Impact of Intraoperative Hypotension and Blood Loss on Brain Damage Biomarkers in Metopic Craniosynostosis Surgery

Background: Recent studies show that levels of the brain injury biomarkers glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) are elevated postoperatively in infants undergoing surgery for craniosynostosis. The aim of this study was to investigate the relationship between intraoperative hypotension and blood loss on biomarker levels. Methods: This retrospective study included all consecutive patients undergoing surgery for metopic synostosis at our institution from January 2019 to September 2020 who were included in a previous trial. We extracted data from the medical record on intraoperative blood pressure, heart rate, and intraoperative blood loss. Pre- and postoperative GFAP and NfL levels were measured in stored blood samples. Hypotension was defined as the area under the curve (AUC) of mean arterial blood pressure (MAP) at 4 threshold levels (35, 40, 45, and 50 mm Hg, respectively). This AUC and intraoperative blood loss were used to identify correlations with postoperative changes in baseline GFAP and NfL levels. Results: A total of 20 patients [age: 190±65 d (mean±SD); and weight: 8.0±1.0 kg] undergoing an open cranial vault procedure for metopic synostosis repair were included. Intraoperative blood loss was 27±11 mL/kg, and we did not identify significant association between plasma NfL or GFAP level and any MAP threshold (NfL AUC40 r s =0.08, AUC45 r s =0.15, AUC50 r s =0.30. GFAP AUC40 r s =−0.17, AUC45 r s =0.01, AUC50 r s =−0.06) or blood loss parameter [NfL r s =0.26, GFAP r s =−0.15]. Conclusion: We did not identify a relationship between MAP, blood loss, and markers of brain injury. Our findings suggest that other factors (eg, mechanical manipulation) may explain the observed elevations in brain injury biomarkers after craniosynostosis surgery. This study is limited by its sample size and further investigation is needed.