Introduction and background
Monitoring of blood coagulation status during the perioperative period is crucial for prompt intervention as bleeding and thrombotic complications related to surgery can significantly affect morbidity and mortality. Assessing the coagulation status comprehensively is a challenge since the coagulation cascade is dynamic and depends on the interaction of several factors including primary hemostasis, platelet clot formation, secondary hemostasis, thrombin generation, and fibrinolysis [1]. Traditional coagulation tests such as platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), activated clotting time (ACT), and plasma fibrinogen levels provide only static evaluation of the patient and are not designed for assessment of dynamically changing coagulation conditions during perioperative time; thus, they lack the ability to direct targeted hemostatic therapy [2]. However, viscoelastic coagulation testing such as thromboelastography (TEG) is devised for a quick global assessment of hemostasis more like in vivo hemostasis by continuously monitoring the clotting process from its steps of initiation, amplification, propagation, and termination through fibrinolysis. They produce a rapid numerical and graphical representation that helps clinicians with the early management of goal-directed hemostatic resuscitation and anticoagulation effects [3-6]. Our goal is to systemically search and summarize the existing evidence from studies that have reported the utility of viscoelastic coagulation testing and its impact on clinical outcomes during the perioperative period.
Thromboelastography (TEG)
TEG is a whole blood-based assay that runs at 37°C to mimic natural blood clotting in vivo [7]. The instrument consists of a pin immersed into a cup containing whole blood that begins to clot when a constant rotational force is applied to it. As the viscosity of blood increases, the pin becomes cross-linked to the cup via fibrin and platelet interactions. Now there is a torque between the cup and the pin, and the movement of the pin produces an electrical signal that is traced as a curve over time. As the clot breaks down and torque decreases, the tracing fades. The signals are then interpreted by TEG software where changes in amplitude are plotted, and different parameters of the curve are measured to assess coagulation status [8]. The parameters include reaction (R) time, coagulation (K) time, alpha (α) angle, maximum amplitude (MA), and lysis at 30 minutes (LY30). The tracing and results are available in real-time, enabling prompt interpretation for goal-directed therapy [9]. While TEG is favored in North America, there are other viscoelastic tests such as rotational thromboelastometry (ROTEM) that are favored in Europe. Both the tests are equivalent with interchangeable results and interpretations, yet characteristics and nomenclature differences exist, and they are illustrated in Tables 1-2.
Table 1
Characteristic differences between TEG and ROTEM
TEG: thromboelastography; ROTEM: rotational thromboelastometry
Characteristic | TEG | ROTEM |
Cup motion | Moving | Fixed |
Pin motion | Fixed | Moving |
Pipetting | Manual | Automated |
Detector system | Torsion Wire | Optical |
Samples ran at one time | Two | Four |
Table 2
Nomenclature differences between TEG and ROTEM
TEG: thromboelastography; ROTEM: rotational thromboelastometry
TEG | ROTEM |
Reaction time (R-time) | Clotting time (CT) |
Coagulation time (K-time) | Clot formation time (CFT) |
Maximum amplitude (MA) | Maximum clot firmness (MCF) |
Lysis 30 (LY30) | Lysis Index 30 (LI30) |
Interpretation of parameters
Reaction Time (R-Time)
Reaction time is the first measurement of the coagulation cascade. Its measurement is related to coagulation factor activation. This value is similar to extrinsic and intrinsic clotting pathway measurements by PT and aPTT respectively. The R-time largely reflects the adequacy of coagulation factors and is the most sensitive parameter to measure the effects of heparin therapy including low molecular weight heparin (LMWH) [10, 11]. An elevated or prolonged R-value (more than eight minutes) can signify a deficiency in clotting factors, hemodilution, or the presence of heparin. Therefore, indicating a need for transfusion of fresh frozen plasma. On the other hand, a shortened R-time (less than four minutes) can indicate hypercoagulopathy requiring the use of anticoagulation.
K-Time
It is a measurement of the time interval between R and time to reach 20 mm clot amplitude. K-time and α angle are both related to coagulation factor amplification. Therefore, their values correlate, and they both indicate a deficiency in clot growth kinetics. A low value can indicate a deficiency in fibrinogen and may reveal a need for cryoprecipitate. A high value is similar to the R-time, which represents a hypercoagulable state, and an anticoagulant may be required.
α Angle
It is a measurement of the line tangent to the slope of the curve during clot formation. The computer software calculates the angle based on the slope and time. A number of factors including thrombin generation and fibrinogen levels determine the angle. It identifies states of hyper- or hypo-coagulopathies.
MA Value
It is the maximum amplitude that represents the distance traveled by the cross-linked cup/pin. It is a measurement of maximum clot strength and provides information on both fibrinogen and platelet function. A high MA value may indicate hypercoagulation and the need for an anticoagulant. A low MA value indicates low clot strength, which can be caused by decreased fibrinogen levels, low platelet counts, or decreased platelet function. If a low MA is combined with a decreased K value, this is an indication of cryoprecipitate therapy. MA value is very important when paired with a platelet count because a low platelet count and a normal MA value indicate a patient has a normal platelet function and therefore does not require platelet transfusion. Conversely, treatment with platelets may be indicated for patients with a low MA value, low platelet function, and normal platelet count [12].
LY30
It is clot lysis at 30 minutes. It is the last major TEG parameter and measures the percent of the decrease in area under the curve over 30 minutes. Therefore, it reflects fibrinolysis after maximum amplitude is reached. This measurement is most useful for patients undergoing thrombolytic therapy or during disseminated intravascular coagulation (DIC). A high LY30 percentage indicates hyperfibrinolysis and patients may require antifibrinolytic agents including tranexamic acid, aprotinin, and aminocaproic acid.
Review
Methods
A review of the literature was conducted to identify qualifying publications. The search was conducted in the following databases: PubMed, Medline, Ovid, CINAHL, and ClinicalTrials.gov. Search criteria were defined using the string (thromboelastography or TEG) and (perioperative or postoperative or preoperative or operative) in all search fields. Inclusion criteria for the systematic review included articles that represented original research including as a focal outcome evaluation of TEG procedures; in one or more perioperative settings (pre, intra, or postoperative); in a human population; have been published in a peer-reviewed source and in English. Excluded items included theses or dissertations, conference abstracts, and proceedings, theoretical papers, comments or letters to the editor, or previous reviews. We abstracted data from selected studies that include patient samples, perioperative settings where TEG was utilized, TEG parameters that were assessed, and clinical outcomes that were reported. Because of clinical and methodologic heterogeneity among studies, we expected to report results qualitatively rather than conducting a meta-analysis.
The initial database search described in the methods section yielded 8,200 unique articles after duplicates were removed. Among them, 6,156 reports were included and assessed for eligibility after excluding records without data (N = 75), not in English (N = 425), that were non-peer-reviewed (e.g., conference abstracts) (N = 1,012), that were reviewed (N = 526) and that were not retrievable (N = 6). After further automated and manual screening of assessed reports for eligibility, 210 articles were found to be eligible and included in the review (Figure 1). Reasons for rejection of assessed articles included studies that were ineligible (N = 281), were reviews (N = 249), in which TEG was mentioned but not evaluated (N = 4,959), did not include patient outcomes (N=175), studies not in perioperative settings (N = 71). Also, articles in languages other than English (N = 127), studies with veterinary samples (N = 73), retracted studies (N = 9), and the use of the abbreviation TEG not referring to thromboelastography (N = 2) were excluded.
Figure 1
PRISMA flow diagram with included searches of databases and registers
PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses
The included 210 studies were categorized under various surgical settings. Studies in the cardiovascular settings were the maximum with 64 studies while those based in the surgical intensive care unit (ICU) setting were the least with only one study.
Trauma
TEG finds its clinical application critically useful in trauma; the American College of Surgeons recommends it to be available at all level I and level II trauma centers. Complications from trauma-related surgery such as hemorrhage and thrombosis remain the leading causes of preventable death. Hemorrhage exacerbation is associated with trauma-induced coagulopathy (TIC) and has been shown to be present in more than 25% of severely injured patients upon arrival to the emergency department. TIC is a lethal, unbalanced, and abnormal process. Its early stages are characterized by hypercoagulability and bleeding whereas the later stages are characterized by hypercoagulability with venous thromboembolism and multiple organ failure. In such a scenario, comprehensive information about coagulation status is essential. TEG by analyzing various contributors of both hemostasis and clot dissolution provide extensive information that has been shown to predict mortality as well as positively impact it during TIC [13-15]. TEG parameters such as MA and R-time detect platelet function and coagulation factor deficiency with a high degree of specificity that guide individualized therapy for patients [16, 17]. It is accurate in diagnosing hypofibrinogenemia as well [18]. Their ability to reliably detail the hypercoagulable states in cancer patients and the distorted coagulation status in alcoholic patients during trauma is well demonstrated [19, 20]. Overall, they reflect coagulation status better than traditional coagulation tests [21].
Since TIC is associated with uncontrolled bleeding, TEG's ability to provide insight into both depletion coagulopathy and hyperfibrinolysis allows it to guide massive transfusion protocol (MTP); and predict the associated mortality [22-25]. TEG-guided resuscitation has demonstrated lower blood product usage, shorter ICU and hospital stay, and lower overall costs especially when compared to conventional coagulation tests that come with limitations such as its time-consuming nature, failure to delineate the complex nature of TIC, and unclear value in guiding transfusion [26-29]. This has been shown to improve mortality outcomes, especially in pelvic fractures, penetrating as well as blunt trauma patients, and burn patients [30-33]. While the ability of TEG to predict transfusion has been replicated in the general population it was not the case in the polytrauma population [34]. Using TEG protocols that are directed to reduce blood product usage and improve survival [35, 36], transfusion has become more patient-specific with an average transfusion ratio of 2.5:1:2.9 (red blood cells: plasma: platelets), different from the current 1:1:1 guideline [37]. TEG has been shown to be valid during MTP and results in different patterns of blood transfusion based on individual patient requirements as well as a reduction in overall hemorrhage-related deaths during trauma [38, 39]. When it comes to MTP-related blood product usage, TEG does not differ from conventional testing and ROTEM [40, 41]. During trauma surgery involving the liver and spleen, interestingly, TEG guidance has demonstrated less as well as increased blood product usage but shorter surgery time [42, 43]. With the success of TEG in assessing coagulopathic parameters in trauma patients, TEG has been investigated for detecting and reversing anticoagulants only with limited success, and conventional tests (e.g., PT, INR, PTT) that have shown better results comparatively have been recommended [44-47]. TEG finds its utility in the pediatric trauma population as well where it has been shown to accurately predict MTP requirement, thromboembolism, and mortality [48, 49, while outcomes such as blood product use, ventilator duration, and length of ICU stay were found to be worse with TEG use there was no change in mortality [50] (Table 3).
Table 3
Studies of TEG in trauma perioperative settings
TEG: thromboelastography; TEG-MA: TEG with maximum amplitude; rTEG; rapid thromboelastography; tPA-TEG: tissue plasminogen activator; TEG-PM: TEG with platelet mapping; TBI: traumatic brain injury; VTE: venous thromboembolism; ROTEM: rotational thromboelastometry; MTP: massive transfusion protocol
Citation | Patient Sample | Operative Setting | TEG Procedures Assessed | Clinical Outcomes | Summary of Findings |
Farrell et al., 2021 [13] | 50 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Mortality | “Death diamond” combination of TEG parameters is strongly predictive of mortality after trauma |
Chin et al., 2014 [14] | 98 US trauma patients | Intraoperative | rTEG-MA, rTEG R-time, rTEG-K, rTEG alpha-angle, rTEG-LY30 | Mortality, coagulopathy | rTEG parameters predicted coagulopathy, coagulopathy impacted mortality differently among different subsets of patients |
Albert et al., 2019 [15] | 58 Indian trauma patients with TBI | Intraoperative prior to transfusion | TEG R-time, k-time, alpha-angle | Coagulopathy | TEG values including prolonged k-time and shortened alpha angle predicted coagulopathy after TBI |
Moore et al., 2015 [16] | 58 US trauma patients | Intraoperative | TEG-MA | Platelet function | TEG-MA was predictive of platelet function |
Chow et al., 2020 [17] | 550 US trauma patients | Intraoperative | TEG R-time | Coagulation factor deficiency | TEG R-time predicts coagulation factor deficiency with high specificity but low sensitivity |
Chow et al., 2019 [18] | 623 US trauma patients | Intraoperative | TEG-MA, TEG-K, TEG alpha-angle | Hypofibrinogenemia | TEG parameters predict hypofibrinogenemia with high specificity but low sensitivity |
Mou et al., 2019 [19] | 157 Chinese oncology patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hypercoagulability, VTE, thrombotic complications | TEG parameters were related to hypercoagulability, but not to VTE or thrombosis |
Howard et al., 2014 [20] | 415 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hypocoagulation in relation to alcohol exposure | TEG parameters gave inaccurate indications of hypocoagubility in patients with alcohol exposure |
Liu et al., 2016 [21] | 40 Chinese older adult fracture patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters predicted coagulopathy more accurately than traditional lab values |
Ives et al., 2012 [22] | 118 US trauma patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, MTP, mortality | TEG parameters predicted MTP and mortality |
Coleman et al., 2018 [23] | 343 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Massive transfusion status | TEG parameters are predictive of the need for massive transfusion |
Moore et al., 2017 [24] | 324 US trauma patients | Intraoperative | rTEG tPA–TEG | MTP | tPA-TEG parameters efficiently identify patients needing MTP |
Pezold et al., 2012 [25] | 80 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Mortality | TEG parameters predict early mortality |
Mohamed et al., 2017 [26] | 134 US trauma patients | Intraoperative | TEG-guided resuscitation protocol vs. clinician discretion | Blood product usage, ICU length of stay, hospital length of stay, costs | Introduction of TEG-guided resuscitation protocol resulted in lower blood product usage, shorter ICU length of stay, shorter hospital length of stay, and lower overall costs |
Holcomb et al., 2012 [27] | 1,974 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Blood product usage | TEG parameters were superior predictors of blood product usage compared with conventional coagulation tests |
Kaufmann et al., 1997 [28] | 69 US blunt trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hypercoagulability, transfusion | TEG parameters were predictive of need for transfusion |
Schochl et al., 2010 [29] | 681 Austrian trauma patients | Intraoperative | TEG-guided hemostatic therapy vs. clinician discretion | Blood product usage | TEG-guided protocol resulted in lower blood product usage volume |
Kane et al., 2015 [30] | 131 US pelvic trauma patients | May vary (retrospective record review) | TEG R-time | Mortality | TEG R-time was predictive of mortality risk |
Bostian et al., 2020 [31] | 141 US trauma patients | Preoperative | TEG-LY30 | Mortality, blood loss, transfusion, hemoglobin changes | TEG parameters on intake were associated with extent of blood loss, volume of blood products transfused, and mortality risk |
Tapia et al., 2013 [32] | 289 US trauma patients | Intraoperative | TEG-directed resuscitation protocol vs. standardized MTP protocol | Blood product volume, mortality | TEG-directed resuscitation had better mortality outcomes for penetrating trauma, and lower blood product usage volume for more severe blunt trauma patients compared with standardized MTP protocol |
Huzar et al., 2018 [33] | 65 US burn patients | May vary (retrospective registry study) | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle, TEG-LY30 | Resuscitation, transfusion volumes, mortality | TEG parameters predicted resuscitation, transfusion volumes, and mortality |
Van Wessem and Leenen, 2017 [34] | 135 Dutch trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters were not predictive of coagulopathy |
Gonzalez et al., 2016 [35] | 111 US trauma patients | Intraoperative | TEG-directed MTP protocol vs. conventional MTP protocol (RCT) | Survival, blood product volume | The TEG-directed protocol increased survival and reduced blood product usage |
Sumislawski et al., 2018 [36] | 278 US trauma patients | Intraoperative | TEG-guided resuscitation vs. conventional assay-guided resuscitation | Mortality, coagulopathy | Patients treated with TEG-guided protocols had better survival |
Mamczak et al., 2016 [37] | 40 US trauma patients | Intraoperative | TEG-PM guided transfusion protocol | Blood product usage | TEG-guided transfusion protocol resulted in different patterns of blood product usage from standardized modality |
Stettler et al., 2018 [38] | 825 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle, TEG-LY30 | MTP administration | TEG parameters are valid for use in guiding MTP administration |
Johansson et al., 2013 [39] | 182 Danish trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Survival, transfusion, blood product volume | TEG parameters differed between survivors and non-survivors but did not independently predict survival |
Unruh et al., 2019 [40] | 67 US trauma patients | Intraoperative | TEG-guided MTP vs. conventional testing | Blood product usage | There was no difference in blood product usage between TEG-guided MTP and conventional testing-guided MTP |
Rizoli et al., 2016 [41] | 33 Canadian trauma patients | Intraoperative | TEG vs. ROTEM parameters in comparison | Coagulopathy | TEG and ROTEM parameters had similar performance for detecting intraoperative coagulopathy |
Dudek et al., 2021 [42] | 258 US trauma patients | Intraoperative | TEG-guided transfusion vs. standardized MTP | Volume of blood product use, time to surgery | Patients receiving TEG-guided transfusion received more blood products and had a shorter time to surgery |
Wang et al., 2017 [43] | 166 US trauma patients | Intraoperative liver or spleen surgery | TEG-guided blood component therapy vs. clinician discretion | Blood product usage, hospital length of stay | TEG-guided therapy was associated with lower blood product usage volume and shorter average hospital length of stay |
Barton et al., 2021 [44] | 824 US trauma patients | May vary (retrospective observational study) | TEG-PM | Preoperative anticoagulation | TEG parameters can differentiate some but not all common anticoagulants. Authors recommend investigation of other methods detecting need for anticoagulation reversal |
Kobayashi et al., 2018 [45] | 182 US trauma patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy due to novel oral anticoagulant (NOA) therapy | TEG parameters were not effective at detecting coagulopathy due to NOA therapy |
Ali et al., 2017 [46] | 54 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Preoperative anticoagulation, postoperative coagulopathy | TEG did not differentiate patients with preoperative anticoagulation therapy. Authors recommend using conventional testing methods to identify patients in need of anticoagulation reversal |
Myers et al., 2020 [47] | 100 US trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation reversal detection | TEG parameters correlate with anticoagulation reversal, but conventional tests perform better in clinical settings |
Leeper et al., 2018 [48] | 133 US pediatric trauma patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, thromboembolism, transfusion, mortality | TEG parameters can be combined with other variables as part of a principal components analysis to predict transfusion, thromboembolism, and mortality |
Phillips et al., 2021 [49] | 117 US pediatric trauma patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | MTP implementation | TEG parameters accurately identify patients needing MTP |
Aladegbami et al., 2018 [50] | 125 US pediatric trauma patients | Intraoperative | rTEG vs. other non-TEG assessments (observational study) | Mortality, blood product use, ventilator duration, length of ICU stay | Patients with rTEG had worse outcomes on all measures except mortality (which did not differ). However, rTEG was used primarily for more severely injured patients |
Obstetric
Pregnancy is uniquely a hypercoagulable state. This usually results in thromboembolic complications that can affect the pregnancy, necessitating the need for anticoagulants. Under such circumstances, TEG parameters have been found to be useful in guiding anticoagulation therapy [51]. But its sensitivity has not been found to be adequate to monitor the progress of anticoagulation [10]. On the other hand, pregnancy-related complications such as pre-eclampsia and eclampsia reverse the blood coagulability into the hypercoagulable state as well as hemolysis that can be exacerbated during surgery. Although TEG relates such coagulopathic scenarios during pregnancy with the risk profiles preoperatively [52], they have yet been found to be inferior when compared to conventional coagulation tests in predicting intraoperative coagulopathy and blood loss [53]. They still have been demonstrated to reduce blood product use, costs, risks of ICU admission, and the need for emergency hysterectomy [54] (Table 4).
Table 4
Studies of TEG in obstetric perioperative settings
TEG: thromboelastography; TEG-MA: TEG with maximum amplitude
Citation | Patient Sample | Operative Setting | TEG Procedures Assessed | Clinical Outcomes | Summary of Findings |
Griffiths et al., 2017 [10] | 24 UK obstetric patients | Postoperative Cesarean section | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulant detection | TEG parameters do not have the sensitivity to accurately monitor anticoagulant therapy progress |
Boyce et al., 2011 [51] | 19 UK obstetric patients | Intraoperative Cesarean section | TEG R-time | Response to heparin dosage on coagulation | TEG parameters were useful for guiding heparin dosage |
Karlsson et al., 2014 [52] | 45 Swedish obstetric patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, blood loss | TEG parameters were worse predictors of coagulopathy and blood loss compared with conventional laboratory tests |
Smith et al., 2009 [53] | 54 UK obstetric patients | Preoperative, postoperative Caesarian section | TEG-MA, TEG R-time | Coagulopathy, risk profiles | TEG parameters were associated with postoperative coagulopathy and risk profiles |
Snegovskikh et al., 2018 [54] | 86 US obstetric patients | Preoperative transfusion due to severe hemorrhage | TEG-directed transfusion protocol vs. clinician discretion | Blood loss, blood product use, ICU admission, emergency hysterectomy, costs | Introduction of TEG-directed transfusion protocol reduced blood product use, costs, and risks of ICU admission or emergency hysterectomy |
Orthopedic
Orthopedic surgery in general involves the release of massive tissue factors triggering a coagulation process that requires anticoagulants for venous thromboembolism prevention and treatment. For joint surgeries, neuraxial and peripheral nerve blocks are mainstay anesthesia choices that need information on the patient’s coagulation profile and medications that affect coagulation. So comprehensive information about coagulation status in orthopedic surgery patients is important. In demographic-specific orthopedic surgery patients, TEG has been reported to be a better measure of hypercoagulability compared to conventional measures [55] but has been found not to predict venous thromboembolism risk [56]. In spine surgery, TEG has predicted clotting factor deficiency such as hypofibrinogenemia and was found to be an inferior predictor of coagulation status as a whole compared to traditional laboratory measures [57, 58]. However, their sensitivity to sustained coagulation changes i.e., after seven days is superior compared with traditional measures [59]. When it comes to anticoagulation, TEG has been established to differentiate anticoagulated patients as well as monitor their therapy [60-62]. TEG-guided anticoagulation prophylaxis has better safety and comparable efficacy to conventional prophylaxis strategy [63]. TEG did not find any significance in detecting specific outcomes related to orthopedic surgery such as bone cement implantation syndrome and infections [64, 65] (Table 5).
Table 5
Studies of TEG in orthopedic perioperative settings
TEG: thromboelastography; TEG-PM: TEG with platelet mapping; TEG-MA: TEG with maximum amplitude; VTE: Venous thromboembolism
Citation | Patient Sample | Operative Setting | TEG Procedures Assessed | Clinical Outcomes | Summary of Findings |
Lloyd-Donald et al., 2021 [55] | 52 Australian orthopedic patients | Preoperative, intraoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hypercoagulability | TEG parameters were a better measure of hypercoagulability in this population than conventional measures |
Parameswaran et al., 2016 [56] | 101 Indian orthopedic patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | VTE | TEG parameters did not predict VTE risk |
Horlocker et al., 2001 [57] | 244 US spinal surgery patients | Intraoperative spinal fusion | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters were worse predictors of coagulation status than traditional laboratory measures |
Chen, Hu, et al., 2020 [58] | 39 Chinese adolescent orthopedic patients | Intraoperative scoliosis surgery | TEG-FLEV | Hypofibrinogenemia | TEG-FLEV predicts hypofibrinogenemia |
Bai et al., 2021 [59] | 228 Chinese orthopedic patients | Pre- and post-operative THA | TEG R-time, TEG-MA | Coagulability after anticoagulant prophylaxis (1 and 7 days post-surgery) | TEG R-time and TEG-MA measures were both more sensitive to sustained coagulation changes after 7 days compared with traditional laboratory measures |
Klein et al., 2000 [60] | 24 US orthopedic patients | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation | TEG parameters differentiate anticoagulated patients |
Li et al., 2020 [61] | 80 Chinese orthopedic patients | Intraoperative posterior lumbar fusion | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle, TEG-CI, TEG-PIR | Anticoagulation monitoring | TEG parameters are useful for monitoring anticoagulant therapy |
Tekkesin et al., 2016 [62] | 30 Turkish orthopedic patients | Preoperative, postoperative | TEG R-time | Anticoagulation monitoring | TEG parameters are useful for monitoring anticoagulation therapy perioperatively |
Chen, Ma, et al., 2020 [63] | 197 Chinese orthopedic patients | Intraoperative total joint arthroplasty | TEG-guided risk stratification | Blood loss, transfusion rate, transfusion volume, DVT | TEG-guided risk stratification for anticoagulation prophylaxis resulted in better safety and equal efficacy as conventional prophylaxis strategy |
Qiao and Sun, 2021 [64] | 250 Chinese orthopedic patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Periprosthetic joint infection (PJI) | TEG parameters predicted PJI |
Morda et al., 2017 [65] | 32 Italian orthopedic patients | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bone cement implantation syndrome (BCIS) | TEG parameters were not predictive of BCIS |
ICU
Surgical ICU patients commonly have a myriad of coagulation abnormalities such as thrombocytopenia, prolonged global coagulation times, reduced levels of coagulation inhibitors, or high levels of fibrin split products. Additionally, they are at increased risk of venous thromboembolism due to immobilization, pharmacologic paralysis, repeat surgical procedures, sepsis, mechanical ventilation, vasopressor use, and renal dialysis. Identifying the etiology of these coagulation abnormalities is of utmost importance since each coagulation disorder necessitates different therapeutic strategies. Since TEG provides a comprehensive evaluation of the viscoelastic properties of blood compared to standard plasma assays, in surgical ICU patients TEG has been demonstrated to be predictive of ICU duration, ventilator duration, hospital length of stay, and risk of thromboembolic events [66]. The detection of coagulation abnormalities is even more important in sepsis, a well-known comorbidity during ICU admission since consumption of coagulation factors and subsequent coagulopathy occurs. TEG in this sense has been established to detect coagulopathy and distinguish it among those with and without sepsis so that appropriate management can ensue (Table 6) [66].
Table 6
Studies of TEG in ICU perioperative settings
Citation | Patient Sample | Operative Setting | TEG Procedures Assessed | Clinical Outcomes | Summary of Findings |
Kashuk et al., 2009 [66] | 152 US SICU patients | Intraoperative | r-TEG G | Hypercoagulability, thromboembolic events, transfusion, ICU length of stay, hospital length of stay, ventilator days | TEG-indicated hypercoagulability was predictive of ICU duration, ventilator duration, hospital duration, and risk of thromboembolic event |
Cardiovascular
Blood Product Transfusion
The use of TEG in cardiovascular surgeries significantly reduced blood product transfusion compared to clinician-guided practice [67-76]. However, it was not associated with any change in ICU stay or mortality [69, 71, 72]. Redfern et al. 2020 found that TEG-guided protocol significantly reduced blood product use, costs, and reoperation rates; however, it did not impact mortality compared to clinician discretion in 1098 US cardiac patients [74]. Sun et al. 2014 found that TEG-guided protocol was associated with lower fresh frozen plasma (FFP) and platelet transfusion volume without any association with plasma transfusion volume or platelet count in 39 Chinese cardiac patients during ventricular assist device placement [76].
On the other hand, a weak relationship between thromboelastography with platelet mapping (TEG-PM) and platelet transfusion volume was observed in 44 US pediatric cardiac patients [77]. In addition, Westbrook et al. 2009 showed no significant difference in blood product usage between the TEG-guided and the clinician-guided groups in 69 Australian cardiac patients [78].
Bleeding Prediction
The ability of TEG parameters to predict bleeding was questionable in the literature as some studies showed that the use of TEG-MA, TEG R-time, TEG-K, and TEG α-angle was also predictive of blood loss during the operation [75, 79-88] and even postoperatively [89-96]. They could also predict short-term bleeding complications and micro-bleeding [97, 98]. However, they predicted hemostasis only without cyanosis in 63 Italian cardiac patients [99]. Using TEG-MA was useful in predicting long-term ischemic event risk [100], platelet function [101], and “high on-treatment platelet reactivity” [102].
On the other hand, Terada et al. 2019 found that intraoperative use of TEG-MA, TEG R-time, TEG-K, and TEG α-angle was not predictive of blood loss volume in 50 Japanese cardiac patients [103]. Moreover, another five studies showed that these TEG parameters were not predictive of postoperative bleeding [104-108] or even intraoperative bleeding [109, 110].
While other TEG parameters like TEG-PM, rapid thromboelastography maximal amplitude (rTEG-MAf), and rapid thromboelastography fibrinogen level (rTEG-FLEV) were predictive of blood loss volume in cardiac patients [111, 112].
Coagulopathy and Thrombotic Events
Mostly TEG parameters could predict both coagulopathy and thrombotic events. The use of TEG-MA, TEG R-time, TEG-K, and TEG α-angle in cardiac patients was predictive of both coagulopathy [84, 85, 113-120] and even intracranial hemorrhage [120]. Also, they could predict thrombotic events [97, 121] and even pump thrombosis risk [122]. They detected also the P2Y12 inhibition nonresponse, allowing earlier intervention for patients receiving preoperative inhibition therapy in 453 US vascular patients [123]. In comparison to conventional indicators, TEG parameters were better at predicting bleeding and clotting complications [124]. Heparinase modification allowed TEG parameters to diagnose covert coagulopathy [125, 126]. Only Brothers et al. 1993 found that these parameters were not reliably corresponded to clinical coagulopathy in 10 US cardiac patients [127].
Bhardwaj et al. 2017 found that TEG-MA predicted postoperative thrombocytopenia in 35 Indian cardiac patients [128]. In addition, TEG-MA predicted platelet count in cardiac patients [105, 129, 130]. On the other hand, it did not predict adverse events in 233 Danish vascular patients [131].
Other parameters like rTEG-MAf, rTEG-FLEV, TEG-LY60, and TEG-LY150 were also predictive of coagulopathy events in cardiovascular surgeries [132, 133].
Anticoagulant Efficacy Prediction
Intraoperative use of TEG-MA, TEG R-time, TEG-K, and TEG α-angle was effective for monitoring anticoagulant therapy [134-136]. Postoperatively too they were effective for assessing anticoagulation status [137]. TEG-K was found to be effective in monitoring heparin efficacy intraoperatively in 31 US cardiac patients [138]. They also were useful in monitoring anticoagulation reversal in 40 Singaporean vascular patients [106].
TEG-guided intraoperative anticoagulant therapy was effective in 31 US intracranial aneurysm patients [139]; however, when it was compared to traditional methods, no difference was observed in terms of protamine usage or heparin reversal efficacy [140]. TEG-MA was comparable to ROTEM-EXTEM in terms of guiding anticoagulation reversal in 52 UK cardiac patients [141] (Table 7).
Table 7
Studies of perioperative TEG in cardiovascular perioperative settings
CABG: coronary artery bypass graft; TEG: thromboelastography; VAD: ventricular assist device; TEG-PM: TEG with platelet mapping; TEG-MA: TEG with maximum amplitude; ROTEM: rotational thromboelastometry; FFP: fresh frozen plasma
Citation | Patient Sample | Operative Setting | TEG Procedures Assessed | Clinical Outcomes | Summary of Findings |
Ak et al., 2009 [67] | 224 Turkish CABG patient | Intraoperative CABG | TEG-based algorithm vs. clinician-guided practice (RCT) | Volume of blood products transfused | Significantly lower volume of transfusion was required for patients in the TEG-guided condition |
Aoki et al., 2012 [68] | 100 Japanese vascular surgery patients | Intraoperative | Use of TEG-guided protocol vs. standard of care for transfusion determination (RCT) | Platelet transfusion, bleeding complications | Patients in the TEG-guided protocol group used less platelet transfusion, but had more bleeding complications, compared with the clinician-guided group |
Datta and De, 2020 [69] | 3000 Indian cardiac patients | Intraoperative | TEG-guided transfusion vs. clinician-guided transfusion policy | Transfusion volume, ICU length of stay, mortality | TEG-guided transfusion resulted in use of lower volume of blood product and no change in ICU stay or mortality |
Fleming et al., 2017 [70] | 681 US cardiac patients | Intraoperative | Use of TEG-directed transfusion vs. clinician discretion | Blood product usage | Introduction of TEG-directed transfusion procedures reduced volume of blood product used |
Hasan et al., 2022 [71] | 698 US cardiopulmonary bypass patients | Intraoperative | TEG-guided transfusion protocol vs. conventional testing | Intraoperative blood product usage, postoperative transfusion, mortality | TEG-guided transfusion reduced intraoperative blood product use, but did not reduce postoperative transfusion or mortality rate |
Kane et al., 2016 [72] | 150 US pediatric cardiac patients | Intraoperative | TEG-guided transfusion vs. clinician-guided transfusion | Blood product usage, postoperative complications | Introduction of TEG-guided transfusion protocol resulted in reduction in blood product usage with no increase in complications |
Mendeloff et al., 2009 [73] | 112 US neonatal cardiac patients | Intraoperative | TEG-guided transfusion protocol vs. clinician-guided approach | Blood product usage | Introduction of a TEG-guided transfusion protocol resulted in reduced usage of blood product volume |
Redfern et al., 2020 [74] | 1,098 US cardiac patients | Intraoperative | TEG-guided transfusion protocol vs. clinician discretion | Blood product usage, costs, reoperation rate, mortality | Introduction of TEG-guided transfusion protocol reduced blood product usage, reduced costs, reduced reoperation rates, and did not impact mortality |
Shore-Lesserson et al., 1999 [75] | 105 US cardiac patients | Intraoperative | TEG-guided transfusion protocol vs. conventional protocol | Blood product usage | TEG-guided transfusion protocol was associated with lower blood product usage volume |
Sun et al., 2014 [76] | 39 Chinese cardiac patients | Intraoperative VAD placement | TEG-directed transfusion protocol vs. clinician discretion | Coagulopathy, platelet count, blood product usage | TEG-directed transfusion was associated with lower FFP and platelet transfusion volume, but there was no difference in plasma transfusion volume or platelet count |
Barker et al., 2019 [77] | 44 US pediatric cardiac patients | Intraoperative and postoperative | TEG-PM | Mortality, platelet transfusion volume | Weak relationship between TEG-PM and platelet transfusion volume |
Westbrook et al., 2009 [78] | 69 Australian cardiac patients | Intraoperative | TEG-guided transfusion protocol vs. clinician discretion (RCT) | Blood product usage | There was a no significant difference in blood product usage between the TEG-guided and clinician discretion groups |
Emani et al., 2021 [79] | 703 US pediatric cardiac patients | Intraoperative | TEG-MA | Perioperative bleeding, transfusion volume | TEG-MA was predictive of bleeding volume. TEG-MA guidance had utility for reducing transfusion volume |
Emani et al., 2018 [80] | 511 US pediatric cardiac patients | Intraoperative | TEG-MA | Intraoperative bleeding | TEG-MA predicts intraoperative bleeding volume |
Essell et al., 1993 [81] | 36 US cardiopulmonary bypass patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Intraoperative bleeding | TEG parameters were predictive of hemorrhage risk |
Sivapalan et al., 2017 [82] | 199 Danish cardiac patients | Intraoperative CABG | TEG-MA | Transfusion volume | TEG-MA was predictive of transfusion volume |
Liu et al., 2021 [83] | 398 Chinese vascular patients | Preoperative, intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Blood loss, hemorrhage, transfusion | TEG parameters were predictive of blood loss volume, hemorrhage, and transfusion |
Sharma et al., 2018 [84] | 50 Indian cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, blood loss volume | TEG parameters predicted coagulopathy and blood loss volume |
Tuman et al., 1989 [85] | 42 US cardiac patients | Intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bleeding, hemorrhage, coagulopathy | TEG parameters were predictive of bleeding volume, hemorrhage, and coagulopathy |
Moganasundram et al., 2010 [86] | 50 UK pediatric cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bleeding | TEG parameters predicted bleeding |
Nuttall et al., 1997 [87] | 82 US cardiac patients | Preoperative, intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Intraoperative bleeding | TEG parameters predicted subjective clinician judgment of excessive bleeding |
Singh et al., 2015 [88] | 55 Indian cardiac patients | Intraoperative coronary bypass | TEG-MA | Blood loss | TEG-MA was predictive of blood loss volume |
Cammerer et al., 2003 [89] | 255 German cardiac patients | Preoperative, intraoperative | TEG alpha-angle | Platelet function, surgical bleeding, postoperative bleeding | TEG alpha-angle is a strong predictor of postoperative bleeding |
Martin et. al., 1991 [90] | 22 UK pediatric cardiac patients | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters predicted postoperative bleeding |
Muller et al., 1975 [91] | 9 German cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters predicted postoperative bleeding |
Niebler et al., 2012 [92] | 60 US cardiac patients | Preoperative, intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters are predictive of postoperative bleeding |
Preisman et al., 2010 [93] | 59 Israeli vascular patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Excessive blood loss | TEG parameters predicted excessive postoperative blood loss |
Shih et al., 1997 [94] | 43 Chinese cardiac patients | Intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters are predictive of postoperative bleeding |
Smith et al., 2020 [95] | 120 US cardiac patients | Intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters are associated with postoperative bleeding |
Williams et al., 1999 [96] | 494 US pediatric cardiac patients | Intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters predicted postoperative bleeding |
Rymuza et al., 2018 [97] | 54 Polish vascular patients | Preoperative, intraoperative TAVI | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bleeding complications | TEG parameters predicted short-term bleeding complications |
Xu et al., 2016 [98] | 261 Chinese vascular patients | Intraoperative SAC embolization | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Microbleeding complications | TEG parameters predicted microbleeding |
Rizza et al., 2017 [99] | 63 Italian cardiac patients | Intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Cyanosis, hemostasis | TEG parameters were predictive of hemostasis but not cyanosis |
Hou et al., 2017 [100] | 759 Chinese vascular patients | Intraoperative PCI | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Platelet function, long-term ischemic events | TEG-MA predicted long-term ischemic event risk |
Kirmani et al., 2017 [101] | 50 UK cardiac patients | Preoperative | TEG-MA | Platelet function | TEG-MA is predictive of platelet function |
Cheng et al., 2020 [102] | 110 Chinese vascular patients | Intraoperative PCI | TEG R-time, TEG-MA | Identification of high-on treatment platelet reactivity (HTPR) | TEG parameters were effective for predicting HTPR complications |
Terada et al., 2019 [103] | 50 Japanese cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Blood loss | TEG parameters were not predictive of blood loss volume |
Carroll et al., 2006 [104] | 19 US cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters were not related to postoperative bleeding |
Pekelharing et al., 2013 [105] | 107 UK pediatric cardiac patients | Postoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding, platelet count | TEG-MA is associated with platelet count, but TEG parameters are not predictive of postoperative bleeding |
Ti et al., 2002 [106] | 40 Singaporean vascular patients | Preoperative CABG | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation reversal monitoring, bleeding | TEG parameters were not predictive of postoperative bleeding but were useful for monitoring anticoagulation reversal |
Welsh et al., 2014 [107] | 76 US cardiac patients | Intraoperative cardiopulmonary bypass | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding, cause of bleeding | TEG parameters did not predict postoperative blood loss, and did not distinguish causes of bleeding |
Agarwal et al., 2006 [108] | 54 UK cardiac patients | Coronary artery bypass surgery, preoperative and postoperative | TEG-PM post-operative | Post-bypass platelet function; blood loss at 4 hours; blood loss at 12 hours | TEG-PM post-operative was not related to any outcomes; authors recommend using pre-operative measures to predict outcomes |
Dorman et al., 1993 [109] | 60 US vascular patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Blood loss | TEG parameters did not predict blood loss |
Sharma et al., 2014 [110] | 439 US cardiac patients | Intraoperative | TEG-MA, TEG alpha-angle | Bleeding volume | TEG parameters did not improve prediction of bleeding volume |
Weitzel et al., 2012 [111] | 40 US cardiac patients | Intraoperative | TEG-PM | Postoperative blood loss | TEG parameters predicted postoperative blood loss volume |
Miao et al., 2014 [112] | 100 Chinese pediatric cardiac patients | Intraoperative | rTEG-MAf, rTEG-FLEV | Blood loss, transfusion volume | rTEG parameters were related to postoperative blood loss volume |
Koster et al., 2001 [113] | 19 German cardiopulmonary bypass patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters predicted coagulopathy and were useful in guiding intraoperative treatment |
Miller et al., 2000 [114] | 85 US pediatric cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters predicted coagulopathy |
Spiess et al., 1987 [115] | 38 US cardiac patients | Preoperative, intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters predicted coagulopathy |
Vlot et al., 2021 [116] | 89 Dutch cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters were associated with coagulopathy |
Yamamoto et al., 2021 [117] | 40 Japanese cardiac patients | Intraoperative | TEG-MA | Coagulopathy | TEG-MA was predictive of coagulopathy |
Yan et al., 2021 [118] | 521 Chinese cardiac patients | Intraoperative | TEG-MA | Hypercoagulability | TEG-MA values predicted hypercoagulable states |
Zisman et al., 2009 [119] | 62 Israeli cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters predicted postoperative coagulopathy |
Liang et al., 2020 [120] | 240 Chinese ischemic stroke patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, intracranial hemorrhage | TEG parameters were predictive of coagulopathy and intracranial hemorrhage |
Tuman et al., 1991 [121] | 80 US vascular patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Thrombotic events, coagulopathy | TEG parameters predicted thrombotic events |
Xia et al., 2020 [122] | 90 US cardiac patients | Intraoperative, postoperative LVAD placement | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Pump thrombosis | Differences in the rate of change in TEG parameters over time in the postoperative period predicted risk of pump thrombosis |
Rogers et al., 2021 [123] | 453 US vascular patients | Intraoperative CABG | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Detection of P2Y12 inhibition | TEG parameters detected P2Y12 inhibition nonresponse, allowing earlier intervention for patients receiving preoperative inhibition therapy |
Mack et al., 2021 [124] | 25 US vascular patients | Preoperative, intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bleeding, platelet count, clotting complications | TEG parameters provided more accurate indication of bleeding and clotting complications compared with conventional indicators |
Tuman et al., 1994 [125] | 51 US cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation monitoring | Heparinase modification can be combined with TEG parameters to enable monitoring of coagulation status in the presence of anticoagulants |
Yabrodi et al., 2022 [126] | 100 US pediatric cardiac ECMO patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | Heparinase modification may allow TEG parameters to diagnose covert coagulopathy |
Brothers et al., 1993 [127] | 10 US cardiac patients | Intraoperative abdominal aortic aneurysm surgery | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters did not reliably correspond to clinical coagulopathy. Authors suggest the clinical value of TEG is not supported |
Bhardwaj et al., 2017 [128] | 35 Indian cardiac patients | Intraoperative cardiac bypass | TEG-MA, ROTEM-FIBTEM | Coagulopathy, chest drain output | TEG-MA predicts postoperative thrombocytopenia, ROTEM-FIBTEM predicts postoperative hyperfibrinogenemia |
Bhatia et al., 2017 [129] | 4 German pediatric cardiac patients | Postoperative VAD placement | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Platelet count | TEG-MA is a strong predictor of platelet count. Authors recommend using r-TEG in preference to traditional laboratory measures |
Gautam et al., 2017 [130] | 105 US pediatric cardiac patients | Intraoperative | FFTEG | Platelet count | FFTEG values are predictive of platelet count |
Dridi et al., 2014 [131] | 233 Danish vascular patients | Intraoperative percutaneous coronary intervention (PCI) | TEG-MA | Adverse events | TEG-MA did not predict adverse events |
Miao et al., 2015 [132] | 80 Chinese pediatric cardiac patients | Intraoperative | rTEG-MAf, rTEG-FLEV | Coagulopathy | rTEG parameters were predictive of coagulopathy |
Vanek et al., 2007 [133] | 65 Czech vascular patients | Postoperative | TEG-LY60, TEG-LY150 | Coagulopathy | TEG parameters were associated with coagulopathy |
Koster et al., 2008 [134] | 15 German cardiopulmonary bypass patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bivalirudin anticoagulation | TEG parameters are effective for intraoperative monitoring of anticoagulation therapy |
Martin et al., 1994 [135] | 15 UK vascular patients | Preoperative, intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation monitoring | TEG parameters are more useful for intraoperative anticoagulation monitoring than conventional tests |
Wasowicz et al., 2009 [136] | 38 Canadian cardiac patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation monitoring | TEG parameters were more effective than conventional laboratory measures at monitoring intraoperative anticoagulation |
Murray et al., 1997 [137] | 36 US vascular patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation detection | TEG was effective at assessing postoperative anticoagulation status |
Chavez et al., 2004 [138] | 31 US cardiac patients | Intraoperative cardiopulmonary bypass | TEG TF/K | Heparin anticoagulation efficacy | TEG parameters were effective for monitoring heparin efficacy intraoperatively |
McTaggart et al., 2015 [139] | 31 US intracranial aneurysm patients | Intraoperative | TEG-guided anticoagulant therapy | Platelet function, complications | TEG-guided intraoperative anticoagulant therapy was effective |
Levin et al., 2014 [140] | 82 South African coronary bypass patients | Intraoperative | Use of TEG-guided anticoagulation compared with conventional methods | Protamine dosage, heparin reversal | TEG-guided anticoagulation methods did not differ from traditional methods in terms of protamine usage or heparin reversal efficacy |
Ortmann et al., 2015 [141] | 52 UK cardiac patients | Intraoperative | TEG-MA, ROTEM-EXTEM | Anticoagulation reversal detection | TEG and ROTEM parameters were comparable in terms of guiding anticoagulation reversal |
Transplant
Perioperative TEG is used in organ transplantation surgeries such as liver, kidney, pancreas-kidney, or bowel because of their abilities in the prediction of coagulopathy and thrombotic events. While Abuelkasem et al. found that TEG-R could not predict coagulopathy in liver transplant surgeries as effectively as ROTEM [142], other studies have demonstrated that TEG parameters like TEG-MA, TEG R-Time, TEG-K, and TEG α-angle could predict or be related to coagulopathy [143-149]. Despite the relation of TEG parameters to coagulopathy, they were not related to bleeding time [144] which was supported by Sujka et al. who compared TEG-directed transfusion protocol and the clinician-directed transfusion system and found no difference between both methods in decreasing the blood loss amount [150].
Also, TEG parameters predicted hypercoagulable status and thrombotic events [149, 151-153] even in comparison to the conditional laboratory tests [154] while Krzanicki et al. found that they could predict hypercoagulable status only without thrombotic events in liver transplant patients [155]. On the other hand, Sujka et al. found that TEG-directed blood transfusion increased the thromboembolic events compared to the clinician-directed protocol in liver transplant patients [150].
Regarding the use of blood products, the studies revealed different results. TEG parameters reduced the usage of blood products [156-158]; however, in comparison to other conventional tests or clinician-directed transfusion system, no differences were observed except for Sujka et al. who found TEG-directed transfusion system reduced only FFP use between other blood products [150, 159, 160]. Coakley et al. investigated both TEG and ROTEM parameters and found that ROTEM improved clinicians’ decisions compared to TEG usage [161].
In postoperative outcomes like survival, graft function, and hospital stay, controversial results were observed in the studies. Sam et al. found that TEG did not relate to renal graft function while Walker et al. found that it is an indicator of graft function [146, 162]. This controversy was seen also in the prediction of liver cirrhosis [148, 163]. TEG’s usage was not associated with mortality or survival rates [156, 160]. On the other hand, it decreased hospital stay length and reoperation needs [147, 160] (Table 8).
Table 8
Studies of TEG in transplant perioperative settings
TEG: thromboelastography; TEG-PM: TEG with platelet mapping; TEG-MA: TEG with maximum amplitude; ROTEM: rotational thromboelastometry; TEG-CI: TEG with coagulation index; FFP: fresh frozen plasma
Citation | Patient Sample | Operative Setting | TEG Procedures Assessed | Clinical Outcomes | Summary of Findings |
Abuelkasem et al., 2016 [142] | 36 US liver transplant patients | Intraoperative liver transplant | TEG R-time; ROTEM CT (INTEM-CT and EXTEM-CT) | Coagulopathy | INTEM-CT and EXTEM-CT were effective predictors of coagulopathy, but TEG-R was not |
Burke et al., 2004 [143] | 85 US diabetic simultaneous pancreas-kidney (SPK) transplant patients and 54 non-diabetic kidney transplant patients | Intraoperative during SPK or kidney transplant surgery | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters were useful for guiding transplant surgery and were validated in SPK for diabetic patients |
Davis & Chandler, 1995 [144] | 120 US kidney transplant patients | Intraoperative renal biopsy | TEG-K, TEG alpha-angle | Bleeding time, coagulopathy | TEG parameters were related to coagulopathy but not to bleeding time |
Kettner et al., 1998 [145] | 72 Austrian liver transplant patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters can distinguish between some causes of bleeding complications |
Sam et al., 2021 [146] | 25 Indian kidney transplant patients | Intraoperative | TEG R-time, TEG-CI, TEG-MA | Coagulopathy, graft function | TEG parameters were related to coagulopathy but not graft function |
Schulick et al., 2020 [147] | 40 US liver transplant patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, re-operation, length of stay | TEG parameters were predictive of coagulopathy, re-operation, and length of hospital stay |
Tanner et al., 2018 [148] | 33 US liver transplant patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, cirrhosis | TEG parameters predict coagulopathy but do not differentiate between patients with and without postoperative cirrhosis |
Raveh et al., 2018 [149] | 48 US visceral transplant patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Thrombotic complications, hemorrhagic complications | TEG parameters were predictive of thrombotic and hemorrhagic complications |
Sujka et al., 2018 [150] | 38 US pediatric liver transplant patients | Intraoperative | TEG-directed transfusion protocol vs. clinician discretion | Blood loss, blood product usage, FFP use, thromboembolic complications | Introduction of TEG-directed transfusion protocol was associated with decreased FFP usage, but no overall change in blood product usage or blood loss. Thromboembolic complications increased |
De Pietri et al., 2020 [151] | 27 Italian liver transplant patients | Intraoperative and postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle, TEG-G, TEG-LY30, TEG-LY60 | Portal vein thrombosis (PVT), hepatic artery thrombosis (HAT) | TEG-G and TEG-LY60 were predictive of PVT and HAT events |
Eldeen et al., 2016 [152] | 828 UK liver transplant patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Early hepatic artery thrombosis (E-HAT) | TEG parameters predict E-HAT |
Pivalizza et al., 1998 [153] | 19 Italian bowel transplant patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle, TEG-CL50 | Hypocoagulation | TEG-MA was related to hypocoagulation |
Garg et al., 2021 [154] | 50 Indian kidney donors | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative hypercoagulability | TEG parameters were better predictors of postoperative hypercoagulability compared with traditional lab tests |
Krzaniki et al., 2013 [155] | 124 UK liver transplant patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hypercoagulability, thrombotic complications | TEG parameters were predictive of hypercoagulability but not thrombotic complications |
De Pietri et al., 2015 [156] | 386 Italian liver transplant patients | Intraoperative | Comparison of two alternate TEG-based transfusion algorithms | Blood product volume, mortality | Improved algorithm employing additional TEG measures of functional fibrinogen and maximum amplitude of functional fibrinogen resulted in reduced blood product usage with no change in mortality |
Kang et al., 1985 [157] | 66 US liver transplant patients | Intraoperative | TEG-guided transfusion | Blood product usage | TEG-guided transfusion protocol was associated with reduction in blood product usage |
Zamper et al., 2018 [158] | 237 Brazilian liver transplant patients | Intraoperative liver transplant | TEG-guided transfusion protocol vs. clinician discretion | Blood product usage | Introduction of TEG-guided transfusion protocol reduced blood product usage volume |
Gaspari et al., 2021 [159] | 226 Italian liver transplant patients | Intraoperative | TEG-guided vs. conventional coagulation test (CCT)-guided transfusion strategies | Blood product usage | After propensity matching, there was no difference between blood product usage between TEG and CCT-guided transfusion techniques |
Gopal et al., 2020 [160] | 68 UK pancreas-kidney transplant patients | Intraoperative | TEG-directed vs. conventional anticoagulation protocol | Blood product usage, hospital length of stay, 1 year survival | The TEG-directed anticoagulation protocol resulted in reduced blood product usage and shorter length of stay, with no difference in survival |
Coakley et al., 2006 [161] | 20 UK liver transplant patients | Intraoperative | Kaolin TEG, kaolin heparinase TEG, ROTEM-NITEM, ROTEM-FIBTEM | Time to administer blood transfusion | TEG and ROTEM parameters differed on transfusion guidance, with ROTEM judged to have made better clinical decisions |
Walker et al., 2020 [162] | 71 US kidney transplant patients | Preoperative, postoperative | TEG-LY30 | Graft function | TEG-LY30 was predictive of good graft function |
Kohli et al., 2019 [163] | 164 US liver transplant patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Cirrhosis severity | TEG parameters identified cirrhosis severity |
Miscellaneous
TEG is used in many other sites involving neurological, gastrointestinal, general, cardiopulmonary, plastic, urological, and oncological procedures.
Neurological
TEG parameters showed an evitable role in improving hematological outcomes in people who underwent neurosurgeries whether they were adults [164-168] or children [169]. TEG parameters like TEG-R, TEG-MA, TEG-K, and TEG α-angle could predict hypercoagulation or thrombotic complications [164, 166, 168, 169]; however, compared to control treatment, no difference was observed [170]. In addition, these parameters predicted bleeding and hypo-coagulation status whether intraoperative or postoperative [166, 169, 171, 172] besides using them could decrease bleeding complications risk compared to other conventional labs [170]. TEG-guided transfusion was effective to decrease the transfusion of blood products compared to the clinician-guided protocol [172]. Also, TEG-guided use of intraoperative antiplatelet therapy succeeded to prevent major complications [167] while only TEG-R was rare to be associated with postoperative complications [164].
Only TEG-PM could not predict thrombotic events or even bleeding complications through neurosurgical procedures [173]; however, it showed good ability in the prediction of platelet inhibition in comparison to other modalities [165].
Gastrointestinal
TEG parameters showed promising results in gastroenterology surgeries [174]. Using TEG in bariatric surgeries could predict hypercoagulability conditions [175-177] and this ability especially increased in females and older patients [175]. However, in liver-related surgeries, TEG efficacy was controversial as Oo 2020 et al. and Vieira da Rocha 2009 et al. showed that the essential TEG parameters were not predictive of ulcerative bleeding risk or hemostasis variation [178, 179]. On the other hand, Okida 1991 et al. and Zanetto 2021 et al. showed the efficacy of these parameters in the prediction of coagulopathy and perioperative bleeding [180, 181]. Moreover, compared to clinician-guided transfusion, TEG-guided transfusion decreased the usage of blood products; however, it was not different to reduce the complications rate [182]. TEG usage could not predict postoperative sepsis in oesophagectomy surgeries [183]. In patients with obstructive jaundice, TEG parameters also could not predict coagulopathy or platelet function during their surgeries for drainage of obstructive jaundice [184] while they predicted bleeding and coagulopathy in cystectomy operations [185, 186]. Also, they could predict deep venous thrombosis risk in gastric cancer patients comorbid with portal hypertension [187].
General
Few studies investigated the role of TEG among pediatric patients undergoing general surgical procedures and they found that applying TEG or ROTEM in pediatric patients increased coagulopathy risk and blood products use [188] while in neonates, TEG parameters predicted sepsis early [189]. Also, TEG-guided transfusion decreased blood products use compared to clinician-guided transfusion while in mortality and morbidity risks, no differences were detected [190]. The use of TEG among adults undergoing general surgical procedures was better described in the literature. They were effective in the prediction of bleeding [191]. Using TEG-PM in monitoring platelet inhibition in patients on clopidogrel was useful in decreasing unneeded treatment cancellations besides the patient risk [192]. However, comparing the conventional transfusion protocol to TEG-guided transfusion revealed no significant difference in detecting bleeding [193]. The conventional TEG parameters with the celite-activated ones were predictive or associated with hypercoagulability or thrombotic events [194-196]. Coagulopathy prediction was achieved also by TEG-guided transfusion compared to the use of conventional methods [193]. Also, they showed better prediction values of survival rates compared to other conventional methods [197]. On the other hand, TEG-guided transfusion was not different to the conventional protocol in the prediction of mortality [193]. They could predict the blood products use [191] and using TEG-guided transfusion was effective in reducing the need for blood products [193]. Moreover, they resembled a good option to guide the optimal treatment, especially in patients comorbid with Gaucher disease who undergoing general surgeries [198]. In flap operations, the TEG parameters could not predict the flap loss risks [199]; however, they were predictive of coagulopathy and thrombotic events [200]. Also, in maxillary surgeries, they could predict both bleeding and platelet count [201].
Extracorporeal Membrane Oxygenation (ECMO)
Applying TEG in surgical procedures in patients on ECMO was controversial in the literature in both adults and pediatric patients. In pediatric patients, TEG-guided anticoagulation protocol significantly reduced blood products usage, decreased complications, and increased ECMO circuit life compared to the clinician-guided system [202, 203] which was supported by Moynihan 2017 et al. who found that they were useful in monitoring intraoperative anticoagulation [204]. Moreover, TEG-R significantly predicted thrombotic events [205]. On the other hand, the bleeding complications predictive value of conventional TEG parameters was controversial as Saini et al. showed that they could not predict bleeding [206] while Sleeper et al. found that these parameters predicted bleeding [207]. Also, TEG kaolin and heparinase had a poor indication ability of aPTT and an acceptable indication of platelet count which recommended the usage of conventional laboratory tests [208]. Regarding their use in adult patients on ECMO, TEG-R, ROTEM-INTEM, and conventional methods had the same efficacy in anticoagulation monitoring [209]. Also, the TEG flat line reading had no relation to the perioperative bleeding [210]. However, other studies showed that the conventional TEG parameters were effective to monitor anticoagulation [211] and to predict coagulopathy in adults on ECMO patients [212].
Others
TEG was also used in monitoring hematological outcomes in urological procedures such as prostatectomy [213, 214] and renal biopsy [215] or even in nephrotic syndrome patients [216]. However, its efficacy was questionable as in prostatectomy procedures, TEG clot lysis correlated with bleeding [214] while other parameters like TEG-LY30 and TEG-LY40 were not able to predict postoperative coagulopathy [213]. Also, during the renal biopsy, TEG-MA was not effective to predict bleeding time [215]. However, TEG parameters like TEG-MA, TEG-R, TEG-K, and TEG α-angle were associated with coagulopathy complications and could distinguish different renal pathologies in 713 Chinese nephrotic syndrome patients [216]. TEG parameters were predictive in oncology patients regarding platelet count, hypercoagulability, tumor type, resection success, and postoperative complications [217-219]. Also, they were useful in monitoring the anticoagulation status in patients who underwent thoracic surgeries [220] and patients on mechanical circulatory support devices [221] (Table 9).
Table 9
Studies of TEG in miscellaneous perioperative settings
TEG: thromboelastography; TEG-PM: TEG with platelet mapping; TEG-MA: TEG with maximum amplitude; ROTEM: rotational thromboelastometry; aPTT: activated partial thromboplastin time
Citation | Patient Sample | Operative Setting | TEG Procedures Assessed | Clinical Outcomes | Summary of Findings |
Abrahams et al., 2002 [164] | 46 US neurosurgery patients | Intraoperative craniotomy | TEG R-time | Hypercoagulability, DVT, hematoma | TEG was useful for predicting hypercoagulability throughout procedure; post-operative adverse outcomes were too rare to be statistically associated with TEG parameters |
Corliss et al., 2017 [165] | 23 US neurosurgery patients | Intraoperative | TEG-PM | Platelet inhibition | TEG-PM provides a better indicator of platelet inhibition compared with other methodologies |
Javed et al., 2021 [166] | 118 US intracranial aneurysm patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Complications | TEG parameters were predictive of hemorrhagic and ischemic complications |
Wu et al., 2019 [167] | 183 Chinese neurosurgery patients | Intraoperative cerebrovascular stent placement | TEG-guided intraoperative antiplatelet therapy | Major complications | TEG-guided therapy was effective at avoiding major complications in the context of intraoperative antiplatelet therapy |
Parker et al., 2012 [168] | 39 UK head and neck surgery patients | Preoperative free tissue transfer | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Thrombotic complications | TEG parameters are predictive of thrombotic complications |
El Kady et al., 2009 [169] | 40 Egyptian pediatric neurosurgery patients | Preoperative, intraoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hypocoagulation | TEG parameters predicted hypocoagulation |
Li et al., 2021 [170] | 188 Chinese cranial patients | Intraoperative | TEG-guided treatment vs. control | Bleeding, complications | TEG-guided treatment resulted in less bleeding and no difference in thrombotic complications |
Zhang et al., 2017 [171] | 181 Chinese neurosurgery patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Intraoperative blood loss | TEG parameters predicted intraoperative blood loss |
Zhou et al., 2019 [172] | 82 Chinese intracerebral hemorrhage patients | Intraoperative | TEG-guided transfusion protocol vs. clinician discretion | Transfusion volume, bleeding outcomes | TEG-guided transfusion resulted in reduced intraoperative and postoperative bleeding and in lower transfusion volumes |
Corliss et al., 2020 [173] | 191 US neurosurgery patients | Intraoperative | TEG-PM | Hemorrhagic complications, thrombotic complications | TEG-PM parameters are not predictive of hemorrhagic or thrombotic complications |
Mahla et al., 2001 [174] | 20 Austrian abdominal surgery patients | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative hypercoagulability | TEG parameters detect postoperative hypercoagulability up to a week after surgery that conventional diagnostics do not detect |
Duman Guven et al., 2020 [175] | 54 Turkish bariatric patients | Preoperative, postoperative | TEG-MA | Hypercoagulability | TEG-MA is predictive of hypercoagulability in morbidly obese patients, and is more predictive among female patients and older patients |
Kupcinskiene et al., 2017 [176] | 60 Lithuanian bariatric patients | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hypercoagulability | TEG parameters were useful for perioperative monitoring of coagulability |
Cowling et al., 2021 [177] | 422 US bariatric surgery patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | Preoperative TEG parameters predict postoperative coagulopathy in morbidly obese patients |
Oo et al., 2020 [178] | 41 Australian liver surgery patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hemostasis | TEG parameters did not accurately indicate variations from hemostasis |
de Rocha et al., 2009 [179] | 150 Brazilian hepatic patients | Intraoperative variceal band ligation | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Ulcerative bleeding | TEG parameters were unrelated to risk of ulcerative bleeding |
Okida et al., 1991 [180] | 16 Japanese liver surgery patients | Preoperative, intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters predict coagulopathy |
Zanetto et al., 2021 [181] | 80 US cirrhosis patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Perioperative bleeding | TEG parameters predicted perioperative bleeding |
Vuyyuru et al., 2020 [182] | 58 Indian liver disease patients | Intraoperative | TEG-guided transfusion protocol vs. clinician discretion (RCT) | Blood product usage, complications | The TEG-guided transfusion protocol resulted in lower blood product usage volume with no difference in complications |
Durila et al., 2012 [183] | 43 Czech oesophagectomy patients | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative sepsis | TEG parameters did not predict sepsis |
Cakir et al., 2009 [184] | 23 obstructive jaundice Turkish patients | Intraoperative during surgery for drainage of obstructive jaundice | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, platelet function | No effects detected |
Rasmussen et al., 2015 [185] | 40 Danish cystectomy patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hemorrhage, coagulation competence | TEG parameters were predictive of blood loss and coagulopathy |
Rasmussen et al., 2016 [186] | 39 Danish cystectomy patients | Intraoperative | TEG-MA | Blood loss | TEG-MA was related to blood loss volume |
Gong et al., 2021 [187] | 172 Chinese gastric cancer patients with portal hypertension | Preoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Occurrence of DVT | TEG parameters were predictive of DVT risk |
Burton et al., 2021 [188] | 265 US pediatric general surgery patients | May vary (retrospective registry study) | TEG or ROTEM vs. no use of viscoelastic testing | Coagulopathy, blood product use | Patients receiving TEG or ROTEM had more coagulopathy and used more blood products than other patients |
Grant & Hadley, 1997 [189] | 103 South African neonatal general surgery patients | Postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Differentiation of patients with and without sepsis | TEG parameters were effective at early identification of neonatal sepsis |
Raffaeli et al., 2022 [190] | 139 Italian neonatal general surgery patients | Intraoperative | TEG-guided transfusion protocol vs. clinician discretion | Blood product usage, mortality, morbidity | Introduction of a TEG-guided transfusion protocol decreased blood product usage volume and did not impact mortality or morbidity |
Zhang et al., 2014 [191] | 55 Chinese general surgery patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding, blood product usage | TEG parameters predicted postoperative bleeding and blood product usage |
Kasivisvanathan et al., 2014 [192] | 182 UK general surgery patients taking clopidogrel therapy | Intraoperative | Stratification of bleeding risk by TEG-PM | Detection of platelet inhibition | TEG-PM was effective at minimizing patient risk |
Shi et al., 2019 [193] | 74 Chinese general surgery patients | Intraoperative | TEG-guided transfusion protocol vs. conventional protocol | Coagulopathy, blood product usage, blood loss, bleeding, mortality | TEG-guided transfusion reduced blood product usage, and TEG estimated coagulopathy better, but there was no difference between groups in bleeding outcomes or mortality |
Mao et al., 2021 [194] | 106 Chinese general surgery patients | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | DVT, hypercoagulability | TEG parameters were associated with DVT status and hypercoagulability |
McCrath et al., 2005 [195] | 240 US general surgery patients | Postoperative | TEG-MA | Complications | TEG-MA was predictive of thrombotic complications and myocardial infarction |
Yamakage et al., 1998 [196] | 30 Japanese general surgery patients | Intraoperative | TEGc | Coagulopathy | Celite-activated TEG parameters are predictive of coagulopathy |
Bhattacharyya et al., 2021 [197] | 50 critically ill Indian general surgery patients | Postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Survival time, mortality | TEG parameters immediately postoperative were better predictors of survival than alternative measures |
Ioscovich et al., 2016 [198] | 22 Israeli general surgery patients with Gaucher disease | Preoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Hemostasis | TEG parameters may be useful in guiding treatment in this population |
Ekin et al., 2019 [199] | 77 Turkish reconstructive surgery patients | Preoperative, intraoperative, postoperative free flap reconstruction | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Free flap loss | TEG parameters were not predictive of free flap loss |
Zavlin et al., 2019 [200] | 100 US reconstructive surgery patients | Preoperative, intraoperative, postoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, thrombosis | TEG parameters predicted coagulopathy and thrombosis |
Madsen et al., 2012 [201] | 21 Danish maxillary patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Blood loss, platelet count | TEG parameters predicted blood loss and platelet count |
Phillips et al., 2020 [202] | 46 US neonatal ECMO patients | Intraoperative congenital diaphragmatic hernia surgery | TEG-guided anticoagulation vs. clinician discretion | Blood product usage | Introduction of TEG-guided anticoagulation protocol resulted in reduced blood product usage |
Northrop et al., 2015 [203] | 366 US pediatric ECMO patients | Intraoperative | TEG-guided anticoagulation protocol vs. clinician discretion | Blood product usage, hemorrhagic complications, ECMO circuit life | Introduction of TEG-guided anticoagulation protocol resulted in reduced blood product usage, decreased complications and increased ECMO circuit life |
Moynihan et al., 2017 [204] | 31 Australian pediatric ECMO patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation monitoring | TEG parameters are useful for intraoperative anticoagulation monitoring |
Henderson et al., 2018 [205] | 49 US pediatric ECMO patients | Intraoperative | TEG R-time | Hypocoagulation, thrombotic complications | TEG R-time was a predictor of thrombotic complication |
Saini et al., 2016 [206] | 46 US pediatric ECMO patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bleeding complications | TEG parameters did not predict bleeding complications |
Sleeper et al., 2021 [207] | 40 US pediatric ECMO patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Bleeding events | TEG parameters are predictive of bleeding events |
Alexander et al., 2010 [208] | 27 Australian pediatric ECLS patients | Intraoperative | TEG kaolin and heperinase | aPTT, platelet count | TEG was a poor indicator of aPTT and an acceptable indicator of platelet count. Authors recommend using conventional laboratory tests in this population |
Giani et al., 2021 [209] | 25 Italian ECMO patients | Intraoperative | TEG R-time, ROTEM-INTEM | Anticoagulation monitoring | TEG R-time, ROTEM-INTEM, and conventional diagnostics had similar utility for monitoring anticoagulation status in ECMO |
Panigada et al., 2016 [210] | 32 Italian ECMO patients | Intraoperative | TEG “flat line” reading | Perioperative bleeding | TEG “flat line” was not related to bleeding outcomes |
Ranucci et al., 2016 [211] | 31 Italian ECMO patients | Intraoperative | TEG-MA, TEG R-time | Anticoagulation monitoring | TEG parameters are effective for intraoperative anticoagulation monitoring |
Stammers et al., 1995 [212] | 17 US ECMO patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy | TEG parameters predicted coagulopathy |
Ziegler et al., 2008 [213] | 49 Italian prostatectomy patients | Intraoperative, postoperative | TEG-LY30, TEG-LY40 | Coagulopathy | TEG parameters did not predict postoperative coagulopathy |
Bell et al., 1996 [214] | 30 UK urology patients | Intraoperative and postoperative transurethral prostatectomy (TURP) | TEG clot lysis | Postoperative coagulation, blood loss | TEG clot lysis correlates with blood loss |
Gal-Oz et al., 2020 [215] | 417 Israeli renal biopsy patients | Intraoperative | TEG-MA | Bleeding time | TEG-MA did not predict bleeding time |
Lu et al., 2020 [216] | 713 Chinese renal patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Coagulopathy, VTE | TEG parameters were associated with coagulopathy and VTE and distinguished between patients with different renal diagnoses |
Gatt et al., 2014 [217] | 24 Maltese oncology patients | Preoperative and postoperative transfusion | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Platelet count, coagulation | TEG parameters were predictive of platelet count |
Moore et al., 2018 [218] | 100 US oncology patients | Preoperative | TEG-MA, TEG R-time, TEG alpha-angle, TEG-LY30 | Coagulopathy, tumor type, resection success | TEG parameters were associated with hypercoagulability, tumor type, and resection success |
Wang et al., 2018 [219] | 80 Chinese oncology patients | Intraoperative prostate malignancy resection | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Postoperative bleeding | TEG parameters were predictive of postoperative bleeding |
Lin et al., 2020 [220] | 43 Chinese thoracic surgery patients | Preoperative, intraoperative | TEG-guided monitoring of intraoperative anticoagulation | Coagulopathy | TEG procedures were useful for monitoring anticoagulation status during surgery |
Volod et al., 2017 [221] | 98 US mechanical circulatory support device patients | Intraoperative | TEG-MA, TEG R-time, TEG-K, TEG alpha-angle | Anticoagulation monitoring | TEG parameters are useful for monitoring anticoagulation status |
Strengths and limitations
To our knowledge, this is one of the reviews that addressed the application of TEG usage in monitoring the hematological outcomes in the perioperative periods including nearly all surgical procedures. Therefore, this review opens the doors for clinicians to reach out to recent evidence about TEG applications on patients having any surgery or procedure to enhance transfusion and coagulation-related management. In addition, we searched many databases and screened the relevant records in detail to include all relevant studies, which provide the recent updates in TEG applications in multiple surgeries.
The limitation is that this is only a literature review that summarizes existing research on TEG. It does not include other viscoelastic tests such as ROTEM. Most of the studies lacked comparison groups. While comparing with standardized laboratory tests, a controversy was observed between the related studies in the literature. In addition, lacking direct statistical analysis including all related studies made it difficult to solve the controversy about the efficacy of TEG usage in some surgeries.
Summary
TEG showed promising results in detecting and improving hematological outcomes in patients who underwent major surgeries and procedures or who were critically ill; however, more comparative studies are needed to establish this efficacy. These promising results were observed in trauma surgeries regarding predicting mortality, hypercoagulability, and bleeding even when it was compared to conventional methods; however, its role to guide blood product transfusion was questionable.
TEG was useful in monitoring anticoagulant therapy in orthopedics operations; however, its roles in predicting thrombotic events, hypercoagulability, or complications were questionable among the studies. The same controversy was observed in obstetric operations; however, it showed promising results in ICU patients, especially in the prediction or improvement of sepsis, coagulopathy, thrombotic events, ICU duration, hospital stay, and ventilator duration.
In transplant surgeries, they effectively predicted hypercoagulation; however, their roles in predicting bleeding, blood product needs, and thrombotic events were still questionable. Regarding cardiovascular surgeries, they were effective in the prediction of the need for blood products, coagulopathy, and thrombotic events and they were effective in monitoring anticoagulation therapy.
TEG parameters were useful in predicting coagulation and bleeding, preventing complications, and decreasing blood product transfusion in neurological surgeries; however, compared to the conventional tools, they were better in all these outcomes except for hypercoagulation, which had the same results. In abdominal surgeries, TEG was effective in bariatric, cystectomy, and gastric cancer surgeries; however, their results were controversial in hepatic, esophagectomy, and obstructive jaundice surgeries. The efficacy of TEG usage was also controversial in patients on ECMO whether they were adults or pediatrics. However, in general surgeries, a controversy was observed in pediatric patients while a promising efficacy was observed in adults regarding predicting hypercoagulation, thrombotic events, and blood product transfusion.
Conclusions
Based on the evidence reviewed here we conclude that TEG can be used in a wide range of perioperative settings to guide transfusion and coagulation management and thereby influence certain outcomes. Because of some limitations addressed in this review, we recommend performing more randomized clinical trials comparing TEG parameters with standardized tools and performing meta-analyses to pool all related studies’ data to solve the controversy between studies. More clinical trials also are needed to investigate the usage of TEG in critically ill patients, especially in cardiothoracic, obstetric and oncology surgeries as well as patients on ECMO; geriatric and pediatric patients, and patients with renal disease.
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Abstract
Assessing coagulation status is essential for prompt intervention to reduce morbidity and mortality related to bleeding and thrombotic complications during the perioperative period. Traditional coagulation tests such as platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and activated clotting time (ACT) provide only static evaluation. These tests are not designed for assessment of dynamically changing coagulation conditions during the perioperative time. However, viscoelastic coagulation testing such as thromboelastography (TEG) produces a rapid numerical and graphical representation that helps to detect and direct targeted hemostatic therapy. Searching the literature through PubMed, Medline, Ovid, CINAHL, and ClinicalTrials.gov we retrieved 210 studies, which represent the use of TEG in the perioperative period. The included studies were categorized under various settings such as trauma, obstetrics, orthopedics, intensive care unit (ICU), cardiovascular, transplant, and miscellaneous scenarios. TEG showed promising results in trauma surgeries in predicting mortality, hypercoagulability, and bleeding even when it was compared to conventional methods. TEG was also useful in monitoring anticoagulant therapy in orthopedic and obstetric surgeries; however, its role in predicting thrombotic events, hypercoagulability, or complications was questionable. In ICU patients, it showed promising results, especially in the prediction or improvement of sepsis, coagulopathy, thrombotic events, ICU duration, hospital stay, and ventilator duration. TEG parameters effectively predicted hypercoagulation in transplant surgeries. Regarding cardiovascular surgeries, they were effective in the prediction of the need for blood products, coagulopathy, thrombotic events, and monitoring anticoagulation therapy. More randomized clinical trials comparing TEG parameters with standardized tools are needed to produce robust results to standardize its use in different perioperative settings.
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