M. Terese Verklan

The chilling details: Hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is one of the most important complications found in the newborn period. It is the result of a deprivation of oxygen and glucose to the neural tissue, which may be the result of either hypoxemia or ischemia. Experimental animal research and clinical observations in humans have noted that the pattern of injury occurs in 2 phases. The first phase is a primary energy failure related to the insult, and then a second energy failure occurs some hours later. The combined effects of cellular energy failure, acidosis, glutamate release, intracellular accumulation of calcium, lipid peroxidation, and nitric oxide neurotoxicity destroy essential components of the cell, culminating in cell death. The clinical presentation depends on the severity, timing, and duration of the insult, with symptoms typically evolving over approximately 72 hours. Hypothermia strategies are aimed at targeting this narrow window of opportunity to ameliorate the brain injury.

Spectral Analysis of Heart Rate Variability: An Emerging Tool for Assessing Stability During Transition to Extrauterine Life

Transition from fetal to neonatal life is likely the most physiologically demanding time of life. Complex changes in major organ system functioning and reorganization of metabolic processes must occur rapidly to achieve postnatal homeostasis. Identifying the neonate with subtle signs of unsuccessful transition is a challenge to the perinatal health care provider. Alterations in fetal or neonatal heart rate and heart rate variability may serve as an indicator of the neural control influencing cardiac function and a sensitive indicator of compromised health. Evaluation of the neural control of the heart can be done noninvasively and provides a discriminating measure of the level of stress vulnerability the fetus or newborn may be experiencing. This article reviews the origins of physiological variability of the fetal and neonatal heart rate in the transition to extrauterine life. The technique of spectral analysis as a new tool for surveillance of the at-risk fetus and neonate is then introduced, and implications for clinical practice and future research avenues are discussed.

Physiologic variability during transition to extrauterine life

The first 24 hours of life can be the most precarious in a persons lifespan. Physical changes occur so quickly during the transformation from fetus to neonate that any deviations from the expected need to be identified and acted on immediately to assist the baby toward successful adaptation to extrauterine life. Newborns respond to physiologic stress by becoming less responsive, often giving few cues that a problem is arising. Transition and physiologic stability have traditionally been measured in the time domain. However, heart beat or respiratory rate per minute are gross measures that do not reliably alert the health care provider to subtle signs of stress. Physiologic variability is mainly due to the interaction of the sympathetic and parasympathetic nervous systems. Patterns in the variability may be used as indexing variables for the assessment of neurophysiologic status. Linear and non-linear analysis of the variability promises to provide a sensitive, noninvasive measure for the identification of neurophysiologic stress that can better inform the health care provider of the fetal and neonatal response to stress.

A comparison of fetal and neonatal heart rate variability at similar post-menstrual ages

Substantial differences of heart rate variability (HRV) were found between fetuses and prematurely born neonates in the high-frequency band of the power spectrum. The range of post-menstrual ages of the fetuses and neonates were closely matched in this study. Growth of HRV was observed in low-frequency and high-frequency bands, reflecting maturation of the autonomic nervous system. The higher level of fetal HRV in the high-frequency band persisted even after accounting for age-related changes. Multiscale entropy was also higher in fetuses than in prematurely born neonates. These results suggest that the autonomic balance is poorer among neonates born prematurely than in fetuses of identical post-menstrual age.

Oxygen saturation levels in the first 30 minutes of life.

PURPOSETo report a serendipitous finding from a larger investigation describing physiologic variability of healthy and sick pre- and full-term neonates transitioning to extrauterine life in whom the oxygen arterial saturations rose to 90% very quickly. SUBJECTSThirty-four healthy pre- and full-term neonates and 40 sick pre- and full-term neonates. DESIGNDescriptive, comparative. MethodsWithin the first 15–30 seconds of life, a pulse oximeter probe was placed on the dorsum of the neonates foot. The signal was uploaded from the Hewlett Packard Viridia cardiopulmonary/oxygen saturation monitor to a data acquisition module at the bedside. Healthcare personnel performed their routine caregiving procedures for the neonate beginning transition to extrauterine life. They were at liberty to administer oxygen when they felt it was clinically necessary. MAIN OUTCOME MEASURESOxygen saturation as measured by pulse oximetry. PRINCIPAL RESULTSOxygen saturation values reached higher levels much faster for all groups of neonates than what has been previously reported in the literature. CONCLUSIONSIn light of recent controversies regarding oxygen therapy, the practice of randomly administering oxygen to healthy infants at time of delivery should be examined.

Complications of Long-Term Prostaglandin E1 Use in Newborns with Ductal-Dependent Critical Congenital Heart Disease

Prostaglandin E1 (PGE1) has been used for decades in the medical treatment of ductal dependent critical congenital heart disease in neonates. The article is a report of a retrospective evaluation of the long-term effects of PGE1 in a neonatal intensive care unit in Saudi Arabia. There were 22 subjects with a wide spectrum of cardiac defects maintained on PGE1 for a mean of 38 days (range: 6-200 days). The majority of the complications included hypokalemia, hypotension, and apnea/bradycardia. Pseudo-Barett syndrome and gastric outlet obstruction were also found. While long-term administration of PGE1 is rare in North America, it is important to be aware of possible adverse effects of fluid and electrolyte imbalance, gastric outlet obstruction, and feeding difficulties.

Social Justice Considerations in Neonatal Care for Nurse Managers and Executives

This article presents the struggle between social justice and market justice within the current health care system, specifically issues affecting neonatal care. Community benefit is described and discussed as an aspect of social justice demonstrated by hospitals. The federal and state Childrens Health Insurance Program also is discussed in relation to social justice and health care costs. Implications for managers and executives overseeing neonatal care are presented in relation to the economic and social issues.

Change in complexity of fetal heart rate variability.

In a pilot study of fetal heart rate variability using magnetocardiograms it was found that substantial changes occur in complexity as the fetus matures. The self-similarity parameter increased sharply from 26 weeks to 30 weeks gestational age, while the relationship of entropy to timescale reversed during the same period. This suggests that there is distinct maturation of the autonomic nervous system during this period

Persistent pulmonary hypertension of the newborn: not a honeymoon anymore.

Persistent pulmonary hypertension of the newborn is a disorder of transition to extrauterine life, in which the newly born baby cannot decrease the high pulmonary vascular resistance and low pulmonary blood flow, characteristic of the fetus, to that of a low pulmonary vascular resistance and high pulmonary blood flow necessary for postnatal survival. The syndrome primarily affects the neonate 34 weeks postmenstrual age and greater. The article will summarize the latest understanding of the pathophysiology and review innovations in management strategies that have greatly decreased mortality and morbidity since the advent of neonatal intensive care units.

Heart Rate Variability as an Indicator of Outcome in Congenital Diaphragmatic Hernia With and Without ECMO Support

OBJECTIVE: To examine differences in the spectral power content in neonates diagnosed with congenital diaphragmatic hernia (CDH) who survive or succumb.STUDY DESIGN: A case-series study design evaluated four neonates diagnosed with CDH, two of which were supported by extracorporeal membrane oxygenation (ECMO). The electrocardiogram signal was digitized at 1000 Hz and the Lomb periodogram was computed for the series of interbeat intervals.RESULTS: Neonates with CDH who survived had log total power values greater than 2. Those with CDH who did not survive had log total power less than 2, but generally exceeded 3 while they were supported by ECMO.CONCLUSIONS: Neonates who consistently displayed increasing total spectral energies had a better outcome than those whose spectral energies were low. Subjects who succumbed expressed the lowest values, suggesting that a frequency-based evaluation of HRV may be a sensitive prognosticator of outcome that requires further investigation.