Risk Of Hypoxic-ischemic Encephalopathy Research Articles

Resuscitation of Newborn Infants with 21% or 100% Oxygen: An Updated Systematic Review and Meta-Analysis

Background: The issue of whether 21% O₂ is more effective than 100% O₂ for resuscitation of newborn infants remains controversial. Objectives: We have updated the systematic review and meta-analysis including all studies reporting resuscitation of newborn infants with 21 or 100% O₂. Methods: Randomized or quasi-randomized studies of depressed newborn infants resuscitated with 21 or 100% O₂ with or without masking of treatment were considered for inclusion. The outcomes of interest included neonatal mortality and hypoxic ischemic encephalopathy. Results: Ten studies fulfilled the inclusion criteria. Of these, 6 studies were identified as being strictly randomized. In total, 1,082 infants were allocated to resuscitation with 21% O₂ and 1,051 infants with 100% O₂. The risk of neonatal mortality was reduced in the 21% O₂ group compared to the 100% O₂group both in the analysis of all studies (typical RR 0.69, 95% CI 0.54, 0.88) and in the analysis of strictly randomized studies (typical RR 0.32, 95% CI 0.12, 0.84). A trend toward a decrease in the risk of hypoxic ischemic encephalopathy stage 2 and 3 was noted with resuscitation in 21% O₂ in the analysis of all studies (typical RR 0.88, 95% CI 0.72, 1.08). Conclusions: There is a significant reduction in the risk of neonatal mortality and a trend towards a reduction in the risk of severe hypoxic ischemic encephalopathy in newborns resuscitated with 21% O₂.

Prediction of Seizures in Asphyxiated Neonates

Early continuous video electroencephalography was used to detect seizures in term infants at high risk of hypoxic ischemic encephalopathy (HIE) in a study at University College Cork, and St Vincent’s University Hospital, Dublin, Ireland.

Does Training in Obstetric Emergencies Improve Neonatal Outcome?

The investigators report a retrospective observational study carried out at a tertiary referral maternity unit within a teaching hospital to learn whether training in how to manage obstetric emergencies improves neonatal outcomes. The cohort consisted of 19,460 singleton infants born in the years 1998 through 2003. Those with a gestational age of less than 37 weeks were excluded. The participants, a multidisciplinary group including midwives, obstetricians, and anesthetists, took part in a 1-day training course. The major outcomes were the rate of 5-minute Apgar scores of 6 or higher and the occurrence of neonatal hypoxic–ischemic encephalopathy (HIE). The morning session emphasizes cardiotocographic interpretation and uses a range of teaching methods, including a workbook with cases to be completed before the course, lectures on guidelines for fetal monitoring, small group case discussions, and instruction in documentation using a structured reportorial format. The afternoon session features obstetric emergency drill stations dealing with shoulder dystocia, postpartum hemorrhage, eclampsia, twin birth, breech presentation, adult resuscitation including cardiopulmonary resuscitation, and neonatal resuscitation. An in-house multiprofessional steering group developed all materials for the course. Women in the posttraining group (2001–2003) were older than those in the pretraining group (1998–1999) and more often nulliparous. They also were likelier to have an emergency cesarean section. The 2 groups were similar with respect to gestational age at the time of delivery and neonatal birth weights. There were significant reductions in the rates of both abnormal Apgar scores and HIE. Moderate and severe HIE tended to be less frequent in the posttraining phase of the study, but not significantly so. Rates of antepartum and intrapartum intrauterine deaths did not change during the course of the study. These findings suggest that specific training of relevant personnel in how best to manage obstetric emergencies is a practical idea and may in fact improve neonatal outcomes, specifically elevated 5-minute Apgar scores and the risk of HIE. This is the first time that an educational intervention has been associated with clinically important and lasting improvement in neonatal status.

55 Impairment of fetal growth and the risk of hypoxic ischemic encephalopathy

55 Impairment of fetal growth and the risk of hypoxic ischemic encephalopathy

Measurement of the Urinary Lactate:Creatinine Ratio for the Early Identification of Newborn Infants at Risk for Hypoxic-Ischemic Encephalopathy

Because increased urinary lactate excretion can be detected by magnetic resonance spectroscopy in hypoxic newborn infants, a study was planned to learn whether the urinary lactate and creatinine levels, measured within hours after birth, are a specific and sensitive means of predicting hypoxic-ischemic encephalopathy (HIE). Forty consecutive neonates with perinatal asphyxia, all born at 36 weeks’ gestation or later, were studied. Urinary proton magnetic resonance spectroscopy was done to determine the lactate:creatinine ratio within 6 hours of birth and again at age 2 to 3 days. Fifty-eight normal infants served as a control group. Real-time ultrasonography was done at intervals up to 10 days after birth to detect increased echogenicity or encephalomalacia. Surviving infants were assessed neurodevelopmentally at age 12 months. HIE developed in 16 of the 40 asphyctic infants but none of the control group. These groups did not differ in birth weight or gestational age. Hyperechogenicity in the basal ganglia and thalamus, as well as diffuse brain edema, were frequent findings in infants who developed HIE. The mean urinary lactate:creatinine ratio within 6 hours of birth was 16.75 in those infants who later developed HIE, 88-fold higher than in asphyctic infants who did not follow this course, and 186 times higher than in normal infants. A ratio of 0.64 or higher was 94 percent sensitive and 100 percent specific in predicting HIE. The ratio tended to increase with the severity of encephalopathy, although not to a significant degree. When they were 2 to 3 days old, infants who developed HIE still had ratios 10 times higher than normal infants and nearly 5-fold higher than asphyctic infants who did not develop HIE. Ten of 16 children who developed HIE neonatally had an adverse outcome; 5 of them had severe neurodevelopmental impairment, and 5 died before age 4 months. Only one of these infants had a postdelivery lactate:creatinine ratio of <1.00, and all but one had a ratio of 3.12 or higher. These ratios were significantly higher than in infants who had a favorable outcome. Estimating the urinary lactate:creatinine ratio by magnetic resonance spectroscopy shortly after birth can help predict which asphyctic infants will develop HIE, and thereby help guide intervention. N Engl J Med 1999;341:328–335

Asphyxial complications in the term newborn with severe umbilical acidemia

OBJECTIVE: Our purpose was to determine the relationship of umbilical acid-base status and Apgar score to neonatal asphyxial sequelae in infants with severe acidemia (pH \\lt 7.00).STUDY DESIGN: The obstetric and neonatal course of 129 term, nonanomalous singleton infants with umbilical pH \\lt 7.00 was reviewed.RESULTS: There were three stillbirths (failed resuscitation). Seventy-two of 126 (57%) were admitted to the neonatal intensive care unit. Thirty-eight percent had pulmonary dysfunction, 26% renal dysfunction, 31% cardiac dysfunction, and 31% hypoxic ischemic encephalopathy (seizures and hypotonia, n = 29; seizures only, n = 3; hypotonia only, n = 10). There were five neonatal deaths. In 109 cases umbilical arterial values were available, and among these infants there was a significant increase in the incidence of seizures with declining pH from 9% (5/57), with a pH of 6.90 to 6.99, to 80% (8/10), with a pH of 6.61 to 6.70. Respiratory acidemia (Pco2 τ 65, base deficit \\lt 10) was identified in 28 of 109 (26%), all but six occurring in the pH range above 6.90. Compared with infants with comparable umbilical artery pH, infants with respiratory acidemia did not differ significantly with respect to asphyxial end-organ injury in general (8/35 vs 6/22), but there was a trend toward a lower incidence of hypoxic ischemic encephalopathy (6/35 vs 1/22, p = 0.06). All infants with definite abnormal outcome (five neonatal deaths and 10 severe neurologic deficit) had seizures, hypotonia, and at least one other organ system dysfunction. Twenty-four of 29 infants (83%) who developed seizures had a 5-minute Apgar score \\lt 7, but only 12 of 29 (41%) \\lt had a 5-minute Apgar score of ≤ 3. Two infants with Apgar scores of 6 and 7 at 5 minutes and no evidence of nonasphyxial comorbidity subsequently manifested profound neurologic deficit.CONCLUSIONS: Infants with severe umbilical acidemia can be separated with regard to risk of hypoxic ischemic encephalopathy and abnormal neurologic outcome by consideration of the severity and composition of the acidemia and evidence of other end-organ dysfunction. Even in this pH range the Apgar score is not highly predictive of asphyxial complications. (AM J OBSTET GYNECOL 1992;162:1506-12.)

Echoencephalographic findings in neonates assciiated with maternal cocaine and methamphetamine use: Incidence and clinical correlates

Term neonates (n = 74) exposed antenatally to cocaine, methamphetamine, or cocaine and a narcotic but without any other known perinatal complications were prospectively examined with cranial ultrasonography to detect the presence of central nervous system injury. These studies were compared with those of a drug-free but clinically ill group of infants (n = 87) at risk for hypoxicischemic encephalopathy, and with those of infants who were well. Cranial abnormalities were detected by ultrasonography in 35.1% of the drug-exposed infants, similar to the incidence in the infants at risk for hypoxic-ischemic injury (p = 0.7) but significantly greater than the 5.3% incidence of abnormalities in normal infants (p less than 0.001). The lesions in the drug-exposed infants were intraventricular hemorrhage, echodensities known to be associated with necrosis, and cavitary lesions; they were focused in the basal ganglion, frontal lobes, and posterior fossa. The presence of ultrasonographic abnormalities was not predicted by standard neonatal clinical assessment or by other perinatal risk factors present in the drug-using population. The types of cerebral injury are consistent with those seen in adult cocaine and methamphetamine abusers and are probably related to the vasoconstrictive properties of these drugs. Antenatal exposure to stimulant drugs is associated with significant risk for cerebral injury, even among seemingly normal term neonates.

18 BLOOD VOLUME OF PRETERM NEONATES DURING FLUID RESTRICTION

Fluid restriction in neonates reduces the incidence of patent ductus arteriosus and introcranial hemorrhage, enhances the elimination of excess lung water, but may cause hypovolemia with impaired renal and cerebral blood flow. We studied changes in blood volume (BV) during a loss of 10% of body weight in 10 AGA infants of 750-1500g after birth, at the time of minimal weight (3.2±1.3d) and when birth weight was regained (11±3d). Plasma volume (PV) was measured by the Evans Blue dilution technique, BV and RBC mass were calculated from PV and venous HCT. Results (mean±SD; *p<0.05) are given in the table: When weight decreased by 10%. BV decreased by 7.5%. This reduction of BV was not associated with hypotension or oliguria. It may not increase the risk of hypoxic ischemic encephalopathy. Amarked fall in RBC mass and O2 capacity, despite substitution of sampled RBC's, may be of clinical relevance. To maintain RBC mass, additional RBC transfusion appears necessary.