Reduced risk of venous thromboembolism with the use of intermittent pneumatic compression after craniotomy: a randomized controlled prospective study

Influence of postoperative D-dimer evaluation and intraoperative use of intermittent pneumatic vein compression (IPC) on detection and development of perioperative venous thromboembolism in brain tumor surgery

BACKGROUND OBJECTIVE

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common complication in craniotomy patients and is associated with increased morbidity and mortality. The duration of surgery is a known risk factor. Other factors such as positioning and tumor entity have hardly been investigated or are controversial. In two pilot studies, the determination of plasma D-dimer concentration led to a high detection rate of DVT, while the use of intermittent pneumatic venous compression (IPC) drastically reduced the incidence of VTE. In the present study we investigated the efficacy of the two approaches, either alone or in combination, in a large patient cohort.

METHODS

1759 patients who underwent elective craniotomy between 2009 and 2023 were retrospectively analyzed. The staggered use of D-dimer determination and intraoperative use of IPC resulted in 3 groups: Group 1: no procedure; Group 2: D-dimer evaluation; Group 3: IPC and D-dimer evaluation. If the D-dimer level was ≥ 2 mg/l (Fibrinogen equivalent units; FEU), venous ultrasound was performed. Age, gender, tumor entity, duration and extent of surgery, patient positioning, type of VTE were also recorded and analyzed.

RESULTS

The introduction of postoperative D-dimer evaluation increased the rate of detection of thrombosis from 1.7% in group 1 to 22.6% in group 2. The addition of IPC reduced the rate of thrombosis to 4.4%. Age, gender and patient positioning did not affect the rate of VTE. We were able to confirm the duration of surgery as an individual risk factor and showed that WHO grade 4 tumors and metastasis have an increased VTE risk.

CONCLUSIONS

If D-Dimer levels are not analyzed routinely about 20% of craniotomy patients suffer from a clinically silent thrombosis. Each with the risk of fate PE. Intraoperative use of IPC during craniotomy dramatically reduces the risk of VTE.

The effect of intraoperative intermittent pneumatic compression on deep venous thrombosis prophylaxis in patients undergoing elective craniotomy

Objective

Postoperative deep venous thrombosis (DVT) is commonly observed in patients undergoing craniotomy and is associated with a high incidence of pulmonary embolism and poor clinical outcomes. Herein, we investigated the prophylactic effect of DVT of intraoperative intermittent pneumatic compression (IPC) in patients undergoing craniotomy.

Methods

A total of 516 patients who underwent elective craniotomy between December 2021 and December 2022 were enrolled in this study. Patients were randomly assigned to the intervention group (received intraoperative IPC) or control group (without IPC). Lower extremity ultrasound was performed on both legs before and after surgery (1 h, 24 h, and 7 days post-intervention). DVT was defined as the visualization of a thrombus within the vein lumen of the leg. Coagulation and platelet function were measured at the start and end of the craniotomy.

Results

A total of 504 patients (251 in the intervention group and 253 in the control group) completed the study. Among these patients, 20.4% (103/504) developed postoperative DVT within the first week after surgery, with 16.7% occurring within 24 h. The incidence of postoperative DVT in the intervention group (9.6%, 24/251) was significantly lower than that in the control group (22.9%, 58/253, p < 0.001). Intraoperative IPC reduced the risk of DVT by 64.6% (0.354, 95% CI, 0.223-0.564, p < 0.001). There was no significant difference in coagulation and platelet function between the two groups (all p > 0.05).

Conclusion

DVT may develop within 24 h after the craniotomy. Intraoperative application of IPC reduces the incidence of postoperative DVT.

Intermittend pneumatic venous thrombembolism (VTE) prophylaxis during neurosurgical procedures

BACKGROUND

The management of perioperative venous thrombembolism (VTE) prophylaxis is highly variable between neurosurgical departments and general guidelines are missing. The main issue in debate are the dose and initiation time of pharmacologic VTE prevention to balance the risk of VTE-based morbidity and potentially life-threatening bleeding. Mechanical VTE prophylaxis with intermittend pneumatic compression (IPC), however, is established in only a few neurosurgical hospitals, and its efficacy has not yet been demonstrated. The objective of the present study was to analyze the risk of VTE before and after the implementation of IPC devices during elective neurosurgical procedures.

METHODS

All elective surgeries performed at our neurosurgical department between 01/2018-08/2022 were investigated regarding the occurrence of VTE. The VTE risk and associated mortality were compared between groups: (1) only chemoprophylaxis (CHEMO; surgeries 01/2018-04/2020) and (2) IPC and chemoprophylaxis (IPC; surgeries 04/2020-08/2022). Furthermore, general patient and disease characteristics as well as duration of hospitalization were evaluated and compared to the VTE risk.

RESULTS

VTE occurred after 38 elective procedures among > 12.000 surgeries. The number of VTEs significantly differed between groups with an incidence of 31/6663 (0.47%) in the CHEMO group and 7/6688 (0.1%) events in the IPC group. In both groups, patients with malignant brain tumors represented the largest proportion of patients, while VTEs in benign tumors occurred only in the CHEMO group.

CONCLUSION

The use of combined mechanical and pharmacologic VTE prophylaxis can significantly reduce the risk of postoperative thromboembolism after neurosurgical procedures and, therefore, reduce mortality and morbidity.

Venous thromboembolism and intracranial hemorrhage in patients undergoing glioblastoma surgery

In the perioperative management of patients with glioblastoma (GBM), physicians face the question of whether and when to administer prophylactic or therapeutic anticoagulation (AC). In this study, we investigate the effects of the timing of postoperative heparinization on thromboembolic events (TE) and postoperative hemorrhage (bleeding, PH) as well as the interactions between the two in the context of an underlying intracerebral malignancy. For this retrospective data analysis, 222 patients who underwent surgery for grade IV glioblastoma, IDH-wildtype (2016 CNS WHO) between 01/01/2014 and 31/12/2019 were included. We followed up for 12 months. We assessed various biographical and clinical data for risk factors and focused on the connection between timepoint of AC and adverse events. Subgroup analyses were performed for pulmonary artery embolism (PE), deep vein thrombosis, and postoperative intracranial hemorrhage (PH) that either required surgical intervention or was controlled radiologically only. Statistical analysis was performed using Mann-Whitney U-Test, Chi-square test, Fisher's exact test and univariate binomial logistic regression. p values below 0.05 were considered statistically significant. There was no significant association between prophylactic AC within 24 h and more frequent major bleeding (p = 0.350). AC in patients who developed major bleeding was regularly postponed by the physician/surgeon upon detection of the re-bleeding; therefore, patients with PH were anticoagulated significantly later (p = 0.034). The timing of anticoagulant administration did not differ significantly between patients who experienced a thromboembolic event and those who did not (p = 0.634). There was considerable overlap between the groups. Three of the six patients (50%) with PE had to be lysed or therapeutically anticoagulated and thereafter developed major bleeding (p < 0.001). Patients who experienced TE were more likely to die during hospitalization than those with major bleeding (p = 0.022 vs. p = 1.00). Prophylactic AC within 24 h after surgery does not result in more frequent bleeding. Our data suggests that postoperative intracranial hemorrhage is not caused by prophylactic AC but rather is a surgical complication or the result of antithrombotic therapy. However, thromboembolic events worsen patient outcomes far more than postoperative bleeding. The fact that bleeding may occur as a complication of life-saving lysis therapy in the setting of a thromboembolic event should be included in this cost-benefit consideration.

Development and Validation of a Clinical Prediction Model for Venous Thromboembolism Following Neurosurgery: A 6-Year, Multicenter, Retrospective and Prospective Diagnostic Cohort Study

BACKGROUND

Based on the literature and data on its clinical trials, the incidence of venous thromboembolism (VTE) in patients undergoing neurosurgery has been 3.0%~26%. We used advanced machine learning techniques and statistical methods to provide a clinical prediction model for VTE after neurosurgery.

METHODS

All patients (n = 5867) who underwent neurosurgery from the development and retrospective internal validation cohorts were obtained from May 2017 to April 2022 at the Department of Neurosurgery at the Sanbo Brain Hospital. The clinical and biomarker variables were divided into pre-, intra-, and postoperative. A univariate logistic regression (LR) was applied to explore the 67 candidate predictors with VTE. We used a multivariable logistic regression (MLR) to select all significant MLR variables of MLR to build the clinical risk prediction model. We used a random forest to calculate the importance of significant variables of MLR. In addition, we conducted prospective internal (n = 490) and external validation (n = 2301) for the model.

RESULTS

Eight variables were selected for inclusion in the final clinical prediction model: D-dimer before surgery, activated partial thromboplastin time before neurosurgery, age, craniopharyngioma, duration of operation, disturbance of consciousness on the second day after surgery and high dose of mannitol, and highest D-dimer within 72 h after surgery. The area under the curve (AUC) values for the development, retrospective internal validation, and prospective internal validation cohorts were 0.78, 0.77, and 0.79, respectively. The external validation set had the highest AUC value of 0.85.

CONCLUSIONS

This validated clinical prediction model, including eight clinical factors and biomarkers, predicted the risk of VTE following neurosurgery. Looking forward to further research exploring the standardization of clinical decision-making for primary VTE prevention based on this model.

Analysis of risk factors for postoperative deep vein thrombosis after craniotomy and nomogram model construction

BACKGROUND

Deep vein thrombosis (DVT) of the lower extremity is one of the most common postoperative complications, especially after craniocerebral surgery. DVT may lead to pulmonary embolism, which has a devastating impact on patient prognosis. This study aimed to investigate the incidence and risk factors of DVT in the lower limbs following craniocerebral surgery.

AIM

To identify independent risk factors for the development of postoperative DVT and to develop an effective risk prediction model.

METHODS

The demographic and clinical data of 283 patients who underwent craniocerebral surgery between December 2021 and December 2022 were retrospectively analyzed. The independent risk factors for lower extremity DVT were identified by univariate and multivariate analyses. A nomogram was created to predict the likelihood of lower extremity DVT in patients who had undergone craniocerebral surgery. The efficacy of the prediction model was determined by receiver operating characteristic curve using the probability of lower extremity DVT for each sample.

RESULTS

Among all patients included in the analysis, 47.7% developed lower extremity DVT following craniocerebral surgery. The risk of postoperative DVT was higher in those with a longer operative time, and patients with intraoperative intermittent pneumatic compression were less likely to develop postoperative DVT.

CONCLUSION

The incidence of lower extremity DVT following craniocerebral surgery is significant, highlighting the importance of identifying independent risk factors. Interventions such as the use of intermittent pneumatic compression during surgery may prevent the formation of postoperative DVT.

Thromboembolic prophylaxis in neurosurgical practice: a systematic review

BACKGROUND

In neurosurgical patients, the risk of developing venous thromboembolism (VTE) is high due to the relatively long duration of surgical interventions, usually long immobilization time after surgery, and possible neurological deficits which can negatively influence mobility. In neurosurgical clinical practice, there is lack of consensus on optimal prophylaxis against VTE, mechanical or pharmacological.

OBJECTIVE

To systematically review available literature on the incidence of VTE in neurosurgical interventions and to establish an optimum prevention strategy.

METHODS

A literature search was performed in PubMed, Embase, Web of Science, Cochrane Library, and EmCare, based on a sensitive search string combination. Studies were selected by predefined selection criteria, and risk of bias was assessed by Newcastle-Ottawa Quality Assessment Scale and Cochrane risk of bias.

RESULTS

Twenty-five studies were included, half of which had low risk of bias (21 case series, 3 comparative studies, 1 RCT). VTE was substantially higher if the evaluation was done by duplex ultrasound (DUS), or another systematic screening method, in comparison to clinical evaluation (clin). Without prophylaxis DVT, incidence varied from 4 (clin) to 10% (DUS), studies providing low molecular weight heparin (LMWH) reported an incidence of 2 (clin) to 31% (DUS), providing LMWH and compression stockings (CS) reported an incidence of 6.4% (clin) to 29.8% (DUS), and providing LMWH and intermittent pneumatic compression devices (IPC) reported an incidence of 3 (clin) to 22.3% (DUS). Due to a lack of data, VTE incidence could not meaningfully be compared between patients with intracranial and spine surgery. The reported incidence of pulmonary embolism (PE) was 0 to 7.9%.

CONCLUSION

Low molecular weight heparin, compression stockings, and intermittent pneumatic compression devices were all evaluated to give reduction in VTE, but data were too widely varying to establish an optimum prevention strategy. Systematic screening for DVT reveals much higher incidence percentages in comparison to screening solely on clinical grounds and is recommended in follow-up of neurosurgical procedures with an increased risk for DVT development in order to prevent occurrence of PE.

A systematic review of venous thromboembolism mechanical prophylaxis devices during surgery

PURPOSE

Hospitalisation and surgery are major risk factors for venous thromboembolism (VTE). Intermittent pneumatic compression (IPC) and graduated compression stockings (GCS) are common mechanical prophylaxis devices used to prevent VTE. This review compares the safety and efficacy of IPC and GCS used singularly and in combination for surgical patients.

METHODS

Ovid Medline and Pubmed were searched in a systematic review of the literature, and relevant articles were assessed against eligibility criteria for inclusion along PRISMA guidelines.

RESULTS

This review is a narrative description and critical analysis of available evidence. Fourteen articles were included in this review after meeting the criteria. Results of seven studies comparing the efficacy of IPC versus GCS had high heterogeneity but overall suggested IPC was superior to GCS. A further seven studies compared the combination of IPC and GCS versus GCS alone, the results of which suggest that combination mechanical prophylaxis may be superior to GCS alone in high-risk patients. No studies compared combination therapy to IPC alone. IPC appeared to have a superior safety profile, although it had a worse compliance rate and the quality of evidence was poor. The addition of pharmacological prophylaxis may make mechanical prophylaxis superfluous in the post-operative setting.

CONCLUSION

IPC may be superior to GCS when used as a single prophylactic device. A combination of IPC and GCS may be more efficacious than GCS alone for high-risk patients. Further high-quality research is needed focusing on clinical relevance, safety and comparing combination mechanical prophylaxis to IPC alone, particularly in high-risk surgical settings when pharmacological prophylaxis is contraindicated.

Incidence and Risk Factors for Superficial and Deep Vein Thrombosis in Post-Craniotomy/Craniectomy Neurosurgical Patients

Background Venous thromboembolism (VTE) is quite common among post-operative neurosurgical patients. This study aims to identify the incidence of deep vein thrombosis (DVT) and superficial vein thrombosis (SVT) among post-craniotomy/craniectomy patients and further evaluate established hypercoagulability risk factors such as trauma, tumors, and surgery. Methodology This single-center retrospective study investigated 197 patients who underwent a craniotomy/craniectomy. The incidences of DVT and SVT were compared, along with laterality and peripherally inserted central catheter (PICC) line involvement. A multivariate logistic regression analysis was conducted to identify risk factors for post-craniotomy/craniectomy VTE. This model included variables such as age, post-operative days before anticoagulant administration, female sex, indications for surgery such as tumor and trauma, presence of a PICC line, and anticoagulant administration. Results Among the 197 post-craniotomy/craniectomy patients (39.6% female; mean age 53.8±15.7 years), the incidences of DVT, SVT, and VTE were 4.6%, 9.6%, and 12.2%, respectively. The multivariate logistic regression analysis found that increasing the number of days between surgery and administration of anticoagulants significantly increased the risk of VTE incidence (odds ratio 1.183, 95% CI 1.068-1.311, p = 0.001). Conclusions Contrary to existing evidence, this study did not find trauma or the presence of tumors to be risk factors for VTE. Future prospective studies should assess VTE risk assessment models such as "3 Bucket" or "Caprini" to develop universal guidelines for administering anticoagulant therapy to post-craniotomy/craniectomy patients that consider the timing of post-operative therapy initiation.

Ultra-early therapeutic anticoagulation after craniotomy - A single institution experience

There is a paucity of information regarding the optimal timing of initiation or re-initiation of therapeutic anticoagulation after intracranial surgery. Anticoagulation that is started too soon after surgery may increase the risk of catastrophic intracranial bleeding. However, there are scenarios that necessitate the use of anticoagulation in the immediate post-operative period despite the increased risk of hemorrhage. Therefore, we sought to report our experience with ultra-early therapeutic anticoagulation after craniotomy. Retrospective chart review of patients from a single institution between 1/1/2010 and 10/1/2021 who were treated with therapeutic anticoagulation for venous thromboembolism on or before 7-days after a craniotomy or craniectomy. The primary endpoint was intracranial hemorrhage resulting in death or return to the operating room for hematoma evacuation. Secondary endpoints included extra-cranial hemorrhage, length of hospital stay, and 90-day readmission rate. Eighteen patients were included for analysis. The median time that therapeutic anticoagulation was started was post-operative day 5 (range 1-7 days). One patient (5.6%) met the primary endpoint as they experienced an intracranial hemorrhage 5 days after starting anticoagulation, which required surgical evacuation. No patients experienced an extra-cranial hemorrhage. The median length of hospitalization was 13 days (range 4-89 days). No patients were readmitted within 90 days. The 90-day survival rate was 100%. Ultra-early anticoagulation after craniotomy resulted in a 5.6% risk of intracranial hemorrhage. Thus, ultra-early anticoagulation can be performed safely but it does carry a substantial risk of intracranial bleeding that may require emergent hematoma evacuation or result in permeant neurologic deficits or death.

Comparison of the Safety of Prophylactic Anticoagulants After Intracranial Surgery

BACKGROUND

Venous thromboembolism (VTE) represents a rare but preventable postoperative complication. Unfractionated heparin (UH) and low-molecular-weight heparin (LMWH) are used to prevent VTE, but comparative studies of their safety and efficacy in the neurosurgical context are limited.

OBJECTIVE

To determine the relative safety and efficacy of UH and LMWH for prophylaxis after cranial surgery.

METHODS

We performed a retrospective analysis of 3204 elective intracranial surgical admissions in 2901 patients over the period 2013 to 2018. From chart review, we extracted demographic and clinical features, including diagnosis and procedure, drugs administered, and the occurrence of VTE events. To compare postoperative outcomes, we performed propensity score matching of patients receiving different drugs, and reviewed postoperative cranial imaging. To contextualize our results, we selected 14 prior neurosurgical studies of VTE prophylaxis to compare our outcomes to the existing literature.

RESULTS

In our sample of 3204 admissions, the overall rate of VTE was 0.8% (n = 27). Rates of VTE were not statistically different in matched cohorts receiving UH and LMWH (1.7% vs 1.0%, respectively); however, LMWH was associated with a higher rate of clinically significant intracranial hemorrhage (ICH) (3.4% vs 0.5%, P = .008). Literature review and meta-analysis supported these findings. Across studies, UH and LMWH were associated with similar rates of VTE. Studies in which patients received LMWH reported significantly higher rates of ICH (4.9% higher, P = .005).

CONCLUSION

We find that LMWH and UH show similar efficacy in preventing VTE; however, LMWH is associated with higher rates of ICH.

Perioperative anticoagulation in patients with intracranial meningioma: No increased risk of intracranial hemorrhage?

OBJECTIVE

Anticoagulation (AC) is a critical topic in perioperative and post-bleeding management. Nevertheless, there is a lack of data about the safe, judicious use of prophylactic and therapeutic anticoagulation with regard to risk factors and the cause and modality of brain tissue damage as well as unfavorable outcomes such as postoperative hemorrhage (PH) and thromboembolic events (TE) in neurosurgical patients. We therefore present retrospective data on perioperative anticoagulation in meningioma surgery.

METHODS

Data of 286 patients undergoing meningioma surgery between 2006 and 2018 were analyzed. We followed up on anticoagulation management, doses and time points of first application, laboratory values, and adverse events such as PH and TE. Pre-existing medication and hemostatic conditions were evaluated. The time course of patients was measured as overall survival, readmission within 30 days after surgery, as well as Glasgow Outcome Scale (GOS) and modified Rankin Scale (mRS). Statistical analysis was performed using multivariate regression.

RESULTS

We carried out AC with Fraxiparin and, starting in 2015, Tinzaparin in weight-adapted recommended prophylactic doses. Delayed (216 ± 228h) AC was associated with a significantly increased rate of TE (p = 0.026). Early (29 ± 21.9h) prophylactic AC, on the other hand, did not increase the risk of PH. We identified additional risk factors for PH, such as blood pressure maxima, steroid treatment, and increased white blood cell count. Patients' outcome was affected more adversely by TE than PH (+3 points in modified Rankin Scale in TE vs. +1 point in PH, p = 0.001).

CONCLUSION

Early prophylactic AC is not associated with an increased rate of PH. The risks of TE seem to outweigh those of PH. Early postoperative prophylactic AC in patients undergoing intracranial meningioma resection should be considered.

The use of intermittent pneumatic compression to prevent venous thromboembolism in neurosurgical patients-A systematic review and meta-analysis

OBJECTIVE

The incidence of venous thromboembolism (VTE) remains high despite the use of low-molecular weight heparin (LMWH) and compression stocking (CS). We aimed to evaluate the use of IPC as VTE prophylaxis in neurosurgical patients.

PATIENTS AND METHODS

We conducted meta-analysis to assess the use of IPC as VTE prophylaxis in neurosurgical patients from several databases.

RESULTS

There was a total of 7.515 subjects from 5 studies. Reduction in VTE incidence was demonstrated by the IPC group (OR 0.40 [0.31, 0.52], p < 0.001; I²: 44 %). IPC was shown to reduce the incidence of deep venous thrombosis (DVT) (OR 0.43 [0.32, 0.57], p < 0.001; I²: 0 %) compared to the control group. Incidence of pulmonary embolism (PE) was lower (OR 0.42 [0.25, 0.70], p < 0.001; I²: 80 %) in IPC. Upon sensitivity analysis, PE was significantly lower in IPC (OR 0.24 [0.13, 0.45], p < 0.001; I²: 0 %). Subgroup analysis on patients undergoing neurosurgical intervention (operation) and receiving LMWH + CS shows a markedly reduced incidence of VTE (OR 0.37 [0.28, 0.50], p < 0.001; I²: 3 %), DVT (OR 0.39 [0.28, 0.54], p < 0.001; I²: 0 %), and PE (OR 0.22 [0.11, 0.43], p < 0.001; I²: 0 %) in IPC.

CONCLUSION

Intermittent pneumatic compression was associated with less VTE in neurosurgical patients, especially in those who received neurosurgical interventions, however, the certainty of evidence remained inadequate for creating a strong recommendation and further randomized controlled trials are needed before drawing a definite conclusion.

Venous thromboembolic events in patients undergoing craniotomy for tumor resection: incidence, predictors, and review of literature

OBJECTIVE

The authors sought to investigate the incidence and predictors of venous thromboembolic events (VTEs) after craniotomy for tumor resection, which are not well established, and the efficacy of and risks associated with VTE chemoprophylaxis, which remains controversial.

METHODS

The authors investigated the incidence of VTEs in a consecutive series of patients presenting to the authors' institution for resection of an intracranial lesion between 2012 and 2017. Information on patient and tumor characteristics was collected and independent predictors of VTEs were determined using stepwise multivariate logistic regression analysis. Review of the literature was performed by searching MEDLINE using the keywords "venous thromboembolism," "deep venous thrombosis," "pulmonary embolism," "craniotomy," and "brain neoplasms."

RESULTS

There were 1622 patients included for analysis. A small majority of patients were female (52.6%) and the mean age of the cohort was 52.9 years (SD 15.8 years). A majority of intracranial lesions were intraaxial (59.3%). The incidence of VTEs was 3.0% and the rates of deep venous thromboses and pulmonary emboli were 2.3% and 0.9%, respectively. On multivariate analysis, increasing patient age (unit OR 1.02, 95% CI 1.00-1.05; p = 0.018), history of VTE (OR 7.26, 95% CI 3.24-16.27; p < 0.001), presence of motor deficit (OR 2.64, 95% CI 1.43-4.88; p = 0.002), postoperative intracranial hemorrhage (OR 4.35, 95% CI 1.51-12.55; p < 0.001), and prolonged intubation or reintubation (OR 3.27, 95% CI 1.28-8.32; p < 0.001) were independently associated with increased odds of a VTE. There were 192 patients who received VTE chemoprophylaxis (11.8%); the mean postoperative day of chemoprophylaxis initiation was 4.6 (SD 3.8). The incidence of VTEs was higher in patients receiving chemoprophylaxis than in patients not receiving chemoprophylaxis (8.3% vs 2.2%; p < 0.001). There were 30 instances of clinically significant postoperative hemorrhage (1.9%), with only 1 hemorrhage occurring after initiation of VTE chemoprophylaxis (0.1%).

CONCLUSIONS

The study results show the incidence and predictors of VTEs after craniotomy for tumor resection in this patient population. The incidence of VTE within this cohort appears low and comparable to that observed in other institutional series, despite the lack of routine prophylactic anticoagulation in the postoperative setting.