Bleeding is a necessary and unavoidable part of spine surgery. It is important to the surgeons and anesthesiologists to know how much blood a patient has lost during surgery in order to care for them in the best way possible. Different methodology has been employed to estimate how much blood is lost during surgery, but unfortunately none of the methods used have been reliable. The study will calculate surgical blood loss by determining perioperative change in red cell volume that is directly measured by using a special method that relies on radioisotope I-131-labeled albumin administration (BVA-100) during the surgery. This benchmarked blood loss estimate will then be compared to estimates calculated using the Gross equation, the Bourke and Smith equation, and the Camarasa formula. In addition, blood loss will be estimated volumetrically by utilizing formulas based on the amount of salvaged blood produced by an intraoperative salvaging system (Cell Saver®). Blood loss estimates based on salvaged blood volume will also be compared to the benchmark.
