Strictly conservative indications for endovascular occlusive embolization as the algorithm basis for the intraoperative blood loss reduction and blood transfusion prevention in the juvenile nasopharynx and skull base angiofibromas
Purpose of the study: to create an algorithm for the intraoperative blood loss reduction and blood transfu-sion prevention based on conservative indications for endovascular embolization of juvenile angiofibromas of the nasopharynx (JAN) and skull base (SB) at the preoperative stage. Material and methods. The article describes a prospective experimental study with non-randomized inclusion and randomized stratification into groups with sample size calculated a priori. The study was designed to identify factors affecting the volume of intraoperative blood loss and prognosis of patients, and to assess the actual influence value and direction of the devascularization degree on the blood loss volume and the transfusions frequency. Results. The study included 60 patients, and 7 patients dropped out of the study. Patients were initially assigned to groups according to the randomization protocol; subgrouping was based on the degree of devascularization at the preoperative stage. The study identified the main clinically and statistically significant prognostic factors for an increase in intraoperative blood loss: 1) destruction of the greater wing of the sphenoid bone (26.4-34.2% of the circulating blood volume - CBV; p=<0.001-0.016); 2) Fisch-Andrews stage (6.0-16.0% CBV; p=0.001- 0.248) with increase of a stage by one unit; 4) tumor volume, cm3 (0.2-0.4% CBV; p = 0.010-0.377) with each increase in the volume by 1 cm3. The “degree of tumor devascularization” variable was a predictor of a decrease in blood loss (by 10.0-10.8% CBV; p=0.028-0.048 with increase of a rate by one unit). The analysis also showed no statistically significant effect of the devascularization degree on the volume of intraoperative blood loss as compared with transnasal removal of the lesion using endoscopic clipping of the supplying vessels (mainly of the maxillary artery - MA). Results. We developed a statistically significant (x<sup>2</sup>-criterion for assessing the model coefficients =15.698; p<0.001), consistent with the initial data (x<sup>2</sup> criterion according to Hosmer & Lemeshow =5.315; p=0.723) model to predict the need for intraoperative blood transfusion, which can be recommended for routine clinical practice. According to this model, the destruction of the large wing of the sphenoid bone increases the chance of blood transfusion by 5.3 times, and an increase in the tumor volume by 1 cm<sup>3</sup> increases the chance of blood transfusion by 3.3%. The model to predict the intraoperative blood loss above 15% CBV showed good quality (AUC=0.744; SE=0.069; 95% CI 0.608-0.879; p<0.001) and can be recommended for routine clinical practice in specialized medical and prophylactic institutions (MPI) by an experienced interdisciplinary team. Based on the data obtained, we developed a strictly conservative algorithm, according to which the embolization is indicated in patients with IIIb - IVb Fisch-Andrews stage, and in case of destruction of the large wing of the sphenoid bone by tumor (regardless of the disease stage). In other cases, transnasal removal of a tumor with endoscopic MA clipping is indicated. Conclusion. The algorithm of perioperative measures presented in the study aims to reduce the in-traoperative blood loss and prevent blood transfusion using conservative indications for a tumor devas-cularization at the preoperative stage, and has a high potential to increase the effectiveness and phar-macoeconomic acceptability of treatment, while maintaining the radical nature of surgical treatment in JAN and SB.