Coagulation Profile of Patients with Adolescent Idiopathic Scoliosis Undergoing Posterior Spinal Fusion

Perioperative Risk Factors for Bleeding in Adolescents Undergoing Pedicle Screw Instrumentation for Scoliosis

Progressive scoliosis eventually leads to extensive spinal fusion surgery, which carries a risk for significant bleeding. Neuromuscular scoliosis (NMS) patients have an additional inherent risk of major perioperative bleeding. The purpose of our research was to investigate the risk factors for measured (intraoperative, drain output) and hidden blood loss related to pedicle screw instrumentation in adolescents, divided into adolescent idiopathic scoliosis (AIS) and NMS patient groups. A retrospective cohort study with prospectively collected data of consecutive AIS and NMS patients undergoing segmental pedicle screw instrumentation at a tertiary level hospital between 2009 and 2021 was conducted. In total, 199 AIS (mean age 15.8 years, 143 females) and 81 NMS patients (mean age 15.2 years, 37 females) were included in the analysis. In both groups, levels fused, increased operative time, and smaller or larger size of erythrocytes were associated with perioperative blood loss (p < 0.05 for all correlations). In AIS, male sex (p < 0.001) and the number of osteotomies correlated with more drain output. In NMS, levels fused correlated with drain output, p = 0.00180. In AIS, patients' lower preoperative MCV levels (p = 0.0391) and longer operation times, p = 0.0038, resulted into more hidden blood loss, but we did not find any significant risk factors for hidden blood loss in NMS patients.

Blood Conservation Techniques and Strategies in Orthopedic Anesthesia Practice

Orthopedic surgery procedures involving joint arthroplasty, complex spine, long bone and pelvis procedure, and trauma and oncological cases can be associated with a high risk of bleeding and need for blood transfusion, making efforts to optimize patient care and reduce blood loss very important. Patient blood management programs incorporate efforts to optimize preoperative anemia, develop transfusion protocols and restrictive hemoglobin triggers, advance surgical and anesthesia practice, and use antifibrinolytic therapies. Perioperative management of anticoagulant therapies, a multidisciplinary decision-making task, weighs in risks and benefits of thromboembolic risk and surgical bleeding and is patient- and surgery-specific.

Does Abnormal Preoperative Coagulation Status Lead to More Perioperative Blood Loss in Spinal Deformity Correction Surgery?

This study aims to analyze the potential association between the preoperative coagulation status and perioperative blood loss in spinal deformity correction surgery. The preoperative coagulation status and estimated blood loss (EBL) during operation, postoperative wound drainage, and allogeneic transfusion during and after operation were recorded and analyzed. Among the 164 patients, 26 had a longer prothrombin time (PT), 13 had a lower fibrinogen level, 55 had a longer activated partial thromboplastin time (APTT), and 2 had a longer thrombin time (TT), and the platelet count (PLT) was all normal or higher than the normal level. The mean EBL per surgical level was 77.8 ml (range, 22–267 ml), and the mean drainage per surgical level was 52.7 ml (range, 7–168 ml). Fifty-five patients and 12 patients underwent allogeneic transfusion during and after the operation, respectively. The differences in EBL per surgical level, mean drainage per surgical level, the occurrences of allogeneic transfusion during and after operation between the patients with a longer PT, lower fibrinogen level, longer APTT or longer TT, and the normal controls were not significant (all P’s > 0.05). The Spearman correlation analysis showed that there was no correlation between PT, fibrinogen, APTT, TT or PLT with EBL per surgical level, mean drainage per surgical level, or allogeneic transfusion during and after the operation (all P’s > 0.05). The abnormal preoperative coagulation status but not hemophilia does not lead to more perioperative blood loss or a higher rate of perioperative allogeneic transfusion in spinal deformity correction surgery.

Comparison of the Effect of Two Different Doses of Labetalol to Induce Controlled Hypotension on Hemodynamic Changes During Spinal Fusion Surgery

Background: Spinal fusion surgery is often associated with heavy bleeding. Labetalol is one of the most effective drugs used to control bleeding in surgery. Objectives: Here, we measured the effect of two therapeutic doses of labetalol on the amount of bleeding. Methods: This is a randomized clinical trial that was performed in 2020-2021 in Al-Zahra hospital in Isfahan, Iran, on patients that were candidates for posterior spinal fusion surgery under general anesthesia. A total number of 64 patients were entered and randomized into two groups, one receiving labetalol at the dose of 2 mg/min and another group at 4 mg/min during surgery. The amount of bleeding in patients, heart rate, blood pressure, blood oxygen saturation, hypotension or bradycardia, and the mean length of stay in the recovery room were measured and compared between the groups. Results: Extubation time (14 ± 4) and recovery time (76 ± 17) were significantly lower in patients that received labetalol (2 mg/min) compared to another group (21 ± 7 for intubation time and 116 ± 32 for recovery time (P < 0.001 for both items). Patients that received labetalol (4 mg/min) had significantly lower amounts of hemorrhage compared to other group (P = 0.001), and the surgeon's satisfaction was significantly higher in the second group (P = 0.001). The frequency of hypotension and bradycardia during the surgery were significantly higher among patients that received labetalol at the dose of 4 mg/min (P = 0.002 and P = 0.001, respectively). The patients in the group labetalol at 4 mg/min had also significantly lower systolic and diastolic blood pressure and lower mean arterial pressure (MAP) compared to the other group (P < 0.05). Conclusions: Administration of labetalol at the dose of 4 mg/min had significantly desirable effects on hemodynamics that resulted in reduced bleeding volume and blood pressures compared to labetalol at the dose of 2 mg/min.

The Prognostic Performance of Rotational Thromboelastometry for Excessive Bleeding and Increased Transfusion Requirements in Hip Fracture Surgeries

BACKGROUND

 Hip fracture surgeries are associated with considerable blood loss, while the perioperative coagulopathy is associated with the bleeding risk of these patients. We aimed to evaluate the ability of rotational thromboelastometry (ROTEM) to detect patients at high risk for excessive bleeding and increased transfusion requirements.

METHODS

 We conducted a prospective observational study of 221 patients who underwent hip fracture surgeries. ROTEM analysis was performed preoperatively and immediately postoperatively. Blood loss parameters including blood loss volume, number of transfused red blood cell (RBC) units, and drop in hemoglobin levels were recorded. ROTEM parameters were compared between patients with and without excessive bleeding, and between patients with and without increased transfusion requirements (i.e., ≥2 RBC units).

RESULTS

 The postoperative FIBTEM MCF value ≤15 mm had 66.6% (95% confidence interval [CI]: 59.7-74.1%) sensitivity and 92.0% (95% CI: 80.7-97.7%) specificity to prognose excessive bleeding, and preoperative FIBTEM MCF value ≤15 mm had 80.4% (95% CI: 73.5-86.2%) sensitivity and 91.2% (95% CI: 80.7-97.0%) specificity to prognose increased transfusion requirements. Preoperative FIBTEM MCF ≤11 mm and postoperative FIBTEM MCF ≤15 mm were associated with considerably increased risks of excessive bleeding (odds ratio [OR]: 44.8, 95% CI: 16.5-121.3, p < 0.001; and OR: 23.0, 95% CI: 7.8-67.0, p < 0.001, respectively).

CONCLUSION

 ROTEM parameters demonstrated high prognostic accuracy for excessive bleeding and increased transfusion requirements. This can enable implementation of blood sparing strategies in high-risk patients, while blood banks could be better prepared to ensure adequate blood supply.

The incidence and risk factors for perioperative allogeneic blood transfusion in primary idiopathic scoliosis surgery

STUDY DESIGN

Case-control study.

OBJECTIVES

Evaluate the rate and risk factors for perioperative allogeneic blood transfusion (ABT) in primary idiopathic scoliosis surgery at a single institution. Avoiding perioperative ABT is ideal as transfusions are associated with adverse reactions, increased rates of infection, prolonged hospitalization, additional laboratory testing, and increased cost. Risk factors identified in other studies have differed, and to our knowledge, few studies have identified clinical strategies to predict patients at high risk for ABT.

METHODS

We reviewed 402 idiopathic scoliosis patients who underwent primary posterior spinal fusion and instrumentation (PSFI) at a single institution from 2015 to 2017. Medical records and radiographs were reviewed for all patients. Transfused patients were compared to the remaining cohort to find significant differences and identify predictors of higher ABT risk.

RESULTS

ABT occurred in 73 patients (18.2%), with the majority of transfusions occurring intraoperatively (41%) or postoperatively on the day of surgery (25%). The seven surgeons involved varied significantly in incidence of ABT (2.4-35.8%, p = 0.002). Patients who had ABT were younger (13.3 vs. 14.1 years, p < 0.01), had lower BMI (48th vs. 61st percentile, p < 0.001), and lower preoperative hemoglobin (13.1 vs. 13.7 g/dL, p < 0.01). Greater preoperative major Cobb angle (69° vs. 61.5°, p < 0.001), number of fusion levels (11.8 vs. 10.3, p < 0.001), and estimated blood loss (770 vs. 448 mL, p < 0.001) also predicted ABT.

CONCLUSIONS

ABT was associated with several risk factors, five of which are known preoperatively. Surgeons can use knowledge of these risk factors to assess transfusion risk preoperatively and plan surgery, blood management, and laboratory testing accordingly. The development of best practices for ordering ABT is possible given the variation amongst providers.

LEVEL OF EVIDENCE

Level III.

Usefulness of perioperative rotational thrombelastometry during scoliosis surgery in children

OBJECTIVE

Surgical correction of scoliosis in pediatric patients is associated with significant blood loss. Rotational thrombelastometry (ROTEM) might help to decrease the use of blood transfusion products by enabling an early point of care (POC) diagnosis of coagulopathy, thus helping to provide targeted therapy. The aim of this case-control study was to find out whether POC use of ROTEM during scoliosis surgery in children helps to reduce the need for blood transfusion products.

METHODS

Data were prospectively analyzed from all patients treated during 2016-2018 who received ROTEM-based therapy during scoliosis surgery. These patients were compared with a group of historical controls treated during 2014-2016 whose scoliosis treatment did not include ROTEM. Perioperative blood loss, consumption of blood transfusion products, and hospital LOS were compared between the groups.

RESULTS

A total of 37 patients were analyzed, 22 patients in the non-ROTEM group and 15 patients in the ROTEM group. In the ROTEM group compared with the non-ROTEM group, there was significantly lower perioperative blood loss and administration of packed red blood cell units, no administration of fresh-frozen plasma, and shorter overall hospital LOS (p < 0.05).

CONCLUSIONS

ROTEM use during scoliosis surgery in children seems to help to decrease blood loss and the use of blood transfusion products and may also shorten the hospital LOS.Clinical trial registration no.: NCT03699813 (clinicaltrials.gov).

Safety and Effectiveness of Antifibrinolytics in Posterior Scoliosis Surgery for Adolescent Idiopathic Scoliosis: An Analysis of the NSQIP-Pediatric Database

STUDY DESIGN

This was a retrospective study of prospectively collected data.

OBJECTIVE

To utilize a large national database with prospectively collected data [National Surgical Quality Improvement Program Pediatric (NSQIP-Pediatric)] to study the safety and effectiveness of antifibrinolytic use during multilevel posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

There is currently a lack of consensus and evidence regarding the safety and effectiveness of antifibrinolytic use for pediatric patients undergoing corrective surgery for AIS.

MATERIALS AND METHODS

Patients who underwent multilevel PSF for AIS in the 2016 NSQIP-Pediatric database were identified. Preoperative and procedural characteristics were compared between patients who received antifibrinolytics versus those who did not. Multivariate regressions were used to compare perioperative transfusion rates and postoperative outcomes, such as rate of return to the operating room, 30-day readmission, and intensive care unit and hospital length of stay between the 2 treatment groups.

RESULTS

This study included 975 patients who received antifibrinolytics and 223 patients who did not. Patients who received these agents tended to have more levels fused, osteotomies performed, and longer operative times. After controlling for these variances, there were no statistical differences in rate and volume of transfusion, rate of return to the operating room, 30-day readmission, 30-day postoperative complications, or intensive care unit or hospital length of stay between the 2 treatment groups.

CONCLUSIONS

This study did not demonstrate transfusion reduction in the group that received antifibrinolytics. This finding may be, in part, secondary to nonoptimized or nonstandardized protocols for antifibrinolytic use in pediatric deformity surgery or the inability to adequately control for selection bias, as those with greater surgical invasiveness may be more likely to receive antifibrinolytics. Nonetheless, using antifibrinolytics in this population appears safe and not associated with increased perioperative complications.

LEVEL OF EVIDENCE

Level III.

Acute Normovolemic Hemodilution in Spinal Deformity Surgery

Objective  To prospectively compare the clinical and laboratorial aspects of patients undergoing spine deformity surgery, using the acute normovolemic hemodilution technique with tranexamic acid, versus a control group with tranexamic acid alone, and to evaluate the influence of hemodilution in intraoperative bleeding and the need for homologous transfusion.

Materials and Methods  Comparative prospective study with patients aged between 12 and 65 years undergoing spine deformity surgery with the acute normovolemic hemodilution technique associated with tranexamic acid versus a control group to which only tranexamic acid (15 mg/kg) was administered. Laboratorial exams were performed and analyzed in three different moments.

Results  A total of 30 patients were included in the present study: 17 in the hemodilution group, and 13 in the control group. The mean duration of the surgery in the hemodilution group was longer. The number of levels submitted to surgery ranged from 7 to 16 in the hemodilution group, and from 4 to 13 in the control group. Osteotomy, predominantly of the posterior kind, was performed in 20 patients. There was more intraoperative bleeding in the control group. All patients were stable during the procedures. Only 6 participants needed homologous blood transfusion, mostly from the control group ( p  > 0.05).

Conclusion  There was no significant difference between the two groups regarding the need for blood transfusion and intraoperative bleeding. The severity of the deformity was the main determinant for homologous blood transfusion.

Coagulative function assessed preoperatively via the clot formation and lysis assay as a prognostic factor for blood loss in adolescents undergoing posterior spinal fusion for idiopathic scoliosis

BACKGROUND

Posterior spinal fusion for adolescent idiopathic scoliosis is a complex surgery often associated with clinically significant blood loss leading to perioperative blood transfusion. Knowledge of risk factors for blood loss and transfusion stems mostly from retrospective studies.

AIM

We sought to prospectively investigate putative prognostic factors for intraoperative blood loss and perioperative blood transfusion in adolescent idiopathic scoliosis patients undergoing posterior spine fusion, including clinical characteristics, surgical factors, and preoperative assessment of overall coagulative and fibrinolytic functions in plasma using the clot formation and lysis (CloFAL) assay.

METHODS

Following Internal Review Board approval, adolescents 10 to <21 years old with idiopathic scoliosis undergoing posterior spine fusion were enrolled preoperatively in a single-institutional prospective cohort and biobanking study. Clinical data were collected on patient characteristics, surgical approach, perioperative management, intraoperative estimated blood loss, and blood transfusion through hospital discharge. Coagulative and fibrinolytic functions in plasma were measured on preoperative samples by CloFAL assay (Coagulation Index and modified Fibrinolytic Index). Univariate linear regression and multivariable linear regression were performed to identify predictors of weight-indexed intraoperative estimated blood loss EBL (EBL/kg).

RESULTS

The final study population included 74 patients. Median age was 14.8 years (SD = 2.2). After adjustment for other putative prognostic factors via multivariable linear regression, coagulative function as determined preoperatively by CloFAL Coagulation Index was an independent predictor of intraoperative (EBL)/kg. Specifically, each 10% increase in CloFAL CI was associated with 3% decrease in the geometric mean of EBL/kg (OR 0.97, 95%CI 0.94-0.99, P = .01).

CONCLUSION

In adolescents undergoing posterior spinal fusion for idiopathic scoliosis, increased coagulative function measured preoperatively using the CloFAL assay is independently associated with decreased intraoperative blood loss. Future studies should expand upon these investigations of plasma coagulative and fibrinolytic capacities in combination with clinical factors, to guide precise preventive strategies against blood loss and blood transfusion in this patient population.

Comparison of the Coagulation Profile of Adolescent Idiopathic Scoliosis Patients Undergoing Posterior Spinal Fusion With and Without Tranexamic Acid

STUDY DESIGN

Prospective, observational cohort study.

OBJECTIVE

To improve the understanding of coagulation and bleeding mechanisms during spinal deformity surgery.

SUMMARY OF BACKGROUND DATA

Fibrinolysis is the mechanism of bleeding for adolescent idiopathic scoliosis undergoing posterior spinal fusion. Antifibrinolytics have become popular; however, literature to support their use remains mixed. The mechanism of action has not been demonstrated.

METHODS

The coagulation profile of 88 adolescent idiopathic scoliosis patients undergoing posterior spinal fusion was analyzed. Standard coagulation laboratory investigations and thromboelastograms were drawn hourly through the case. Fifty-eight patients received no antifibrinolytic, whereas 30 patients received tranexamic acid by standardized protocol. The coagulation parameters, estimated blood loss, and transfusion requirements were compared in the two groups.

RESULTS

The two cohorts had no differences in demographic or surgical characteristics. Mean age was 13.6 years, 83% were female, a mean of 11.1 levels were fused, and the mean duration of surgery was 209 minutes. The tranexamic acid cohort did not demonstrate a decrease in blood loss. The transfusion rate, however, dropped from 47% in the non-tranexamic acid cohort to 23% in the tranexamic acid cohort (p = .03). Standard coagulation parameters did not differ between the groups. Fibrinolysis was diminished in the tranexamic acid cohort as measured by a Fibrinolysis score (mean maximum value 2.0 without tranexamic acid vs. 0.7 with tranexamic acid, p < .0001) and the lysis percent at 30 minutes by thromboelastogram (elevated to 3.9% without tranexamic acid vs. 1.2% with tranexamic acid at the 3-hour mark, p = .05).

CONCLUSIONS

This study provides confirmation of antifibrinolytic activity during posterior spinal fusion for adolescent idiopathic scoliosis. The presented data of fibrinolysis are proposed as standard measurements for future work on controlling blood loss during scoliosis surgery.

LEVEL OF EVIDENCE

Level 2, prospective comparative study.

Thromboelastography for the Orthopaedic Surgeon

Evaluation of coagulation is vital in the care of the orthopaedic patients, particularly in the subspecialties of trauma, spine, arthroplasty, and revision surgery resulting from blood loss and coagulopathies. Although conventional tests (prothrombin time/international normalized ratio, activated partial thromboplastin time, platelet count, and fibrinogen) are most commonly used, others like thromboelastography (TEG) are also available to the orthopaedic surgeons. TEG is a blood test developed in the 1950s, which provides a snapshot of a patient's coagulation profile by evaluating clot formation and lysis. Recently, TEG has been used to assess traumatic coagulopathy. The coagulation parameters measured by the TEG are reaction time (R-time), time to reach a certain clot strength (K-value), speed of fibrin build up (α-angle), maximum clot amplitude, and percentage decrease of clot in 30 minutes (LY30). Using these values, traumatologists have developed a better, faster, and more accurate overview of a patient's resuscitation and more successfully direct blood product use. However, many orthopaedic surgeons-despite performing surgical procedures that risk notable blood loss and postoperative clotting complications-are unaware of the existence of the TEG blood test and the critical information it provides. Increasing awareness of the TEG among orthopaedic surgeons could have a notable effect on numerous aspects of musculoskeletal care.

Predictors for blood loss in pediatric patients younger than 10 years old undergoing primary posterior hemivertebra resection: a retrospective study

Background

Blood loss during hemivertebra resection may be substantial. Few studies have examined the risk factors of blood loss undergoing hemivertebra resection, especially those in patients under 10 years old.

Methods

Patients under 10 years old diagnosed with congenital scoliosis and hemivertebra were retrospectively included from January 2014 to October 2017. They all had primary posterior hemivertebra resection at Peking Union Medical College Hospital. Perioperative information was collected and multivariable linear logistic regression was performed to determine the independent risk factors of blood loss.

Results

One hundred three patients were included. The mean total blood loss was 346 + 178 ml. The percentage of total blood loss to the EBV was 27.0 + 13.3%. Multivariable linear logistic regression indicated that preoperative total Cobb angle (P = 0.046) and the number of fused levels (P < 0.001) were independent risk factors of total blood loss. Preoperative platelet count and preoperative coagulation function were not associated with blood loss in patients undergoing hemivertebra resection.

Conclusions

Preoperative total Cobb angle and the number of fused levels determined the blood loss for patients undergoing hemivertebra resection.

Differential proteome analysis in adolescent idiopathic scoliosis patients with thoracolumbar/lumbar curvatures

BACKGROUND

Although the pathogenesis of adolescent idiopathic scoliosis (AIS) remains unclear, there are little evidences of the pathogenesis in patients with thoracolumbar/lumbar AIS. The purpose of this study was to identify proteins or proteomes that may be causally related to the pathogenesis of AIS with structured thoracolumbar/lumbar curvature using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE).

METHODS

A total of 20 control volunteers and 61 AIS in patients with thoracolumbar/lumbar curvature were included. First, the plasma samples of each five AIS with pure thoracolumbar/lumbar curvature and control samples were subjected to 2D-DIGE analysis. Protein spots that were expressed differently by the AIS and control groups were selected and identified by nanoscale liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) analysis. To characterize the differently-expressed proteins in AIS patients, we performed functional pathway analysis using the Protein ANalysis THrough Evolutionary Relationships (PANTHER) system. Additionally, the proteins were compared between control and AIS using western blotting. Lastly, prospectively collected 15 control and 41 AIS with thoracolumbar/lumbar curvature samples were compared to the differentially expressed proteins.

RESULTS

A total of 3862 ± 137 spots were detected, of which 11 spots met the criteria when compared with controls. Nine proteins were identified by nanoLC-MS/MS. Functional analysis showed the association of the proteins in AIS patients with blood coagulation using the PANTHER system. Of the proteins, vitamin D binding protein (DBP) significantly correlated with Cobb angle in thoracolumbar/lumbar curvatures. DBP expression of the prospectively collected AIS samples were significantly higher than those of controls (P < 0.05).

CONCLUSIONS

This study suggests that DBP and several coagulation-related proteins may play a role in the pathogenesis of AIS. DBP appears to be a marker of severity of AIS with thoracolumbar/lumbar curvature.

Development of Consensus Based Best Practice Guidelines for Perioperative Management of Blood Loss in Patients Undergoing Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

STUDY DESIGN

Delphi process with multiple iterative rounds using a nominal group technique.

OBJECTIVE

The aim of this study was to use expert opinion to achieve consensus on various methods for minimizing blood loss in patients undergoing posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS).

BACKGROUND DATA

Perioperative blood loss management represents a critical component of safely performing PSF in children with AIS. Little consensus exists on ways to mitigate excessive blood loss after PSF.

METHODS

An expert panel composed of 21 pediatric spine surgeons was selected. Using the Delphi process and iterative rounds using a nominal group technique, participants in this panel were presented with a detailed literature review and asked to voice opinion collectively during three rounds of voting. Agreement >80% was considered consensus. Interventions without consensus were discussed and revised, if feasible.

RESULTS

Consensus was reached to support 21 best practice guideline measures for perioperative management of blood loss in patients undergoing PSF for AIS. Areas included preoperative assessment and preparation, intraoperative strategies to decrease blood loss, and postoperative transfusion indications.

CONCLUSION

We present a consensus-based best practice guideline consisting of 21 recommendations for strategies to minimize and manage blood loss during PSF. This can serve to reduce variability in practice in this area, help develop hospital specific protocols, and guide future research.

A Comparative Analysis of the Metabolic and Coagulative Profiles in Patients with Idiopathic Scoliosis, Congenital Scoliosis and Healthy Controls: A Case-Control Study

Study Design

Single-center, observational, case–control study.

Purpose

Comparison and analysis of the metabolic and coagulative profiles in patients with idiopathic scoliosis, patients with congenital scoliosis, and healthy controls.

Overview of Literature

Serum melatonin deficiency has been a controversial topic in the etiopathogenesis of scoliosis. Low bone mineral density, low vitamin D3 levels, and high parathyroid hormone levels are common metabolic abnormalities associated with scoliosis that may be responsible for its pathogenesis. In addition to metabolic defects, several studies have shown coagulation defects that either persist from the preoperative period or occur during surgery and usually lead to more than the expected amount of blood loss in patients undergoing deformity correction for scoliosis.

Methods

The study population (n=73) was classified into those having congenital scoliosis (n=31), those with idiopathic scoliosis (n=30), and healthy controls (n=12). After detailed clinicoradiological evaluation of all the subjects, 10-mL blood samples were collected, measured, and analyzed for various metabolic and coagulation parameters.

Results

The mean serum melatonin levels in patients with idiopathic scoliosis were significantly lower than those in the healthy controls. Although the mean serum melatonin level in the congenital group was also low, the difference was not statistically significant. Serum alkaline phosphatase and parathyroid hormone levels were higher in the scoliosis groups, whereas the vitamin D level was lower. No differences were observed in the coagulation profiles of the different groups.

Conclusions

Low serum melatonin levels associated with scoliosis can be a cause or an effect of scoliosis. Moreover, low bone mineral density, high bone turn over, and negative calcium balance appear to play an important role in the progression, if not the onset, of the deformity.

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.