Perioperative coagulation assessment of patients undergoing major elective orthopedic surgery

Venous Thromboembolism in Total Hip and Total Knee Arthroplasty

Importance

The optimal pharmacologic thromboprophylaxis agent after total hip and total knee arthroplasty is uncertain and consensus is lacking. Quantifying the risk of postoperative venous thromboembolism (VTE) and bleeding and evaluating comparative effectiveness and safety of the thromboprophylaxis strategies can inform care.

Objective

To quantify risk factors for postoperative VTE and bleeding and compare patient outcomes among pharmacological thromboprophylaxis agents used after total hip and knee arthroplasty.

Design, Setting, and Participants

This retrospective cohort study used data from a large health care claims database. Participants included patients in the United States with hip or knee arthroplasty and continuous insurance enrollment 3 months prior to and following their surgical procedure. Patients were excluded if they received anticoagulation before surgery, received no postsurgical pharmacological thromboprophylaxis, or had multiple postsurgery thromboprophylactic agents. In a propensity-matched analysis, patients receiving a direct oral anticoagulant (DOAC) were matched with those receiving aspirin.

Exposures

Aspirin, apixaban, rivaroxaban, enoxaparin, or warfarin.

Main Outcomes and Measures

The primary outcome was 30-day cumulative incidence of postdischarge VTE. Other outcomes included postdischarge bleeding.

Results

Among 29 264 patients included in the final cohort, 17 040 (58.2%) were female, 27 897 (95.2%) had inpatient admissions with median (IQR) length of stay of 2 (1-2) days, 10 948 (37.4%) underwent total hip arthroplasty, 18 316 (62.6%) underwent total knee arthroplasty; and median (IQR) age was 59 (55-63) years. At 30 days, cumulative incidence of VTE was 1.19% (95% CI, 1.06%-1.32%) and cumulative incidence of bleeding was 3.43% (95% CI, 3.22%-3.64%). In the multivariate analysis, leading risk factors associated with increased VTE risk included prior VTE history (odds ratio [OR], 5.94 [95% CI, 4.29-8.24]), a hereditary hypercoagulable state (OR, 2.64 [95% CI, 1.32-5.28]), knee arthroplasty (OR, 1.65 [95% CI, 1.29-2.10]), and male sex (OR, 1.34 [95% CI, 1.08-1.67]). In a propensity-matched cohort of 7844 DOAC-aspirin pairs, there was no significant difference in the risk of VTE in the first 30 days after the surgical procedure (OR, 1.14 [95% CI, 0.82-1.59]), but postoperative bleeding was more frequent in patients receiving DOACs (OR, 1.36 [95% CI, 1.13-1.62]).

Conclusions and Relevance

In this cohort study of patients who underwent total hip or total knee arthroplasty, underlying patient risk factors, but not choice of aspirin or DOAC, were associated with postsurgical VTE. Postoperative bleeding rates were lower in patients prescribed aspirin. These results suggest that thromboprophylaxis strategies should be patient-centric and tailored to individual risk of thrombosis and bleeding.

Rotational Thromboelastometry Predicts Transfusion Requirements in Total Joint Arthroplasties

The frequency of red blood cell (RBC) transfusions is high in total joint arthroplasties, and the hemorrhagic risk is associated with both surgery- and patient-related factors. This study aims to assess the ability of rotational thromboelastometry (ROTEM) to identify patients at high risk for transfusion and excessive bleeding. A prospective observational study was conducted including 206 patients who underwent total knee or hip arthroplasties. Assessment of the coagulation status was performed preoperatively and immediately postoperatively using ROTEM analysis and conventional coagulation tests. The number of RBC transfusions and the postoperative hemoglobin drop were recorded. ROTEM findings were compared between transfused and nontransfused patients, and also between patients with and without excessive bleeding. Higher values of postoperative FIBTEM maximum clot firmness (MCF) were associated with lower risks of transfusion (odds ration [OR]: 0.66, 95% confidence interval [CI]: 0.57-0.78, p<0.001) and excessive bleeding (OR: 0.58, 95% CI: 0.36-0.94, p=0.028). A postoperative FIBTEM MCF value ≤10mm had 80.1% (95% CI: 73.1-85.9%) sensitivity with 75.5% (95% CI: 60.4-87.1%) specificity to predict transfusion requirements, and 70.5% (95% CI: 63.6-76.8%) sensitivity with 88.8% (95% CI: 51.7-99.7%) specificity to predict excessive bleeding. The estimated average probability of transfusion in patients with FIBTEM MCF values of 0 to 4mm is 86.3%. ROTEM assay demonstrated high predictive ability for transfusion and excessive bleeding. Identification of patients at risk for transfusion could allow blood banks to ensure adequate blood supply, while also more intense blood-salvaging strategies could be implemented in these patients.

Preoperative thromboelastography in the prediction of post-tonsillectomy hemorrhage by coblation tonsillectomy: a post-hoc analysis

BACKGROUND

Post-tonsillectomy hemorrhage (PTH) affects around 4% of patients after tonsillectomy. We hypothesized that preoperative thromboelastography (TEG) might identify patients at higher risk of PTH.

OBJECTIVE

Investigate whether evaluation of coagulation function by preoperative TEG might help to predict PTH after tonsillectomy by coblation tonsillectomy (TE).

DESIGN

Post-hoc analysis of randomized controlled study.

SETTING

Otolaryngology Department between January 2017 and August 2019.

PATIENTS AND METHODS

This post-hoc analysis included adults who underwent coblation TE for benign tonsillar disorders. Routine blood tests and TEG were performed preoperatively. The TEG parameters evaluated included coagulation reaction time (R) and maximum thrombus amplitude (MA).

MAIN OUTCOME MEASURES

The main outcome was PTH during the 4-week postoperative period.

SAMPLE SIZE AND CHARACTERISTICS

284 RESULTS: The 19 patients (6.7%) that experienced PTH had a higher prevalence of diabetes mellitus, lower use of intraoperative suturing, fewer patients with grade I and II tonsillar enlargement, a higher white blood cell count, lower platelet count, lower fibrinogen level, lower R value, and a lower MA value than patients without PTH (all P<.05). Multivariate logistic regression revealed that diabetes mellitus (P<.053), fibrinogen level ≤2.735 g/L (P<.027), R≤6.55 min (P<.011) and MA≤59.15 mm (P<.012) were independently associated with PTH. A regression model incorporating these four factors predicted PTH with a sensitivity of 73.7% and specificity of 83.8%.

CONCLUSION

Preoperative evaluation of diabetes mellitus history, fibrinogen level, and TEG parameters might help to identify patients at higher risk of PTH after coblation TE.

LIMITATIONS

Single-center study with a small sample size; possibly underpowered statistically. TEG measurements might not accurately reflect coagulation function, and a validation cohort was unavailable.

CONFLICT OF INTEREST

None. CHINESE CLINICAL TRIAL REGISTRY NUMBER OF STUDY USED IN THIS ANALYSIS: ChiCTR2000032171. http://www.chictr.org.cn/showprojen.aspx?proj=52553.

Viscoelastic Hemostatic Assays for Orthopedic Trauma and Elective Procedures

The application of viscoelastic hemostatic assays (VHAs) (e.g., thromboelastography (TEG) and rotational thromboelastometry (ROTEM)) in orthopedics is in its relative infancy when compared with other surgical fields. Fortunately, several recent studies describe the emerging use of VHAs to quickly and reliably analyze the real-time coagulation and fibrinolytic status in both orthopedic trauma and elective orthopedic surgery. Trauma-induced coagulopathy—a spectrum of abnormal coagulation phenotypes including clotting factor depletion, inadequate thrombin generation, platelet dysfunction, and dysregulated fibrinolysis—remains a potentially fatal complication in severely injured and/or hemorrhaging patients whose timely diagnosis and management are aided by the use of VHAs. Furthermore, VHAs are an invaluable compliment to common coagulation tests by facilitating the detection of hypercoagulable states commonly associated with orthopedic injury and postoperative status. The use of VHAs to identify hypercoagulability allows for an accurate venous thromboembolism (VTE) risk assessment and monitoring of VTE prophylaxis. Until now, the data have been insufficient to permit an individualized approach with regard to dosing and duration for VTE thromboprophylaxis. By incorporating VHAs into routine practice, orthopedic surgeons will be better equipped to diagnose and treat the complete spectrum of coagulation abnormalities faced by orthopedic patients. This work serves as an educational primer and up-to-date review of the current literature on the use of VHAs in orthopedic surgery.

A Prospective Observational Study on Multiplate®-, ROTEM®- and Thrombin Generation Examinations Before and Early After Implantation of a Left Ventricular Assist Device (LVAD)

Background

Heart failure patients are frequently on coagulation-active medications before LVAD implantation and perioperative bleeding is a frequent complication after left ventricular assist device (LVAD) implantation. The role of point-of-care coagulation tests in assessing bleeding risk for LVAD implantation and the early postoperative time course of these tests is not well established.

Methods

We prospectively enrolled 25 patients with terminal heart failure undergoing LVAD implantation. Study related TRAP-, ASPI- and ADP- tests of Multiplate^® platelet aggregometry, ROTEM^® rotational thromboelastometry (INTEM, EXTEM, FIBTEM), thrombin generation assay and conventional laboratory studies were measured at 11 predefined time-points during the first 21 postoperative days. We examined if preoperative TRAP-, ASPI-, ADP- and ROTEM values are correlated with estimated total blood loss (primary outcome parameter) during the first 21 days after LVAD implantation and compared the baseline values of these measurements between patients with a bleeding event to those without. We performed Spearman's correlation and non-parametric tests for paired and non-paired comparisons.

Results

7 out of 25 (28%) patients experienced a bleeding event of which 4 required surgical revision. Of the preoperatively performed measurements the TRAP test [Spearman's Rho (ρ) = −0.5, p = 0.01], INTEM CFT (ρ = 0.72, p < 0.001), INTEM alpha (−0.7, p < 0.001), EXTEM MCF (ρ = −0.63; p < 0.001), EXTEM alpha (ρ = −0.67; p < 0.001), FIBTEM MCF (ρ = −0.41; p = 0.042), Fibrinogen (Clauss) (ρ = −0.5; p = 0.011), Anti-thrombin activity (ρ = −0.49; p = 0.013) and platelet count (ρ = −0.42; p = 0.034) were significantly correlated to total blood loss. Patients undergoing a surgical bleeding revision had significantly reduced values in TRAP—[31.5 IQR (17.25–43.5U) vs. 69 IQR (52.5–87U); p = 0.004], ASPI—[16.5 IQR (5.5–35.7U) vs. 39 IQR (24.5–62.5U); p = 0.038], ADP—[30 IQR (22–69U) vs. 12.5 IQR (8.7–21.5U); p = 0.01], EXTEM MCF—[63 IQR (57.7–63.7) vs. 67 IQR (65–75.5); p = 0.019] and EXTEM alpha [74 IQR (68.75–74) vs. 79 IQR (78–80.5); p = 0.002] values before LVAD implantation.

Conclusion

Multiplate^® and ROTEM^® measurements before LVAD implantation may identify LVAD candidates with platelet dysfunction and alterations of the primary hemostasis and could guide anesthetists and intensive care practitioners in bleeding risk stratification and in the perioperative clinical management.

The Prognostic Performance of Rotational Thromboelastometry for Excessive Bleeding and Increased Transfusion Requirements in Hip Fracture Surgeries

BACKGROUND

 Hip fracture surgeries are associated with considerable blood loss, while the perioperative coagulopathy is associated with the bleeding risk of these patients. We aimed to evaluate the ability of rotational thromboelastometry (ROTEM) to detect patients at high risk for excessive bleeding and increased transfusion requirements.

METHODS

 We conducted a prospective observational study of 221 patients who underwent hip fracture surgeries. ROTEM analysis was performed preoperatively and immediately postoperatively. Blood loss parameters including blood loss volume, number of transfused red blood cell (RBC) units, and drop in hemoglobin levels were recorded. ROTEM parameters were compared between patients with and without excessive bleeding, and between patients with and without increased transfusion requirements (i.e., ≥2 RBC units).

RESULTS

 The postoperative FIBTEM MCF value ≤15 mm had 66.6% (95% confidence interval [CI]: 59.7-74.1%) sensitivity and 92.0% (95% CI: 80.7-97.7%) specificity to prognose excessive bleeding, and preoperative FIBTEM MCF value ≤15 mm had 80.4% (95% CI: 73.5-86.2%) sensitivity and 91.2% (95% CI: 80.7-97.0%) specificity to prognose increased transfusion requirements. Preoperative FIBTEM MCF ≤11 mm and postoperative FIBTEM MCF ≤15 mm were associated with considerably increased risks of excessive bleeding (odds ratio [OR]: 44.8, 95% CI: 16.5-121.3, p < 0.001; and OR: 23.0, 95% CI: 7.8-67.0, p < 0.001, respectively).

CONCLUSION

 ROTEM parameters demonstrated high prognostic accuracy for excessive bleeding and increased transfusion requirements. This can enable implementation of blood sparing strategies in high-risk patients, while blood banks could be better prepared to ensure adequate blood supply.

Institutionally Adopted Perioperative Blood Management Program Significantly Decreased the Transfusion Rate of Patients Having Primary Total Hip Replacement Surgery

Perioperative transfusion in patients undergoing orthopedic surgery increases the number of postoperative complications. Thus, we have introduced an institution-tailored perioperative blood management program (PBM) to decrease the amount of blood transfused in patients going through primary total hip replacement (THR) surgery. We have conducted a before-after observational cohort study in two predetermined observational periods. Demographic and clinical data, ASA scores, laboratory parameters, features of surgical procedure, and anesthesia were registered. Parameters of perioperative fluid administration, transfusion rate, and postoperative complications were also assessed. One hundred patients in the first and 108 patients in the second observational period were enrolled. Eventhough the ratio of posttraumatic THR procedures increased (9% vs. 17%), the PBM protocol has been utilized effectively and a significant decrease in perioperative blood transfusion rate has been observed (61% vs. 21%). The abolishment of routine preoperative LMWH prophylaxis (90% vs. 16%), intraoperative use of tranexamic acid (10% vs. 84%), and the encouraged exploitation of our postoperative observational facility (5% vs. 39%) were abided by our colleagues. Patients still requiring transfusion had lower preoperative hemoglobin levels (129 vs. 147 g/l), scored higher in ASA (ASA III: 46% vs. 19%), and more often presented postoperative hypotension (40% vs. 7%), oliguria (23% vs. 5%), and infections (9% vs. 2%). We conclude that the individualized perioperative blood management protocol was successfully implemented and yielded a lower transfusion rate and better outcomes. Our study suggests that a partial, institution-tailored PBM program may be suitable and beneficial in countries where the modalities of perioperative blood management are limited.

Effect of blood loss during caesarean section on coagulation parameters

INTRODUCTION

Venous thrombosis is the leading cause of pregnancy-related maternal morbidity and mortality. The thrombosis risk is increased by caesarean section and blood loss, though underlying mechanisms of these prothrombotic changes remain unknown.

MATERIALS AND METHODS

This prospective study recruited 50 pregnant women at term undergoing elective caesarean section at University Hospital Magdeburg, Germany. Blood loss during surgery was correlated with the changes in total protein S, full length TFPI (TFPI_fl), prothrombin, the endogenous thrombin potential (ETP) and resistance to activated protein C (APCsr) determined via calibrated automated thrombography.

RESULTS

Mean blood loss was 506 ml (95%CI: 456 to 557 ml). Total protein S was 0.63 (95%CI: 0.60 to 0.67) U/ml preoperatively, decreased by 14.8% after caesarean section and almost normalised five days later. TFPI_fl was 0.47 (95%CI: 0.41 to 0.53) U/ml before, remained unchanged immediately after and increased by 11.5% five days after surgery. Prothormbin was 1.10 (95%CI: 1.03 to 1.16) U/ml preoperatively, reduced by 10.4% immediately after and increased again five days after caesarean section, exceeding the preoperative values by 4.4% (-0.7 to 9.6). The ETP decreased by 3.9%, whereas the APCsr increased by 37.0% immediately after caesarean section. The changes in total protein S, prothrombin, thrombin generation and APC resistance showed a trend to be more pronounced in the subgroups with higher blood loss.

DISCUSSION

Moderate blood loss during caesarean section hardly reduces thrombin generation but aggravates pregnancy-induced APC resistance and combined deficiency of TFPI and protein S, which can account for the increased thrombosis risk in early puerperium.

Clinical and pathophysiologic aspects of ECMO-associated hemorrhagic complications

Extracorporeal membrane oxygenation (ECMO) is increasingly used to treat severe cases of acute respiratory or cardiac failure. Hemorrhagic complications represent one of the most common complications during ECMO, and can be life threatening. The purpose of this study was to elucidate pathophysiological mechanisms of ECMO-associated hemorrhagic complications and their impact on standard and viscoelastic coagulation tests. The study cohort included 27 patients treated with VV-ECMO or VA-ECMO. Hemostasis was evaluated using standard coagulation tests and viscoelastic parameters investigated with rotational thromboelastometry. Anticoagulation and hemorrhagic complications were analyzed for up to seven days depending on ECMO duration. Hemorrhagic complications developed in 16 (59%) patients. There were 102 discrete hemorrhagic episodes among 116 24-hour-intervals, of which 27% were considered to be clinically significant. The highest number of ECMO-associated hemorrhages occurred on the 2^nd and 3^rd day of treatment. Respiratory tract bleeding was the most common hemorrhagic complication, occurring in 62% of the 24-hour intervals. All 24-hours-intervals were divided into two groups: “with bleeding” and “without bleeding”. The probability of hemorrhage was significantly associated with abnormalities of four parameters: increased international normalized ratio (INR, sensitivity 71%, specificity 94%), increased prothrombin time (PT, sensitivity 90%, specificity 72%), decreased intrinsic pathway maximal clot firmness (MCFin, sensitivity 76%, specificity 89%), and increased extrinsic pathway clot formation time (CFTex, sensitivity 77%, specificity 87%). In conclusions, early ECMO-associated hemorrhagic complications are related to one traditional and two novel viscoelastic coagulation abnormalities: PT/INR elevation, reduced maximum clot firmness due to intrinsic pathway dysfunction (MCFin), and prolonged clot formation time due to extrinsic pathway dysfunction (CFTex). When managing hemostasis during ECMO, derangements in PT/INR, MCFin and CFT_ex should be focused on.

Post-operative hypercoagulable whole blood profiles in patients undergoing open thoracotomy vs video-assisted thoracoscopic surgery

BACKGROUND

Patients undergoing video-assisted thoracoscopic surgery (VATS) have a lower risk of thrombosis compared to those undergoing open thoracotomy (OT) which may be due to several post-operative factors such as early mobilisation, shorter hospital stays, lower transfusion rates and lower risk of infections. Whether the higher thrombotic risk after OT is also linked to a peri-operative hypercoagulable state is a matter of debate. We therefore conducted a case-control study to compare peri-operative coagulation profiles in patients with primary lung cancer undergoing VATS vs OT.

MATERIALS AND METHODS

All consecutive patients undergoing VATS or OT for primary lung cancer at the Department of Thoracic Surgery of Padua University Hospital, Italy, between February and June 2018 were enrolled. Each patient provided a venous blood sample at least 30 min prior to surgical incision (T0) and 4±1 days after surgery (T1). Peri-operative coagulation profiles were assessed via traditional, viscoelastic whole blood (ROTEM^® [Instrumentation Laboratory-Werfen]) and impedance aggregometry (Multiplate^® Analyser [Roche Diagnostics]) tests.

RESULTS

We enrolled 65 patients (males 43, females 22; mean age 65±13 years) of whom 35 (54%) underwent VATS and 30 (46%) underwent OT. Compared to healthy controls, the surgical group (VATS and OT patients) had a significantly shorter clot formation time and higher alpha angle and maximum clot firmness values, as well as increased mean platelet function. In the post-operative period, patients who underwent OT had a significantly shorter clot formation time, higher alpha angle and maximum clot firmness values and higher mean platelet function vs VATS patients.

DISCUSSION

Whole blood ROTEM^® profiles and Multiplate^® aggregometry identified a more hypercoagulable post-operative state in patients who underwent OT than in those who underwent VATS. Larger studies are warranted to confirm our results and ascertain whether the observed hypercoagulability might promote post-operative thrombosis.