Prospective validation of a scoring system for predicting neonatal morbidity after acute perinatal asphyxia

doi:10.1016/S0022-3476(98)70349-X

The Journal of Pediatrics

Volume 132, Issue 4, April 1998, Pages 619-623

https://doi.org/10.1016/S0022-3476(98)70349-X Get rights and content

Abstract

Objective: To prospectively validate a previously reported scoring system for identifying the near-term infant at risk for the multiple organ system sequelae of acute perinatal asphyxia. Study design: Prospective observational study. Setting: Three Denver teaching hospitals, each providing comprehensive obstetric care. Subjects: Newborn infants of 36 weeks or more gestation. Intervention: None. Statistical analysis: Chi-squared analysis with Fisher's exact test. Outcome: Scores consisting of graded abnormalities in fetal heart rate monitoring, umbilical arterial base deficit, and 5-minute Apgar score were calculated by the research nurse after admission of the infant to the nursery (range of possible scores, 0 to 9). A second nurse, blinded to these data, prospectively followed the newborn's hospital course for multiple organ system morbidity. Results: Three thousand two hundred thirty-eight newborns were studied; 366 required neonatal intensive care unit admission. Eleven newborns had a score ≥ 6 (mean umbilical artery pH = 6.98, base deficit = 17.1 mEq/L). Morbidities in these 11 newborns included seizures (2), hypoxic-ischemic encephalopathy (5), respiratory distress (9), hypotension (7), renal dysfunction (9), hypoglycemia/hypocalcemia (4), and thrombocytopenia or disseminated intravascular coagulopathy (3). The odds ratio (OR) and 95% confidence interval (CI) for newborns admitted to the neonatal intensive care unit with a score ≥ 6 for having multiple organ system morbidity, defined as three or more affected organ systems, was 38.5 (95% CI, 9.2 to 127.8). The scoring system showed a stronger relationship with multiple organ system morbidity than did isolated individual indicators commonly used to identify asphyxia calculated on the same subjects: for those with pH < 7.00, OR 24 (95% CI, 6.4 to 94.1); base deficit ≥ 10 mEq/L, OR 4.5 (95% CI, 1.9 to 10.3), and 5-minute Apgar score ≤ 3, OR 7.4 (95% CI, 1.3 to 38.1). Conclusion: This scoring system, encompassing both immediate intrapartum and postpartum measures and acid-base status proximate to the time of delivery, is useful for rapidly identifying the term and near-term newborn at risk for multiple organ system morbidity after acute perinatal asphyxia. (J Pediatr 1998;132:619-23)

Section snippets

Methods

Enrollment in this observational study was open to all infants of 36 or more weeks' gestation with available scoring measures at the three participating Denver hospitals (Fitzsimons Army Medical Center, University Hospital, and Denver General Hospital) from October 1988 through October 1990. Each of these hospitals serve diverse obstetric populations with both high-risk and uncomplicated gestations and each has Level II and Level III neonatal intensive care unit capabilities. Electronic FHR

RESULTS

We enrolled 3238 newborns in the study; 366 required NICU care, representing 11.3% of the enrolled newborns. This report encompasses all subjects of ≥36 weeks' gestation requiring NICU care at the participating hospitals. Among those subjects admitted to Level II and III beds, the three most common final diagnoses were rule-out sepsis, unspecified respiratory distress, and hypoglycemia.

The median score of the 366 infants admitted to NICUs was 1, not suggestive of significant asphyxia or great

DISCUSSION

We have demonstrated the validity of a clinical scoring system, encompassing graded abnormalities of intrapartum FHR monitoring, umbilical arterial BD, and the 5-minute Apgar score for identifying newborns ≥ 36 weeks' gestation at risk for the multiple organ system sequelae of acute perinatal asphyxia. By using measures that are both readily available to the clinician and well recognized for their ability to identify at-risk fetuses and newborns, we believe that this scoring system allows for

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Threshold of metabolic acidosis associated with newborn cerebral palsy: medical legal implications
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Citation Excerpt :
There was a significant increase in the rate of death with BD ≥25 mmol/L, compared with BD ≥20 mmol/L, but no report of increased infant disability. Studies that have reported scoring systems for the prediction of neonatal morbidity after acute perinatal asphyxia have not demonstrated a predictive value of increasing umbilical artery BD but rather use only the threshold BD.57–60 In fact, several studies emphasize that the degree of fetal acidemia does not correlate with long-term neurodevelopmental sequela.61–63
Obstetricians and gynecologists belong to 1 of the medical specialties with the highest rate of litigation claims. Among birth injury cases, those cases with cerebral palsy outcomes account for litigation settlements or judgments often in the millions of dollars. In cases of potential perinatal asphyxia, a threshold level of metabolic acidosis (base deficit ≥12 mmol/L) is necessary to attribute neonatal encephalopathy to an intrapartum hypoxic event. With increasing duration or severity of a hypoxic stress resulting in metabolic acidosis, newborn infant umbilical artery base deficit increases. It may be alleged that, as base deficit levels increase beyond 12 mmol/L, there is an increased likelihood and severity of cerebral palsy. As a corollary, it may be claimed that an earlier delivery (by minutes) would reduce the base deficit and prevent or reduce the severity of cerebral palsy. This issue is of relevance to obstetricians as defendants, because retrospective “expert” analysis of cases may suggest that optimal management decisions would have resulted in an earlier delivery. In addressing the association of metabolic acidosis and cerebral palsy, base deficit should be measured as the extracellular component (base deficit_{extracellular fluid}) rather than the commonly used base deficit_blood. Studies suggest that, beyond the base deficit threshold of 12 mmol/L, the incidence and severity of cerebral palsy does not significantly increase (until ≥20 mmol/L), although the risk of neonatal death rises markedly. Thus, among most infants with hypoxia-associated neonatal encephalopathy, the occurrence of cerebral palsy is unlikely to be impacted by delivery time variation of few minutes, and this argument should not serve as the basis for medical legal claims.
Intrauterine, Intrapartum Assessments in the Term Infant
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The assessment of fetal well-being is a critical tool in ensuring optimal neonatal outcomes from both pregnancy and labor. This is particularly relevant for the recognition of the infant that may be at risk of hypoxic-ischemic cerebral injury. The identification of an intrauterine disturbance in gas exchange between the human fetus and mother (i.e., asphyxia) or the likelihood that such a disturbance will occur during labor or delivery is critical to improving the neurological outcomes for all infants, particularly those at greatest risk such as the growth-restricted infant. Moreover, attempts at prevention of the brain injury caused by intrauterine asphyxia, antepartum and intrapartum, demand precise awareness of when such injury is imminent. Although the most definitive information concerning the detection of hypoxic-ischemic insult to the fetus still applies primarily to the intrapartum period, major advances in antepartum assessment have been made. Thus, this chapter reviews the major current means of antepartum assessment of the fetus and then the approach to intrapartum assessment. In addition, we briefly summarize novel fetal and placental imaging techniques using magnetic resonance imaging.
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Neonatal encephalopathy occurs in 2 to 5/1000 live births and is principally related to hypoxic-ischemic injury to the newborn brain in the immediate peripartum period. In the last decade, there have been significant advances in neuroprotection that have been successful in reducing the risk of death and disability in infants who have suffered from a potential hypoxic-ischemic cerebral injury. The advent of therapeutic hypothermia has led to a major focus on the early clinical recognition of infants that may benefit from such therapies. In addition, optimal recognition and therapeutic targeting of neonatal seizures, with other neuroprotective approaches, have been emphasized. This chapter will summarize the clinical presentation, neuropathological correlates, neurodiagnostic evaluation, prognosis, and management of this condition.
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Our objective was to identify perinatal risk factors that are available within 1 hour of birth that are associated with severe brain injury after hypothermia treatment for suspected hypoxic-ischemic encephalopathy.
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Worsening metabolic acidosis at birth, longer time to spontaneous respirations, and lack of exposure to oxytocin correlated with severe brain injury in neonates who were treated with whole-body hypothermia. These risk factors may help quickly identify neonatal candidates for time-sensitive investigational therapies for brain neuroprotection.
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^☆: From the Department of Pediatrics, Newborn Medicine Service, Fitzsimons Army Medical Center, Denver, Colorado; Perinatal Clinical Research Center, University Hospital, Denver, Colorado; and Department of Pediatrics, Lubchenco Perinatal Centers, University of Colorado School of Medicine, Denver, Colorado.

^☆☆: Supported by Grant No. 5MO1 RR00069 General Clinical Research Centers Program, National Centers for Research Resources, National Institutes of Health.

^★: Reprint requests: Gerald B. Merenstein, MD, Lubchenco Perinatal Centers, University of Colorado School of Medicine, 4200 East Ninth Ave., Box C-219, Denver, CO 80262.

^★★: 0022-3476/98/$5.00 + 0 9/21/83079

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Prospective validation of a scoring system for predicting neonatal morbidity after acute perinatal asphyxia☆,☆☆,★,★★

Abstract

Section snippets

Methods

RESULTS

DISCUSSION

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Am J Obstet Gynecol

Am J Obstet Gynecol

Clin Perinatol

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Clin Perinatol

Systematic pH-measurements in the umbilical artery: causes and predictive value of neonatal acidosis

J Perinat Med