clinician is the one managing the airway. He/she will have to relinquish that responsibility to another to be free to emergently evacuate the chest of air or fluid. Team flexibility is a requirement rather than a luxury.

Team Training

In addition to completing and maintaining NRP certification, each team member should be responsible for participating in periodic mock codes. These training exercises are extremely valuable for evaluating the team member’s knowledge of resuscitation procedures, adequacy of communication systems and response times, and for identifying general logistical problems unique to each institution (reliability of elevators, distance to operating rooms and delivery rooms, location of personnel and adequacy of equipment, etc). After each mock and real code, a debriefing to evaluate team performance is strongly recommended. This activity creates the methodology to systematically identify and correct deficiencies noted during the code.

Communication

Critical to successfully completing a neonatal resuscitation is getting the resuscitation team to the delivery. This may seem a trite comment to make, and, therefore, one not worth making. However, once the delivering department of a hospital comes to rely upon a designated team of individuals to provide a service, no one else is likely to provide it. A simple and effective communication means the backbone of the team’s function, notifying members of the timing and location of the anticipated need. This is accomplished by facilities in many ways.

Some utilize broadcast paging. This method allows multiple so-called code pagers to be accessed with a single pager number entry. This minimizes the time required for contacting multiple parties but is vulnerable to pager battery life and black out areas. Others employ overhead paging that disturbs uninvolved patients and staff, is vulnerable to ambient noise interference and areas not served with speakers, and can be confusing. Many institutions use both of the above. Recent technological communication advances have increasingly permitted direct voice communication between staff members. This is accomplished both by localized FM transmitted telephone communications (zone phones), direct voice-to-voice technologies (modified walkie-talkies), or by digital cellular telephones with web-based direct connection to on-call clinicians. The latter permits user to call one telephone number and access the communication device of the clinician(s) on call using a web-based system that also permits the entry of backup providers. While dependent upon battery life and signal adequacy, direct voice-to-voice communication allows clinicians to share critical case-specific information while simultaneously proceeding to the location required (ie, time waiting for someone to return their page is mitigated).

Once alerted, the team should be familiarized with the details of the case to allow them to adequately prepare for any needs particular to each circumstance (Tables 24-5 and 24-6). Again, adequate preparation should not be undervalued.

Inventory and Maintenance

A list of standard equipments needed for neonatal resuscitation is presented in Table 24-8. Medications for resuscitation and their doses and indications are listed in Table 24-9. These items should be placed in the same order and in the same place at all resuscitation stations. The identification of individuals responsible for ensuring that each equipment and medication store is adequately stocked is critical. Confirmation of adequate supplies should be accomplished in each shift and after each resuscitation. Documentation of this confirmation is strongly encouraged. Inadequate supplies noted during resuscitation are inexcusable.

Since the preparation has been accomplished and the clinician is now armed with a fundamental understanding of the pathophysiology of perinatal asphyxia and has advanced warning about the clinical scenario of each case, he/she is prepared to provide emergency care to a recently delivered depressed newborn. Figure 24-3 depicts the general considerations of performing essential tasks. It is imperative not to underestimate the importance of a patent airway and adequate gas exchange. The overwhelming proportion of newborns requiring the institution of life-sustaining support in the delivery room will respond to proper oxygenation and ventilation alone. No amount of external cardiac compressions or intravenous/intratracheal epinephrine will adequately restore the heart rate and perfusion if appropriate gas exchange cannot be achieved. Medications for resuscitation and their doses and indications are shown in Table 24-9. The interested reader is again encouraged to complete NRP certification.

Tables 24-10 and 24-11 show survival and outcome data for in excess of 56,000 infants born recently in the United States. The first of the 2 tables (Table 24-10) shows pure survival by both birth weight and estimated gestational age (EGA). The second (Table 24-11) demonstrates survival without 2 significant disorders that are predictive of impaired long-term neurological development (severe intraventricular hemorrhage and retinopathy of prematurity). This format is particularly useful to the obstetric clinician since at the bedside, GA is more often used to discuss pregnancy status than is birth weight. If both birth weight and GA are known, then the tables are especially valuable. The obvious advantages of reaching birth weight higher than 1000 g and EGA of 29 weeks and more is evident. At these levels, good survival exceeds 90%. Intentional resuscitation of infants of less than 24 weeks’ gestation remains the subject of significant controversy. Families considering this option should be heavily counseled about the poor survival rates of infants born at less than 24 weeks’ gestation and the poor long-term neurodevelopmental outcome of those that do survive.

The most important resuscitation elements are understanding the capabilities and limitations of the facility, followed by temperature support, the provision of adequate ventilation and oxygenation, and reestablishing cardiovascular stability. Once these important technical aspects of perinatal resuscitation are understood and the organization and management of obstetric and pediatric emergency services are in place, what remains are the ethical and legal concerns regarding the provision of life-sustaining support. The obstetric provider is encouraged to seek out additional information regarding national- and institution-specific survival and morbidity data and state-specific statutes that govern perinatal care.