Predicting death despite therapeutic hypothermia in infants with hypoxic-ischaemic encephalopathy

Objective: To determine precooling attributes possibly predicting death in infants with hypoxic-ischaemic encephalopathy (HIE) despite therapeutic cooling. Methods: Eighty-five consecutive infants of ≥36 weeks' gestation who received cooling for HIE were reviewed. Logistic regression analysis was performed using precooling clinical and laboratory variables with death related to HIE during the first 9 months of life as the primary outcome. Results: Thirteen (15%) of the 85 infants died during 9-18 months of follow-up despite cooling. 27 of the 85 were asystolic at birth but only 12 had Apgar scores of zero at both 5 and 10 min. Univariate analysis identified Apgar scores of zero at 5 and 10 min, pH <6.7, base deficit >22 mmol/l, and absent spontaneous movement as significantly associated with death during the first 9 months despite cooling. On multivariate analysis, only the Apgar score of zero at 10 min (p<0.001, OR 51.7, 95% CI 9.9 to 269.5) remained significantly associated with the primary outcome of death from HIE. Of the 12 infants who were asystolic at and beyond 10 min of life, nine died from HIE, two had spastic quadriparesis and global delay at 18-24 months, and one had extensive encephalomalacia on brain MRI during follow-up. Conclusions: Of the selected precooling variables, only the 10 min Apgar score is independently associated with death despite therapeutic cooling in infants with HIE. Infants who remain asystolic at 10 min and beyond are unlikely to survive despite cooling, and the rare survivor is likely to have severe disability.