Among patients undergoing major orthopedic and spine surgery, antifibrinolytic agents compared to placebo reduce bleeding, reduce the risk of transfusion and do not appear to increase the risk of myocardial infarction, stroke, deep vein thrombosis or pulmonary embolism [8, 12–19]. These observations are consistent with those found in the cardiovascular surgery literature [20, 21].
The aim of the present study was to evaluate the efficacy of tranexamic acid in reducing blood loss and the need for allogenic blood transfusion in patients undergoing posterior lumbar spine surgery. Our results suggest a less blood loss as shown by the higher postoperative hemoglobin concentration and lower cell saver volume in the tranexamic acid group. But we found no significant reduction of allogenic blood transfusion rate with the use of tranexamic acid. No adverse events with the use of tranexamic acid were seen in our population.
Heterogeneous patient populations (adolescent scoliosis, neuromuscular scoliosis, acquired degenerative instability, etc.), differences in surgical techniques (anterior, posterior, anterior-posterior, lumbar and cervical), heterogeneity in the doses and type of antifibrinolytic agent, timing of administration, and a lack of standardized dose regimens and transfusion thresholds may help to explain why the results of the present study are different from those previously published, which showed differences in blood loss and transfusion between patients who received tranexamic acid and those who did not.
Elwatidy et al. reported on the efficacy and safety of a large dose of tranexamic acid in spine surgery . They enrolled 64 patients of whom 18 had multilevel anterior cervical discectomies, 22 had decompressive surgery for multisegmental stenosis, 15 had laminectomy and posterior instrumentation and nine had laminectomy and resection of a spinal tumor. The blood loss during surgery from patients in TA group was almost half the amount lost from patients in Placebo group (49% reduction). Consequently the amount of blood transfusion was 80% less in TA than in placebo group. The heterogeneity of this study population makes it difficult to compare the results because these procedures entailed more or less significant blood losses.
Another study by Baldus et al. compared the safety and efficacy of aprotinin and tranexamic acid in controlling blood loss during lumbar pedicle subtraction osteotomy (PSO) in adults . The main difference from the present study is that the surgical procedure of PSO is substantially more complex (duration in the operating room: 7.5 hours versus 8.1 hours) and entails greater blood loss (mean 1114 ml - 2260 ml) than decompressive surgery with interbody fusion and instrumentation
Colomnia et al. performed a retrospective case control study to determine the impact of aprotinin or tranexamic acid use on reducing intraoperative blood loss and transfusion needs in complex spine surgery. They enrolled patients with diagnoses of adult scoliosis, neuromuscular scoliosis, congenital scoliosis, degenerative lumbosacral disease and posttraumatic kyphosis. The surgical procedures varied and included posterior instrumented fusion, anterior instrumented fusion, anterior plus posterior instrumented fusion, posterior lumbar interbody fusion (PLIF), pedicle subtraction osteotomy and Smith-Peterson osteotomy. The duration of surgery was 448 min, the numbers of levels fused 7.6 and the total blood loss was 1608 ml for tranexamic acid group. Therefore the total transfusion rate was 2.6. The authors found that the duration of surgery was the main predictive factor of total blood loss among the patients .
In conclusion, the present authors presume that the duration of the surgical procedure and type of surgery are predictive factors for significant blood loss and transfusion requirement in spine surgery. It is likely that tranexamic acid use results in a greater reduction in blood loss and transfusion the longer the surgical procedure lasts and therefore the greater the blood loss is.
Although we conducted a retrospective case-control study and the possibility of the results being affected by recall bias due to historical controls cannot be ruled out, the study provides evidence that the use of tranexamic acid in posterior lumbar spine surgery is not always necessary.
Given the small volume of blood loss in the patients, it seems that this study is underpowered to show a difference in transfusion rates. A much larger sample size would be necessary to prove this.
But the strengths of this study are the homogenous patient population in both groups, and the fact that the surgery was performed by a single surgeon.