Thromboelastography for Monitoring Prolonged Hypercoagulability After Major Abdominal Surgery

Point-of-care viscoelastic coagulation assessment in healthy dogs during the perianesthetic period

Background

The viscoelastic coagulation monitor (VCM Vet) is a novel, portable device that provides a global assessment of hemostasis. The study aims were to evaluate serial viscoelastic analysis during the perianesthetic period in healthy dogs and to compare the agreement between two VCM Vet devices. Twenty healthy dogs undergoing orthopedic surgery were enrolled. Whole blood samples were collected from an intravenous catheter at four time points: baseline, 15 min after premedication, 60 min after inhalant initiation, and 60 min after inhalant termination. Viscoelastic tests were performed in duplicate on different devices, providing: clot time (CT; seconds), clot formation time (CFT; seconds), alpha angle (α; degrees), amplitude (units) at 10 (A10) and 20 (A20) minutes post clot time, maximum clot firmness (MCF; units), and lysis index (%) at 30 (Li30) and 45 (Li45) minutes post maximum clot formation.

Results

One hundred sixty samples were analyzed. The speed of CT and CFT significantly decreased an average of 25.5 s (95% confidence interval [CI]15.9–35.0) and 6.9 s (95% CI 3.1–10.7) per time point, respectively. There were no significant changes in clot strength or lysis variables. The Bland–Altman style plot shows an acceptable rate of agreement for all variables with intra-class correlation ranging from 0.64–0.94.

Conclusion

The rate of clot formation (CT and CFT) decreased over the perianesthetic period in healthy dogs undergoing surgery. These changes were small and occurred without changes in clot strength or fibrinolysis rate, thus were not clinically relevant. There was clinically acceptable consistency between devices.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03442-x.

Development of Models to Predict Postoperative Complications for Hepatitis B Virus-Related Hepatocellular Carcinoma

Background

Surgical treatment remains the best option for patients with hepatocellular carcinoma (HCC) caused by chronic hepatitis B virus (HBV) infection. However, there is no optimal tool based on readily accessible clinical parameters to predict postoperative complications. Herein, our study aimed to develop models that permitted risk of severe complications to be assessed before and after liver resection based on conventional variables.

Methods

A total of 1,047 patients treated by hepatectomy for HCC with HBV infection at three different centers were recruited retrospectively between July 1, 2014, and July 1, 2018. All surgical complications were recorded and scored by the Comprehensive Complication Index (CCI). A CCI ≥26.2 was used as a threshold to define patients with severe complications. We built two models for the CCI, one using preoperative and one using preoperative and postoperative data. Besides, CCI and other potentially relevant factors were evaluated for their ability to predict early recurrence and metastasis. All the findings were internally validated in the Hangzhou cohort and then externally validated in the Lanzhou and Urumqi cohorts.

Results

Multivariable analysis identified National Nosocomial Infections Surveillance (NNIS) index, tumor number, gamma-glutamyltransferase (GGT), total cholesterol (TC), potassium, and thrombin time as the key preoperative parameters related to perioperative complications. The nomogram based on the preoperative model [preoperative CCI After Surgery for Liver tumor (CCIASL-pre)] showed good discriminatory performance internally and externally. A more accurate model [postoperative CCI After Surgery for Liver tumor (CCIASL-post)] was established, combined with the other four postoperative predictors including leukocyte count, basophil count, erythrocyte count, and total bilirubin level. No significant association was observed between CCI and long-term complications.

Conclusion

Based on the widely available clinical data, statistical models were established to predict the complications after hepatectomy in patients with HBV infection. All the findings were extensively validated and shown to be applicable nationwide. Such models could be used as guidelines for surveillance follow-up and the design of post-resection adjuvant therapy.

Ratiometric Bioluminescent Indicator for a Simple and Rapid Measurement of Thrombin Activity Using a Smartphone

Hemostasis is an essential function that repairs tissues and maintains the survival of living organisms. To prevent diseases caused by the abnormality of the blood coagulation mechanism, it is important to carry out a blood test periodically by a method that is convenient and less burdensome for examiners. Thrombin is a protease that catalyzes the conversion of fibrinogen, and its cleavage activity can be an index of coagulation activity. Here, we developed a ratiometric bioluminescent indicator, Thrombastor (thrombin activity sensing indicator), which reflects the thrombin cleavage activity in blood by changing the emission color from green to blue. Compared to the current thrombin activity indicator, the rapid color change of the emission indicated a 2.5-fold decrease in the K_m for thrombin, and the cleavage rate was more than two times faster. By improving the absolute bioluminescence intensity, detection from a small amount of plasma could be achieved with a smartphone camera. Using Thrombastor and a versatile device, an effective diagnosis for preventing coagulation disorders can be provided.

Coagulopathy and Venous Thromboembolic Events Following Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

Background

Coagulopathy after cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is recognized but few details have been studied.

Objectives

The aim of this study was to investigate changes in coagulation biomarkers and their predictive ability for venous thromboembolism (VTE).

Methods

Patients undergoing CRS and HIPEC at Uppsala University Hospital, Sweden, from 2004 to 2014 were included in a prospective study of coagulation biomarkers. Prothrombin time international normalized ratio (PT-INR), activated partial thromboplastin time (APTT), fibrinogen, antithrombin, D-dimer, and platelets were sampled on postoperative days 1, 2, 5, and 10. Logistic regression analysis was used to evaluate predictive capacity for coagulation-related complications.

Results

Overall, 380 patients were included (214 females, mean age 56 years); 38 patients had a history of thromboembolism and 57 were active smokers. Mean perioperative blood loss was 1228 mL and 231 (61%) received perioperative blood transfusions. PT-INR and APTT were elevated directly after surgery but returned to normal levels on postoperative day 5. Conversely, fibrinogen, platelet count, D-dimer, and antithrombin increased by postoperative day 5 and continued to increase up to day 10. There were 23 radiologically verified cases of VTE within 6 months. The multivariate analysis identified a completeness of cytoreduction score of 2–3 (p = 0.047) and day 2 D-dimer (p = 0.0082) as independent risk factors for postoperative VTE.

Conclusion

Significant postoperative changes in coagulation biomarkers occur with dynamic changes over 10 days postoperatively. The incidence of symptomatic VTE was low. Residual tumor at completion of surgery and elevated D-dimer on day 2 were independent risk factors for postoperative VTE.

Clinical effectiveness and safety of salvia miltiorrhiza depside salt combined with aspirin in patients with stable angina pectoris: A multicenter, pragmatic, randomized controlled trial

BACKGROUND

Salvia Miltiorrhiza Depside Salt (SMDS) was extracted from Salvia miltiorrhiza with high-quality control of active principles. In 2005, China's FDA approved the use of SMDS for stable angina pectoris (SAP), but the evidence of SMDS combined with aspirin remains unclear.

PURPOSE

The aim of this study was to assess the clinical effectiveness and safety of SMDS combined with aspirin in patients with SAP.

METHODS

A multicenter, pragmatic, three-armed parallel group and an individually randomized controlled superiority trial was designed. Participants aged 35 to 75 years old with SAP were recruited from four "Class Ⅲ Grade A" hospitals in China. Participants who were randomized into the SMDS group were treated with SMDS by intravenous drip. Participants in the control group received aspirin enteric-coated tablets (aspirin). Participants who were randomly assigned to the combination group received SMDS combined with aspirin. All participants received standard care from clinicians, without any restrictions. The primary outcome measure was thromboelastography (TEG). Secondary outcome measures included symptom score of the Seattle Angina Questionnaire (SAQ), visual analogue scale (VAS) score of traditional Chinese medicine (TCM) symptoms, platelet aggregation measured by light transmittance aggregometry (LTA), and fasting blood glucose. Effectiveness evaluation data were collected at baseline and ten days after treatment. Researchers followed up with participants for one month after treatment to determine whether adverse events (AEs) or adverse drug reactions (ADRs) such as bleeding tendency occurred. All statistical calculations were carried out with R 3.5.3 statistical analysis software.

RESULTS

A total of 135 participants completed follow-up data on the primary outcome after ten days of treatment. Participants in the SMDS combined aspirin group had the highest improvement rate of sensitivity in AA% [p < 0.001, 95% CI (0.00-0.00)], from 30.6% before treatment to 81.6% after treatment. Participants with drug resistance (AA% < 20%) in the SMDS combined with aspirin group also had the highest sensitivity rate [p < 0.001, 95% CI (0.00-0.00)] after treatment (accounting for 81.0% of the combination group and 60.7% of the sensitive participants). The improvement of TCM symptoms in participants treated with SMDS combined with aspirin was significantly better than that of the aspirin group [MD = 1.71, 95% CI (0.15-3.27), p = 0.032]. There were no significant differences in other indexes (R, TPI, MA, K, CI, α value) of TEG, SAQ, platelet aggregation and fasting blood glucose among the three groups. No bleeding tendency or ADRs occurred in all participants.

CONCLUSION

SMDS combined with aspirin is a clinically effective and safe intervention to treat adults aged 35 and older with SAP. This trial shows that SMDS combined with aspirin can significantly improve the sensitivity rate of AA% in TEG and the VAS score of TCM symptoms. Further large samples and high-quality research are needed to determine if certain participants might benefit more from SMDS combined with aspirin. The study protocol was registered in the Clinical Trials USA registry (registration No. NCT02694848).

Ability of Thromboelastography to Detect Hypercoagulability: A Systematic Review and Meta-Analysis

OBJECTIVE

To review the current literature on the use of viscoelastic hemolytic assays, such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM), during the perioperative period of patients and determine the ability of TEG and ROTEM to detect hypercoagulability and identify increased risk of the development of venous thromboembolism (VTE).

DATA SOURCES

PubMed, EMBASE, and Cochrane online databases were queried through February 11, 2018, by pairing the terms "thromboelastography," "viscoelastic hemostatic assays," and "rotational thromboelastometry" with "venous thromboembolism," "deep vein thrombosis," "pulmonary embolism," and "hypercoagulability."

STUDY SELECTION

Inclusion and exclusion criteria were established to determine relevance and quality of data, of which 2.54% of initially identified studies met.

DATA EXTRACTION AND SYNTHESIS

Articles and citations were reviewed for relevance by 2 independent individuals following PRISMA guidelines as well as a quality assessment of data as established by Zaza et al. In studies that separated patients postoperatively by VTE development or no VTE development, data were pooled utilizing a modified DerSimmion and Laird random effects model.

RESULTS

One thousand eight hundred ninety-three articles were assessed for eligibility, yielding 370 abstracts. Of the 370 abstracts, 35 studies were included, and of these, only 5 were included in the meta-analysis. Studies included postsurgical patients in a variety of surgical fields, encompassing a total of 8939 patients, with 717 thrombotic events reported. Elevated maximum amplitude (MA) was a statistically significant indicator of hypercoagulability across at least 1 perioperative time point in 17 (50%) of the articles reviewed, consisting of 6348 (72%) patients. The pooled mean MA value for defining hypercoagulability was greater than 66.70 mm. Using a prepublished value for hypercoagulability of 65 mm, the combined effect of MA on the development of VTE in postsurgical patients was determined to be 1.31 (95% confidence, 0.74-2.34, P = 0.175) and was 46% sensitive and 62% specific in predicting a postoperative VTE.

CONCLUSIONS

Only 1 parameter, MA, was consistently used to both define hypercoagulability and be predictive of VTE after traumatic injury and surgical intervention; however, there remains a broad variability in the definition of hypercoagulability as determined by MA and thus limits its predictive ability. In addition, when hypercoagulability was measured throughout the perioperative period, TEG consistently demonstrated hypercoagulability starting on post-op day 1 (POD1).

LEVEL OF EVIDENCE

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

Hyperthermic intraperitoneal chemotherapy enhances blood coagulation perioperatively evaluated by thromboelastography: a pilot study

Background and Objectives: Postoperative thromboembolism is a significant cause of prolonged recovery in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). Thromboelastography (TEG) can detect hypercoagulable states and predict thromboembolic complications after surgery. This study assessed the impact of CRS and HIPEC on TEG values.Methods: TEG parameters reaction time (R), kinetics time (K), angle (α), maximum amplitude (MA), and lysis percent at 60 min (LY60) were determined preoperatively, and at the end of CRS, during HIPEC, and at the end of the operation using blood samples from 15 HIPEC patients. Platelets, P-TT, and aPTT were also determined before and after CRS.Results: A total of 75 samples were analyzed. During CRS, there was a significant reduction in the mean MA (3.06 mm, p = 0.001). The mean P-TT declined by 32% (p < 0.001) and mean platelets by 55 × 10⁹/L (p < 0.001). During HIPEC, the mean R and K shortened by 1.04 min (p = 0.015) and 0.18 min (p = 0.018), respectively, whereas α increased by 2.48° (p = 0.005).Conclusions: During CRS, both TEG and conventional laboratory tests indicated hypocoagulation. During HIPEC, however, the initiation of coagulation and the kinetics of thrombin formation were accelerated.

A preliminary study using rotational thromboelastometry to investigate perioperative coagulation changes and to identify hypercoagulability in obese patients undergoing total hip or knee replacement

Surgery and obesity are known risk factors for thromboembolic events due to the presence of a hypercoagulable state. Rotational thromboelastometry is a viscoelastic assay that can provide a measure of hypercoagulability via a comprehensive assessment of the coagulation process. This prospective study investigates haemostatic changes over time, presence of hypercoagulability and the association between body mass index and thromboelastometry results in patients undergoing major orthopaedic surgery. Fifty adult patients undergoing total hip or knee replacement surgery had serial thromboelastometry measures performed prior to and following surgery, and on postoperative days 1 and 3. A hypercoagulable state, defined by an ExTEM maximum clot firmness G score ≥11 dyne/cm2, was present in 28% of the patients at baseline. The mean ExTEM maximum clot firmness G score increased by an average of three units from 10 (95% confidence interval (CI) 9–11) dyne/cm2 at baseline to 13 (95% CI 13–14) dyne/cm2 on postoperative day 3, with 85% of patients having a G score ≥11 dyne/cm2. A decrease in ExTEM and InTEM clot formation time and an increase in ExTEM, InTEM and FibTEM clot amplitude at 10 minutes, alpha angle and maximum clot firmness were observed by postoperative day 3 ( P <  0.001). There was no significant difference in the mean thromboelastometry values between patients with a body mass index <35 kg/m2or ≥35 kg/m2. Although a modest association between body mass index and the ExTEM maximum clot firmness G score was observed with exploratory data analysis, further study is required in a large cohort to test the effects of confounders, validate these findings, and determine their clinical importance.

Prolonged thromboprophylaxis with low molecular weight heparin for abdominal or pelvic surgery

BACKGROUND

This an update of the review first published in 2009.Major abdominal and pelvic surgery carries a high risk of venous thromboembolism (VTE). The efficacy of thromboprophylaxis with low molecular weight heparin (LMWH) administered during the in-hospital period is well-documented, but the optimal duration of prophylaxis after surgery remains controversial. Some studies suggest that patients undergoing major abdominopelvic surgery benefit from prolongation of the prophylaxis up to 28 days after surgery.

OBJECTIVES

To evaluate the efficacy and safety of prolonged thromboprophylaxis with LMWH for at least 14 days after abdominal or pelvic surgery compared with thromboprophylaxis administered during the in-hospital period only in preventing late onset VTE.

SEARCH METHODS

We performed electronic searches on 28 October 2017 in the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, LILACS and registered trials (Clinicaltrials.gov October 28, 2017 and World Health Organization International Clinical Trials Registry Platform (ICTRP) 28 October 2017). Abstract books from major congresses addressing thromboembolism were handsearched from 1976 to 28 October 2017, as were reference lists from relevant studies.

SELECTION CRITERIA

We assessed randomized controlled clinical trials (RCTs) comparing prolonged thromboprophylaxis (≥ fourteen days) with any LMWH agent with placebo, or other methods, or both to thromboprophylaxis during the admission period only. The population consisted of persons undergoing abdominal or pelvic surgery for both benign and malignant pathology. The outcome measures included VTE (deep venous thrombosis (DVT) or pulmonary embolism (PE)) as assessed by objective means (venography, ultrasonography, pulmonary ventilation/perfusion scintigraphy, spiral computed tomography (CT) scan or autopsy). We excluded studies exclusively reporting on clinical diagnosis of VTE without objective confirmation.

DATA COLLECTION AND ANALYSIS

Review authors identified studies and extracted data. Outcomes were VTE (DVT or PE) assessed by objective means. Safety outcomes were defined as bleeding complications and mortality within three months after surgery. Sensitivity analyses were also performed with unpublished studies excluded, and with study participants limited to those undergoing solely open and not laparoscopic surgery. We used a fixed-effect model for analysis.

MAIN RESULTS

We identified seven RCTs (1728 participants) evaluating prolonged thromboprophylaxis with LMWH compared with control or placebo. The searches resulted in 1632 studies, of which we excluded 1528. One hundred and four abstracts, eligible for inclusion, were assessed of which seven studies met the inclusion criteria.For the primary outcome, the incidence of overall VTE after major abdominal or pelvic surgery was 13.2% in the control group compared to 5.3% in the patients receiving out-of-hospital LMWH (Mantel Haentzel (M-H) odds ratio (OR) 0.38, 95% confidence interval (CI) 0.26 to 0.54; I2 = 28%; moderate-quality evidence).For the secondary outcome of all DVT, seven studies, n = 1728, showed prolonged thromboprophylaxis with LMWH to be associated with a statistically significant reduction in the incidence of all DVT (M-H OR 0.39, 95% CI 0.27 to 0.55; I2 = 28%; moderate-quality evidence).We found a similar reduction when analysis was limited to incidence in proximal DVT (M-H OR 0.22, 95% CI 0.10 to 0.47; I2 = 0%; moderate-quality evidence).The incidence of symptomatic VTE was also reduced from 1.0% in the control group to 0.1% in patients receiving prolonged thromboprophylaxis, which approached significance (M-H OR 0.30, 95% CI 0.08 to 1.11; I2 = 0%; moderate-quality evidence).No difference in the incidence of bleeding between the control and LMWH group was found, 2.8% and 3.4%, respectively (M-H OR 1.10, 95% CI 0.67 to 1.81; I2 = 0%; moderate-quality evidence).No difference in mortality between the control and LMWH group was found, 3.8% and 3.9%, respectively (M-H OR 1.15, 95% CI 0.72 to 1.84; moderate-quality evidence).Estimates of heterogeneity ranged between 0% and 28% depending on the analysis, suggesting low or unimportant heterogeneity.

AUTHORS' CONCLUSIONS

Prolonged thromboprophylaxis with LMWH significantly reduces the risk of VTE compared to thromboprophylaxis during hospital admittance only, without increasing bleeding complications or mortality after major abdominal or pelvic surgery. This finding also holds true for DVT alone, and for both proximal and symptomatic DVT. The quality of the evidence is moderate and provides moderate support for routine use of prolonged thromboprophylaxis. Given the low heterogeneity between studies and the consistent and moderate evidence of a decrease in risk for VTE, our findings suggest that additional studies may help refine the degree of risk reduction but would be unlikely to significantly influence these findings. This updated review provides additional evidence and supports the previous results reported in the 2009 review.

Assessment of hypercoagulability using thromboelastography predicts advanced status in renal cell carcinoma

Background

Thromboelastography (TEG) has been established as a sensitive method to assess the whole coagulation process. The aim of the study was to evaluate the diagnosis significance of TEG on hypercoagulability in patients suffering renal mass.

Methods

A total of 478 patients were diagnosed with renal tumor by histolopathologic examination and were assigned to three groups. Group A: 79 patients with benign renal tumor; Group B: 317 patients with renal cell carcinoma (RCC, Fuhrman grades I and II); Group C: 82 patients with high‐risk RCC (Fuhrman grades III and IV). Subgroup analysis was performed in malignant renal tumor patients according to the TMN classification. The clinical data, whole blood TEG, and conventional coagulation tests were reviewed.

Results

There was no statistically significant difference between subgroups in respect to conventional coagulation tests. Hypercoagulablity was marked in Group C according to the TEG parameters. The elevated platelets and fibrinogen is linked with hypercoagulability in renal tumor. The positive correlation was between fibrinogen and MA value (r = .663, P < .05). The pathologic tumor stages were also associated with the TEG parameters.

Conclusion

Patients suffering advanced RCC are hypercoagulable which can be identified by TEG. MA value could be potential diagnosis indicators for detecting high‐grade RCC.

Prolonged thromboprophylaxis with low molecular weight heparin for abdominal or pelvic surgery

BACKGROUND

This an update of the review first published in 2009.Major abdominal and pelvic surgery carries a high risk of venous thromboembolism (VTE). The efficacy of thromboprophylaxis with low molecular weight heparin (LMWH) administered during the in-hospital period is well-documented, but the optimal duration of prophylaxis after surgery remains controversial. Some studies suggest that patients undergoing major abdominopelvic surgery benefit from prolongation of the prophylaxis up to 28 days after surgery.

OBJECTIVES

To evaluate the efficacy and safety of prolonged thromboprophylaxis with LMWH for at least 14 days after abdominal or pelvic surgery compared with thromboprophylaxis administered during the in-hospital period only in preventing late onset VTE.

SEARCH METHODS

We performed electronic searches on 28 October 2017 in the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, LILACS and registered trials (Clinicaltrials.gov October 28, 2017 and World Health Organization International Clinical Trials Registry Platform (ICTRP) 28 October 2017). Abstract books from major congresses addressing thromboembolism were handsearched from 1976 to 28 October 2017, as were reference lists from relevant studies.

SELECTION CRITERIA

We assessed randomized controlled clinical trials (RCTs) comparing prolonged thromboprophylaxis (≥ fourteen days) with any LMWH agent with placebo, or other methods, or both to thromboprophylaxis during the admission period only. The population consisted of persons undergoing abdominal or pelvic surgery for both benign and malignant pathology. The outcome measures included VTE (deep venous thrombosis (DVT) or pulmonary embolism (PE)) as assessed by objective means (venography, ultrasonography, pulmonary ventilation/perfusion scintigraphy, spiral computed tomography (CT) scan or autopsy). We excluded studies exclusively reporting on clinical diagnosis of VTE without objective confirmation.

DATA COLLECTION AND ANALYSIS

Review authors identified studies and extracted data. Outcomes were VTE (DVT or PE) assessed by objective means. Safety outcomes were defined as bleeding complications and mortality within three months after surgery. Sensitivity analyses were also performed with unpublished studies excluded, and with study participants limited to those undergoing solely open and not laparoscopic surgery. We used a fixed-effect model for analysis.

MAIN RESULTS

We identified seven RCTs (1728 participants) evaluating prolonged thromboprophylaxis with LMWH compared with control or placebo. The searches resulted in 1632 studies, of which we excluded 1528. One hundred and four abstracts, eligible for inclusion, were assessed of which seven studies met the inclusion criteria.For the primary outcome, the incidence of overall VTE after major abdominal or pelvic surgery was 13.2% in the control group compared to 5.3% in the patients receiving out-of-hospital LMWH (Mantel Haentzel (M-H) odds ratio (OR) 0.38, 95% confidence interval (CI) 0.26 to 0.54; I2 = 28%; moderate-quality evidence).For the secondary outcome of all DVT, seven studies, n = 1728, showed prolonged thromboprophylaxis with LMWH to be associated with a statistically significant reduction in the incidence of all DVT (M-H OR 0.39, 95% CI 0.27 to 0.55; I2 = 28%; moderate-quality evidence).We found a similar reduction when analysis was limited to incidence in proximal DVT (M-H OR 0.22, 95% CI 0.10 to 0.47; I2 = 0%; moderate-quality evidence).The incidence of symptomatic VTE was also reduced from 1.0% in the control group to 0.1% in patients receiving prolonged thromboprophylaxis (M-H OR 0.30, 95% CI 0.08 to 1.11; I2 = 0%; moderate-quality evidence).No difference in the incidence of bleeding between the control and LMWH group was found, 2.8% and 3.4%, respectively (M-H OR 1.10, 95% CI 0.67 to 1.81; I2 = 0%; moderate-quality evidence).No difference in mortality between the control and LMWH group was found, 3.8% and 3.9%, respectively (M-H OR 1.15, 95% CI 0.72 to 1.84; moderate-quality evidence).Estimates of heterogeneity ranged between 0% and 28% depending on the analysis, suggesting low or unimportant heterogeneity.

AUTHORS' CONCLUSIONS

Prolonged thromboprophylaxis with LMWH significantly reduces the risk of VTE compared to thromboprophylaxis during hospital admittance only, without increasing bleeding complications or mortality after major abdominal or pelvic surgery. This finding also holds true for DVT alone, and for both proximal and symptomatic DVT. The quality of the evidence is moderate and provides moderate support for routine use of prolonged thromboprophylaxis. Given the low heterogeneity between studies and the consistent and moderate evidence of a decrease in risk for VTE, our findings suggest that additional studies may help refine the degree of risk reduction but would be unlikely to significantly influence these findings. This updated review provides additional evidence and supports the previous results reported in the 2009 review.

Prolonged thromboprophylaxis with low molecular weight heparin for abdominal or pelvic surgery

BACKGROUND

This an update of the review first published in 2009.Major abdominal and pelvic surgery carries a high risk of venous thromboembolism (VTE). The efficacy of thromboprophylaxis with low molecular weight heparin (LMWH) administered during the in-hospital period is well-documented, but the optimal duration of prophylaxis after surgery remains controversial. Some studies suggest that patients undergoing major abdominopelvic surgery benefit from prolongation of the prophylaxis up to 28 days after surgery.

OBJECTIVES

To evaluate the efficacy and safety of prolonged thromboprophylaxis with LMWH for at least 14 days after abdominal or pelvic surgery compared with thromboprophylaxis administered during the in-hospital period only in preventing late onset VTE.

SEARCH METHODS

We performed electronic searches on 28 October 2017 in the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, LILACS and registered trials (Clinicaltrials.gov October 28, 2017 and World Health Organization International Clinical Trials Registry Platform (ICTRP) 28 October 2017). Abstract books from major congresses addressing thromboembolism were handsearched from 1976 to 28 October 2017, as were reference lists from relevant studies.

SELECTION CRITERIA

We assessed randomized controlled clinical trials (RCTs) comparing prolonged thromboprophylaxis (≥ fourteen days) with any LMWH agent with placebo, or other methods, or both to thromboprophylaxis during the admission period only. The population consisted of persons undergoing abdominal or pelvic surgery for both benign and malignant pathology. The outcome measures included VTE (deep venous thrombosis (DVT) or pulmonary embolism (PE)) as assessed by objective means (venography, ultrasonography, pulmonary ventilation/perfusion scintigraphy, spiral computed tomography (CT) scan or autopsy). We excluded studies exclusively reporting on clinical diagnosis of VTE without objective confirmation.

DATA COLLECTION AND ANALYSIS

Review authors identified studies and extracted data. Outcomes were VTE (DVT or PE) assessed by objective means. Safety outcomes were defined as bleeding complications within three months after surgery. Sensitivity analyses were also performed with unpublished studies excluded, and with study participants limited to those undergoing solely open and not laparoscopic surgery. We used a fixed-effect model for analysis.

MAIN RESULTS

We identified seven RCTs (1728 participants) evaluating prolonged thromboprophylaxis with LMWH compared with control or placebo. The searches resulted in 1632 studies, of which we excluded 1528. One hundred and four abstracts, eligible for inclusion, were assessed of which seven studies met the inclusion criteria.For the primary outcome, the incidence of overall VTE after major abdominal or pelvic surgery was 13.2% in the control group compared to 5.3% in the patients receiving out-of-hospital LMWH (Mantel Haentzel (M-H) odds ratio (OR) 0.38, 95% confidence interval (CI) 0.26 to 0.54; I2 = 28%; seven studies, n = 1728; moderate-quality evidence).For the secondary outcome of all DVT, seven studies, n = 1728, showed prolonged thromboprophylaxis with LMWH to be associated with a statistically significant reduction in the incidence of all DVT (M-H OR 0.39, 95% CI 0.27 to 0.55; I2 = 28%; moderate-quality evidence).We found a similar reduction when analysis was limited to incidence in proximal DVT (M-H OR 0.22, 95% CI 0.10 to 0.47; I2 = 0%; moderate-quality evidence).The incidence of symptomatic VTE was also reduced from 1.0% in the control group to 0.1% in patients receiving prolonged thromboprophylaxis (M-H OR 0.30, 95% CI 0.08 to 1.11; I2 = 0%; moderate-quality evidence).No difference in the incidence of bleeding between the control and LMWH group was found, 2.8% and 3.4%, respectively (HM-H OR 1.10, 95% CI 0.67 to 1.81; I2 = 0%; seven studies, n = 2239; moderate-quality evidence).Estimates of heterogeneity ranged between 0% and 28% depending on the analysis, suggesting low or unimportant heterogeneity.

AUTHORS' CONCLUSIONS

Prolonged thromboprophylaxis with LMWH significantly reduces the risk of VTE compared to thromboprophylaxis during hospital admittance only, without increasing bleeding complications after major abdominal or pelvic surgery. This finding also holds true for DVT alone, and for both proximal and symptomatic DVT. The quality of the evidence is moderate and provides moderate support for routine use of prolonged thromboprophylaxis. Given the low heterogeneity between studies and the consistent and moderate evidence of a decrease in risk for VTE, our findings suggest that additional studies may help refine the degree of risk reduction but would be unlikely to significantly influence these findings. This updated review provides additional evidence and supports the previous results reported in the 2009 review.

Effect of dexmedetomidine on blood coagulation in patients undergoing radical gastrectomy under general anesthesia: A prospective, randomized controlled clinical trial

BACKGROUND

Dexmedetomidine can inhibit the perioperative stress response, which plays an important role in postoperative hypercoagulability. This study aimed to investigate whether dexmedetomidine could attenuate the activation of postoperative coagulation.

METHODS

Patients undergoing open radical gastrectomy under total intravenous anesthesia were randomly allocated to the control group (group Con) and the dexmedetomidine group (group Dex). Dexmedetomidine was intravenously infused at 0.5 μg/kg over 10 minutes before anesthesia induction and then infused at a rate of 0.5 μg/kg/h until peritoneal closure in group Dex, whereas saline was administered in group Con. Blood samples were collected for thrombelastograph (TEG) analysis [reaction time (R time), clot formation time (K time), and clot formation rate (α angle)] and laboratory coagulation testing before dexmedetomidine administration and at the end of surgery.

RESULTS

Coagulation was activated after radical gastrectomy, as indicated by TEG analysis and the increased concentrations of plasma fibrin (fibrinogen) degradation product (FDP) and thrombin-antithrombin complex (TAT). The R and K times were significantly prolonged and α angle was significantly decreased in group Dex compared with that in group Con at the end of surgery (P < .05). The concentrations of plasma TAT and FDP in group Dex were significantly lower than those in group Con at the end of surgery (P < .05 or .01).

CONCLUSION

Adjunctive dexmedetomidine with general anesthesia attenuates the activation of coagulation following radical gastrectomy.

Comparison of Rotational Thromboelastography Findings in Pseudoexfoliation Syndrome Patients and Healthy Controls

PURPOSE

Rotational thromboelastography (ROTEM) is a useful test for studying the characteristics of fibrin clot formation. As patients with pseudoexfoliation (PEX) have an increased risk for thrombotic events, clot-forming dysfunction may play a role. The aim of this study is to compare ROTEM findings in PEX syndrome patients with age-matched and sex-matched healthy controls.

PATIENTS AND METHODS

A total of 21 patients with PEX syndrome and 22 age-matched and sex-matched healthy controls were included. All study participants underwent detailed ophthalmologic and systemic medical examination, including blood pressure measurement, hemoglobin-hematocrit levels, platelet count, coagulation parameters including prothrombin time, activated partial thromboplastin time, fibrinogen levels, and D-dimer levels. Peripheral blood samples were collected and analyzed with ROTEM Coagulation Analyzer.

RESULTS

The mean age of patients with PEX and controls was 66.5±8.3 and 65.9±9.5 years, respectively (P=0.7). The 2 groups did not differ with respect to age, sex, hemoglobin, hematocrit, platelet numbers, prothrombin time, activated partial thromboplastin time, fibrinogen levels, D-dimer levels, and glucose levels. When extrinsic thromboelastometry results were analyzed, PEX patients showed a significantly decreased clotting time when compared with healthy controls (79.8 vs. 98.0 s; P=0.01), indicating faster clot formation. Other ROTEM parameters did now show any difference between the 2 groups.

CONCLUSIONS

PEX patients showed faster clotting time when compared with healthy controls. This fibrin clot formation dysfunction may lead to vascular thrombotic events in these patients. Further studies are needed to elucidate the exact underlying mechanism of thrombosis seen in PEX patients.

Preoperative Thromboelastography as a Sensitive Tool Predicting Those at Risk of Developing Early Hepatic Artery Thrombosis After Adult Liver Transplantation

BACKGROUND

Whilst causes of hepatic artery thrombosis (HAT) after liver transplantation (LT) are multifactorial, early HAT (E-HAT) remains pertinent complication impacting on graft and patient survival. Currently there is no screening tool that would identify patients with increased risk of developing E-HAT.

METHODS

We analyzed the native procoagulant state of LT recipients, identified through pretransplant thromboelastographic (TEG) data among other known risk factors, to identify risk factors for E-HAT.

RESULTS

The outcomes of 828 adult patients undergoing LT between 2008 and 2013 were analyzed. Overall, 79 (9.5%) patients experienced HAT, E-HAT was diagnosed in 23, and in the remainder this was "late" HAT. The maximum amplitude (MA) on preoperative TEG was significantly higher in patients diagnosed with E-HAT compared with those who did not (71.2 mm vs 57.9 mm; P < 0.0001). Receiver operating characteristic analysis with the cutoff value for MA of 65 mm or greater returned area under the curve of 0.750 (P < 0.001) predicting E-HAT with a sensitivity of 70%. A total of 7% of patients with an MA of 65 mm or greater went on to develop E-HAT (hazard ratio, 5.28; 95% confidence interval, 2.10-12.29; P < 0.001), whereas only 1.2% patients with an MA less than 65 mm experienced E-HAT.

CONCLUSIONS

Preoperative TEG may reliably identify group of recipients at greater risk of developing E-HAT, and intense surveillance and anticoagulation prophylaxis may avoid this serious complication after LT.

Coagulation Changes following Combined Ablative and Reconstructive Breast Surgery

BACKGROUND

This study assessed hemostatic function in cancer patients at high risk for venous thromboembolism.

METHODS

Thirty-eight female patients (age, 53 ± 9 years) undergoing immediate postmastectomy reconstruction were prospectively studied with informed consent. Blood was sampled preoperatively, on postoperative day 1, and at 1 week follow-up. Rotational thromboelastography clotting time, α-angle (clot kinetics), clot formation time, and maximum clot firmness were studied with three different activating agents: intrinsically activated test using ellagic acid, extrinsically activated test with tissue factor, and fibrin-based extrinsically activated test with tissue factor and the platelet inhibitor cytochalasin D. Thromboprophylaxis was unfractionated heparin plus sequential compression devices if not contraindicated. Hypercoagulability was defined by one or more parameters outside the reference range.

RESULTS

Preoperatively, 29 percent of patients were hypercoagulable, increasing to 67 percent by week 1 (p = 0.017). Clotting time, clot formation time, and α-angle remained relatively constant over time, but maximum clot formation increased in intrinsically activated test using ellagic acid, extrinsically activated test with tissue factor, and fibrin-based extrinsically activated test with tissue factor and the platelet inhibitor cytochalasin D (all p < 0.05). Body mass index was 28 ± 5 kg/m, 23 percent received preoperative chemotherapy, and 15 percent had a history of tobacco use, but there was no association between these risk factors and hypercoagulability.

CONCLUSIONS

Despite perioperative thromboprophylaxis, two-thirds of patients undergoing combined tumor resection and reconstructive surgery for breast cancer were hypercoagulable 1 week after surgery. Hypercoagulability was associated with increased clot strength mediated by changes in platelet and fibrin function.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Monitoring of Hypercoagulability by Thromboelastography in Bariatric Surgery

Background

Obesity is known as a major risk factor for postoperative vein thrombosis. Thromboelastography (TEG) is used to monitor viscoelastic features of blood clots. The aim of this study was to determine hypercoagulable states in patients undergoing bariatric surgery and to assess dynamics of coagulation parameters in the perioperative setting using TEG.

Material/Methods

We included 60 consecutive patients undergoing bariatric surgery. TEG alterations were assessed at 4 time points: at baseline, after the surgery, and on postoperative day 1 (POD1) and 2 (POD2). Hypercoagulable state was defined when patients showed clot strength (G) of ≥11 dynes/cm² or maximum amplitude (MA) ≥68 mm.

Results

Fourteen patients (23.3%) out of 60 showed hypercoagulability prior to surgery on TEG. Fibrinogen levels were significantly higher in the G ≥11 group compared to the G <11 group, at 4.2 and 3.8 g/l, respectively (p=0.02). Seventeen patients (28.3%) had MA ≥68 mm at baseline. Fibrinogen levels increased significantly from 3.90 at baseline to 4.16 g/l in POD2 (p<0.001). There was an increase in mean reaction time from baseline (6.74 s) to POD2 (7.43 s, p=0.022). We found a correlation between baseline fibrinogen levels and MA (R=0.431, p=0.001) or G (R=0.387, p=0.003). ROC curve analysis showed that fibrinogen levels can predict clot strength (G) ≥11 dynes/cm² with AUC=0.680 (p=0.044).

Conclusions

A considerable proportion of patients referred to bariatric surgery show a trend towards hypercoagulability on TEG. This study shows the potential of hypercoagulation monitoring by TEG in the perioperative setting of bariatric surgery.

Platelet reactivity in thromboelastometry. Revision of the FIBTEM test: a basic study

This study aimed to investigate modifications to the FIBTEM test to better assess fibrinogen levels and the quality of fibrin polymerization in citrated blood using Multiplate impedance aggregometry to verify platelet inhibition. Blood samples from 26 healthy volunteers were subjected to thromboelastometry studies (EXTEM/FIBTEM tests) in accordance with the standard study protocol (cytochalasin D) and according to a modified protocol (synthetic IIbIIIa receptor antagonist vs. acetylsalicylic acid [ASA] + synthetic IIbIIIa receptor antagonist instead of cytochalasin D). Independent of thromboelastometry, Multiplate impedance aggregometry was used to assess the degree of restriction by the platelet blocked with the following treatments: (1) cytochalasin D, (2) synthetic IIbIIIa antagonist or (3) ASA + synthetic IIbIIIa antagonist to assess the aggregation response to activation with an agonist (ADP, collagen, thrombin receptor activating peptide-6 [TRAP-6], and arachidonic acid). Via aggregometry, cytochalasin D more weakly inhibited platelet aggregation than simultaneous administration of the -IIbIIIa receptor antagonist with ASA. However, total platelet aggregation inhibition was observed after simultaneous administration of cytochalasin D combined with a synthetic IIbIIIa receptor antagonist. In the thromboelastometry, a significant decrease of the A10, A20 and MCF parameters were observed in the EXTEM/FIBTEM tests after they were modified by the addition of a synthetic IIbIIIa receptor antagonist alone or in combination with ASA. In conclusion, in this Multiplate- and ROTEM-based laboratory approach, a two-way blockade (IIbIIIa-antagonist + cytochalasine D) was sufficient to completely inhibit procoagulant platelet function as observed by aggregometry and thromboelastometry.

Thromboelastography demonstrates perioperative hypercoagulability in hepato-pancreato-biliary patients and supports routine administration of preoperative and early postoperative venous thromboembolism chemoprophylaxis

BACKGROUND

We hypothesized hepato-pancreato-biliary (HPB) surgery patients are more likely to be hypercoagulable than hypocoagulable, and that bleeding risks from VTE chemoprophylaxis are low. This study sought to use thromboelastography (TEG) to compare coagulation profiles with bleeding/thrombotic events in HPB patients receiving standardized perioperative chemoprophylaxis.

METHODS

Consecutive patients undergoing HPB resections by three surgeons at one institution (January 2014-December 2015) received preoperative and early postoperative VTE chemoprophylaxis and were evaluated with TEGs. Coagulation profiles were compared to bleeding/thrombotic events.

RESULTS

Of 87 total patients, 83 (95.4%) received preoperative chemoprophylaxis and 100% received it postoperatively. Median estimated blood loss was 190 ml. Only 2 (2.3%) patients received intraoperative transfusions. None required transfusions at 72-hours. Only 2 were transfused within 30 days. There was 1 (1.1%) 30-day VTE event. Of 83 preoperative TEGs, 29 (34.9%) were hypercoagulable and only 8 (9.6%) were hypocoagulable/fibrinolytic. Of 73 postoperative TEGs, 34 (46.6%) were hypercoagulable and just 8 (11.0%) were hypocoagulable/fibrinolytic. .

CONCLUSION

With routine perioperative chemoprophylaxis, both VTE and bleeding events were negligible. Perioperative TEG revealed a considerable proportion (46.6%) of HPB patients were hypercoagulable. HPB patients can receive standardized preoperative/early postoperative VTE chemoprophylaxis with effective results and minimal concern for perioperative hemorrhage.

Evaluation of hypercoagulability state in perinatal arterial ischemic stroke with rotation thromboelastometry

BACKGROUND

Perinatal arterial ischemic stroke (PAIS) is an important cause of pediatric morbidity and mortality. The etiology of PAIS remains unknown. Several maternal-neonatal disorders, and especially prothrombotic risk factors, have been reported in infants with perinatal stroke (PS). Rotation thromboelastometry (ROTEM) can analyze the coagulation system, from the beginning of coagulation, through clot formation, and ending with fibrinolysis. The aim of this study was to evaluate the hypercoagulability state in PAIS patients using ROTEM.

METHODS

Patients were obtained by evaluating hospital files retrospectively. Twenty patients with PAIS and 19 healthy controls were included in the study. Prothrombotic risk factors and standard coagulation parameters were collected for all patients. Thromboelastometry (TEM) analysis was performed with the ROTEM® Coagulation Analyzer model Gamma 2500 (Tem International, Munich, Germany). Patients were separated into two groups; Group 1 included PAIS patients with prothrombotic risk factors and Group 2 included patients with no prothrombotic risk factors.

RESULTS

Group 1 includes six patients and Group 2 includes fourteen. Maternal risk factors were reported in 55 % and prothrombotic risk factors were detected in 30 % of the patients. ROTEM analyses were done mean age of 11.2 ± 9.4 months. ROTEM analysis showed that maximum clot firmness (MCF) value on both groups was significantly higher than in the control group, which is consistent with a hypercoagulable state. There was no statistical difference between the MCF values of Group 1 and Group 2. No significant correlations were found between the ROTEM parameters and the hematological parameters.

CONCLUSION

The etiology of PAIS is still unclear. Prothrombotic risk factors may be an important etiology for PAIS. However, standard hematological tests for evaluating prothrombotic risk factors are limited. In our study, ROTEM analyses showed higher maximum clot firmness in PAIS patients compared to controls. ROTEM analyses may suggest a hypercoagulable state due to abnormal fibrinolysis in PAIS patients. Normative data and further research is needed to validate our findings.

Peri-operative cardiac protection for non-cardiac surgery

Cardiovascular complications are an important cause of morbidity and mortality after non-cardiac surgery. Pre-operative identification of high-risk individuals and appropriate peri-operative management can reduce cardiovascular risk. It is important to continue chronic beta-blocker and statin therapy. Statins are relatively safe and peri-operative initiation may be beneficial in high-risk patients and those scheduled for vascular surgery. The pre-operative introduction of beta-blockers reduces myocardial injury but increases rates of stroke and mortality, possibly due to hypotension. They should only be considered in high-risk patients and the dose should be titrated to heart rate. Alpha-2 agonists may also contribute to hypotension. Aspirin continuation can increase the risk of major bleeding and offset the benefit of reduced myocardial risk. Contrary to the initial ENIGMA study, nitrous oxide does not seem to increase the risk of myocardial injury. Volatile anaesthetic agents and opioids have been shown to be cardioprotective in animal laboratory studies but these effects have, so far, not been conclusively reproduced clinically.

Assessing the Methodology for Calculating Platelet Contribution to Clot Strength (Platelet Component) in Thromboelastometry and Thrombelastography

The viscoelastic properties of blood clot have been studied most commonly using thrombelastography (TEG) and thromboelastometry (ROTEM). ROTEM-based bleeding treatment algorithms recommend administering platelets to patients with low EXTEM clot strength (e.g., clot amplitude at 10 minutes [A10] <40 mm) once clot strength of the ROTEM® fibrin-based test (FIBTEM) is corrected. Algorithms based on TEG typically use a low value of maximum amplitude (e.g., <50 mm) as a trigger for administering platelets. However, this parameter reflects the contributions of various blood components to the clot, including platelets and fibrin/fibrinogen. The platelet component of clot strength may provide a more sensitive indication of platelet deficiency than clot amplitude from a whole blood TEG or ROTEM® assay. The platelet component of the formed clot is derived from the results of TEG/ROTEM® tests performed with and without platelet inhibition. In this article, we review the basis for why this calculation should be based on clot elasticity (e.g., the E parameter with TEG and the CE parameter with ROTEM®) as opposed to clot amplitude (e.g., the A parameter with TEG or ROTEM®). This is because clot elasticity, unlike clot amplitude, reflects the force with which the blood clot resists rotation within the device, and the relationship between clot amplitude (variable X) and clot elasticity (variable Y) is nonlinear. A specific increment of X (ΔX) will be associated with different increments of Y (ΔY), depending on the initial value of X. When calculated correctly, using clot elasticity data, the platelet component of the clot can provide a valuable insight into platelet deficiency in emergency bleeding.

Hypercoagulability following major partial liver resection - detected by thrombomodulin-modified thrombin generation testing

BACKGROUND

Conventional coagulation tests are frequently prolonged after liver surgery, suggesting a post-operative hypocoagulability. However, these tests are unreliable for assessment of the haemostatic status in these patients. In contrast, thrombin generation testing measures the true balance between pro- and anti-coagulant factors.

AIM

To study the perioperative coagulation status in patients undergoing hemi-hepatectomy using thrombin generation assays.

METHODS

We examined thrombin generation profiles in serial plasma samples taken from seventeen patients undergoing right hemi-hepatectomy. Results were compared to ten patients undergoing pancreatic resection and twenty-four healthy volunteers. In addition, we measured conventional coagulation tests and plasma levels of several haemostatic proteins.

RESULTS

Following liver resection, the endogenous thrombin potential (ETP) slightly decreased until post-operative day 7. However, in the presence of thrombomodulin, the ETP increased [from 542 nM*min (417-694) at baseline to 845 nM*min (789-1050) on post-operative day 3] to values higher than that in healthy subjects (558 nM*min (390-680); P < 0.001), which contrasts with substantially prolonged PT levels. Normal to decreased thrombin generation was observed following pancreatic resection. Thrombin generation was only slightly affected by thrombomodulin after hemi-hepatectomy, while thrombin generation in healthy subjects decreased profoundly upon addition of thrombomodulin. This hypercoagulability following liver resection may be explained by decreased levels of protein C, S, and antithrombin and by elevated levels of factor VIII.

CONCLUSIONS

Thrombin generation in the presence of thrombomodulin revealed hypercoagulability in patients following liver resection. These results support the recently advocated restrictive use of plasma during liver resection and the exploration of more extensive use of post-operative thrombosis prophylaxis.

Rotational thromboelastometry predicts thromboembolic complications after major non-cardiac surgery

Introduction

Thromboembolic complications contribute substantially to perioperative morbidity and mortality. Routine laboratory tests do not detect patients with acquired or congenital hypercoagulability who may be at increased risk of perioperative thromboembolism. Rotational thromboelastometry (ROTEM) is a digitized modification of conventional thromboelastography that is stable and technically easy to use. We designed a prospective observational study to evaluate whether preoperative ROTEM can identify patients at increased risk for postoperative thromboembolic complications after major non-cardiac surgery.

Methods

Preoperative ROTEM analysis using extrinsic rotational thromboelastometry (EXTEM), intrinsic rotational thromboelastometry (INTEM), and fibrinogen rotational thromboelastometry (FIBTEM) activators was performed on 313 patients undergoing major non-cardiac surgery. Patients’ medical records were reviewed after discharge for results of standard coagulation studies - partial thromboplastin time (PTT), international normalized ratio (INR), platelet count - and evidence of thromboembolic complications during their hospital stay. A thromboembolic complication was defined as a new arterial or deep venous thrombosis, catheter thrombosis, or pulmonary embolism diagnosed by ultrasound or spiral chest computed tomography.

Results

Ten patients developed postoperative thromboembolic complications, of whom 9 had received standard prophylaxis with subcutaneous enoxaparin or heparin. There was no indication of by PTT, INR, or platelet count. Preoperative EXTEM and INTEM activators that assess fibrin clot formation and platelet interaction indicated that these patients had significantly lower clot formation time (CFT) and significantly higher alpha angle (α) and maximum clot firmness (MCF), compared to patients without thromboembolic complications. There was no significant difference for any parameter using FIBTEM activator, which excludes platelet interaction. Receiver operating characteristic (ROC) curves were constructed for these variables. INTEM clot firmness at 10 min (A10) was the best predictor of thromboembolic complications, with an ROC area under the curve of 0.751.

Conclusions

Our results indicate that preoperative ROTEM assays that include fibrin clot and platelet interaction may detect patients at increased risk for postoperative thromboembolic complications after major non-cardiac surgery. Future studies need to evaluate the clinical utility and cost effectiveness of preoperative ROTEM and better define the association between ROTEM values and specific hypercoagulable conditions.

FIBTEM PLUS provides an improved thromboelastometry test for measurement of fibrin-based clot quality in cardiac surgery patients

BACKGROUND

The viscoelastic functional fibrinogen (FF) and FIBTEM assays measure the contribution of fibrin to clot strength. Inhibition of platelet function is a necessary precondition for these tests to work. We investigated a novel test for measuring fibrin-based clotting, FIBTEM PLUS, in cardiac surgery and compared it with FF and FIBTEM.

METHODS

A prospective, observational study was performed which included 30 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Blood samples were drawn at the beginning of surgery (pre-CPB), approximately 20 minutes before weaning from CPB and 5 minutes after heparin neutralization. FF, FIBTEM, and FIBTEM PLUS tests were performed in duplicate for all blood samples. Additional coagulation parameters, including platelet count, plasma fibrinogen levels, factor XIII activity, and heparin concentration, were also recorded for each sample.

RESULTS

At all time points, the lowest mean maximum clot firmness (MCF) was observed with FIBTEM PLUS, although a statistically significant difference between FIBTEM and FIBTEM PLUS was observed only at baseline (mean values 22 vs 19 mm, P = 0.01; FF value for comparison: 27.7 mm). FF maximum amplitude (MA) values were significantly higher than FIBTEM MCF and FIBTEM PLUS MCF pre-CPB, during CPB and after heparin neutralization (P ≤ 0.001 for FF MA versus FIBTEM MCF and for FF MA versus FIBTEM PLUS MCF at all time points). The difference between FIBTEM MCF and FIBTEM PLUS MCF correlated with platelet count (r = 0.46;P < 0.001), whereas differences between FF MA and FIBTEM MCF, or FF MA and FIBTEM PLUS MCF did not (r = -0.07, P = 0.51; r = 0.16, P = 0.12, respectively). Differences between the assays were unrelated to heparin levels, which decreased considerably after protamine administration compared with heparin levels recorded before weaning from CPB (decrease from 2.1 to 0.1 U/mL and from 2.8 to 0.2 U/mL for anti-factor IIa and anti-factor Xa, respectively). Agreement between duplicate measurements was similar with FIBTEM and FIBTEM PLUS assays and lower with FF. Significant positive correlations were found between MCF or MA and fibrinogen concentration (all P < 0.001); the highest correlation was with FIBTEM PLUS MCF (r = 0.70).

CONCLUSION

The FIBTEM PLUS assay produces precise results. At baseline, it provides greater inhibition of platelets than FIBTEM, but there is no meaningful difference between FIBTEM PLUS and FIBTEM in patients with low platelet counts.

Monitoring aspirin and clopidogrel response: testing controversies and recommendations

Antiplatelet therapy is the cornerstone of the treatment for patients with coronary artery disease (CAD). Dual therapy with clopidogrel and aspirin is currently the standard treatment after percutaneous coronary interventions. However, despite the use of clopidogrel, a considerable number of patients continue to suffer major adverse cardiac events. There is a growing degree of evidence supporting high on-treatment platelet reactivity (HPR) as a predictive factor for recurrent ischemic complications. Numerous studies have shown an interindividual variability of responsiveness to clopidogrel and aspirin, which is one of the reasons for HPR. There is yet to be established an assay for antiplatelet drug response as the gold standard. This paper provides a background to the current controversies surrounding the issue of testing for the effectiveness of antiplatelet therapy and reviews the various genetic and phenotype-based laboratory tests to measure aspirin and clopidogrel response and their correlation with clinical outcomes. On the basis of the current evidence and trying to be cost-effective, testing should be considered on a case-by-case basis, especially in patients who present with an acute coronary syndrome or stent thrombosis. In the case of stable CAD, we think that testing might be helpful in particular risk groups of patients to avoid ischemic or bleeding complications.

Clinical markers of the hypercoagulable state by rotational thrombelastometry in obese patients submitted to bariatric surgery

BACKGROUND

Metabolic and inflammatory disturbances associated with obesity are considered important trigger factors for venous thromboembolism (VTE). Identification of clinical markers indicating a hypercoagulability state could define a group of high-risk patients in the surgical setting. This study aimed to identify these markers using rotational thrombelastometry (ROTEM) analysis, an established method for hemostasis testing that can detect hyperfunctional stages of the clotting process.

METHODS

From June to December 2010, this study investigated 109 consecutive obese patients (28 women and 22 men, mean age 46 years, body mass index 46.6 ± 7 kg/m(2)) with no history of VTE who were candidates for bariatric surgery. Preoperative clinical and metabolic characteristics and ROTEM analysis were recorded. Hypercoagulable risk was defined when patients showed a clot strength (G) of ≥11 dynes/cm(2).

RESULTS

Of the 109 patients, 20 (18%) were hypercoagulable according to ROTEM analysis. Metabolic/inflammatory biomarkers such as leptin, C-reactive protein, fibrinogen levels, and platelet count were significantly higher in the high-risk patients. In the multivariate analysis, fibrinogen was an independent predictor of G ≥ 11 dynes/cm(2) [odds ratio (OR) 2.92, 95 % confidence interval (CI) 1.80-5.21, p = 0.023]. After adjustment to other data, only waist circumference affected the prediction [OR 4.42, 95 % CI 2.27-6.71, p = 0.009]. Receiver operating characteristic curve analysis showed that 3.95 g/l was the best cutoff point for fibrinogen predictability (sensitivity 100 %, specificity 41%).

CONCLUSION

A hypercoagulability state in obese patients is associated with central obesity and high fibrinogen levels, which should be considered clinical hallmarks of this state. More aggressive perioperative prophylaxis for VTE should be recommended when these hallmarks are present in obese patients.

The role of hemostatic mechanisms in the development of thrombosis in Behcet's disease: an analysis by modified rotation thromboelastogram (ROTEM)

Behcet's disease (BD) is a multisystemic disorder characterised by recurrent oral and genital ulcers. Vasculitis and thrombotic events are the most important causes of mortality. Thrombosis is the major clinical finding in patients with BD, but the cause of the thrombosis is still unclear. Thromboelastography is an alternative method to evaluate almost all steps of the hemostatic system. Today, the modified rotation thromboelastogram (ROTEM) is a newer coagulation test and a more powerful technique. Our aim in this study was to investigate whether hemostatic mechanisms play a role in the development of thrombosis in BD patients by using ROTEM. Thirty BD patients, 20 ankylosing spondylitis patients, and 14 healthy controls who are not taking anti-aggregant or anti-coagulant therapy were included in the study. Whole blood count, protrombin time, activated protrombin time, fibrinogen, D-dimer levels, and ROTEM parameters (clotting time, clot formation time (CFT), and maximum clot formation(MCF)) were determined by INTEM and EXTEM analysis. Of the 30 patients with BD, 19 were women and 11 were men, and mean age was 40.6 ± 11.2. Two of the BD patients had vascular involvement, but none of them were in active phase of the disease during the study. In INTEM assay, MCF (p < 0,001) value was significantly increased, and CFT (p>0.05) value was decreased in BD patients compared with the control group. In the EXTEM assay, there was a similar significant increase in MCF (p=0.002) value and a decrease in CFT (p=0.002) value in BD patients compared with the control group. The results of our study indicated that primary hemostatic mechanisms which can be detected by ROTEM may play a role in the development of thrombosis in patients with BD.

Evaluation of coagulation in dogs with partial or complete extrahepatic biliary tract obstruction by means of thromboelastography

OBJECTIVE

To characterize in vitro coagulation status in a cohort of dogs with extrahepatic biliary tract obstruction (EHBO) and to evaluate these patients for hypercoagulability by means of thromboelastography.

DESIGN

Prospective cohort study. Animals-10 dogs with EHBO and 19 healthy control dogs.

PROCEDURES

Partial or complete EHBO was confirmed via exploratory celiotomy. Venous blood samples were collected for evaluation of prothrombin time (PT) and activated partial thromboplastin time (APTT); fibrinogen and D-dimer concentrations; protein C and antithrombin activities; and factor VII, VIII, and XI coagulant activities in plasma as well as thromboelastography in whole blood. Thromboelastography variables were measured from the thromboelastography tracing, and a coagulation index was calculated. Thromboelastography results were compared with those of healthy control dogs previously evaluated by the same laboratory.

RESULTS

Hypercoagulability was diagnosed in all dogs with EHBO on the basis of a high coagulation index. Thromboelastography variables, including maximal amplitude, α-angle, and coagulation index, were significantly higher, and K (clot formation time) and R (reaction time) were significantly lower in these dogs than in control dogs. All dogs with EHBO had PT and APTT within respective reference ranges. Plasma D-dimer and fibrinogen concentrations were above reference ranges in 8 and 7 dogs, respectively, and protein C and antithrombin activities were below reference ranges in 3 and 1 dogs, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

In vitro hypercoagulability was commonly detected in dogs with naturally occurring EHBO. The traditional view of EHBO as a disease that causes hypocoagulability may need to be reconsidered.

Thrombelastographic evaluation of the influence of 2-RBC apheresis on donor's coagulation system

Rotation thrombelastogram (ROTEM®/TEG®) assays allow rapid global assessment of hemostatic function using whole blood. Since published data about the effects of automated red cell collection on coagulation system are scarce, we aimed to investigate the effects of 2-RBC apheresis on donor's coagulation system using ROTEM® assays. In INTEM assay, CFT was significantly shortened 24h after apheresis compared with baseline value (p<0.05) and MCF was significantly prolonged immediately after apheresis and 24h after apheresis compared with baseline value (p<0.05 and p<0.01, respectively). In EXTEM assay, CFT was significantly prolonged immediately after apheresis and 24h after apheresis compared with baseline value (p=0.001 and p<0.001, respectively) and MCF was significantly prolonged 24h after apheresis compared with baseline value (p<0,001). Our results demonstrate thromboelastographic signs of hypercoagulability in donors undergoing 2-RBC apheresis.

Increased intraoperative bleeding in patients undergoing abdominoplasty after gastroplasty is not due to coagulopathy

BACKGROUND

Abdominoplasties carried out in patients previously underwent gastroplasty present high rates of complications, including increased bleeding in the intra- and postoperative periods.

METHODS

This study evaluated bleeding, coagulation parameters (coagulogram, dosage of fibrinogen, FII, FV, FVII, FVIII, FIX, FX, and FXII), and thromboelastography in two groups of women who underwent abdominoplasties: a group with a history of gastroplasty by the Fobi-Capella technique (group I) and the other group without a history of obesity (group II). Analyses were performed before, during, and after each surgical procedure. Vitamins K and C were also dosed. Bleeding was measured by counting and weighing compresses at the end of each surgery, and the withdrawn surgical specimens were weighed.

RESULTS

Statistically, group I patients had more bleeding than group II in all evaluated operative periods (p = 0.007). There was no significant change in the coagulogram or decrease in coagulation factors that could be associated with increased bleeding in any of the analyzed groups. Thromboelastography, which provides a comprehensive analysis of thrombin generation and of hemostasis in real time, did not differ between groups. Vitamin K was significantly increased in group I patients (p = 0.019). The weight of the surgical specimens removed was significantly higher in group I (p = 0.007) and there was correlation of the weight with the degree of bleeding.

CONCLUSIONS

The results of this study demonstrate an increase of bleeding during the intraoperative period of abdominoplasty in patients with a history of gastroplasty that it is not due to changes in hemostasis.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Viscoelastic and aggregometric point-of-care testing in patients with septic shock - cross-links between inflammation and haemostasis

BACKGROUND

In the pathogenesis of sepsis, inflammation-induced changes in coagulation play a pivotal role.

METHODS

In total, 90 patients (30 patients with septic shock, 30 surgical patients following major abdominal surgery and 30 healthy volunteers) were enrolled. Blood samples from patients with septic shock were collected at the time of sepsis diagnosis as well as 24 h, 4 days, 7 days, 14 days and 28 days later. Samples from surgical patients with a post-surgical inflammatory response were collected three times (before surgery, immediately after surgery and 24 h after surgery) and once from healthy volunteers. Thromboelastometry (ROTEM (®) ), as well as whole blood impedance aggregometry (Multiplate(®) ) were performed. Additionally, plasma concentrations of interleukin-6 and tumour necrosis factor-alpha were measured using enzyme-linked immunosorbent assay kits.

RESULTS

Thromboelastometry lysis index was shown to be a reliable biomarker for septic shock. Furthermore, in septic patients with overt disseminated intravascular coagulation, thromboelastometry revealed signs indicating a hypocoagulable status, whereas patients without overt disseminated intravascular coagulation were found to be hypercoagulable. Platelet aggregation capability, as assessed by whole blood impedance aggregometry, was significantly reduced in septic patients with overt disseminated intravascular coagulation, whereas it was comparable with healthy volunteers and in septic patients without overt disseminated intravascular coagulation.

CONCLUSION

Viscoelastic and aggregometric point-of-care testing was shown to be potentially useful for bedside diagnosis of sepsis. Moreover, viscoelastic and aggregometric point-of-care testing was able to determine the phase of septic coagulopathy (hypercoagulability vs. hypocoagulability) and therefore identified patients at high risk for overt disseminated intravascular coagulation.

Early diagnostic markers of sepsis after oesophagectomy (including thromboelastography)

Background

Early diagnosis of sepsis and its differentiation from the noninfective SIRS is very important in order that treatment can be initiated in a timely and appropriate way. In this study we investigated standard haematological and biochemical parameters and thromboelastography (TEG) in patients who had undergone surgical resection of the oesophagus to find out if changes in any of these parameters could help in early differentiation between SIRS and sepsis development.

Methods

We enrolled 43 patients (aged 41–74 years) of whom 38 were evaluable. Blood samples were obtained on the morning of surgery and then at 24-hour intervals for the next 6 days. Samples were analysed for procalcitonin (PCT), C-reactive protein (CRP), interleukin-6 (IL- 6), aspartate transaminase (AST), alanine transaminase (ALT) , lactate, white blood count (WBC), D-dimers, antithrombin (AT), international normalised ratio (INR), activated partial thromboplastin time (APTT) and parameters of TEG.

Results

Significant differences between patients who developed sepsis during this period (9 patients) and SIRS were found in ALT on Day 1, in AST on Days 1–4, in PCT on Days 2–6; in CRP on Days 3–6; in IL-6 on Days 2–5; in leucocytes on Days 2, 3 and 6; and in D-dimers on Days 2 and 4. Significance values ranged from p < 0.0001 to p < 0.05.

Conclusions

Sequential measurements of ALT, AST, PCT and IL-6 during the early postoperative period can be used for early differentiation of sepsis and postoperative SIRS after oesophagectomy. Among the coagulation parameters measured, only D-dimer concentrations appeared to be helpful in this process. TEG does not seem to be a useful early predictor of sepsis development; however it can be used to differentiate sepsis and SIRS from Day 5 after surgery.

Role of thrombolestagrophy in monitoring perioperative coagulation status and effect of thromboprophylaxis in bariatric surgery

BACKGROUND

Thromboelastography is a technique that surveys the properties of viscoelastic blood clot. The purpose of this paper was to evaluate the hypercoagulability state and the effect of antithrombotic prophylaxis on thromboelastogram (TEG) results in bariatric surgery.

METHODS

Twenty-five patients enrolled received 0.8 ml of nodraparin starting on the day before surgery and continuing postoperatively. TEG profile was collected before induction of anesthesia, on the first and third postoperative days. Each sample was run also in a cup added with heparinase to eliminate the interference of antithrombotic prophylaxis.

RESULTS

TEG analysis with heparinase showed a tendency to reduce the r-time (rate of initial fibrin formation) and k-time (time to clot firmness) and increase the alpha angle (rate of clot growth), while an increase of maximal amplitude (MA, a measure of maximal stiffness of the clot; p = 0.01) and GI or shear elastic modules strength (p = 0.03)was observed from basal to postoperative day 3 (POD3). TEG without heparinase evidenced and increase of r-time (p = 0.02) and k-time (p = 0.05), a reduction of the alpha angle (p = 0.03), and an increase of MA (p = 0.01) and GI (p = 0.03) from basal to POD3. The comparison of TEG techniques showed that normal TEGs had lower values of r-time and k-time and higher values of alpha angles and MA than TEG with heparinase. No differences were evident for basal and POD1 samples and the G values comparing the two TEG technique. No correlation was observed between the variation of normal TEG parameters and dosage of anticoagulant used in each patient.

CONCLUSIONS

Our patients presented a tendency to hypercoagulability determined most by MA and GI. Comparison between TEGs indicates that low-molecular-weight heparin not titrated on weight is able to determine a reduction of hypercoabulable tendency in the early postoperative period with few effects on increasing MA and GI.