Outcome prediction by motor and pupillary responses in children treated with therapeutic hypothermia after cardiac arrest*

Abstract

Clinical neurologic signs considered predictive of adverse outcome after pediatric cardiac arrest may have a different prognostic value in the setting of therapeutic hypothermia. We aimed to determine the prognostic value of motor and pupillary responses in children treated with therapeutic hypothermia after cardiac arrest. Prospective cohort study. Pediatric intensive care unit in tertiary care hospital. Children treated with therapeutic hypothermia after cardiac arrest. Thirty-five children treated with therapeutic hypothermia after cardiac arrest were prospectively enrolled. Examinations were performed by emergency medicine physicians and intensive care unit bedside nurses. Examinations were performed after resuscitation, 1 hr after achievement of hypothermia, during the last hour of hypothermia, 1 hr after achievement of normothermia, after 24 hrs of normothermia, and after 72 hrs of normothermia. The primary outcome was unfavorable outcome at intensive care unit discharge, defined as a pediatric cerebral performance category score of 4-6 at hospital discharge. The secondary outcome was death (pediatric cerebral performance category = 6). The associations between exam responses and unfavorable outcomes (as both pediatric cerebral performance category 4, 5, 6 and pediatric cerebral performance category 6) are presented as positive predictive values, for both all subjects and subjects not receiving paralytics. Statistical significance for these comparisons was determined using Fisher's exact test. At all examination times and examination categories, positive predictive values were higher for the unfavorable outcome pediatric cerebral performance category 4, 5, 6 than the pediatric cerebral performance category 6. By normothermia hour 24, absent motor and pupil responses were highly predictive of unfavorable outcome (pediatric cerebral performance category 4, 5, 6) (positive predictive value 100% and p < .03 for all categories), while at earlier times the predictive value was lower. Absent motor and pupil responses are more predictive of unfavorable outcome when defined more broadly than when defined as only death. Absent motor and pupil responses during hypothermia and soon after return of spontaneous circulation were not predictive of unfavorable outcome while absent motor and pupil responses once normothermic were predictive of unfavorable short-term outcome. Further study is needed using more robust short-term and long-term outcome measures.