Does abnormal Doppler on cranial ultrasound predict disability in infants with hypoxic-ischaemic encephalopathy? A systematic review

Aim: To evaluate whether abnormal resistive index or cerebral blood flow velocity (CBFV) on cranial ultrasound predicts disability (≥1 year) in infants with hypoxic-ischaemic encephalopathy (HIE). Method: This was a systematic review and meta-analysis of studies comparing developmental outcomes of infants with HIE with normal versus abnormal resistive index or CBFV. Results: Twenty-six studies were included (pre-therapeutic hypothermia era, 20; therapeutic hypothermia era, six). Data from 15 studies (pre-therapeutic hypothermia, 10; therapeutic hypothermia, five) were available for meta-analysis. Pooled sensitivity and specificity, summary area under the receiver operating characteristic curve, and diagnostic odds ratio of resistive index or CBFV for predicting ‘death or severe disability’ were as follows. Pre-therapeutic hypothermia era: 0.83 (95% confidence interval [CI] 0.45–0.97) and 0.92 (95% CI 0.74–0.98), 0.94 (95% CI 0.92–0.96), 54 (95% CI 7–391). Therapeutic hypothermia era (measurements before therapeutic hypothermia): 0.62 (95% CI 0.41–0.80) and 0.96 (95% CI 0.88–0.99), 0.93 (95% CI 0.89–0.94), 23 (95% CI 6–91). Therapeutic hypothermia era (measurements during/after therapeutic hypothermia): 0.51 (95% CI 0.24–0.78) and 0.83 (95% CI 0.73–0.90), 0.81 (95% CI 0.78–0.85), 5 (95% CI 2–13). Overall Grading of Recommendations Assessment, Development and Evaluation (GRADE) rating of evidence was ‘low’ or ‘very low’. Interpretation: Low-level evidence suggests that abnormal resistive index or CBFV can predict death or disability with high sensitivity and specificity in infants with HIE who are not cooled. The specificity of these tests was high when performed before starting cooling in infants who received therapeutic hypothermia.