What's New in Neonatal Resuscitation

By Lewis Otero, M.D.

Introduction

Ten percent of all infants born require some intervention at birth, and about one infant in one hundred needs extensive resuscitation efforts to survive. Successful resuscitation by a skilled health care professional is a gratifying experience and prevents problems that can last a lifetime.

This article will review the newest recommendations and special considerations about neonatal resuscitation. In addition, current areas of investigation related to newborn resuscitation will be highlighted, especially as they seek to resolve conflicting evidence or opinions.

History

In 1966 national guidelines for resuscitation of adults were initially recommended. Twelve years later, a working group on pediatric resuscitation was formed by the American Heart Association Emergency Cardiac Care Committee and concluded that resuscitation of newborns should focus on efforts to establish adequate ventilation rather than cardiac defibrillation. In 1985 the American Academy of Pediatrics and the American Heart Association expressed a joint commitment to developing a training program aimed at teaching the principles of neonatal resuscitation. By 1998, more than one million health care providers had been trained in the techniques of neonatal resuscitation.

The AHA conducts periodic International Cardiopulmonary Resuscitation and Emergency Cardiac Care (CPR - ECC) conferences every 5 to 8 years to establish guidelines for resuscitation of all age groups and for all causes of cardiopulmonary arrest. The AAP formally joined the process in 1992 for development of the guidelines for resuscitation of children and newborns. The most recent CPR-ECC conference was held in Dallas in February 2000, and was preceded by a September 1999 Evidence Evaluation Conference which was designed to collect as much published evidence as possible for the February 2000 deliberations.

Recommendations: How were they formulated?

Using questions and controversies identified during the consensus process, members of the participating organizations worked with additional topic experts from various countries to assemble the most current scientific information relating to neonatal resuscitation. From this integration process emerged a class of recommendations for each proposed guideline, based on the level of evidence and critical assessment of the quality of studies, as well as the number of studies, consistency of conclusions, outcome measured, and magnitude of benefit. The proposed guideline changes, as well as their class of recommendation and level of evidence were presented for final debate and ratification at the Guidelines 2000 Conference (February 2000).

The guidelines represent the most effective practices for resuscitation of the newborn infant, based upon current research, knowledge, and experience. They are intended to serve as the foundation for educational programs and national, regional, and local processes, which establish standards of practice.

Major Guidelines Changes

Resuscitation involving meconium (Class I Recommendation)

Twenty to thirty percent of meconium stained infants will have meconium in the trachea despite suctioning, suggesting that intrauterine aspiration occurs in depressed fetuses. As in the past, the person delivering the baby should suction the oropharynx and nares with a catheter or bulb syringe before delivering the shoulders. Subsequent neonatal intervention hinges upon the condition of the infant. For depressed meconium-stained infants, it is recommended that direct laryngoscopy be performed immediately following delivery to suction residual meconium from the hypopharynx (under direct visualization) followed by intubation and direct suctioning of the trachea. The new recommendations, however, advise not to intervene in vigorous infants regardless of the characterization of the meconium-stained amniotic fluid, because the best evidence suggests that laryngoscopy and tracheal suctioning will not improve outcome but rather may increase the risk of complications.

Chest Compression

Previously, it had been recommended to initiate cardiac compressions in a newborn if the heart rate was in the range of 60 to 80 beats per minute and the heart rate was not increasing. In practice, provision of cardiac compressions can sometimes interfere with the provision of effective ventilation. Because no scientific data suggests an evidence-based resolution on the optimal heart rate at which to begin chest compressions, the International Liaison Committee on Resuscitation (ILCOR) Working Group recommended that compression be initiated for a heart rate below 60 beats per minute based on construct validity (easy teaching and skill retention).

Compression Technique (Class IIb Recommendation)

Available data suggest that the two thumb-encircling hands technique may offer some advantages in generating peak systolic and coronary perfusion pressure compared to the two-finger technique. The ILCOR Working Group recommended a relative rather than absolute depth of compression (i.e., compress to approximately one-third of the antero-posterior diameter of the chest) to generate a palpable pulse. This recommendation was based on a consensus in the absence of specific data about ideal compression depth.

Volume Expanders (Class IIb Recommendation)

The acceptable volume expanders are normal saline, Ringer's lactate, and O negative blood cross-matched with mother's blood if time permits. Albumin-containing solutions are no longer the fluid of choice for initial volume expansion due to limited availability, risk of infectious disease, and an observed association with increased mortality. Volume overload or complications such as intracranial hemorrhage may result from inappropriate intravascular volume expansion in asphyxiated newly born infants as well as in preterm infants.

Avoidance of Hyperthermia (Class III Recommendation)

The importance of a neutral thermal environment to the survival of sick newborn infants has long been recognized. The unfavorable circumstances in the delivery room make low body temperature a common outcome of resuscitation. Subsequent rewarming of the infant may result in hyperthermia. Recent observations of infants born to mothers who had chorioamnionitis and women who elected epidural anesthesia provide evidence that maternal fever predisposes to respiratory depression in the infant immediately after delivery. Evidence from animal models and extrapolations of research in older infants and adults provide additional suggestions of harm from hyperthermia. Potentiation of injury after perinatal hypoxic-ischemic insult has been demonstrated in animals. Extension of infarct size and worsening of outcome after ischemic stroke has been documented in adults. An association has been observed between maternal perinatal infection and later cerebral palsy in the offspring. Therefore, efforts to maintain temperature within the neutral thermal zone should continue, and measures to avoid excessive heat loss as well as institution of early monitoring and careful control of temperature are justified.

Initial Evaluation and Implementation of Resuscitation Steps

Recommendations about how to evaluate an infant and how to implement the resuscitation steps have been changed to use a more "integrated" approach, in which the infant's risk factors, appearance, and color are evaluated simultaneously as the initial steps of resuscitation are administered. Then respiration, heart rate, and color are evaluated again as a near-simultaneous process while deciding what further intervention is required.

Assessment integrated:

• Clear of meconium?
• Breathing or crying?
• Good muscle tone?
• Color pink?
• Term gestation?

Evaluation integrated:

• Respiration
• Heart rate
• Color

There are two heart rates to remember: 60 and 100 beats per minute. A heart rate below 60 beats per minute indicates that additional resuscitation steps are needed. A heart rate above 100 beats per minute usually indicates that resuscitation procedures can be stopped.

Special Considerations

Discontinuation of Resuscitation (Class IIb Recommendation)

Discontinuation of resuscitation is appropriate if resuscitation of an infant with cardiorespiratory arrest does not result in spontaneous circulation in 15 minutes. Resuscitation of newborn infants after 10 minutes of asystole is very unlikely to result in survival or survival without severe disability. Local discussions to formulate guidelines consistent with local resources and outcome data are recommended.

Noninitiation of Resuscitation (Class IIb recommendation)

Noninitiation of resuscitation in the delivery room is appropriate for conditions such as:

• Newborn with confirmed gestation of less than 23 weeks or birth weight less than 400 gm.
• Anencephaly
• Babies with confirmed trisomy 13 or 18

The usual techniques used for obstetrical dating are accurate only to ±1-2 weeks. Before deciding not to resuscitate, antenatal predictions should be confirmed by visual examination of the infant. If doubt exists after assessment, initial resuscitation and provision of life support allows time to gather more complete clinical information and to permit more input from the family. Withdrawal of support following collection of such data and discussion with the parents may then be appropriate. The limits of viability have undergone considerable change over the past 30 years; however, no advances are anticipated that will extend the possibility of survival below 22 weeks.

Resuscitation Outside the Hospital

The priority for resuscitating infants during the newborn period, regardless of location, should be to restore adequate ventilation. Strategies to resuscitate outside the hospital or beyond the immediate newborn period should give special attention to temperature control, clearing the airway, ventilation, vascular access, and medications.

Intraosseous access can serve as an alternative route for medications and volume expansion if umbilical vein or other venous access is not readily available (Class IIb recommendation). Epinephrine remains the first drug to use when heart rate persists below 60 beats per minute despite adequate ventilation and chest compression.

Application of Techniques from other Settings

Exhaled Carbon Dioxide Detection

Available data suggests that exhaled carbon dioxide detection is most useful to confirm appropriate endotracheal tube placement in infants who weigh more than 2000 grams in whom adequate lung expansion has been established and who have adequate cardiac output. There is higher incidence of false negative results with exhaled carbon dioxide detectors in extremely low-birthweight infants or asphyxiated infants who are failing to respond to resuscitative efforts. The visible color change of carbon dioxide detection devices depends on a minimum concentration of the gas reaching the detector. Pulmonary expansion and gas exchange may be inadequate to deliver the required concentration of carbon dioxide to the detector device in cases immediately after delivery, as the lungs transition from fluid-filled to air-filled. In such a circumstance, the detector device gives a false-negative reading, prompting withdrawal of the endotracheal tube when, in fact, the necessary action is ventilation with higher pressures or longer inspiratory times to establish adequate lung expansion and increase pulmonary blood flow.

Laryngeal Mask Airway

The laryngeal mask airway (LMA) has been used extensively in Great Britain and Australia, especially under controlled circumstances in the operating room. The device consists of a cushioned, inflatable mask that seats around the glottic opening, occluding the esophagus and effectively isolating the airway so inflating gas is directed into trachea. Several studies have examined the use of the LMA in the delivery room, but certain conditions limit its use, including extremely low birth weight infants because of the

size of the smallest laryngeal mask device. The use of the LMA is excluded in meconium-stained infants where endotracheal intubation skills are necessary. Finally, considerable training and experience are required for atraumatic and efficient insertion of the LMA. The LMA cannot replace endotracheal intubation, but it may offer a good alternative in cases like Pierre-Robin sequence, when prone positioning and a nasopharyngeal tube fail to maintain a stable airway.

Post-resuscitation Issues

Supporting or ongoing care, monitoring, and appropriate diagnostic evaluation are required after resuscitation. After admission to the nursery, it is important to monitor arterial oxygen saturation and blood glucose as well as to check the cord blood gas values and the initial postnatal arterial blood gas and hematocrit. Possible complications include persistent pulmonary hypertension, pneumonia, pneumothorax, hypotension, renal failure, seizures, apnea, hypoglycemia, and hypothermia. For all of these reasons, newborn infants continue to require careful observation following a successful resuscitation.

Areas of Current Investigation

Cerebral Hypothermia

Extensive evidence in animal models and extrapolated evidence from adult stroke and head trauma victims and pediatric near-drowning survivors supports the potential for improved outcome following hypothermia. Prospective data in human infants are limited. A pilot study of whole body hypothermia for neonatal encephalopathy concluded that prolonged mild hypothermia was associated with only minor physiologic abnormalities. Two large, randomized, controlled trials of hypothermia are in progress, and their results will be informed in the next guideline revision. These results may modify our approach of post-resuscitation stabilization for certain infants who have suffered hypoxic-ischemic injury.

Room Air versus 100% Oxygen

Markers of increased oxidative stress have been identified in the cord blood and at 30 days of age in infants resuscitated with 100% oxygen. Molecular, biochemical, and pathologic studies generally have demonstrated equivalence or superiority of room air compared with 100% oxygen for assisted ventilation. Two prospective controlled trials comparing resuscitation of asphyxiated infants with room air O2 have concluded that infants resuscitated with room air exhibit shorter time to first cry. No differences in mortality at 7 to 28 days or the occurrence of hypoxic-ischemic encephalopathy were observed.

The significance of oxygen-free radical injury with respect to neurologic outcome, acute and chronic lung injury, and other organ damage remains uncertain. The available studies of pulmonary physiology with room air versus 100% oxygen have provided sufficient data to state that when supplemental oxygen is unavailable, resuscitation of the newborn should be initiated with positive pressure ventilation and room air. Additionally, the molecular evidence of oxygen-free radical generation and persistence has reinforced the emphasis of normoxia as the goal of supplemental oxygen use during resuscitation. Maintainance of normoxia is more feasible with present advances in oxygen delivery and monitoring systems.

Emergence of Conflicting Evidence

High dose epinephrine

The present indication for use of epinephrine is if the heart rate remains below 60 beats per minute after giving 30 seconds of coordinated chest compressions and ventilation. The dose given is 0.1 to 0.3 ml of 1:10,000 solution. Either intravenous or intratracheal administration is acceptable. Two small case series in pediatric patients suggested that high dose epinephrine resulted in additional cases in which spontaneous circulation returned. However, high-dose epinephrine failed to improve survival or neurologic outcome in any of the studies. Two recent retrospective cohort studies failed to show any difference in survival to hospital discharge, and the neurologic outcome among survivors was poor. Presently, there are no controlled trials using high-dose epinephrine in neonates. The present data shows no evidence to support potential benefits in newborns.

Future Research for Neonatal Resuscitation

Many of the basic principles of neonatal cardiopulmonary resuscitation are based on accepted practice rather than research data. New proposals for guideline recommendations are emerging. Modifications of current guidelines will undoubtedly be made based on the scrupulous analysis of new data gathered by ongoing and future research.

Evaluation of the teaching and performance of neonatal resuscitation cannot be overlooked. Such educational evaluation begins with measuring acquisition and retention of cognitive knowledge and skills, but also extends to monitoring of performance and documentation of impact on the ultimate outcomes of survival and the quality of life among survivors.

References

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Jacksonville Medicine / December, 2001