Cerebral Hemodynamic Monitoring via Transcranial Doppler Ultrasound and Near-Infrared Spectroscopy for Risk-Stratified Pediatric Cardiac Surgery Patients

Background: The objective of this study was to evaluate mean cerebral blood flow velocity, gaseous microemboli (GME) counts, regional cerebral oxygen saturation (rSO₂), and clinical outcomes using multimodality neuromonitoring in risk-stratified congenital cardiac surgery patients and by cyanotic and acyanotic heart disease. Methods: A total of 377 pediatric patients undergoing congenital cardiac surgery with cardiopulmonary bypass (CPB) were stratified by the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) mortality categories and by classification of cyanotic and acyanotic heart disease. Intraoperative mean cerebral blood flow velocity, GME counts, and rSO₂ were assessed at multiple time points. Clinical outcomes were compared between patients of each STAT mortality category and cyanotic classification. Results: Mean cerebral blood flow velocities of STAT Mortality Category 5 patients decreased drastically from baseline values after cross-clamp (down to 56%) and after off-bypass (down to 32%), while rSO₂ values increased significantly during CPB. Patients in STAT mortality category 5 experienced higher GME counts (1.3- to 4.4-fold greater) compared with patients in all other STAT categories. When compared with acyanotic patients, cyanotic patients experienced significantly lower mean blood flow velocity, significantly greater rSO₂ during CPB, and greater GME counts than acyanotic patients (1.3-fold greater). Although 29 patients experienced neurological injury confirmed by electroencephalogram and magnetic resonance imaging, instances of injury were not correlated with GME counts among risk-stratified and cyanotic versus acyanotic patients. Conclusions: Utilization of intraoperative transcranial Doppler, in addition to near-infrared spectroscopy, may help to identify other parameters for cerebral protection, such as drastically decreased cerebral blood flow velocity and increased cerebral microemboli counts, particularly in STAT Mortality Category 5 and cyanotic patients.