Max V. Wohlauer

Primary Fibrinolysis Is Integral in the Pathogenesis of the Acute Coagulopathy of Trauma

Background:The existence of primary fibrinolysis (PF) and a defined mechanistic link to the “Acute Coagulopathy of Trauma” is controversial. Rapid thrombelastography (r-TEG) offers point of care comprehensive assessment of the coagulation system. We hypothesized that postinjury PF occurs early in severe shock, leading to postinjury coagulopathy, and ultimately hemorrhage-related death. Methods:Consecutive patients over 14 months at risk for postinjury coagulopathy were stratified by transfusion requirements into massive (MT) >10 units/6 hours (n = 32), moderate (Mod) 5 to 9 units/6 hours (n = 15), and minimal (Min) <5 units/6 hours (n = 14). r-TEG was performed by adding tissue factor to uncitrated whole blood. r-TEG estimated percent lysis was categorized as PF when >15% estimated percent lysis was detected. Coagulopathy was defined as r-TEG clot strength = G < 5.3 dynes/cm2. Logistic regression was used to define independent predictors of PF. Results:A total of 34% of injured patients requiring MT had PF, which was associated with lower emergency department systolic blood pressure, core temperature, and greater metabolic acidosis (analysis of variance, P < 0.0001). The risk of death correlated significantly with PF (P = 0.026). PF occurred early (median, 58 minutes; interquartile range, 1.2–95.9 minutes); every 1 unit drop in G increased the risk of PF by 30%, and death by over 10%. Conclusions:Our results confirm the existence of PF in severely injured patients. It occurs early (<1 hour), and is associated with MT requirements, coagulopathy, and hemorrhage-related death. These data warrant renewed emphasis on the early diagnosis and treatment of fibrinolysis in this cohort.

Early platelet dysfunction: an unrecognized role in the acute coagulopathy of trauma.

BACKGROUND Our aim was to determine the prevalence of platelet dysfunction using an end point of assembly into a stable thrombus after severe injury. Although the current debate on acute traumatic coagulopathy has focused on the consumption or inhibition of coagulation factors, the question of early platelet dysfunction in this setting remains unclear. STUDY DESIGN Prospective platelet function in assembly and stability of the thrombus was determined within 30 minutes of injury using whole blood samples from trauma patients at the point of care using thrombelastography-based platelet functional analysis. RESULTS There were 51 patients in the study. There were significant differences in the platelet response between trauma patients and healthy volunteers, such that there was impaired aggregation to these agonists. In trauma patients, the median ADP inhibition of platelet function was 86.1% (interquartile range [IQR] 38.6% to 97.7%) compared with 4.2 % (IQR 0 to 18.2%) in healthy volunteers. After trauma, the impairment of platelet function in response to arachidonic acid was 44.9% (IQR 26.6% to 59.3%) compared with 0.5% (IQR 0 to 3.02%) in volunteers (Wilcoxon nonparametric test, p < 0.0001 for both tests). CONCLUSIONS In this study, we show that platelet dysfunction is manifest after major trauma and before substantial fluid or blood administration. These data suggest a potential role for early platelet transfusion in severely injured patients at risk for postinjury coagulopathy.

Goal-directed Hemostatic Resuscitation of Trauma-induced Coagulopathy: A Pragmatic Randomized Clinical Trial Comparing a Viscoelastic Assay to Conventional Coagulation Assays.

Background:Massive transfusion protocols (MTPs) have become standard of care in the management of bleeding injured patients, yet strategies to guide them vary widely. We conducted a pragmatic, randomized clinical trial (RCT) to test the hypothesis that an MTP goal directed by the viscoelastic assay thrombelastography (TEG) improves survival compared with an MTP guided by conventional coagulation assays (CCA). Methods:This RCT enrolled injured patients from an academic level-1 trauma center meeting criteria for MTP activation. Upon MTP activation, patients were randomized to be managed either by an MTP goal directed by TEG or by CCA (ie, international normalized ratio, fibrinogen, platelet count). Primary outcome was 28-day survival. Results:One hundred eleven patients were included in an intent-to-treat analysis (TEG = 56, CCA = 55). Survival in the TEG group was significantly higher than the CCA group (log-rank P = 0.032, Wilcoxon P = 0.027); 20 deaths in the CCA group (36.4%) compared with 11 in the TEG group (19.6%) (P = 0.049). Most deaths occurred within the first 6 hours from arrival (21.8% CCA group vs 7.1% TEG group) (P = 0.032). CCA patients required similar number of red blood cell units as the TEG patients [CCA: 5.0 (2–11), TEG: 4.5 (2–8)] (P = 0.317), but more plasma units [CCA: 2.0 (0–4), TEG: 0.0 (0–3)] (P = 0.022), and more platelets units [CCA: 0.0 (0–1), TEG: 0.0 (0–0)] (P = 0.041) in the first 2 hours of resuscitation. Conclusions:Utilization of a goal-directed, TEG-guided MTP to resuscitate severely injured patients improves survival compared with an MTP guided by CCA and utilizes less plasma and platelet transfusions during the early phase of resuscitation.

Initial experiences with point‐of‐care rapid thrombelastography for management of life‐threatening postinjury coagulopathy

BACKGROUND: Massive transfusion (MTP) protocol design is hindered by lack of accurate assessment of coagulation. Rapid thrombelastography (r‐TEG) provides point‐of‐care (POC) analysis of clot formation. We designed a prospective study to test the hypothesis that integrating TEG into our MTP would facilitate goal‐directed therapy and provide equivalent outcomes compared to conventional coagulation testing.

Viscoelastic clot strength predicts coagulation-related mortality within 15 minutes.

BACKGROUND Predicting refractory coagulopathy early in resuscitation of injured patients may decrease a leading cause of preventable death. We hypothesized that clot strength (G) measured by point-of-care rapid thrombelastography (r-TEG) on arrival in the emergency department can predict massive transfusion (MT) and coagulation-related mortality (MT-death). METHODS Trauma alerts/activations from May 2008 to September 2010 were reviewed. The variables included the following: age, sex, injury severity score (ISS), systolic blood pressure (SBP), base deficit (BD), traditional coagulation tests (international normalized ratio ([INR], partial thromboplastin time [PTT]), TEG-derived G, and blood products transfused within the first 6 hours. Independent predictors of 2 outcomes (MT [≥10 packed red blood cells units/6 h] and MT-related death) were identified using logistic regression. The individual predictive values of BD, INR, PTT, and G were assessed comparing the areas under the receiver operating characteristic curves (AUC ROC), while adjusting for age, ISS, and SBP. RESULTS Among the 80 study patients, 48% required MT, and 21% died of MT-related complications. INR, ISS, and G were independent predictors of MT, whereas age, ISS, SBP, and G were independently associated with MT-death. The predictive power for outcome MT did not differ among INR (adjusted AUC ROC = 0.92), PTT (AUC ROC = 0.90, P = .41), or G (AUC ROC = 0.89, P = .39). For outcome MT-death, G had the greatest adjusted AUC ROC (0.93) compared with the AUC ROC for BD (0.87, P = .05), INR (0.88, P = .11), and PTT (0.89; P = .19). CONCLUSION These data suggest that the point-of-care TEG parameter clot strength (G) provides consistent, independent prediction of MT and MT-death early in the resuscitation of injured patients.

Platelets are dominant contributors to hypercoagulability after injury.

BACKGROUND Venous thromboembolic (VTE) disease has a high incidence following trauma, but debate remains regarding optimal prophylaxis. Thrombelastography (TEG) has been suggested to be optimal in guiding prophylaxis. Thus, we designed a phase II randomized controlled trial to test the hypothesis that TEG-guided prophylaxis with escalating low–molecular weight heparin (LMWH), followed by antiplatelet therapy would reduce VTE incidence. METHODS Surgical intensive care unit trauma patients (n = 50) were randomized to receive 5,000 IU of LMWH daily (control) or to TEG-guided prophylaxis, up to 5,000 IU twice daily with the addition of aspirin, and were followed up for 5 days. In vitro studies were also conducted in which apheresis platelets were added to blood from healthy volunteers (n = 10). RESULTS Control (n = 25) and TEG-guided prophylaxis (n = 25) groups were similar in age, body mass index, Injury Severity Score, and male sex. Fibrinogen levels and platelet counts did not differ, and increased LMWH did not affect clot strength between the control and study groups. The correlation of clot strength (G value) with fibrinogen was stronger on Days 1 and 2 but was superseded by platelet count on Days 3, 4, and 5. There was also a trend in increased platelet contribution to clot strength in patients receiving increased LMWH. In vitro studies demonstrated apheresis platelets significantly increased clot strength (7.19 ± 0.35 to 10.34 ± 0.29), as well as thrombus generation (713.86 ± 12.19 to 814.42 ± 7.97) and fibrin production (274.03 ± 15.82 to 427.95 ± 16.58). CONCLUSION Increased LMWH seemed to increase platelet contribution to clot strength early in the study but failed to affect the overall rise clot strength. Over time, platelet count had the strongest correlation with clot strength, and in vitro studies demonstrated that increased platelet counts increase fibrin production and thrombus generation. In sum, these data suggest an important role for antiplatelet therapy in VTE prophylaxis following trauma, particularly after 48 hours. LEVEL OF EVIDENCE Therapeutic study, level III.

Antiplatelet therapy is associated with decreased transfusion-associated risk of lung dysfunction, multiple organ failure, and mortality in trauma patients.

Objective:To determine whether prehospital antiplatelet therapy was associated with reduced incidence of acute lung dysfunction, multiple organ failure, and mortality in blunt trauma patients. Design:Secondary analysis of a cohort enrolled in the National Institute of General Medical Sciences Trauma Glue Grant database. Setting:Multicenter study including nine U.S. level-1 trauma centers. Patients:A total of 839 severely injured blunt trauma patients at risk for multiple organ failure (age > 45 yr, base deficit > 6 mEq/L or systolic blood pressure < 90 mm Hg, who received a blood transfusion). Severe/isolated head injuries were excluded. Measurements and Main Results:Primary outcomes were lung dysfunction (defined as grades 2–3 by the Denver multiple organ failure score), multiple organ failure (Denver multiple organ failure score >3), and mortality. Patients were documented as on antiplatelet therapy if taking acetylsalicylic acid, clopidogrel, and/or ticlopidine. Fifteen percent were taking antiplatelet therapy prior to injury. Median injury severity score was 30 (interquartile range 22–51), mean age 61 + 0.4 yr and median RBCs volume transfused was 1700 mL (interquartile range 800–3150 mL). Overall, 63% developed lung dysfunction, 19% had multiple organ failure, and 21% died. After adjustment for age, gender, comorbidities, blood products, crystalloid/12 hrs, presence of any head injury, injury severity score, and 12 hrs base deficit > 8 mEq/L, 12 hrs RBC transfusion was associated with a significantly smaller risk of lung dysfunction and multiple organ failure among the group receiving antiplatelet therapy compared with those not receiving it (lung dysfunction p = 0.0116, multiple organ failure p = 0.0291). In addition, antiplatelet therapy had a smaller risk (albeit not significant, p = 0.06) of death for patients receiving RBC compared to those not on antiplatelet therapy after adjustment for confounders, Conclusions:Pre-injury antiplatelet therapy is associated with a decreased risk of lung dysfunction, multiple organ failure, and possibly mortality in high-risk blunt trauma patients who received blood transfusions. These findings suggest platelets have a role in organ dysfunction development and have potential therapeutic implications.

Acute kidney injury and posttrauma multiple organ failure: the canary in the coal mine.

Background: Despite improved resuscitation strategies, acute kidney injury (AKI) remains an important cause of morbidity and high resource use among severely injured patients. Thus, we conducted a comprehensive evaluation of the epidemiology and outcomes of early AKI among severely injured patients as well as its impact on the development of postinjury multiple organ failure (MOF). Methods: We queried our 17-year database of high-risk postinjury patients (Injury Severity Score >15, age >15 years, survival >48 hours, and no isolated head injury). MOF and AKI (creatinine >1.8 mg/dL) were defined by the Denver MOF score. Patients with documented preexisting renal, hepatic, cardiac, or pulmonary disease (120, 5%) were excluded, leaving 2157 for analysis. Results: Early (day 2) AKI was evident in 2.13% of the patients and associated with a 78% MOF incidence and 27% mortality. Both rates were higher than those associated with early heart, lung, or liver failure. Conclusion: Early AKI is a harbinger of adverse outcome postinjury, outperforming hepatic, cardiac, or pulmonary dysfunction as a predictor of MOF and death. Prevention of early AKI and a better understanding of organ crosstalk may help reduce AKI-associated morbidity, mortality, and obligatory costs of this complication. Level of Evidence: I, prognostic study.

Traumatic brain injury causes platelet adenosine diphosphate and arachidonic acid receptor inhibition independent of hemorrhagic shock in humans and rats

BACKGROUND Coagulopathy in traumatic brain injury (CTBI) is a well-established phenomenon, but its mechanism is poorly understood. Various studies implicate protein C activation related to the global insult of hemorrhagic shock or brain tissue factor release with resultant platelet dysfunction and depletion of coagulation factors. We hypothesized that the platelet dysfunction of CTBI is a distinct phenomenon from the coagulopathy following hemorrhagic shock. METHODS We used thrombelastography with platelet mapping as a measure of platelet function, assessing the degree of inhibition of the adenosine diphosphate (ADP) and arachidonic acid (AA) receptor pathways. First, we studied the early effect of TBI on platelet inhibition by performing thrombelastography with platelet mapping on rats. We then conducted an analysis of admission blood samples from trauma patients with isolated head injury (n = 70). Patients in shock or on clopidogrel or aspirin were excluded. RESULTS In rats, ADP receptor inhibition at 15 minutes after injury was 77.6% ± 6.7% versus 39.0% ± 5.3% for controls (p < 0.0001). Humans with severe TBI (Glasgow Coma Scale [GCS] score ⩽ 8) showed an increase in ADP receptor inhibition at 93.1% (interquartile range [IQR], 44.8–98.3%; n = 29) compared with 56.5% (IQR, 35–79.1%; n = 41) in milder TBI and 15.5% (IQR, 13.2–29.1%) in controls (p = 0.0014 and p < 0.0001, respectively). No patient had significant hypotension or acidosis. Parallel trends were noted in AA receptor inhibition. CONCLUSION Platelet ADP and AA receptor inhibition is a prominent early feature of CTBI in humans and rats and is linked to the severity of brain injury in patients with isolated head trauma. This phenomenon is observed in the absence of hemorrhagic shock or multisystem injury. Thus, TBI alone is shown to be sufficient to induce a profound platelet dysfunction.

The computerized rounding report: implementation of a model system to support transitions of care.

OBJECTIVES In response to ACGME work-hour restrictions, residency programs that require continuous inpatient clinical care for educational objectives will be forced to increase the proportion of junior resident experience involved in shift work. Maintaining the balance of education over service at these levels will be a challenge, where a considerable amount of time must be spent gathering data for morning rounds and signing out patients at shift change. Patient safety is an issue with this new paradigm. We hypothesized that computerized sign-out would improve resident efficiency. MATERIALS AND METHODS A multidisciplinary clinical team collaborated to design a computerized rounding and sign-out (CSO) program to automate collection of clinical information in addition to a brief narrative describing ongoing care issues. Residents returned a self-administered questionnaire before (n = 168) and after implementation (n = 83) examining: pre-rounding time, missed patients, handoff quality, and duty hours. RESULTS Residents reported spending 11 fewer min/d pre-rounding (P = 0.006). After implementation, residents missed fewer patients on rounds (P = 0.01). A majority (70%) of responders stated that the new program helped them with duty hours. CONCLUSION The current study demonstrates the reproducibility of the University of Washington model system for rounding and sign-out at an independent site, using basic infrastructure and leadership common to all residency programs. Developing a CSO was associated with a modest reduction in pre-rounding time and fewer patients missed on rounds. Although automating resident tasks may improve workflow in an increasingly complex hospital environment, structured handoff education and other institutional changes are necessary.