Prevention of venous thromboembolism in spinal surgery

Does the choice of chemoprophylaxis affect the prevention of deep vein thrombosis in lumbar fusion surgery? A systematic review of the literature

Introduction

To date, the available guidance on venous thromboembolism (VTE) prevention in elective lumbar fusion surgery is largely open to surgeon interpretation and preference without any specific suggested chemoprophylactic regimen.

Research question

This study aimed to comparatively analyze the incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) with the use of commonly employed chemoprophylactic agents such as unfractionated heparin (UH) and low molecular weight heparin (LMWH) in lumbar fusion surgery.

Material and methods

An independent systematic review of four scientific databases (PubMed, Scopus, clinicaltrials.gov, Web of Science) was performed to identify relevant articles as per the preferred reporting in systematic reviews and meta-analysis (PRISMA) guidelines. Studies reporting on DVT/PE outcomes of lumbar fusion surgery in adult patients with UH or LMWH chemoprophylaxis were included for analysis. Analysis was performed using the Stata software.

Results

Twelve studies with 8495 patients were included in the analysis. A single-arm meta-analysis of the included studies found a DVT incidence of 14% (95%CI [8%-20%]) and 1% (95%CI [-6% - 8%]) with LMWH and UH respectively. Both the chemoprophylaxis agents prevented PE with a noted incidence of 0% (95%CI [0%-0.1%]) and 0% (95%CI [0%-1%]) with LMWH and UH respectively. The risk of bleeding-related complications with the usage of LMWH and UH was 0% (95% CI [0.0%-0.30%]) and 3% (95% CI [0.3%-5%]) respectively.

Discussion and conclusion

Both LMWH and UH reduces the overall incidence of DVT/PE, but there is a paucity of evidence analyzing the comparative effectiveness of the chemoprophylaxis regimens in lumbar fusion procedures. The heterogeneity in data prevents any conclusions, as there remains an evidence gap. We recommend future high-quality randomized controlled trials to investigate in this regard to help develop recommendations on thromboprophylaxis usage.

Reducing Surgical Complications in Spine Patients Through a Medication Management Support Program

STUDY DESIGN

A hospital-wide medication management program was implemented to ensure that high-risk patients would systematically pause antiplatelet and anticoagulant medications. We analyzed complications before and during the implementation of this program.

OBJECTIVE

The goal of the study was to determine if a medication management support program was effective for reducing perioperative complications, including hemorrhage, myocardial infarction, stroke, pulmonary embolism, and deep vein thrombosis.

DATA AND METHODS

Using data from the National Surgical Quality Improvement Program database, we examined the presence of 5 complications before and during the implementation of a medication management support program. There were 9732 patients in the clinic population who underwent elective spine surgery between 2011 and 2020 and were included in this analysis. Of those 9732 patients, 7205 had surgery before the introduction of the program, whereas 2527 had surgery at some point after the program was introduced. We conducted a series of Pearson's χ 2 tests to determine the relative frequencies of the complications before and during the program.

RESULTS

Results showed that during the implementation of the program, patients were relatively less likely to experience hemorrhage (3.16% vs. 1.11%; P <0.001). The reductions in thrombotic complications were clinically significant: myocardial infarction (0.12% vs. 0.00%), stroke (0.10% vs. 0.04%), pulmonary embolism (0.33% vs. 0.28%), and deep vein thrombosis (0.36% vs. 0.28%). These P values ranged from P =0.08 for myocardial infarction to P =0.67 for pulmonary embolism.

CONCLUSIONS

The use of this medication management support program appears effective for reducing the need for blood transfusions and thrombotic complications. While promising, the results should be interpreted with caution as we do not know whether this type of program will be effective for other hospital systems.

Meta-Analysis of the Efficacy and Safety of Tranexamic Acid in Spinal Surgery

Objective. The safety and effectiveness of topical tranexamic acid in spinal surgery has not yet been reached, and further research is needed to confirm it. This study is aimed at detecting the effectiveness and safety on the tranexamic acid in spinal surgery. Methods. The Cochrane Library, PubMed, Embase, CNKI, and other databases were searched. The search time was from 2016 to 2019. All randomized controlled trials comparing the topical tranexamic acid group and the control group were collected. The experimental group used topical application. Tranexamic acid was used to treat bleeding after spinal surgery. The control group was no tranexamic acid or isotonic saline. The total bleeding, blood transfusion rate, and the occurrence of deep vein thrombosis were compared between the two groups. Rev Man 5.2.0 software was used for meta-analysis. Results. A total of 8 randomized controlled trials were included, including 884 patients. Meta-analysis results showed that the total bleeding volume of the tranexamic acid group was lower than that of the control group, and the difference was statistically significant weighted mean difference ( $\left(\text{WMD}\right)=–360.27\text{mL}$ , 95% confidence interval (CI) (–412.68, –307.87) mL, $P<0.00001$ ). The blood transfusion rate in the tranexamic acid group was lower than that in the control group (odds ratio $\left(\text{OR}\right)=0.22$ , 95% CI (0.14, 0.33), $P<0.00001$ ). There was no significant difference in the incidence of deep vein thrombosis between the two groups: $\text{OR}=1.48$ , 95% CI (0.41, 5.34), $P=0.55$ . Conclusion. Tranexamic acid can significantly reduce perioperative total blood loss, intraoperative blood loss, and blood transfusion rate during spinal surgery but has no significant effect on blood transfusion and thrombosis.

The risks and benefits of early venous thromboembolism prophylaxis after elective spinal surgery: A single-centre experience

BACKGROUND

There is a wide ranging incidence of venous thromboembolism after surgery and it continues to be a major cause of morbidity after spinal procedures.This study's aim was to investigate the relationship between timing and administration of venous thromboembolism (VTE) pharmacologic chemoprophylaxis after spinal surgery and the resulting VTE and bleeding complications by reviewing current practices and outcomes at a high-volume single institution to better define opportunities for perioperative intervention to prevent VTE without increasing bleeding complications.

METHODS

All patients who underwent elective one or two-stage lumbar spinal fusion procedures were identified. A logistic regression was used to evaluate (1) risk of symptomatic VTE within 30 days of surgery and (2) bleeding-related complications. The odds of developing a VTE as well as bleeding-related complications were compared among the three treatment groups: no chemoprophylaxis, chemoprophylaxis < 24h of surgery and chemoprophylaxis given > 24h post-surgery.

RESULTS

When adjusted for doses administered, the odds of developing a postoperative VTE within 30 days were 0.189 (95% confidence interval (0.044, 0.808)) in patients who received anticoagulation < 24h postoperatively, compared to those who received no anticoagulation (p = 0.025). There was no difference in bleeding rates.

CONCLUSION

Patients undergoing elective spinal surgery who received anticoagulation within 24h of the conclusion of their procedure had an 81% reduction in the odds of developing a deep vein thrombosis within 30 days with no significant difference in bleeding complications.

The Incidence of Venous Thromboembolism in Patients Undergoing Anterior Lumbar Interbody Fusion: A Proposed Thromboprophylactic Regime

OBJECTIVE

To determine the safety and efficacy of the proposed venous thromboembolism (VTE) prophylaxis regime in patients undergoing anterior lumbar interbody fusion (ALIF) surgery.

BACKGROUND

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are recognized complications after spine surgery, with rates in the literature ranging from 0% to 14% with some form of prophylaxis. Pharmacological thromboprophylaxis can cause postoperative bleeding and hematomas, which can result in significant neural compromise or permanent injury, and wound complications. ALIF surgery involves the handling and compression of major abdominal vessels during surgery and this adds to the risk of both arterial thrombosis and VTE.

METHODS

A retrospective review of data, which were prospectively collected to evaluate the incidence of VTE in 200 consecutive patients undergoing ALIF following our VTE prophylaxis protocol. All patients had low molecular weight heparin, tinzaparin 4500 units subcutaneously on the evening before surgery, then daily for 3 to 5 days, then aspirin (acetylsalicylic acid) 150 mg daily plus lansoprazole 30 mg daily for 4 weeks after surgery. All patients had intermittent pneumatic compression of their calves and thighs intraoperatively and for 24 hours postoperatively then had early mobilization and thromboembolic deterrent stockings for 6 weeks.

RESULTS

There was no incidence of any symptomatic VTE in the any of the 200 patients and no loss to follow-up. There was a 0% incidence of injury to the iliac vessels, symptomatic arterial occlusion, wound hematoma, major intraoperative bleeding, need for transfusion, symptomatic GI bleed, or retroperitoneal hematoma requiring intervention.

CONCLUSIONS

The proposed VTE prophylactic regime is safe and efficacious and may decrease the incidence of symptomatic VTE in patients undergoing an ALIF procedure, and despite the use of chemical thromboprophylaxis, there is no evidence of bleeding complications as a result of using this regime.

LEVEL OF EVIDENCE

4.

Comparing Bleeding and Thrombotic Rates in Spine Surgery: An Analysis of 119 888 Patients

STUDY DESIGN

Retrospective, database review.

OBJECTIVES

Examine the utilization rate of postoperative deep vein thrombosis (DVT) prophylaxis and compare the incidence and severity of bleeding and thrombotic complications in elective spine surgery patients.

METHODS

We utilized PearlDiver, a national orthopedics claims database. All patients who underwent elective spine surgery from 2007 to 2017 were included. Patients were stratified by the presence of DVT prophylaxis drug codes, then by comorbidities for postoperative bleeding/thrombosis. The severity of all bleeding and thrombotic complications in each cohort was studied, including the incidence of complications requiring operative washout, diagnosis of pulmonary embolism, intensive care unit admission, and mortality.

RESULTS

A total of 119 888 patients were included. The majority of patients (118 720, >99%) were not administered postoperative DVT chemoprophylaxis while a minority of patients (1168) were. The overall rates of bleeding and thrombotic complications within the population not receiving DVT prophylaxis were 1.96% and 2.45%, respectively (P < .001). The incidence of surgical intervention for a wound washout was 0.62% compared with 1.05% for pulmonary embolism (P < .001). Intensive care unit admission rates related to a wound washout procedure or pulmonary embolism also significantly differed (0.07% vs 0.34%, P < .001). There were no observed differences in mortality. When controlling for patient comorbidity, patients with atrial fibrillation, cancer, or a prior history of thrombotic complications experienced the greatest increased risks of postoperative thrombosis.

CONCLUSIONS

DVT prophylaxis is not routinely utilized following elective spine procedures. We report that there exist specific populations which may receive benefit from these practices, although further study is necessary to determine optimal prevention strategies for both thrombotic and bleeding complications in spine surgery.

A predictive model of preoperative risk factors for venous thromboembolism after fusion for degenerative conditions of the thoracolumbar spine

BACKGROUND

The purpose of this study was to identify preoperative risk factors for VTE and develop a predictive model that can be integrated into electronic health records (EHRs).

METHODS

Retrospective review of patients undergoing thoracolumbar fusion from 2016 to 2018 in the National Surgical Quality Improvement Program database was performed.

RESULTS

Increasing age, BMI, and several other factors were significant predictors of increased risk for postoperative VTE. The predictive model had an area under the curve of 0.683, indicating acceptable discrimination.

DISCUSSION

Our findings build upon previous studies by presenting a model equation that can be rapidly integrated into EHRs for validation.

Comparison of inpatient versus post-discharge venous thromboembolic events after spinal surgery: A single institution series of 6869 consecutive patients

STUDY DESIGN

retrospective chart review.

OBJECTIVE

We aimed to determine the perioperative risk factors that lead to inpatient or post-discharge venous thromboembolism (VTE) events after spinal surgery.

SUMMARY OF BACKGROUND DATA

While many studies relate the risk factors in a post-surgical setting to the incidence of VTE, this study aims to separate these VTE into inpatient and post-discharge categories to examine timing and risk factors.

METHODS

We analyzed 6869 patients from 2009 to 2015 using Current Procedural Technology codes from a single tertiary academic institution. Patients were stratified based on occurrence and setting of VTE then controlled for perioperative characteristics with exclusion criteria being patients undergoing minor spine surgeries or secondary procedures.

RESULTS

In 170 VTE events, these factors were associated with increased risk for: Inpatient DVT only: IVC filter (OR 6.380 [3.414-11.924]), longer length of hospital stay (OR 1.083 [1.047-1.120]), a prior history of DVT (OR 3.640 [1.931-6.856]). Post-discharge DVT only: history of PE (OR 45.142 [6.785-300.351]), having a corpectomy (OR 26.670 [3.477-204.548]), and having an osteotomy (OR 18.877 [1.129-315.534]). Inpatient PE only: surgery >4 h (OR 30.820, p < 0.001), fracture (OR 6.913, p = 0.004), IVC filter (OR 3.135, p = 0.029). Post-discharge PE only: corpectomy (OR 541.271, p = 0.009), foraminotomy (OR 40.137, p = 0.013), EBL > 500cc (OR 2467.798, p = 0.002). Time to onset of VTE events was significantly longer for patients undergoing osteotomy (7.43 days) than for patients with fracture (4.28 days), which is consistent with our findings that fracture was an independent predictor of inpatient VTE, and osteotomy was an independent predictor of post-discharge VTE (p = 0.018).

CONCLUSIONS

Time-to-VTE varies between types of surgeries. Some risk factors are independently associated with VTE at all times during the 30-day postoperative period, while other factors are only associated with either inpatient or post-discharge VTE. Those patients with high-risk features for post-discharge VTE merit increased study for thromboprophylaxis management.

The True Effect of a Lumbar Dural Tear on Complications and Cost

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

The aim of this study was to match risk factors for complications in patients who did and did not sustain a dural tear while undergoing posterior lumbar spine surgery and compare local and systemic complications.

SUMMARY OF BACKGROUND DATA

Current data do not adequately define whether the event of sustaining an isolated dural tear increases the risk for postoperative complications while controlling for other confounding risk factors.

METHODS

The PearlDiver Database was queried for patients who underwent posterior lumbar spine decompression and/or fusion for degenerative pathology. Patients with and without dural tears were 1:2 matched based on demographic variables and comorbidities. Complications, cost, length of stay (LOS), and readmission rates were analyzed.

RESULTS

The 1:2 matched cohort included 9038 patients with a dural tear and 17,340 patients without a dural tear. All complications assessed were significantly higher in the dural tear group (P < 0.03). Venothromboembolic (VTE) events occurred in 1.3% of patients with a dural tear and 0.9% of patients without a dural tear (odds ratio [OR] 1.46, P < 0.0001). Meningitis occurred in 25 patients (0.3%) with a dural tear and eight patients (<0.1%) without a dural tear (OR 6.0, P < 0.0001). Patients with a dural tear had 120% higher medical costs, 200% greater LOS, and were two times more likely to be readmitted (P < 0.0001).

CONCLUSION

Sustaining a dural tear while undergoing posterior lumbar spinal decompression and/or fusion for degenerative pathology significantly increased the risk of complications and increased length of stay, risk of readmission, and overall 90-day hospital cost. Dural tears specifically increased the risk of a VTE complication by 1.46 times and meningitis by six times; these are important complications to have a high degree of suspicion for in the setting of durotomy, as they can lead to significant morbidity for the patient.

LEVEL OF EVIDENCE

3.

Time-to-event analyses of lower-limb venous thromboembolism in aged patients undergoing lumbar spine surgery: a retrospective study of 1620 patients

After spine surgery, venous thromboembolism (VTE) is not uncommon in aged patients. This study investigates time-to-event risk factors of postoperative VTE based on medical records of aged patients (age≥60 yr) between January 2013 and December 2018. All participants had undergone lower extremity ultrasonography pre- and postoperatively at the first, second, fourth, eighth, and twelfth weeks. Mann-Whitney U tests and chi-square tests were used for univariate analyses, and Cox regression was utilized for multivariate analyses. A total of 1620 cases were recruited, VTE group (N=382, 23.6%) and non-VTE group (N=1238, 76.4%), aged 67 (IQR 11) years and 65 (IQR 6) years, respectively. The univariate analyses indicated significant differences between the VTE and non-VTE groups regarding advanced age, VTE history, hypertension, fusion, hospital stay, FIB, HDL, D-dimer, and TC (all P<0.05). The Cox regression showed that advanced age (OR=1.108; 95% CI, 1.091–1.126), VTE history (OR=4.962; 95% CI, 3.849–6.397), and hypertension (OR=1.344; 95% CI, 1.084–1.667) were the risk factors for postoperative VTE (P<0.05). The time-to-event analyses indicated that the hazard of VTE formation was highest in the first postoperative week. In conclusion, advanced age, VTE history, and hypertension are main risks for VTE formation, particularly in the first postoperative week.

Risk Factors for Postoperative Venous Thromboembolic Events in Patients Undergoing Lumbar Spine Surgery

STUDY DESIGN

Retrospective, database study.

OBJECTIVES

The aim of this study was to investigate incidence and risk factors associated with venous thromboembolic events (VTEs) after lumbar spine surgery.

METHODS

Patients who underwent lumbar surgery between 2007 and 2014 were identified using the Humana within PearlDiver database. ICD-9 (International Classification of Diseases Ninth Revision) diagnosis codes were used to search for the incidence of VTEs among surgery types, patient demographics and comorbidities. Complications including DVT and PE were queried each day from the day of surgery to postoperative day 7 and for periods 0 to 1 week, 0 to 1 month, 0 to 2 months, and 0 to 3 months postoperatively.

RESULTS

A total of 64 892 patients within the Humana insurance database received lumbar surgery between 2007 and 2014. Overall VTE rate was 0.9% at 1 week, 1.8% at 1 month, and 2.6% at 3 months postoperatively. Among patients that developed a VTE within 1 week postoperatively, 45.3% had a VTE on the day of surgery. Patients with 1 or more identified risk factors had a VTE incidence of 2.73%, compared with 0.95% for patients without risk factors (P < .001). Risk factors associated with the highest VTE incidence and odds ratios (ORs) were primary coagulation disorder (10.01%, OR 4.33), extremity paralysis (7.49%, OR 2.96), central venous line (6.70%, OR 2.87), and varicose veins (6.51%, OR 2.58).

CONCLUSIONS

This study identified several patient comorbidities that were independent predictors of postoperative VTE occurrence after lumbar surgery. Clinical VTE risk assessment may improve with increased focus toward patient comorbidities rather than surgery type or patient demographics.

Factors associated with venous thromboembolic events following ICU admission in patients undergoing spinal surgery: an analysis of 1269 consecutive patients

In BriefIn a retrospective study the authors examined 1269 patients who underwent spinal surgery and were admitted to the intensive care unit (ICU) and identified factors that are associated with venous thromboembolic events (VTEs) in this "high risk" group. Amongst these high-risk factors were: surgeries longer than 4 hours, comorbid disease, patients needing an osteotomy, and patients undergoing spinal stabilization for fractures. Identification of factors that can be optimized prior to surgery will decrease the rates of VTE.

Venous thromboembolism events following spinal fractures: A single center experience

OBJECTIVE

Venous thromboembolic events (VTE), including deep venous thrombosis (DVT) and pulmonary embolism (PE), are a major cause of readmission, morbidity, and mortality after spine surgery. Patients with spinal fractures are particularly at an increased risk for VTE. The objective of this study is to understand VTE risk factors in this patient population and to examine current institutional practices.

PATIENTS AND METHODS

We retrospectively examined records from 195 consecutive patients with spinal fractures who underwent spinal stabilization surgeries- amongst a cohort of 6869 patients who underwent spinal surgery. We collected data on patient demographics, surgery, hospital course, and 30-day rates of VTE, readmission, reoperation. Multivariable logistic regression was used to identify independent predictors of each outcome.

RESULTS

Among 195 patients undergoing surgery for spinal fractures, 9.2% experienced a VTE, compared to 2.3% among all other spine patients (OR 4.466, p < 0.0001). 48.7% spine fracture patients received chemoprophylactic anticoagulation, compared to 35.7% of all other spine patients (OR 2.657, p < 0.0001). Within 30 days of surgery, estimated blood loss (EBL) was associated with VTE (OR 1.001, p = 0.0415) and DVT (OR 1.001, p = 0.049), and comorbid cardiac disease burden showed a trend toward significance in predicting both VTE (OR 1.890, p = 0.0956) and DVT (OR 4.228, p = 0.0549). Number of levels in surgery predicted PE within 30 days of surgery (OR 1.573, p = 0.0107).

CONCLUSIONS

Compared to all other patients undergoing spine surgery, patients with spinal fractures are more likely to receive chemoprophylactic anticoagulation, but nevertheless have a higher rate of VTE events. EBL and comorbid disease burden predict VTE events in patients with spine fractures.

Venous Thromboembolism Prophylaxis in Spine Surgery

Venous thromboembolism (VTE) is a source of morbidity and mortality in patients undergoing orthopaedic surgery. A substantial body of literature supports the use of VTE prophylactic agents in patients undergoing lower extremity surgery. Treatment options include early mobilization, mechanical prophylaxis via pneumatic compression devices, pharmacologic agents, and venous filters. No consensus has been established regarding utilization or timing of VTE prophylaxis measures after spine surgery. The risk of VTE in patients undergoing spine surgery is not well characterized and varies substantially by the procedure and degree of neurologic compromise. In addition, the risk of clinically notable VTE must be weighed against the risk of postoperative bleeding and epidural hematoma after spine surgery. A standardized approach to VTE prophylaxis in patients undergoing spine surgery must take into account the available studies of risk factors, choice of prophylactic agents, and timing of prophylaxis.

Risk factors and pharmacologic prophylaxis for venous thromboembolism in elective spine surgery

BACKGROUND CONTEXT

Venous thromboembolism (VTE) is a known complication after spine surgery, but prophylaxis guidelines are ambiguous for patients undergoing elective spine surgery.

PURPOSE

The objective of this study was to characterize the incidence and risk factors for VTE and the association of pharmacologic prophylaxis with VTE and bleeding complications after elective spine surgery.

STUDY DESIGN/SETTING

This is a retrospective cohort study of patients undergoing elective spine surgery in the National Surgical Quality Improvement Program (NSQIP) database and a retrospective cohort analysis at an academic medical center.

PATIENT SAMPLE

This study included 109,609 patients in the NSQIP database from 2005 to 2014 and 2,855 patients at the authors' institution from January 2013 to March 2016 who underwent elective spine surgery.

OUTCOME MEASURES

The incidence and risk factors for VTE were assessed in both cohorts based on the NSQIP criteria. The incidence of bleeding complications requiring reoperation was assessed based on operative reports in the institutional cohort.

MATERIALS AND METHODS

Associations of patient and procedure factors with VTE were characterized in the NSQIP population. In the single-institution cohort, in addition to NSQIP variables, a chart review was completed to determine the use of VTE prophylaxis, the history of prior VTE, and the incidence of hematoma requiring reoperation. The association of patient and procedure variables, including pharmacologic prophylaxis and history of prior VTE, with VTE and hematoma requiring reoperation were determined with multivariate regression.

RESULTS

Among 109,609 elective spine surgery patients in NSQIP, independent risk factors for VTE were greater age, male gender, increasing body mass index, dependent functional status, lumbar spine surgery, longer operative time, perioperative blood transfusion, longer length of stay, and other postoperative complications. There were 2,855 patients included in the institutional cohort. Pharmacologic prophylaxis was performed in 56.3% of the institutional patients, of whom 97.1% received unfractionated heparin. When controlling for patient and procedural variables, pharmacologic prophylaxis did not significantly influence the rate of VTE, but was associated with a significant increase in hematoma requiring a return to the operating room (relative risk=7.37, p=.048).

CONCLUSIONS

Pharmacologic prophylaxis, primarily with unfractionated heparin, after elective spine surgery was not associated with a significant reduction in VTE. However, there was a significant increase in postoperative hematoma requiring reoperation among patients undergoing prophylaxis. This raises questions about the routine use of unfractionated heparin for VTE prophylaxis and supports the need for further consideration of risks and benefits of chemoprophylaxis after elective spine surgery.

Fibrin polymerization simulation using a reactive dissipative particle dynamics method

The study on the polymerization of fibrinogen molecules into fibrin monomers and eventually a stable, mechanically robust fibrin clot is a persistent and enduring topic in the field of thrombosis and hemostasis. Despite many research advances in fibrin polymerization, the change in the structure of fibrin clots and its influence on the formation of a fibrous protein network are still poorly understood. In this paper, we develop a new computational method to simulate fibrin clot polymerization using dissipative particle dynamics simulations. With an effective combination of reactive molecular dynamics formularies and many body dissipative particle dynamics principles, we constructed the reactive dissipative particle dynamics (RDPD) model to predict the complex network formation of fibrin clots and branching of the fibrin network. The 340 kDa fibrinogen molecule is converted into a spring-bead coarse-grain system with 11 beads using a topology representing network algorithm, and using RDPD, we simulated polymerization and formation of the fibrin clot. The final polymerized structure of the fibrin clot qualitatively agrees with experimental results from the literature, and to the best of our knowledge this is the first molecular-based study that simulates polymerization and structure of fibrin clots.

The timing of venous thromboembolic events after spine surgery: a single-center experience with 6869 consecutive patients

OBJECTIVE

Venous thromboembolic events (VTEs), including both deep venous thrombosis (DVT) and pulmonary embolism, are a major cause of morbidity and mortality after spine surgery. Prophylactic anticoagulation, or chemoprophylaxis, can prevent VTE. However, the timing of VTEs after spine surgery and the effect of chemoprophylaxis on VTE timing remain underinvestigated.

METHODS

The records of 6869 consecutive spine surgeries were retrospectively examined. Data on patient demographics, surgical variables, hospital course, and timing of VTEs were collected. Patients who received chemoprophylaxis were compared with those who did not. Appropriate regression models were used to examine selection for chemoprophylaxis and the timing of VTEs.

RESULTS

Age (OR 1.037, 95% CI 1.023–1.051; p < 0.001), longer surgery (OR 1.003, 95% CI 1.002–1.004; p < 0.001), history of DVT (OR 1.697, 95% CI 1.038–2.776; p = 0.035), and fusion surgery (OR 1.917, 95% CI 1.356–2.709; p < 0.001) predicted selection for chemoprophylaxis. Chemoprophylaxis patients experienced more VTEs (3.62% vs 2.03% of patients, respectively; p < 0.001), and also required longer hospital stays (5.0 days vs 1.0 days; HR 0.5107; p < 0.0001) and had a greater time to the occurrence of VTE (median 6.8 days vs 3.6 days; HR 0.6847; p = 0.0003). The cumulative incidence of VTEs correlated with the postoperative day in both groups (Spearman r = 0.9746, 95% CI 0.9457–0.9883, and p < 0.0001 for the chemoprophylaxis group; Spearman r = 0.9061, 95% CI 0.8065–0.9557, and p < 0.0001 for the nonchemoprophylaxis group), and the cumulative incidence of VTEs was higher in the nonchemoprophylaxis group throughout the 30-day postoperative period. Cumulative VTE incidence and postoperative day were linearly correlated in the first 2 postoperative weeks (R = 0.9396 and p < 0.0001 for the chemoprophylaxis group; R = 0.8190 and p = 0.0003 for the nonchemoprophylaxis group) and the remainder of the 30-day postoperative period (R = 0.9535 and p < 0.0001 for the chemoprophylaxis group; R = 0.6562 and p = 0.0058 for the nonchemoprophylaxis group), but the linear relationships differ between these 2 postoperative periods (p < 0.0001 for both groups).

CONCLUSIONS

Anticoagulation reduces the cumulative incidence of VTE after spine surgery. The cumulative incidence of VTEs rises linearly in the first 2 postoperative weeks and then plateaus. Surgeons should consider early initiation of chemoprophylaxis for patients undergoing spine surgery.

Impact of venous thromboembolism chemoprophylaxis on postoperative hemorrhage following operative stabilization of spine fractures

BACKGROUND

Prophylactic anticoagulation may decrease the risk of venous thromboembolism (VTE) in patients with spine fractures following blunt trauma but comes with the threat of postoperative bleeding in patients requiring stabilization of these fractures. The purpose of this study was to evaluate the impact of preoperative anticoagulation on VTE and bleeding complications in patients with blunt spine fractures requiring operative stabilization.

METHODS

All patients with blunt spine fractures requiring operative stabilization over a 6-year period were identified. Patients with a hospital stay of less than 48 hours or missing data were excluded. Patients were stratified by age; severity of shock, spinal cord injury, fracture location, injury severity; and timing and duration of anticoagulation. Outcomes included bleeding complications (wound hematoma/infection and development of epidural hematoma) and VTE (pulmonary embolism and deep venous thrombosis). Outcomes were evaluated to determine risk factors for bleeding complications and VTE in the management of operative spine fractures.

RESULTS

Seven hundred five patients were identified: 355 patients received one dose or more of preoperative anticoagulation, and 350 did not receive preoperative anticoagulation. Seventy-two percent were male, with a mean injury severity score and Glasgow Coma Scale score of 21 and 14, respectively. Bleeding complications occurred in 18 patients (2.6%), and 20 patients (2.8%) had VTE. Patients with VTE were more severely injured (Glasgow Coma Scale score of 13 vs 15, p ≤ 0.001 and injury severity score of 27 vs 18, p = 0.008). Despite longer time to mobilization (4 vs 2 days, p < 0.001), patients who received 50% or more of their scheduled preoperative doses had fewer episodes of pulmonary embolism (0.4% vs 2.2%, p < 0.05), with no difference in bleeding complications (2.1% vs 2.9%, p = 0.63) compared to patients who received either no preoperative anticoagulation or less than 50% of their scheduled preoperative doses.

CONCLUSIONS

Preoperative anticoagulation in patients with operative spine fractures reduced the risk of pulmonary embolism without increasing bleeding complications. Preoperative anticoagulation is both safe and beneficial in patients with operative spine fractures.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Predictors of Readmissions and Reoperations Related to Venous Thromboembolic Events After Spine Surgery: A Single-Institution Experience with 6869 Patients

BACKGROUND

Readmission and reoperation are used as hospital and surgeon quality metrics. Venous thromboembolic (VTE) events, including deep vein thrombosis and pulmonary embolism (PE), are a major cause of readmission, morbidity, and mortality after spine surgery. Specific procedural, perioperative, and patient characteristics may be associated with these outcomes.

METHODS

We retrospectively examined records from 6869 consecutive spine surgeries at our institution. We collected data on patient demographics, surgery, hospital course, and 30-day rates of VTE, readmission, reoperation, and epidural hematoma. Stepwise multivariable logistic regression was used to identify independent predictors of each outcome.

RESULTS

Factors associated with VTE within 30 days of surgery include a history of VTE (odds ratio [OR] 3.92 [confidence interval 1.83-8.36], P < 0.001), estimated blood loss (EBL; OR 1.017 [1.005-1.029], P = 0.004), fracture (OR 5.42 [2.09-14.05], P = 0.001), history of PE (OR 4.04 [1.22-13.42], P = 0.023), and transfusion (OR 2.26 [1.07-4.77], P = 0.033). Factors associated with readmission were a history of PE (OR 3.27 [1.07-9.97], P = 0.038), PE (OR 8.07 [2.26-28.8], P = 0.001), transfusion (OR 2.54 [1.55-4.17], P < 0.001), comorbid disease burden (OR 1.35 [1.01-1.80], P = 0.041), and tumor surgery (OR 2.84 [1.32-6.10], P = 0.007). Factors associated with reoperation were EBL (OR 1.024 [1.006-1.042], P = 0.008), transfusion (OR 3.86 [1.38-10.79], P = 0.01), and PE (OR 6.05 [1.03-35.62], P = 0.046). Transfusion was associated with epidural hematoma within 30 days (OR 7.38 [1.37-39.83], P = 0.02).

CONCLUSIONS

Transfusion and EBL are associated with numerous negative outcomes. Transfusion is an independent predictor of VTE, readmission, reoperation, and epidural hematoma requiring evacuation. Specific pathologies were associated with specific negative outcomes.

Risk of Deep vein thrombosis in neurosurgery: State of the art on prophylaxis protocols and best clinical practices

OBJECTIVE

To analytically discuss some protocols in Deep vein thrombosis (DVT)/pulmonary Embolism (PE) prophylaxis currently use in Neurosurgical Departments around the world.

DATA SOURCES

Analysis of the prophylaxis protocols in the English literature: An analytical and narrative review of literature concerning DVT prophylaxis protocols in Neurosurgery have been conducted by a PubMed search (back to 1978).

DATA EXTRACTION

80 abstracts were reviewed, and 74 articles were extracted.

DATA ANALYSIS

The majority of DVT seems to develop within the first week after a neurosurgical procedure, and a linear correlation between the duration of surgery and DVT occurrence has been highlighted. The incidence of DVT seems greater for cranial (7.7%) than spinal procedures (1.5%). Although intermittent pneumatic compression (IPC) devices provided adequate reduction of DVT/PE in some cranial and combined cranial/spinal series, low-dose subcutaneous unfractionated heparin (UFH) or low molecular-weight heparin (LMWH) further reduced the incidence, not always of DVT, but of PE. Nevertheless, low-dose heparin-based prophylaxis in cranial and spinal series risks minor and major postoperative haemorrhages: 2-4% in cranial series, 3.4% minor and 3.4% major haemorrhages in combined cranial/spinal series, and a 0.7% incidence of major/minor haemorrhages in spinal series.

CONCLUSION

This analysis showed that currently most of the articles are represented by case series and case reports. As long as clear guidelines will not be defined and universally applied to this diverse group of patients, any prophylaxis for DVT and PE should be tailored to the individual patient with cautious assessment of benefits versus risks.

Incidence and risk factors for preoperative deep venous thrombosis in 314 consecutive patients undergoing surgery for spinal metastasis

OBJECTIVE The authors of this study aimed to identify the incidence of and risk factors for preoperative deep venous thrombosis (DVT) in patients undergoing surgical treatment for spinal metastases. METHODS Univariate analysis of patient age, sex, ethnicity, laboratory values, comorbidities, preoperative ambulatory status, histopathological classification, spinal level, and surgical details was performed. Factors significantly associated with DVT univariately were entered into a multivariate logistic regression model. RESULTS The authors identified 314 patients, of whom 232 (73.9%) were screened preoperatively for a DVT. Of those screened, 22 (9.48%) were diagnosed with a DVT. The screened patients were older (median 62 vs 55 years, p = 0.0008), but otherwise similar in baseline characteristics. Nonambulatory status, previous history of DVT, lower partial thromboplastin time, and lower hemoglobin level were statistically significant and independent factors associated with positive results of screening for a DVT. Results of screening were positive in only 6.4% of ambulatory patients in contrast to 24.4% of nonambulatory patients, yielding an odds ratio of 4.73 (95% CI 1.88-11.90). All of the patients who had positive screening results underwent preoperative placement of an inferior vena cava filter. CONCLUSIONS Patients requiring surgery for spinal metastases represent a population with unique risks for venous thromboembolism. This study showed a 9.48% incidence of DVT in patients screened preoperatively. The highest rates of preoperative DVT were identified in nonambulatory patients, who were found to have a 4-fold increase in the likelihood of harboring a DVT. Understanding the preoperative thrombotic status may provide an opportunity for early intervention and risk stratification in this critically ill population.

Ultra-delayed lumbar surgical wound hematoma

Background:

There exists an inherent risk of increased venous thromboembolism (VTE) in surgical spine patients, which is independent of their existing risk factors. Prophylaxis and treatment of VTE is an imprecise practice and may have serious complications even well after the initial surgery. Furthermore, there are no clear guidelines on how to manage postoperative spine patients with regards to the timing of anticoagulation.

Case Description:

Here, we present the case of a middle-aged male, status post L2/3 laminectomy and discectomy who developed bilateral below the knee deep venous thrombosis. He was started on Enoxaparin and transitioned to Warfarin and returned with axial back pain, and was found to have a postoperative hematoma almost 3 weeks later in a delayed fashion.

Conclusion:

Delayed surgical wound hematoma with neural compression is an important complication to identify and should remain high on the differential diagnosis in patients on warfarin who present with axial spinal pain.

The incidence of deep venous thrombosis in high-risk Indian neurosurgical patients: Need for early chemoprophylaxis?

INTRODUCTION

Deep venous thrombosis (DVT) is thought to be less common in Asians than in Caucasian population. The incidence of DVT in high-risk groups, especially the neurosurgical (NS) patients, has not been well studied. This leaves no firm basis for the start of early prophylactic anticoagulation within first 5 postoperative days in Indian NS patients. This is a prospective observational study to determine the early occurrence of DVT in the NS patients.

PATIENTS AND METHODS

We screened 137 consecutive high-risk NS patients based on inclusion and exclusion criteria. The femoral veins were screened using Doppler ultrasound on day 1, 3, and 5 of admission into the NS Intensive Care Unit (ICU) at tertiary center from South India.

RESULTS

Among 2887 admissions to NICU 147 patients met inclusion criteria. One hundred thirty seven were screened for DVT. There was a 4.3% (6/137) incidence of DVT with none of the six patients having signs or symptoms of pulmonary embolism. Among the risk factors studied, there was a significant association with femoral catheterization and a probable association with weakness/paraparesis/paraplegia. The mortality in the study group was 10.8% with none attributable to DVT or pulmonary embolism.

CONCLUSION

There is a low incidence of DVT among the high risk neurosurgical population evaluated within the first 5 days of admission to NICU, limiting the need for early chemical thrombo-prophylaxis in these patients. With strict protocols for mechanical prophylaxis with passive leg exercise, early mobilization and serial femoral Doppler screening, heparin anticoagulation can be restricted within the first 5 days of ICU admission in high risk patients.

Incidence of Deep Vein Thrombosis in Patients Undergoing Degenerative Spine Surgery onProphylactic Dalteparin; A Single Center Report

OBJECTIVE

To determine the incidence of deep vein thrombosis (DVT)in patients undergoing spinal surgeries receiving prophylactic doses of Deltaparin in a single center in central Iran.

METHOD

This cross-sectional study was conducted in Shariatee hospital of Isfahan during a 12-month period. We included all the patients undergoing elective spinal surgeries in our center during the study period who received prophylactic dosages of subcutaneous Dalteparin (5000unit daily) thefirst postoperative day. Those with absolute contraindications of anticoagulation therapy were not included in the study. Patients were followed for 3 months clinically and the incidence of DVT was recorded. DVT was suspected clinically and was confirmed by color Doppler sonography.

RESULTS

Overall we included 120 patients with mean age of 44.8 ± 12.6years among whom there were 54 (45%) men and 66 (55%) women. Lumbar discectomy (32.9%)and laminectomy (20.2%)were the most common performed procedures. DVT was detected in 1 (0.83%) patient in postoperative period. None of the patients developed pulmonary embolism and none hemorrhagic adverse event was recorded. The patient was treated with therapeutic unfractionated heparin and was discharged with warfarin.

CONCLUSION

Our results shows the efficacy of LMWH (Dalteparin) in reducing the incidence of DVT to 0.83%. These results also show the safety of Dalteparin in spine surgery because of lack of bleeding complication.

Prevalence and Risk Factors of Deep Vein Thrombosis in Patients Undergoing Lumbar Interbody Fusion Surgery: A Single-Center Cross-Sectional Study

This cross-sectional study was designed to obtain the current prevalence of deep vein thrombosis (DVT) and analyze related risk factors in patients undergoing lumbar interbody fusion. Medical record data were collected from Department of Spinal Surgery, The Third Hospital of Hebei Medical University, between July 2014 and March 2015. Both univariate analysis and binary logistic regression analysis were performed to determine risk factors for DVT. A total of 995 patients were admitted into this study, including 484 men and 511 women, aged from 14 to 89 years old (median 50, IQR 19). The detection rate of lower limb DVT by ultrasonography was 22.4% (223/995) in patients undergoing lumbar interbody fusion. Notably, average VAS (visual analog scale) score in the first 3 days after surgery in the DVT group was more than that in the non-DVT group (Z = -21.69, P < 0.001). The logistic regression model was established as logit P = -13.257 + 0.056*X1 - 0.243*X8 + 2.085*X10 + 0.001*X12, (X1 = age; X8 = HDL; X10 = VAS; X12 = blood transfusion; x = 677.763, P < 0.001). In conclusion, advanced age, high postoperative VAS scores, and blood transfusion were risk factors for postoperative lower limb DVT. As well, the logistic regression model may contribute to an early evaluation postoperatively to ascertain the risk of lower limb DVT in patients undergoing lumbar interbody fusion surgery.

Impact of Increasing Age on Outcomes of Spinal Fusion in Adult Idiopathic Scoliosis

OBJECTIVE

To investigate the role of advancing age on postoperative complications and revision surgery after fusion for scoliosis.

METHODS

A retrospective, cohort study was performed using the Thomson Reuters MarketScan database, examining patients with adult scoliosis who underwent spinal fusion from 2000 to 2009. Primary outcomes included infection, hemorrhage and pulmonary embolism (PE) within 90 days of surgery, and refusion. The effect of increasing age was estimated using the odds ratio (OR) of complications in a multivariate logistic regression analysis, and a Cox proportional hazard model estimated the hazard ratio of refusion.

RESULTS

A total of 8432 patients were included in this study. Overall, the average age was 53.3 years, with 26.90% males and 39% with a Charlson Comorbidity Score of ≥ 1. Most patients had commercial insurance (66.81%), with 26.03% and 7.16% covered by Medicare and Medicaid, respectively. Increasing age (per 5-year increment) was a significant predictor of hemorrhagic complication (OR, 1.06; confidence interval [CI], 1.01-1.11; P = 0.0196), PE (OR, 1.09; CI, 1.03-1.16; P = 0.0031), infection (OR, 1.04; CI, 1.01-1.07; P = 0.0053), and refusion (hazard ratio, 1.07; CI, 1.02-1.13; P = 0.0103).

CONCLUSIONS

In this study, age was associated with increased risk of hemorrhage, PE, infection, and refusion. With the aging population, the role of patient age on postoperative healing and outcomes deserves deeper investigation after repair of adult idiopathic scoliosis.

Efficacy of ankle-brachial index as a preoperative screening in spine surgery

PURPOSE

The aims of this study were to investigate the prevalence of peripheral arterial disease (PAD) and specify the patients who are necessary to measure ankle-brachial index (ABI) as a preoperative PAD screening in spine surgery.

METHODS

A total of 1425 consecutive patients with non-emergency spine surgery underwent a PAD screening using ABI measurement. We reviewed their ABI data, age, smoking status, and co-morbidities including diabetes mellitus (DM), cerebrovascular disease (CVD) and ischemic heart disease (IHD). CT- or MR-angiography was used for a definitive diagnosis of PAD when the ABI was 0.9 or less.

RESULTS

Of 1425 patients, 37 patients (2.5%) showed less than 0.9 in ABI; 24 patients (1.6%) were eventually diagnosed as PAD. Of 24 patients with PAD, 22 patients (91.6%) were over 65 years. The prevalence of DM was 58.3% in the PAD group versus 18.7% in the non-PAD group (P < 0.05). Patients with CVD or IHD were more likely to have PAD, but the differences were not significant. Smoking rate was 62.5% in the PAD group versus 42.4% in the non-PAD group (P < 0.05).

CONCLUSIONS

The current preoperative PAD screening data showed that age over 65 years, DM and smoking habit were the risk factors for PAD development. Based on the current results, we advocate preoperative ABI measurement for over 50-year patients who had co-morbidities and/or smoking habit and all the patients aged 65 years or more.

Medication reconciliation for patients undergoing spinal surgery

PURPOSE

In recent years, a marked increase of spinal operations prompted a debate on quality issues. Besides obvious factors, such as the surgical technique, medication safety has been identified as one of the major risk factors for patients undergoing anesthesia and surgery. While the issue has already been addressed by hospital pharmacist and anesthesiologists, the prescription of correct medication remains within the surgeons' responsibility. We, therefore, investigated medication-related errors in spinal instrumentation patients and applied current medication reconciliation strategies.

METHODS

We performed a data survey on all patients undergoing spinal instrumentation in 2011. Risk factors for medication safety were identified and prioritized. Specific counter-measures were introduced in 2012 and evaluated in 2013.

RESULTS

147 patients were included in the 2011 and 162 in the 2013 survey. As top five risk factors we identified the preoperative stopping of medication, recording the medication history, prescription process of postoperative analgetics and anticoagulants and the medication list at discharge. Specific counter-measures included standardization of preparations, doses and the prescription process and improving access to this information (online and via a smartphone application). In elective patients, recording the medication histories was delegated to a hospital pharmacist and informative flyers and posters were used to integrate the patients themselves into the process. Counter-measures directed against the first four risk factors resulted in a significant reduction of medication errors. The last risk factor was targeted by instructing the responsible staff only, which proved to be a rather ineffective measure.

CONCLUSIONS

Medication safety could be significantly improved by implementation of counter-measures specific to the identified risk factors.

Prevalence and risk factors for development of venous thromboembolism after degenerative spinal surgery

STUDY DESIGN

Prospective clinical study.

OBJECTIVE

To identify the incidence and risk factors for venous thromboembolism (VTE) associated with degenerative spinal surgery procedures at the different spinal levels for various pathologies.

SUMMARY OF BACKGROUND DATA

Spinal surgery includes procedures for treatment of various pathologies at different spinal levels. There have been no studies on VTE after degenerative spinal surgery with respect to screening patients for both deep venous thrombosis and pulmonary thromboembolism (PE).

METHODS

We prospectively investigated the occurrence of VTE after degenerative spinal surgery in 459 patients who were divided into 5 groups: group 1, patients with cervical degenerative disease treated with posterior decompression; group 2, patients with cervical degenerative disease treated with instrumentation for spinal fusion; group 3, patients with thoracolumbar degenerative disease treated with instrumentation for spinal fusion; group 4, patients with lumbar spinal stenosis treated with posterior decompression; and group 5, patients with lumbar spondylolisthesis treated with 1-level posterior lumbar interbody fusion. A deep venous thrombosis and PE screening was performed for all patients. Binomial logistic regression analysis was used to assess the association of risk factors.

RESULTS

The incidence of VTE was 2.8%, 3.4%, 10.8%, 12.5%, and 10.1% in groups 1, 2, 3, 4, and 5, respectively. Female sex, advanced age, spinal level, and neurological deficits, were all risk factors. Cervical spinal surgery in particular had an associated low risk. In patients with PE, 3 of the 4 had no deep venous thrombosis, indicating that screening for PE is also needed in high-risk patients.

CONCLUSION

The prevalence of VTE after elective spinal surgery was different in each group.

LEVEL OF EVIDENCE

3.

Japanese 2011 nationwide survey on complications from spine surgery

BACKGROUND

The Japanese Society for Spine Surgery and Related Research (JSSR) previously carried out two nationwide surveys in 1994 and 2001 on complications from spine and spinal cord surgery. More than 10 years have now elapsed since 2001. Rapidly ageing populations have major impacts on society, particularly in the medical field. The purpose of this study was therefore to examine the present situation for spine surgery in Japan.

METHODS

The JSSR research team prepared a computerized questionnaire made up of two categories in order to capture clinicopathological information and surgical information. A recordable optical disc for data storage was sent to surgeons who were certified for spine surgery by JSSR. The data was analyzed.

RESULTS

The JSSR carried out a nationwide survey of complications of 31,380 patients. Patients aged 60 years or older comprised 63.1 % of the overall cohort. This was considerably higher than observed in previous surveys. Degenerative spinal diseases increased 79.7 %. With regard to surgical approach, the incidence of anterior surgery has decreased, while that of posterior surgery has increased compared to the earlier surveys (both p < 0.05). Spinal instrumentation was applied in 30.2 % cases, compared to 27.0 and 34.0 % cases in the 1994 and 2001 surveys, respectively. Intraoperative and postoperative complications were reported in 10.4 % and were slightly increased compared to 8.6 % in the earlier surveys (both p < 0.05). Diseases associated with a high incidence of complication included intramedullary tumor (29.3 %) and primary malignant tumor (22.0 %). The highest incidence of complication was dural tear (2.1 %), followed by neurological complication (1.4 %).

Symptomatic Thromboembolism as an Uncommon Postoperative Complication in Young Patients with Spinal Deformity

Background/Purpose

Thromboembolism continues to be one of the most appalling postoperative complications. We aim to extend the findings of earlier authors on clinically symptomatic thromboembolic complications in young patients (<30 years old) operated due to major spinal deformity.

Methods

We retrospectively studied 297 patients (98 males and 199 females), with a mean age of 17.8 ± 4.2 years (range, 1.8–29.8 years) and a mean follow-up period of 12.3 ± 5.9 months (range, 6–84 months), who had been operated due to major spinal deformity from August 2005 to December 2012. A complete clinical examination was performed in all patients throughout the postoperative period to find out any symptomatic thromboembolism.

Results

We found three (1.01%) and two (0.67%) cases with symptomatic thromboembolism and extensive pulmonary embolism, respectively. All of them had a positive history of anterior spine surgery, and one of them had been placed in a poor posture for a long time to improve the inflammation of a surgical wound.

Conclusion

Despite the rarity of thromboembolism after surgery for major spinal deformities in young patients, the possibility still exists, and patients with a positive history of anterior spinal surgery or poor posturing are probably more susceptible.

Up-to-date thromboprophylaxis in elective spinal surgery. A systematic review

Deep vein thrombosis (DVT) and pulmonary embolism (PE) present a high incidence after surgery, posing a high risk in surgical practice. Although a consensus does exist on thromboprophylaxis in orthopedic surgery, this topic remains controversial in regard to spinal surgery. In this current paper, we review and discuss the different forms of prophyilaxis presented in literature, in order to develop guidelines on prophylactic measures in spinal surgery, improving patient´s outcomes and reducing any medical/legal problems that could arise from a thrombotic complication.

Hospital outcomes and complications of anterior and posterior cervical fusion with bone morphogenetic protein

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

A nationwide population-based database was analyzed to identify the incidence of complications and mortality associated with bone morphogenetic protein (BMP) utilization in cervical spine fusion surgery.

SUMMARY OF BACKGROUND DATA

"Off-label" use of BMP as an adjunct in cervical fusions has been associated with increased complication rates in small case series. The incidence of complications with utilization of BMP is not well characterized on a national level.

METHODS

Data from the Nationwide Inpatient Sample were obtained for each year from 2002-2009. Patients undergoing anterior cervical fusion (ACF) or posterior cervical fusion for diagnoses of cervical myelopathy and/or radiculopathy were identified and separated into cohorts ("BMP" and "No BMP"). Patient demographics and comorbidities were compared. Complications, length of stay, costs, and mortality rates were assessed. Student t test and χ test were used to assess significant differences. A P value of less than 0.0005 was used to denote significance.

RESULTS

A total of 213,421 ACFs and 20,334 posterior cervical fusions were identified from 2002-2009; 6.2% of all ACFs and 12.5% of posterior cervical fusions utilized BMP. Patients receiving BMP in the ACF group were older with greater comorbidities than patients who did not receive BMP (P < 0.0005). Both surgical groups with BMP experienced increased length of stay and costs. Overall complication rates were significantly greater when BMP was utilized in ACFs (P < 0.0005) due to a significantly higher rate of dysphagia (37.2 vs. 22.5 per 1000 cases) (P < 0.0005).

CONCLUSION

Our study found that "off-label" use of BMP as an adjunct to cervical fusions was associated with increased rates of dysphagia in ACFs and increased costs for all cervical fusions. Our study does not measure long-term outcomes after discharge; however, the impact of increased inhospital costs, length of stay, and incidence of dysphagia with utilization of BMP should be considered prior to its use in cervical fusions.

The incidence and mortality of thromboembolic events in lumbar spine surgery

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

A population-based database was analyzed to identify the incidence, risk factors, and mortality associated with thromboembolic events after lumbar spine surgery.

SUMMARY OF BACKGROUND DATA

Pulmonary embolism (PE) and deep vein thrombosis (DVT) are potential complications that may occur after orthopedic procedures. The incidence of these complications is not well characterized after lumbar spine surgery.

METHODS

Data from the Nationwide Inpatient Sample was obtained from 2002-2009. Patients undergoing lumbar decompression (LD), or lumbar fusion (LF) for degenerative conditions were identified. Acute PE and DVT incidences and mortality rates were calculated. Comorbidities were calculated using a modified Charlson Comorbidity Index. Statistical analysis was performed using the Student t test for discrete variables and χ test for categorical data. Logistic regression was used to identify independent predictors of thromboembolic events. A P value of less than or equal to 0.0005 was used to denote statistical significance.

RESULTS

A total 578,457 LDs and LFs were identified from 2002-2009. DVT incidences were 2.4 and 4.3 per 1000 cases in the LD and LF groups, respectively. PE incidences were 1.0 and 2.6 per 1000 cases in the LD and LF groups, respectively. Patients who had undergone LF with thromboembolic events were younger, had fewer comorbidities, and incurred greater costs than patients who had undergone LD. Statistically significant predictors of DVT were pulmonary circulation disorders, coagulopathy, fluid/electrolyte disorders, anemia, obesity, teaching hospital status, and larger hospitals. Predictors for the development of PE were pulmonary circulation disorders, fluid/electrolyte disorders, anemia, black ethnicity and teaching hospital status.

CONCLUSION

Patients undergoing LD or LF are at inherent risk of thromboembolic events. DVT and PE are more common after LF procedures. Preoperative pulmonary circulation disorders, fluid/electrolyte disorders, deficiency anemia, and teaching hospital status were significant risk factors for developing both DVT and PE. Preventive measures in patients at risk may decrease the incidence of thromboembolic events.

LEVEL OF EVIDENCE

4.

The incidence and mortality of thromboembolic events in cervical spine surgery

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

A nationwide population-based database was analyzed to identify the incidence, risk factors, and mortalities associated with venous thromboembolism (VTE) after cervical spine surgery.

SUMMARY OF BACKGROUND DATA

Pulmonary embolism (PE) and deep vein thrombosis (DVT) are potential complications that may occur after orthopedic procedures. Incidences of these complications are not well characterized after cervical spine surgery.

METHODS

Data from the Nationwide Inpatient Sample database were obtained from 2002 to 2009. Patients undergoing anterior cervical fusion, posterior cervical fusion, and posterior cervical decompression (i.e., laminoforaminotomy, laminectomy, laminoplasty) for the diagnosis of cervical myelopathy and/or radiculopathy were identified. Incidences of PE and DVT were calculated. Comorbidities were calculated using the modified Charlson Comorbidity Index. Mortality associated with these complications was assessed in the 3 surgical subgroups. Statistical analysis was performed to assess significant differences between groups. Logistic regression was used to identify independent predictors of VTE. A P value of <0.0005 was used to denote significance.

RESULTS

There were 273,396 cervical procedures recorded in the Nationwide Inpatient Sample database from 2002 to 2009. Posterior cervical fusion-treated patients had statistically the highest incidences of DVT and PE, whereas the lowest PE and DVT rates were found in anterior cervical fusion-treated patients (P < 0.0005). All patients with thromboembolic events had significantly increased rates of mortality, hospitalization, and costs compared with patients without VTE across all procedural groups. Logistic regression analysis demonstrated statistically significant predictors of VTE to be male sex, pulmonary circulation disorders, fluid/electrolyte disorders, and teaching-hospital status.

CONCLUSION

Thromboembolic events are potential complications of cervical spine surgery. The highest rates of VTE were identified in those patients undergoing posterior cervical fusion. Regardless of approach, DVT and PEs resulted in increased mortality rates and hospitalization. We recommend a thorough preoperative assessment to identify patients at risk for VTE and treat accordingly to decrease the incidence of these thromboembolic events.

Comparative study of the prevalence of venous thromboembolism after elective spinal surgery

To the authors' knowledge, no comparative studies exist of venous thromboembolism (VTE) based on different pathologies, surgical procedures, or spinal levels after spinal surgery. The authors prospectively investigated VTE after elective spinal surgery. The study comprised 4 patient groups. Group 1 comprised 79 patients with lumbar spinal stenosis treated with posterior decompression without fusion; group 2 comprised 90 patients with lumbar or lower thoracic degenerative disease treated with instrumentation for spine fusion; group 3 comprised 89 patients with cervical degenerative disease treated with posterior decompression or instrumentation for fusion; and group 4 comprised 82 patients with spinal tumors treated with total spondylectomy or piecemeal excision with stabilization. Deep venous thrombosis (DVT) and pulmonary thromboembolism (PTE) screening was performed for all 340 patients 7 to 10 days postoperatively. Binomial logistic regression analysis was used to assess the association of risk factors. The incidence of VTE was 15.2% in group 1, 13.3% in group 2, 4.5% in group 3, and 22.0% in group 4. The overall incidence of PTE was 2.9% (10/340 patients). Of the 10 cases of PTE, 2 were symptomatic and 8 were asymptomatic. No DVT occurred in 6 of 10 PTE-positive patients. Multivariate analysis showed that spinal tumors, neurologic deficits, and advanced age were risk factors for VTE. Spinal tumor surgery carries a high risk of critical VTE, whereas cervical spine surgery carries a low risk. No DVT occurred in 60% of PTE-positive patients. This result indicates that screening for PTE is also needed in patients who are at high risk for VTE.

Thromboprophylaxis in spinal surgery: a survey

BACKGROUND

Venous Thromboembolism (VTE) is the most common complication following major joint surgery. While attention has been focused upon the incidence of thromboembolic disease following total hip or knee arthroplasty or emergency surgery for hip fracture, there exists a gap in the medical literature examining the incidence of VTE in spinal surgery. Evidence suggests that the prevalence of DVT after spinal surgery is higher than generally recognized but with a shortage of epidemiological data, guidelines for optimal prophylaxis are limited. This survey, of individuals attending the 2009 British Association of Spinal Surgeons Annual Meeting, sought to examine prevailing trends in VTE thromboprophylaxis in spinal surgery, adherence to guideline outlined by the National Institute for Health and Clinical Excellence (NICE) and to compare selections made by orthopaedic and neurosurgeons.

METHODS

We developed a questionnaire with eight clinical scenarios. Participants were asked to supply details on their specialty and to select which method(s) of thromboprophylaxis they would employ for each scenario. Chi squared analysis was used for statistical comparison of the questionnaire responses.

RESULTS

73% of neurosurgical respondents' and 31% of orthopaedic surgeons employed low molecular weight heparin (p < 0.001). Neurosurgeons also selected anti-embolism stockings more frequently (79% v 50%) while orthopaedic surgeons preferred mechanical prophylaxis (26% v 9%). There was no significant difference between trauma and non-trauma scenarios (p = 0.05).

CONCLUSION

There is no clear consensus in thromboprophylaxis in spinal surgery. There was a significant difference in selections across surgical disciplines with neurosurgeons more closely adhering to national guidelines. Further research examining the epidemiology of venous thromboembolism in spinal surgery and the risks-benefit relationship of thromboprophylaxis is warranted.

Efficacy and safety of low molecular weight heparin prophylaxis for venous thromboembolism following lumbar decompression surgery

OBJECTIVE

To evaluate the efficacy and safety of low molecular weight heparin (LMWH) prophylaxis for venous thromboembolism (VTE) after lumbar decompression surgery.

METHODS

Patients at high or the highest risk of VTE who underwent lumbar spine surgery in Peking Union Medical College Hospital from January 2004 to April 2011 were included in the present study. All the patients received a half dose of LMWH 6 hours after surgery followed by a full dose LMWH once per day until discharge. We recorded incidences of deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding complications, and medication side effects.

RESULTS

Seventy-eight consecutive patients were eligible and enrolled in this study. The mean hospital stat was 8.5±4.5 days. No symptomatic DVT, PE, or major bleeding events were observed. One patient developed wound ecchymosis, another developed wound bleeding, four had mild hepatic aminotransferase level elevation, and one developed a suspicious allergic reaction.

CONCLUSION

LMWH may be applied as an effective and safe prophylaxis for VTE in high-risk patients undergoing lumbar decompression surgery.

Heparin in the prophylaxis and treatment of venous thromboembolism and other thrombotic diseases

In this chapter, we discuss the key-role of heparin in the prophylaxis and treatment of venous thromboembolism (VTE) and other thrombotic disorders. Heparin exerts its antithrombotic effects by facilitating the ability of antithrombin (AT), a plasma serum protease inhibitor, to inhibit thrombin (factor IIa) and factor Xa. Different heparin formulations can be used for the prophylaxis of thrombosis and treatment, going from unfractionated heparin (UFH), different low-molecular-weight heparin (LMWH) preparations, to the recently introduced synthetic pentasaccharide fondaparinux. All heparin formulations can be administrated only by the parenteral route, including the intravenous (iv) and the subcutaneous (sc) route. We will overview the clinical evidence for the use of different heparin formulations in the prophylaxis and treatment of venous thromboembolism, of superficial vein thrombosis and of acute coronary syndromes (ACS). Special issues, like the use of heparins in pregnancy or in children, will also be discussed. Although heparin is an almost one century-old drug it remains a cornerstone of antithrombotic treatment.

Thromboembolic Complications Following Spine Surgery Assessed with Spiral CT Scans: DVT/PE Following Spine Surgery

Spine surgery is associated with a significant risk of postoperative pulmonary embolism (PE) and/or deep vein thrombosis (DVT). The goal of this study was to determine which symptoms and risk factors were associated with spiral CT scans positive for PE and/or DVT in the postoperative spine surgery patient. We conducted a retrospective review of all spine patients who underwent a postoperative CT to rule out PE during the period of March 2004-February 2006. The type of surgical procedure, risk factors, symptoms prompting scan ordering, anticoagulation, and treatment were recorded. Logistic regression models were used to determine significant predictors of a positive CT in this patient population. Of the 3,331 patients that had spine surgery during the study period, 130 (3.9%) had a spiral CT scan to rule out PE and/or proximal DVT. Thirty-three of the 130 (25.4%) CT scans were positive for PE only, five (3.8%) for PE and DVT, and three (2.3%) for DVT only. Only 24.5% (32) patients had risk factors for thromboembolic disease, and of these, a history of PE and/or DVT was the only significant risk factor for a positive scan (p = 0.03). No presenting symptoms or demographic variables were noted to have a significant association with PE and/or DVT. The type of surgical procedure (i.e., anterior, posterior, and percutaneous) was not associated with an increased risk for PE and/or DVT. Patients who are undergoing spine surgery with a history of thromboembolic disease should be carefully monitored postoperatively and may benefit from more aggressive prophylaxis.

Pulmonary embolism in spine surgery: a comparison of combined anterior/posterior approach versus posterior approach surgery

STUDY DESIGN

retrospective review.

OBJECTIVE

to determine if Anterior/Posterior Combined approach spine surgery is associated with an increased risk of pulmonary embolism (PE) compared to Posterior Only approach surgery.

SUMMARY OF BACKGROUND DATA

combined anterior/posterior approach spine surgery is associated with a significantly increased risk for PE. However, it is uncertain if there is any difference in risk between combined approaches versus a posterior-only approach.

METHODS

a prospective cohort of patients who underwent anterior/posterior combined approach spine surgery from January 2002 to January 2006 was compared to a retrospective cohort of consecutive patients who underwent posterior only approach spine surgery from September2007 to September 2008. Patient demographics, medical history, body-mass indexes, type of surgery, length of surgery, transfusions, and instrumented vertebral levels were collected from hospital and office records. Hospital records were used to identify patients who developed PE based on diagnosis by spiral CT scan. CT scans were only performed when a patient's clinical picture raised suspicion of PE. Fisher exact test for significance, χ test and odds ratios were used for analysis.

RESULTS

a total of 119 patients were included in the study: 63 patients underwent posterior approach spine surgery and 66 patients underwent combined anterior/posterior approach surgery. One patient (1.6%) developed PE after posterior approach surgery while 5 patients (7.5%) developed PE in the combined approach group. Those undergoing combined approaches were 5.08 times more likely to suffer from PE, but this increase was not significant (P = 0.208). Overall, increased risk for PE was associated with the number of levels fused (P = 0.006), total blood loss (P = 0.029), and number of units transfused (P = 0.030). The combined approach was associated with older age (P < 0.001), higher BMI (P = 0.023), more instrumented vertebrae (P < 0.001), greater total blood loss (P < 0.001) and cell saver infusion (P = 0.004) compared to the posterior only approach.

CONCLUSION

combined anterior/posterior approach spine surgery is associated with an increased risk for pulmonary embolism compared to posterior only approaches. However, regardless of the surgical approach, risk factors for PE common in both groups were operative time, total blood loss, number of levels fused, and the number of units transfused. Patients who undergo spine surgery with prolonged operative times and greater blood loss should be recognized as higher risk patients.

The prevalence of and specific risk factors for venous thromboembolic disease following elective spine surgery

BACKGROUND

Venous thromboembolic disease, including deep venous thrombosis and pulmonary embolism, is a serious and potentially life-threatening complication following orthopaedic surgical procedures. We sought to investigate the prevalence of thromboembolism as well as the efficacy and complications of various prophylactic measures in a population of patients who had undergone elective spine surgery.

METHODS

A meta-analysis and univariate logistic regression were performed on selected studies to determine the prevalence of and risk factors for deep venous thrombosis and pulmonary embolism following elective spine surgery. Studies were included on the basis of the selection criteria (specifically, the inclusion of only patients undergoing spine surgery, or the treatment of patients undergoing spine surgery as an independent cohort; the use of an objective diagnostic modality for the diagnosis of deep venous thrombosis, including Doppler ultrasonography or venography; the use of an objective diagnostic modality for the diagnosis of pulmonary embolism, including computed tomography of the chest or a ventilation-perfusion scan; and a study population of more than thirty patients). Patients with a known spinal cord injury were excluded.

RESULTS

Fourteen studies (including a total of 4383 patients) met our selection criteria. On the basis of the meta-analysis, the prevalence of deep venous thrombosis was 1.09% (95% confidence interval, 0.54% to 1.64%) and the prevalence of pulmonary embolism was 0.06% (95% confidence interval, 0.01% to 0.12%) following elective spine surgery. The use of pharmacologic prophylaxis significantly reduced the prevalence of deep venous thrombosis relative to either mechanical prophylaxis (p = 0.047) or no prophylaxis (p < 0.01). One fatal pulmonary embolism was reported. An epidural hematoma requiring surgical evacuation was reported in eight of 2071 patients receiving pharmacologic prophylaxis; three of these patients had a permanent neurologic deficit.

CONCLUSIONS

The risk of deep venous thrombosis and pulmonary embolism is relatively low following elective spine surgery, particularly for patients who receive pharmacologic prophylaxis. Unfortunately, pharmacologic prophylaxis exposes patients to a greater risk of epidural hematoma. More evidence is needed prior to establishing a protocol for prophylaxis against venous thromboembolic disease in patients undergoing elective spine surgery. Future prospective studies should seek to define the safety of various prophylactic modalities and to identify specific subpopulations of patients who are at greater risk for venous thromboembolism.

Detection of Pulmonary Embolism in the Postoperative Orthopedic Patient Using Spiral CT Scans

Orthopedic surgery is associated with a significant risk of postoperative pulmonary embolism (PE) and/or deep vein thrombosis (DVT). This study was performed to compare the clinical presentations of a suspected versus a documented PE/DVT and to determine the actual incidence of PE/DVT in the post-operative orthopedic patient in whom CT was ordered. All 695 patients at our institution who had a postoperative spiral CT to rule out PE/DVT from March 2004 to February 2006 were evaluated and information regarding their surgical procedure, risk factors, presenting symptoms, location of PE/DVT, and anticoagulation were assessed. Statistical analysis was performed using an independent samples t test with a two-tailed p value to examine significant associations between the patient variables and CT scans positive for PE. Logistic regression models were used to determine which variables appeared to be significant predictors of a positive chest CT. Of 32,854 patients admitted for same day surgery across all services, 695 (2.1%) had a postoperative spiral CT based on specific clinical guidelines. The incidence of a positive scan was 27.8% (193/695). Of these, 155 (22.3%) scans were positive for PE only, 24 (3.5%) for PE and DVT, and 14 (2.0%) for DVT only. The most common presenting symptoms were tachycardia (56%, 393/695), low oxygen saturation (48%, 336/695), and shortness of breath (19.6%, 136/695). Symptoms significantly associated with DVT were syncope and chest pain. A past medical history of PE/DVT was the only significant predictor of a positive scan. Patients who have a history of thromboembolic disease should be carefully monitored in the postoperative setting.

Thromboprophylaxis in traumatic and elective spinal surgery: analysis of questionnaire response and current practice of spine trauma surgeons

STUDY DESIGN

A survey on thromboprophylaxis in spinal surgery and trauma was conducted among spine trauma surgeons.

OBJECTIVE

Neurosurgeons and orthopedic surgeons from the Spinal Trauma Study Group were surveyed in an attempt to understand current practices in the perioperative administration of thromboprophylaxis in spinal surgery.

SUMMARY OF BACKGROUND DATA

Although much research has been invested in the prevention of thromboembolic events following surgical procedures, there have been few investigations specific to spinal surgery, especially in the context of trauma.

METHODS

A total of 47 spine surgeons were provided with a 24-question survey pertaining to deep vein thrombosis prophylaxis in spine surgical patients. There was 100% response to the survey, and 46 of the 47 physicians (98%) responded to the case scenarios.

RESULTS

Institutional protocols for deep vein thrombosis prophylaxis existed for 42 (89%) of the respondents; however, only 27 (57%) indicated that these protocols included spinal cord injury (SCI) patients. Before surgery, no prophylaxis or mechanical prophylactic measures for SCI and non-SCI spinal fracture patients were routinely used by 36 (77%) and 40 (85%) respondents, respectively. After surgery, pharmacologic prophylaxis was prescribed by 42 (91%) and 28 (62%) surgeons for SCI and non-SCI spinal fracture patients, respectively. There was a statistically significant tendency to use more intensive prophylactic measures for patients with SCI (x2, 10.86; P < 0.01) as well as a statistically significant longer duration of proposed thromboprophylaxis (x2, 24.62; P < 0.001). Postoperative pharmacologic thromboprophylaxis for elective anterior thoracolumbar spine surgery was reported by 23 (51%) of the respondents, whereas only 18 (40%) used pharmacological prophylaxis in elective posterior thoracolumbar spine cases. Spine complications from low-molecular weight heparin were reported by 22 (47%) surgeons, including fatal pulmonary embolism by 19 (40%) surgeons.

CONCLUSION

A basis for a consensus protocol on thromboprophylaxis in spinal trauma was attempted. No more than mechanical prophylaxis was recommended before surgery for non-SCI patients or after surgery for elective cervical spine cases. Chemical prophylaxis was commonly used after surgery in patients with SCI and in patients with elective anterior thoracolumbar surgery.