Jichun Shi ¹ Shuangxiang Xu ¹ Yu Feng ¹ WEI WEI ¹ Yichun Zou ¹ Wenping Xiong ¹ Wenyuan Zhao ¹ Zhang T. Bao ^1* Hao Peng ^2,3* Jincao Chen ^1*

• ¹ Department of Neurosurgery, Zhongnan Hospital, Wuhan University, Wuhan, China
• ² Department of Neurosurgery, Hainan Second People's Hospital, Haikou, China
• ³ Department of Neurosurgery, Hainan General Hospital, Haikou, Hainan Province, China

Objective: Intraoperative blood loss poses a great challenge for brain arteriovenous malformation (AVM) microsurgery, although systematic researches are still lacking. This study aimed to identify factors predicting intraoperative major blood loss in brain AVM microsurgery and to investigate its impact on patient outcome. To deal with the fierce bleeding, we introduced a modified hemostatic method, bone-wax (BW) coated bipolar electrocoagulation. Methods: The authors retrospectively analyzed the clinical data of 131 patients (50/81 in intraoperative major/non-major blood loss cohort) with brain AVMs who underwent microsurgery in our center during the period between January 2018 and April 2023. According to previous studies, major blood loss was defined as blood loss of at least 1000mL. The accuracy and objectivity of our grouping methodology were validated by comparing the hemoglobin mass loss, hematocrit loss and factors associated with intraoperative bleeding. Potential clinical and radiological predictors for intraoperative major blood loss were evaluated using a multivariate stepwise logistic regression. And outcomes of patients in the two cohorts were also compared. At last, the performance of BW coated bipolar electrocoagulation in brain AVM microsurgery was illustrated by the case presentation, histological staining and transmission electron microscopy of the coagulated nidus vessels. Results: Hemoglobin mass loss, hematocrit loss and factors associated with intraoperative bleeding were significant different between the two cohorts. five independent factors predicting intraoperative major blood loss were identified: 1) clinical manifestations; 2,3) location and size of the nidus; 4) deep venous drainage; and 5) the number of draining veins. And the intraoperative major blood loss can not only adversely affect the surgical progression, but also predict poor perioperative outcomes for patients. Regarding the application of BW coated bipolar electrocoagulation, we found the novel hemostatic method exerted efficient hemostatic effect and reduced the damage to the vascular structure in brain AVM microsurgery. Conclusions: This study proposed a nomogram for neurosurgeons to predict intraoperative major blood loss in brain AVM microsurgery preoperatively. And intraoperative major blood loss is associated with poor patient outcomes. In addition, BW coated bipolar electrocoagulation, can be applied to control ferocious bleeding during brain AVM microsurgery, which still remains further researches.