Intraoperative methods for assessing blood loss: A review

Massive blood loss that develops during surgery is a common cause of life-threatening conditions and deaths in patients of any age. This study aimed to analyze domestic and foreign publications that present methods for determining the volume of intraoperative blood loss. The literature sources were searched in PubMed, Scopus, Web of Science, MEDLINE, eLibrary, and Russian Science Citation Index databases. The search was conducted in Russian and English using the following keywords: intraoperative blood loss, severity of blood loss, methods for assessing blood loss, direct methods, and indirect methods. The literature review included five articles from PubMed, nine from Scopus, six from Web of Science, two from MEDLINE, six from eLibrary, and four from Russian Science Citation Index. Massive blood loss is understood as a one-time loss according to some authors of 30% and according to others of 50% of the volume of the circulating blood or blood loss equal in volume to 23 mL/kg/min. Risk factors for the development of intraoperative complications such as massive blood loss are, in addition to surgical interventions, the features of surgical intervention, i.e., size of the incision, surgical duration, and anesthesia, which can increase blood loss. The intensity and degree of blood loss are very important in determining the indications for transfusion of blood components, replenishing the volume of circulating blood, and determining indications for intraoperative hemostasis, both medical and surgical. In neonates and young children, the risk of dangerous intraoperative blood loss is associated with anatomical and physiological features, i.e., a small volume of circulating blood and insufficiently mature compensatory mechanisms. In older children, a high risk of massive blood loss is associated with comorbidities, features of hemostasis, and use of drugs that slow down the blood coagulation process. To date, several methods are available for assessing intraoperative blood loss, but only a few are used in routine clinical practice. Each method has advantages and disadvantages. One of the main disadvantages is the complexity of the mechanisms for assessing blood loss, for example, weighing surgical materials or the patient before and after surgery, determining hemoglobin in the liquid after soaking the used surgical materials, and calculating indices using formulas. Most often, the assessment of blood loss is conducted according to the clinical picture (pallor of the skin and mucous membranes, weak pulse, lowering blood pressure, etc.). The results of the literature analysis showed insufficient research on determining the volume of intraoperative blood loss in pediatric practice, as evidenced by the small number of published scientific papers and the complete absence of randomized trials. Thus, further study of this problem is necessary.