Transfusion guidelines in adult spine surgery: a systematic review and critical summary of currently available evidence

Background Context: Red blood cell transfusion can be associated with complications in medical and surgical patients. Acute anemia in ambulatory patients undergoing surgery can also impede wound healing and independent self-care. Current transfusion threshold guidelines are still based on evidence derived from critically-ill intensive care unit medical patients and may not apply to spine surgery candidates. Purpose: We aimed to provide the reader with a synthesis of the best available evidence to recommend transfusion trigger thresholds and guidelines in adult patients undergoing spine surgery. Study Design/Setting: This is a systematic review. Outcome measures: Physiological measure: Blood transfusion thresholds and associated posttransfusion complications (morbidity, mortality, length of stay, infections, etc) of the published articles. Patient Sample: Adult spine surgery patients. Methods: A systematic review of the literature using the PubMed, Google Scholar, and Web of Science electronic databases was made according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Focus was set on papers discussing thresholds for blood transfusion in adult surgical spine patients, as well as complications associated with transfusion after acute surgical blood loss in the operating room or postoperative period. Publications discussing pediatric cases, blood type analyses, blood loss prevention strategies and protocols, systematic reviews and letters to the editor were excluded. Results: A total of 22 articles fitting our search criteria were reviewed. Patients who received blood transfusion in these studies were older, of female gender, had more severe comorbidities except for smoking, and had prolonged surgical time. Blood transfusion was associated with multiple adverse postoperative complications, including a higher rate of superficial or deep surgical site infections, sepsis, urinary and pulmonary infections, cardiovascular complications, return to the operating room, and increased postoperative length of stay and 30 day readmission. Analysis of transfusion thresholds from these studies showed that a pre-operative hemoglobin (Hb) of > 13 g/dL, and an intraoperative and post-operative Hb nadir above 9 and 8 g/dL, respectively, were associated with better outcomes and fewer wound infections than lower thresholds (Level B Class III). Additionally, it was generally recommended to transfuse autologous blood that was < 28 days old, if possible, with a limit of 2 to 3 units to minimize patient morbidity and mortality. Conclusions: Blood transfusion thresholds in surgical patients may be specialty-specific and different than those used for critically-ill medical patients. For adult spine surgery patients, red blood cell transfusion should be avoided if Hb numbers remain > 9 and 8 g/dL in the intraoperative and direct post-operative periods, respectively.