The accuracy of the Thompson score in predicting early outcome in neonates with hypoxic ischaemic encephalopathy treated with therapeutic cooling in a tertiary hospital.

BACKGROUND: Hypoxic ischaemic encephalopathy (HIE) is one of the major contributors to neonatal mortality and morbidity in developing countries. Scarcity of resources limits clinicians in optimally caring for these patients. Optimal utilisation of clinical tools such as the Thompson score (TS) can assist in improving care by classifying the severity of HIE followed by appropriate treatment.

OBJECTIVES: The primary objective was to study the correlation of the TS and early neonatal outcomes in infants with HIE who received therapeutic hypothermia (TH). Secondary objectives were to investigate the correlation of blood gas values with the TS, need for resuscitation with TS, target organ damage (TOD) with TS and the most common risk factors associated with HIE in Tembisa Provincial Tertiary Hospital (TPTH).

METHODS: This was a retrospective record review of infants admitted with HIE from January 2018 to August 2019 at the TPTH neonatal unit. Infants had to have successfully completed TH.

RESULTS: Ninety-three infants met the inclusion criteria, with 32, 48 and 13 being classified into the mild, moderate and severe categories by TS, respectively. The median length of stay (LOS) was noted to rise with a rising TS, recorded to be 7, 8 and 9 days in the mild, moderate and severe groups, respectively. The mortality rate in the study was calculated to be 2.1%, and there was no significant difference across the groups (p=0.231). A need for antiseizure medication (ASM) on discharge was significantly associated with severe HIE (p=0.028). Hypertension was a frequent chronic illness, noted in 11.3% of the mothers. The most frequent perinatal risk factor was meconium aspiration (50.5%), followed by prolonged second stage of labour (PSSL) (17.2%). A higher TS (severe group) was associated with prolonged resuscitation for >10 minutes (p=0.001) and a need for adrenaline (p=0.008). The frequency of cardiac impairment, liver impairment and clinical seizures increased with a higher TS category (p=0.23, p=0.35 and p=0.51, respectively). On blood gas analysis, a low pH and a high base deficit were associated with severe HIE (p=0.027, p=0.061 respectively).

CONCLUSION: The TS is still a useful clinical tool in the era of TH as it is able to predict some early neonatal outcomes such as LOS and a need for ASM at discharge. It is also able to demonstrate increased frequency of duration of resuscitation and a need for adrenaline in severely encephalopathic infants compared with mild. A high TS is also associated with severe metabolic acidosis and increased frequency of TOD. Maternal hypertension, meconium-stained liquor and PSSL are the common risk factors for HIE at TPTH.