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

Thromboelastography-Based Profiling of Coagulation Status in Patients Undergoing Bariatric Surgery: Analysis of 422 Patients

INTRODUCTION/PURPOSE

Some clinical indicators suggest hypercoagulability/hyperaggregability in patients with morbid obesity. Thromboelastography (TEG®) has been used to profile coagulation status in surgical patients. We aimed to assess coagulation profiles in patients with morbid obesity undergoing bariatric surgery by correlating demographic and patient characteristics to pre-operative TEG® values.

MATERIALS AND METHODS

Pre-operative TEG® values from 422 patients undergoing bariatric surgery were evaluated. TEG® results were analyzed by gender, use of medications known to alter the coagulation profile, and body mass index (BMI).

RESULTS

Patients have a mean of 45.03 ± 11.8 years, female (76.3%), and with a mean BMI of 42 kg/m ¹. The overall coagulation profile of female patients was significantly different from males, even in the sub-cohort without use of medications known to alter coagulation. The majority of patients (94%) with a G value > 15 dynes/cm ¹ (clot strength) were female. In females, there was no association between BMI and TEG® values; however, in men, there was a statistically significant difference in TEG® values for those with BMI < 40 kg/m ¹ compared to those with BMI > 50 kg/m².

CONCLUSIONS

TEG®-based analysis of coagulation profiles offers unique insights. Compared to laboratory normal values (R time, angle, maximal amplitude, and G values), patients with morbid obesity may have a tendency for hypercoagulability/hyperaggregability, with mean values at the higher limit. A significant hypercoagulable difference in TEG® values was identified in female as compared to male patients. Male patients with a BMI greater than 50 kg/m² were also found to be increasingly hypercoagulable.

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.

Thromboelastography Values Remain Hypercoagulative 6 Months After Obesity Surgery: a Pilot Study

PURPOSE

Obesity causes a prothrombotic state and is known as a predisposing factor for thromboembolic events. In this pilot study, we assessed the impact of surgery for obesity and the subsequent weight loss on blood coagulation using traditional coagulation tests and thromboelastography (TEG).

MATERIAL AND METHODS

We studied blood samples from 18 patients receiving bariatric surgery. Besides traditional blood coagulation tests and high-sensitivity C-reactive protein (hsCRP) as a marker of inflammation, the TEG parameters reaction time (R), kinetics time (K), angle (α), maximum amplitude (MA), clot strength (G), and lysis percent at 60 min (LY60) were determined preoperatively and on the first postoperative day and 6 months after surgery.

RESULTS

Altogether, 54 samples were analyzed. The median MA (71.3 mm), G (12,403.3 d/sc), and hsCRP (3.5 mg/l) were elevated preoperatively. The median hsCRP further increased on the first day postoperatively, but declined to the normal range 6 months after surgery, while MA and G remained elevated. In traditional coagulation tests, there was an increase in median fibrinogen and D-dimer postoperatively. D-dimer normalized (0.4 mg/l) during the study period, while the fibrinogen level (4.1 g/l) remained above the upper limit of normal.

CONCLUSIONS

Measured by TEG, patients receiving bariatric surgery have hemostatic abnormalities indicating hypercoagulation at the 6-month follow-up visit, suggesting an elevated risk for thromboembolic events for at least 6 months after surgery.

Prospective assessment of fibrinolysis in morbid obesity: tissue plasminogen activator resistance improves after bariatric surgery

BACKGROUND

Morbid obesity is associated with an increased risk of thrombotic events, which has been attributed to increased thrombotic activity. Multiple mechanisms have been proposed to explain this increased risk, including an inflammatory state with upregulation of procoagulant and antifibrinolytic proteins. We therefore hypothesize that patients with morbid obesity are hypercoagulable and will revert to normal after bariatric surgery.

OBJECTIVES

To evaluate changes in the hypercoagulable state after bariatric surgery.

SETTING

University Hospital, Bariatric Center of Excellence, United States.

METHODS

Thromboelastography (TEG) data were collected on 72 subjects with morbid obesity, with 36 who had 6 months of follow-up after bariatric surgery. TEG data of 75 healthy subjects (HS) without obesity, recent trauma or surgery, acute infection, or chronic conditions (e.g., liver, cardiovascular, or kidney disease; cancer; diabetes; autoimmune or inflammatory disorders; and disorders of coagulation) were used for comparison. TEG was performed alone and with the addition of 75 and 150 ng/mL tissue plasminogen activator (tPA) to quantify fibrinolysis resistance (tPA-challenged TEG).

RESULTS

The bariatric surgery cohort had a median age of 40.5 years, a median body mass index of 44.6 kg/m², and 90% female patients. Median body mass index reduced significantly 6 months post surgery but remained elevated compared with the HS group (31.4 versus 25.4 kg/m², P < .0001). At 6 months post surgery, subjects had longer reaction time (mean difference, 1.3; P = .02), lower maximum amplitude (-2.4, P = .01), and increased fibrinolysis with low-dose (3.1, P < .0001) and high-dose tPA-challenged TEG (9, P < .0001). Compared with HS, the postsurgery TEG values were still more likely to be abnormal (all P < .05).

CONCLUSIONS

Patients with morbid obesity form stronger clots more rapidly and are more resistant to fibrinolysis than subjects without obesity. Bariatric surgery significantly improved the hypercoagulable profile and fibrinolysis resistance of morbid obesity.

Thromboelastographic changes during laparoscopic fundoplication

Introduction

Thromboelastography (TEG) is a technique that measures coagulation processes and surveys the properties of a viscoelastic blood clot, from its formation to lysis.

Aim

To determine the possible hypercoagulability state and the effect of antithrombotic prophylaxis on thromboelastogram results and development of venous thrombosis during laparoscopic fundoplication.

Material and methods

The study was performed on 106 patients who were randomized into two groups. The first group received low-molecular-weight heparin (LMWH) 12 h before the operation, and 6 and 30 h after it. The second group received LMWH only 1 h before the laparoscopic fundoplication. The TEG profile was collected before LMWH injection, 1 h after the introduction of the laparoscope and 15 min after the surgery was completed.

Results

There was no significant difference in thromboelastography R-time between the groups before low-molecular-weight heparin injection. In group I preoperative R-values significantly decreased 1 h after the introduction of the laparoscope, after the end of surgery and on the third postoperative day. K-time values decreased significantly on the third postoperative day compared with the results before low-molecular-weight heparin injection, and after the operation. In group II, preoperative R-values significantly decreased 1 h after the introduction of the laparoscope, and after surgery. K-time values did not change significantly during or after the laparoscopic operation.

Conclusions

Our study results demonstrated that the hypercoagulation state (according to the TEG results) was observed during and after laparoscopic fundoplication in patients when LMWH was administered 12 h before the operation together with intraoperative intermittent pneumatic compression. The optimal anticoagulation was obtained when LMWH was administered 1 h before fundoplication.

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.

Low molecular weight heparin once versus twice for thromboprophylaxis following esophagectomy: a randomised, double-blind and placebo-controlled trial

BACKGROUND

Venous thromboembolism (VTE) remained common complication following surgical resection of esophageal cancer. In this prospective randomized double-blind placebo-controlled trial (NCT01267305), we aim to compare the safety and efficacy between low molecular weight heparin (LMWH) once-daily (QD) and twice-daily (BID) for the prophylaxis of VTE following esophagectomy.

METHODS

During August 2012 to July 2013, patients underwent esophagectomy were randomly assigned to nadroparin calcium QD (4,100 AxaIU qd + placebo qd, group QD), or nadroparin calcium BID (4,100 AxaIU q12h, group BID) in the prophylaxis of VTE. All patients received thrombelastography (TEG) before and 0/24/48/72 hours after operation. Daily vascular ultrasound of lower extremities was followed during the first 7 postoperative days to confirm the suspected deep venous thrombosis (DVT). Cumulatively postoperative chest drainage at 72 hours after the surgery was collected to identify the difference in volume and red blood cell (RBC) counts between the two groups. Any bleeding events and thromboembolic events were also documented.

RESULTS

A total of 117 patients were enrolled in this study, and 111 eligible patients were randomly assigned (group QD: 55 patients; group BID: 56 patients). Patients' clinical features were close between the two groups. TEG analysis [R time, K time, alpha angel and maximum amplitude (MA)] before and instantly after operation showed nearly identical results. However, compared with group QD, all TEG measurements of 24/48/72 hours postoperatively showed significantly prolonged R time and K time, and decreased alpha angel in group BID. In ultrasound follow-ups, a total of four cases of DVT (four cases in group QD and no case in group BID) were found in this cohort (7.27% versus 0%, P=0.046), and one case of pulmonary embolism (PE) (in group QD) was observed. The incidence of VTE was lower in group BID (9.09% versus 0%, P=0.032). At 72 hours after surgery, the cumulative volume of chest drainage were close between these two groups (1,001.39±424.58 versus 1,133.61±513.93 mL, P=0.406). RBC counts in chest drainage were also identical between two groups [(2.56±1.98)×10(5) versus (2.71±4.67)×10(5), P=0.61]. No patient died due to VTE or bleeding events.

CONCLUSIONS

For the prophylaxis of VTE, BID LMWH provided more potent efficacy and equal safety when compared to QD LMWH in patients undergoing selective esophagectomy. Further study based on larger population is required to confirm these findings.

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.