1. Departments of Oral and Maxillofacial Surgery, Rambam Health Care Campus, affiliated to the Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
3. Department of Anesthesiology Baruch Padeh Medical Center, Tiberius, Israel.
Background: Acute normovolemic hemodilution (ANH) is a technique used during anesthesia for major operations, usually to reduce homologous blood transfusion. We studied ANH in large head and neck operations, for which controlled hypotension is required. We selected those procedures since ANH addresses issues of both decreasing blood pressure and minimizing blood loss.
Methods: This is a prospective study of 45 adult patients who underwent elective large maxillofacial resections and orthognathic operations, which duration was predicted to be 3 hours or more. The patients were randomly divided into 2 groups: ANH group (19 patients) and a control group (26 patients). In ANH group one unit of blood was drawn from the patient after the induction of general anesthesia and was returned at the end of the surgery. Target mean blood pressure during the surgery was 30% below the patient's usual pressure, with a minimum of 50 mm Hg. Various hemodynamic and laboratory parameters as well as postoperative outcome were monitored.
Results: Patients in the ANH group receive significantly lower dose of fentanyl comparing to the control group (p=0.02), and had higher blood pressure at the end of the surgery. No significant difference was found between the groups regarding age, gender, weight, ASA class, duration of surgery, usage of hypotensive drugs and blood transfusion during the surgery.
Conclusions: ANH is a safe technique to use in anesthesia for head and neck operations; it facilitates using a smaller dose of fentanyl and assists in resuming higher blood pressure at the end of surgery.
Keywords: Anaesthesia, general, anaesthetic technique, hypotensive, surgery, head and neck, normovolemic hemodilution, acute