Early clinical signs in neonates with hypoxic ischemic encephalopathy predict an abnormal amplitude-integrated electroencephalogram at age 6 hours.

BACKGROUND: An early clinical score predicting an abnormal amplitude-integrated electroencephalogram (aEEG) or moderate-severe hypoxic ischemic encephalopathy (HIE) may allow rapid triage of infants for therapeutic hypothermia. We aimed to determine if early clinical examination could predict either an abnormal aEEG at age 6 hours or moderate-severe HIE presenting within 72 hours of birth. METHODS: Sixty infants ≥ 36 weeks gestational age were prospectively enrolled following suspected intrapartum hypoxia and signs of encephalopathy. Infants who were moribund, had congenital conditions that could contribute to the encephalopathy or had severe cardio-respiratory instability were excluded. Predictive values of the Thompson HIE score, modified Sarnat encephalopathy grade (MSEG) and specific individual signs at age 3-5 hours were calculated. RESULTS: All of the 60 infants recruited had at least one abnormal primitive reflex. Visible seizures and hypotonia at 3-5 hours were strongly associated with an abnormal 6-hour aEEG (specificity 88% and 92%, respectively), but both had a low sensitivity (47% and 33%, respectively). Overall, 52% of the infants without hypotonia at 3-5 hours had an abnormal 6-hour aEEG. Twelve of the 29 infants (41%) without decreased level of consciousness at 3-5 hours had an abnormal 6-hour aEEG (sensitivity 67%; specificity 71%). A Thompson score ≥ 7 and moderate-severe MSEG at 3-5 hours, both predicted an abnormal 6-hour aEEG (sensitivity 100 vs. 97% and specificity 67 vs. 71% respectively). Both assessments predicted moderate-severe encephalopathy within 72 hours after birth (sensitivity 90%, vs. 88%, specificity 92% vs. 100%). The 6-hour aEEG predicted moderate-severe encephalopathy within 72 hours (sensitivity 75%, specificity 100%) but with lower sensitivity (p = 0.0156) than the Thompson score (sensitivity 90%, specificity 92%). However, all infants with a normal 3- and 6-hour aEEG with moderate-severe encephalopathy within 72 hours who were not cooled had a normal 24-hour aEEG. CONCLUSIONS: The encephalopathy assessment described by the Thompson score at age 3-5 hours is a sensitive predictor of either an abnormal 6-hour aEEG or moderate-severe encephalopathy presenting within 72 hours after birth. An early Thompson score may be useful to assist with triage and selection of infants for therapeutic hypothermia.

Early clinical predictors of a severely abnormal amplitude-integrated electroencephalogram at 48 hours in cooled neonates.

AIM: There is a need to identify infants with hypoxic ischaemic encephalopathy who have a poor outcome despite therapeutic hypothermia. A severely abnormal amplitude-integrated electroencephalogram at 48 h predicts death or disability. Our aim was to determine whether clinical assessment at age 3-5 h predicts a severely abnormal amplitude-integrated electroencephalogram at 48 h or death in cooled infants. METHODS: Forty-one cooled infants, ≥36 weeks' gestation, with moderate-to-severe hypoxic ischaemic encephalopathy, were prospectively enrolled. Infants who were moribund, had congenital conditions associated with encephalopathy or had severe cardio-respiratory instability were excluded. The predictive abilities of the Thompson encephalopathy score and individual signs at age 3-5 h were assessed. RESULTS: All infants with a Thompson score ≥16 at 3-5 h had a severely abnormal amplitude-integrated electroencephalogram at 6 h and an abnormal short-term outcome. At 48 h, 75% had a severely abnormal aEEG or died vs. 18% with a score <16 (p = 0.004). Multivariate analysis did not find a significant independent association with any of the individual signs. CONCLUSION: The Thompson score could be useful to identify infants who will have a poor outcome despite cooling. A score ≥16 should be validated as a prespecified variable in prospective studies.

Defining hypoxic ischemic encephalopathy in newborn infants: benchmarking in a South African population.

OBJECTIVES: There are few population-based studies of hypoxic ischemic encephalopathy (HIE) in sub-Saharan Africa, and the published criteria that are used to define and grade HIE are too variable for meaningful comparisons between studies and populations. Our objectives were (1) to investigate how the incidence of HIE in our region varies with different criteria for intrapartum hypoxia and (2) to determine how encephalopathy severity varies with different grading systems. METHOD: We reviewed the records of infants with a diagnosis of HIE born between September 2008 and March 2009 in public facilities in the Southern Cape Peninsula, South Africa.The incidence of HIE was calculated according to four definitions of intrapartum hypoxia and graded according to three methods. RESULTS: Depending on which defining criteria were applied,the incidence of HIE varied from 2.3 to 4.3 per 1000 live births, of mild HIE ranged from 0.4 to 1.3 per 1000 live births, and of moderate-severe HIE ranged from 1.5 to 3.7 per 1000 livebirths. Ninety-seven of the 110 (88%) infants reviewed had at least one intrapartum-related abnormality. Only 62 (56%) infants had a blood gas performed in the fi rst hour of life. CONCLUSION: The incidence and grade of HIE can vary more than 2-fold in the same population, depending on which defining criteria are used. Consensus definitions are needed for benchmarking.