Evolution of early cerebral NIRS in hypoxic ischaemic encephalopathy

Abstract Aim To describe early cerebral oxygenation (cSO 2 ) and fractional tissue oxygen extraction (FTOE) values and their evolution over the first days of life in infants with all grades of hypoxic‐ischaemic encephalopathy (HIE) and to determine whether cSO 2 and FTOE measured early (6 and 12 h) can predict short‐term outcome. Methods Prospective, observational study of cerebral near‐infrared spectroscopy (NIRS) in infants >36 weeks' gestation with HIE. Ten one‐hour epochs of cSO 2 and FTOE were extracted for each infant over the first 84 h. Infants with moderate and severe HIE received therapeutic hypothermia (TH). Abnormal outcome was defined as abnormal magnetic resonance imaging (MRI) and/or death. Results Fifty‐eight infants were included (28 mild, 24 moderate, 6 severe). Median gestational age was 39.9 weeks (IQR 38.1–40.7) and birthweight was 3.35 kgs (IQR 2.97–3.71). cSO 2 increased and FTOE decreased over the first 24 h in all grades of HIE. Compared to the moderate group, infants with mild HIE had significantly higher cSO 2 at 6 h ( p = 0.003), 9 h ( p = 0.009) and 12 h ( p = 0.032) and lower FTOE at 6 h ( p = 0.016) and 9 h (0.029). cSO 2 and FTOE at 6 and 12 h did not predict abnormal outcome. Conclusion Infants with mild HIE have higher cSO 2 and lower FTOE than those with moderate or severe HIE in the first 12 h of life. cSO 2 increased in all grades of HIE over the first 24 h regardless of TH status.