D-Dimer Formation During Cardiac and Noncardiac Thoracic Surgery

Effect of Tranexamic Acid on Blood Loss, D-Dimer, and Fibrinogen Kinetics in Adult Spinal Deformity Surgery

BACKGROUND

Antifibrinolytics such as tranexamic acid reduce operative blood loss and blood product transfusion requirements in patients undergoing surgical correction of scoliosis. The factors involved in the unrelenting coagulopathy seen in scoliosis surgery are not well understood. One potential contributor is activation of the fibrinolytic system during a surgical procedure, likely related to clot dissolution and consumption of fibrinogen. The addition of tranexamic acid during a surgical procedure may mitigate the coagulopathy by impeding the derangement in D-dimer and fibrinogen kinetics.

METHODS

We retrospectively studied consecutive patients who had undergone surgical correction of adult spinal deformity between January 2010 and July 2016 at our institution. Intraoperative hemostatic data, surgical time, estimated blood loss, and transfusion records were analyzed for patients before and after the addition of tranexamic acid to our protocol. Each patient who received tranexamic acid and met inclusion criteria was cohort-matched with a patient who underwent a surgical procedure without tranexamic acid administration.

RESULTS

There were 17 patients in the tranexamic acid cohort, with a mean age of 60.7 years, and 17 patients in the control cohort, with a mean age of 60.9 years. Estimated blood loss (932 ± 539 mL compared with 1,800 ± 1,029 mL; p = 0.005) and packed red blood-cell transfusions (1.5 ± 1.6 units compared with 4.0 ± 2.1 units; p = 0.001) were significantly lower in the tranexamic acid cohort. In all single-stage surgical procedures that met inclusion criteria, the rise of D-dimer was attenuated from 8.3 ± 5.0 μg/mL in the control cohort to 3.3 ± 3.2 μg/mL for the tranexamic acid cohort (p < 0.001). The consumption of fibrinogen was 98.4 ± 42.6 mg/dL in the control cohort but was reduced in the tranexamic acid cohort to 60.6 ± 35.1 mg/dL (p = 0.004).

CONCLUSIONS

In patients undergoing spinal surgery, intravenous administration of tranexamic acid is effective at reducing intraoperative blood loss. Monitoring of D-dimer and fibrinogen during spinal surgery suggests that tranexamic acid impedes the fibrinolytic pathway by decreasing consumption of fibrinogen and clot dissolution as evidenced by the reduced formation of D-dimer.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Microvascular Inflammatory Response in Cardiac Surgery

Cardiac surgical procedures, with or without cardiopulmonary bypass, elicit a systemic inflammatory response in patients that induces the elaboration of multiple cytokines, chemokines, adhesion molecules, and destructive enzymes. This inflammatory reaction involves multiple interdependent and redundant cell types and humoral cascades, which allows for amplification and positive feedback at numerous steps. This systemic inflammatory response ultimately results in a broad spectrum of clinical manifestations, with multiple organ failure being the most severe form. Investigative efforts have focused on understanding the mechanism of this systemic inflammatory response syndrome in order to develop potential therapeutic targets to inhibit it, thereby possibly decreasing postoperative morbidity and mortality. Multiple therapeutic methods have been investigated, including pharmacologic inhibitors and modifications of surgical technique and the cardiopulmonary bypass circuit. Although studies have demonstrated that the use of these therapies in experimental and clinical settings has attenuated the systemic inflammatory response, they have failed to conclusively show clinical benefit from these therapies. These therapies may be too specific to minimize the deleterious effects of a systemic inflammatory response that results from the activation of multiple, interdependent, and redundant inflammatory cascades and cell types. Hence, further studies that investigate the molecular and cellular events underlying the systemic inflammatory response syndrome and the resultant effects of anti-inflammatory therapies are warranted to ultimately achieve improvements in clinical outcome after cardiac surgical procedures.

Tranexamic acid in off-pump coronary surgery: a preliminary, randomized, double-blind, placebo-controlled study

BACKGROUND

We evaluated the hemostatic effects of tranexamic acid, a synthetic antifibrinolytic drug, in patients undergoing beating-heart coronary surgery.

METHODS

Forty consecutive patients were in a double-blind manner, prospectively randomized into two groups: 20 patients received tranexamic acid (bolus of 1 g before skin incision, followed by continuous infusion of 400 mg/hr during surgery), and 20 patients received saline. As primary outcomes, bleeding and allogeneic transfusions were considered. D-dimer and fibrinogen plasma levels were also evaluated to monitor the activation of fibrinolysis. Major postoperative thrombotic events, as a potential consequence of antifibrinolytic treatment, were recorded.

RESULTS

The treatment group had significantly lower postoperative bleeding (median [25th to 75th percentiles]: 400 mL [337 to 490 mL] vs 650 ml [550 to 862 mL], p < 0.0001), lower need for allogeneic blood products (1,200 vs 5,300 mL, p < 0.001), and lower postoperative D-dimer plasma levels. No postoperative thrombotic complications were observed in either group.

CONCLUSIONS

In this initial series of patients undergoing off-pump coronary surgery, tranexamic acid appears to be effective in reducing postoperative bleeding and the need for allogeneic blood products.