Coagulopathy and Hyperfibrinolysis in Ruptured Abdominal Aortic Aneurysm Repair

The Impact of Heparin on Mortality Following Open Ruptured Abdominal Aortic Aneurysm Repair

BACKGROUND

Systemic administration of heparin is widely used in patients undergoing open elective abdominal aortic aneurysm (AAA) repair. However, no clear consensus exists in the use of intraoperative heparin during open ruptured AAA (rAAA) repair. In this study, we assessed the safety of intravenous heparin administration in patients undergoing open rAAA repair.

METHODS

A retrospective cohort study comparing patients who received and did not receive heparin during open rAAA repair in the Vascular Quality Initiative database between 2003 and 2020 was conducted. The primary outcomes were 30-day and 10-year mortality. The secondary outcomes included estimated blood loss, number of packed red blood cells transfused, early postoperative transfusions, and postsurgical complications. Propensity score matching was used to adjust for potentially confounding variables. The outcomes were compared between the 2 groups using relative risk for binary outcomes and paired t-test and the Wilcoxon rank-sum test for normally and non-normally distributed continuous variables, respectively. Survival was examined using Kaplan-Meier curves and compared using a Cox proportional hazards model.

RESULTS

A total of 2,410 patients who underwent open rAAA repair between 2003 and 2020 were studied. Of the 2,410 patients, 1,853 patients received intraoperative heparin and 557 did not. Propensity score matching on 25 variables yielded 519 pairs for the heparin to no heparin comparison. Thirty-day mortality was lower in the heparin group (risk ratio: 0.74; 95% confidence interval [CI]: 0.66-0.84) and in-hospital was also lower in the heparin group (risk ratio: 0.68; 95% CI: 0.60-0.77). Furthermore, estimated blood loss was 910 mL (95% CI: 230 mL to 1,590 mL) lower in the heparin group and the mean number of packed red blood cells transfused intraoperatively and postoperatively were 17 units lower in the heparin group (95% CI: 8-42). Ten-year survival was higher for patients who received heparin, and their rate of survival was approximately 40% higher than those who did not receive heparin (hazard ratio: 0.62; 95% CI, 0.53-0.72; P < 0.0001).

CONCLUSIONS

In patients who received systemic heparin administration at the time of open rAAA repair, there were significant short-term and long-term survival benefits within 30 days and at 10 years. Heparin administration may have afforded a mortality benefit or been a surrogate for healthier and less moribund patients at the time of the procedure.

Characterization of immediate and early mortality after repair of ruptured abdominal aortic aneurysm

BACKGROUND

We sought to compare immediate and early mortality among patients undergoing ruptured abdominal aortic aneurysm (RAAA) repair. Evaluation of RAAA has focused on 30-day postoperative mortality. Other emergency conditions such as trauma have demonstrated a multimodal mortality distribution within the 30-day window, expanding the pathophysiologic understanding and allowing for intervention investigations with practice changing and lifesaving results. However, the temporal distribution and risk factors of postoperative morbidity and mortality in RAAA have yet to be investigated.

METHODS

We evaluated factors associated with RAAA postoperative mortality in immediate (<1 day) and early (1-30 days) postoperative periods in a landmarked retrospective cohort study using data from the Vascular Quality Initiative (2010-2020).

RESULTS

We identified 5157 RAAA repairs (mean age, 72 ± 10 years; 77% male; 88% White; 61% endovascular). The mortality rate in the immediate period was 10.2% (528/5157) and the early mortality rate was 22.1% (918/4163). In multivariable regression analyses, signs of hemorrhagic shock (ie, hemoglobin <7 g/dL: adjusted odds ratio [aOR], 1.87 [95% confidence interval [CI], 1.14-3.06]; any preoperative systolic blood pressure <70 mm Hg: aOR, 1.40 [95% CI, 1.04-1.89]; and estimated blood loss >40%: aOR, 3.65 [95% CI, 2.29-5.83]) were associated with an increased risk of immediate mortality. Comorbid conditions (heart failure: aOR, 1.38 [95% CI, 1.00-1.92]; pulmonary disease: aOR, 1.29 [95% CI, 1.05-1.58]; elevated creatinine: aOR 1.26 [95% CI, 1.31-1.41]) were associated with increased risk of early mortality.

CONCLUSIONS

Immediate deaths were associated predominantly with shock from massive hemorrhage, whereas early deaths were associated with comorbid conditions predisposing patients to multisystem organ failure despite successful repair. These temporal distinctions should guide future mechanistic and intervention evaluations to improve RAAA mortality.

Relevance of Type II Endoleak After Endovascular Repair of Ruptured Abdominal Aortic Aneurysms: A Retrospective Single-Center Cohort Study

INTRODUCTION

Endovascular aortic repair (EVAR) is widely used as an alternative to open repair in elective and even in emergent cases of ruptured abdominal aortic aneurysm (rAAA). One of the most frequent complications after EVAR is type II endoleak (T2EL). In elective therapy, evidence-based therapeutic recommendations for T2EL are limited. Completely unclear is the role of T2EL after EVAR for rAAA (rEVAR). This study aims to investigate the significance of T2ELs after rEVAR.

PATIENTS AND METHODS

This is a retrospective single-center data analysis of all patients who underwent rEVAR between January 2010 and December 2020 with primary T2EL. The outcome criteria were overall and T2EL-related mortality and reintervention rate as well as development of aneurysm diameter over follow-up (FU).

RESULTS

During the study period between January 2010 and December 2020, 35 (25%) out of 138 patients with rEVAR presented a primary postoperative T2EL (age 74±11 years, 34 males). At rupture, mean aneurysm diameter was 73±12 mm. Follow-up was 26 (0-172) months. The reintervention-free survival was 69% (95% confidence interval [CI]: 55%-86%) at 30 days, 58% (95% CI: 43%-78%) at 1 year, and 52% (95% CI: 36%-75%) at 3 years. In 40% (n=14), T2ELs resolved spontaneously within a median time of 3.4 (0.03-85.6) months. The overall and T2EL reintervention rates were 43% (n=15) and 9% (n=3), respectively. Within 30 days, 11 patients (31%) required reintervention, of which 2 were T2EL related. Aneurysm sac growth by ≥5 mm was seen in 3 patients (9%), and aneurysm shrinkage rate was significantly higher in sealed T2EL group (86% vs 5%, p<0.0001). The overall survival was 85% (95% CI: 74%-98%) at 30 days, 75% (95% CI: 61%-92%) at 1 year, and 67% (95% CI: 51%-87%) at 3 years. Six deaths were aneurysm related, while 1 was T2EL related within the first 30 days due to persistent hemorrhage. During FU, one more patient died due to a T2EL-related secondary rupture (T2EL-related mortality, 5.7%, n=2). Multivariable analysis revealed that arterial hypertension was associated with an increased risk for reintervention (hazard ratio [HR]: 27.8, 95% CI: 1.48-521, p=0.026) and age was associated with an increased risk for mortality (HR 1.14, 95% CI: 1.04-1.26, p=0.005).

CONCLUSION

T2ELs after rEVAR showed a benign course in most cases. In the short term, the possibility of persistent bleeding should be considered. In the mid term, a consequent FU protocol is required to detect known late complications after EVAR at an early stage and to prevent secondary rupture and death.

A review of hyperfibrinolysis in cats and dogs

The fibrinolytic system is activated concurrently with coagulation; it regulates haemostasis and prevents thrombosis by restricting clot formation to the area of vascular injury and dismantling the clot as healing occurs. Dysregulation of the fibrinolytic system, which results in hyperfibrinolysis, may manifest as clinically important haemorrhage. Hyperfibrinolysis occurs in cats and dogs secondary to a variety of congenital and acquired disorders. Acquired disorders associated with hyperfibrinolysis, such as trauma, cavitary effusions, liver disease and Angiostrongylus vasorum infection, are commonly encountered in primary care practice. In addition, delayed haemorrhage reported in greyhounds following trauma and routine surgical procedures has been attributed to a hyperfibrinolytic disorder, although this has yet to be characterised. The diagnosis of hyperfibrinolysis is challenging and, until recently, has relied on techniques that are not readily available outside referral hospitals. With the recent development of point-of-care viscoelastic techniques, assessment of fibrinolysis is now possible in referral practice. This will provide the opportunity to target haemorrhage due to hyperfibrinolysis with antifibrinolytic drugs and thereby reduce associated morbidity and mortality. The fibrinolytic system and the conditions associated with increased fibrinolytic activity in cats and dogs are the focus of this review article. In addition, laboratory and point-of-care techniques for assessing hyperfibrinolysis and antifibrinolytic treatment for patients with haemorrhage are reviewed.

The association of preoperative atrial fibrillation with post-cardiopulmonary bypass hyperfibrinolysis in rheumatic valvular heart disease patients

OBJECTIVE

The purpose of this study was to assess the fibrinolytic status after cardiopulmonary bypass in rheumatic valvular heart disease patients, and detect the associated factors of post-cardiopulmonary bypass hyperfibrinolysis.

METHODS

According to the fibrinolytic status after cardiopulmonary bypass, 203 rheumatic valvular heart disease patients were divided into two groups: hyperfibrinolysis group (H group, n = 78) and non-hyperfibrinolysis group (NH group, n = 125). The demographic characteristics, operative variables, and postoperative follow-ups were compared between these two groups.

RESULTS

The incidence of hyperfibrinolysis was 38.4% after cardiopulmonary bypass. Patients in the H group had a significant higher incidence of preoperative atrial fibrillation than patients in the NH group (92.3% vs. 55.2%, P < 0.01). Furthermore, postoperative daily drainage (655.3 ± 131.5 ml vs. 535.4 ± 161.4 ml, P < 0.01), transfusion volume of fresh frozen plasma (621.8 ± 220.2 ml vs. 455.2 ± 208.5 ml, P < 0.01), and red blood cells (5.9 ± 2.2 u vs. 4.7 ± 2.8 u, P < 0.01) was greater in the H group than in the NH group. Moreover, the logistic regression analysis revealed that preoperative atrial fibrillation was associated with post-cardiopulmonary bypass hyperfibrinolysis (OR = 19.691, 95% CI = 6.849-56.612; P < 0.05).

CONCLUSION

Preoperative artial fibrillation is associated with post-cardiopulmonary bypass hyperfibrinolysis in rheumatic valvular heart disease patients.

Massive Blood Transfusion in Patients with Ruptured Abdominal Aortic Aneurysm

OBJECTIVES

The aim was to study blood transfusions and blood product ratios in massively transfused patients treated for ruptured abdominal aortic aneurysms (rAAAs).

METHODS

This was a registry based cohort study of rAAA patients repaired at three major vascular centres between 2008 and 2013. Data were collected from the Swedish Vascular Registry, hospitals medical records, and local transfusion registries. The transfusion data were analysed for the first 24 h of treatment. Massive transfusion (MT) was defined as 4 or more units of red blood cell (RBC) transfused within 1 h, or 10 or more RBC units within 24 h. Logistic regression was used to calculate the odds ratio of 30 day mortality associated with the ratios of blood products and timing of first units of platelets (PLTs) and fresh frozen plasma (FFP) transfused.

RESULTS

Three hundred sixty nine rAAA patients were included: 80% men; 173 endovascular aneurysm repairs (EVARs) and 196 open repairs (ORs) with median RBC transfusion 8 units (Q1-Q3, 4-14) and 14 units (Q1-Q3, 8-28), respectively. A total of 261 (71%) patients required MT. EVAR patients with MT (n = 96) required less transfusion than OR patients (n = 165): median RBC 10 units (Q1-Q3, 6-16.5) vs. 15 units (Q1-Q3, 9-26) (p = .002), FFP 6 units (Q1-Q3, 2-14.5) vs. 13 units (Q1-Q3, 7-24) (p < .001), and PLT 0 units (Q1-Q3, 0-2) vs. 2 units (Q1-Q3, 0-4) (p = .01). Median blood product ratios in MT patients were FFP/RBC (EVAR group 0.59 [0.33-0.86], OR group 0.84 [0.67-1.2]; p < .001], and PLT/RBC (EVAR 0 [0-0.17], OR 0.12 (0-0.18); p < .001]. In patients repaired by OR a FFP/RBC ratio close to 1 was associated with reduced 30 day mortality (p = .003). The median PLT/RBC ratio was higher during the later part of the study period (p < .001, median test), whereas there was no significant difference in median FFP/RBC ratio (p = .101, median test).

CONCLUSION

The majority of rAAA patients undergoing EVAR required MT. EVAR patients treated with MT had lower FFP/RBC and PLT/RBC ratios than OR patients with MT. The mortality risk was lower with FFP/RBC ratio close to 1:1 in open repaired patients requiring MT. The 24 h PLT/RBC ratio increased over the study period.

Intravenous heparin during ruptured abdominal aortic aneurysmal repair

BACKGROUND

There have been enormous advances in the screening, diagnosis, intervention and overall prognosis of abdominal aortic aneurysms (AAAs) in the last decade, but despite these, ruptured AAAs (rAAAs) still cause around 3500 to 6000 deaths in England and Wales each year. Open repair remains standard treatment for rAAA in most centres but increasingly endovascular aneurysm repair (EVAR) is being adopted. This has a 30-day postoperative mortality of 40%. This has remained static despite surgical, anaesthetic and critical care advances.One significant change to current practice for elective repairs of AAAs, as opposed to emergency repairs of rAAAs, has been the introduction of intravenous heparin. This provides a protective effect against cardiac and thrombotic disease in the postoperative period. This practice has not gained widespread acceptance for emergency repairs of rAAA even though a reduction in mortality and morbidity has been demonstrated in elective repairs.

OBJECTIVES

The primary objective was to assess the effect of intravenous heparin on all-cause mortality in ruptured abdominal aortic aneurysm (rAAA) management in people undergoing an emergency repair.The secondary objectives were to assess the effect of intravenous heparin in rAAA management on the incidence of general arterial disease, for example, cardiovascular, cerebral, pulmonary and renal pathologies, in people undergoing emergency repair.

SEARCH METHODS

The Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (December 2015). In addition the CIS searched CENTRAL;2015, Issue 11). The CIS searched clinical trials registries for details of ongoing or unpublished studies.

SELECTION CRITERIA

We sought all published and unpublished randomised controlled trials (RCTs) and controlled clinical trials (CCTs) of intravenous heparin in rAAA repairs (including parallel designs).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies identified for potential inclusion in the review. We used standard methodological procedures in accordance with the Cochrane Handbook for Systematic Review of Interventions.

MAIN RESULTS

We identified no RCTs or CCTs that satisfied the inclusion criteria.

AUTHORS' CONCLUSIONS

We identified no RCTs or CCTs of intravenous heparin in rAAA repairs (including parallel designs). Therefore, we were unable to assess the effect of intravenous heparin on all-cause mortality and incidence of general arterial disease, for example, cardiovascular, cerebral, pulmonary and renal pathologies in rAAA management in people undergoing an emergency repair. It is clear that an RCT is needed to address this question in rAAA management as there is no high quality evidence.

The Abdominal Aortic Aneurysm and Intraluminal Thrombus: Current Concepts of Development and Treatment

The pathogenesis of the abdominal aortic aneurysm (AAA) shows several hallmarks of atherosclerotic and atherothrombotic disease, but comprises an additional, predominant feature of proteolysis resulting in the degradation and destabilization of the aortic wall. This review aims to summarize the current knowledge on AAA development, involving the accumulation of neutrophils in the intraluminal thrombus and their central role in creating an oxidative and proteolytic environment. Particular focus is placed on the controversial role of heme oxygenase 1/carbon monoxide and nitric oxide synthase/peroxynitrite, which may exert both protective and damaging effects in the development of the aneurysm. Treatment indications as well as surgical and pharmacological options for AAA therapy are discussed in light of recent reports.

Preoperative hypofibrinogenemia is associated with increased intraoperative bleeding in ruptured abdominal aortic aneurysms

INTRODUCTION

Ruptured abdominal aortic aneurysm (rAAA) is associated with coagulopathy and intraabdominal hemorrhage. Fibrinogen acts as a key coagulation factor and has previously been suggested as a biomarker for increased perioperative bleeding in other surgical areas. The aim of the present study was to investigate fibrinogen and standard laboratory parameters and their association to preoperative hemodynamic status, intraoperative bleeding (IOB), and outcome in treatment of rAAA.

METHODS

This is a single university center retrospective cohort study of 91 consecutive patients with rAAA undergoing open surgery or endovascular aneurysm repair (EVAR) between 2008 and 2013. Patients were analyzed using the Swedish Vascular Registry (Swedvasc), and local hospital medical and laboratory records. Laboratory data analyzed included fibrinogen, hemoglobin, platelet count, prothrombin time ratio, activated partial thrombin time, and creatinine. Odds ratios (OR) with 95% confidence intervals (CI) were calculated in a logistical regression model.

RESULTS

In the study cohort (n = 91), median age was 74 (57-91) years; 80 % men; open surgical repair (n = 72; 77%); EVAR (n = 19; 23%). Median preoperative fibrinogen concentration was 1.8 g/L (IQR = 1.4) and varied significantly across bleeding groups: ≤1999 ml 2.3g/L, IQR = 1.4 (n = 35); 2000-4999 ml 1.6 g/L, IQR = 1.5 (n = 33); ≥5000 ml 1.4 g/L, IQR = 1.0 (n = 23) (P < 0.001). Preoperative fibrinogen concentration showed a linear relationship with preoperative blood pressure (r = .447, P = 0.01). When analyzing other preoperative laboratory values, only platelets showed a similar linear relationship with preoperative blood pressure (r = .247, P = 0.05). Patients with blood pressure <70 mmHg had an associated median fibrinogen concentration of less than 1.5 g/L (P = 0.001). In the multivariable logistic regression analysis, preoperative fibrinogen < 1.5 g/L [OR 10.0, CI (1.8-57.1), P = 0.009] was associated with IOB >2000 ml and preoperative blood pressure < 70 mmHg was associated with IOB >2 000 ml [OR 3.7, CI (1.1-12.6), P = 0.03] and >5000 ml [OR 5.2, CI (1.3-21.1), P = 0.02]. Low fibrinogen concentration (< 1.5 g/L) was associated with 30-day mortality in the univariate analysis but not in the multivariable logistic regression analysis.

CONCLUSION

Low preoperative fibrinogen concentration was significantly associated with preoperative hypotension and increased intraoperative bleeding in patients with rAAA. Patients in hemodynamic shock with blood pressure <70 mmHg had an associated fibrinogen concentration of less than 1.5 g/L. A fibrinogen concentration less than 1.5 g/L was associated with a ten-fold increased risk of intraoperative hemorrhage of more than 2000 ml.

Discrepant fibrinolytic response in plasma and whole blood during experimental endotoxemia in healthy volunteers

Background

Sepsis induces early activation of coagulation and fibrinolysis followed by late fibrinolytic shutdown and progressive endothelial damage. The aim of the present study was to investigate and compare the functional hemostatic response in whole blood and plasma during experimental human endotoxemia by the platelet function analyzer, Multiplate and by standard and modified thrombelastography (TEG).

Methods

Prospective physiologic study of nine healthy male volunteers undergoing endotoxemia by means of a 4-hour infusion of E. coli lipopolysaccharide (LPS, 0.5 ng/kg/hour), with blood sampled at baseline and at 4 h and 6 h. Physiological and standard biochemical data and coagulation tests, TEG (whole blood: TEG, heparinase-TEG, Functional Fibrinogen; plasma: TEG±tissue-type plasminogen activator (tPA)) and Multiplate (TRAPtest, ADPtest, ASPItest, COLtest) were recorded. Mixed models with Tukey post hoc tests and correlations were applied.

Results

Endotoxemia induced acute SIRS with increased HR, temperature, WBC, CRP and procalcitonin and decreased blood pressure. It also induced a hemostatic response with platelet consumption and reduced APTT while INR increased (all p<0.05). Platelet aggregation decreased (all tests, p<0.05), whereas TEG whole blood clot firmness increased (G, p = 0.05). Furthermore, during endotoxemia (4 h), whole blood fibrinolysis increased (clot lysis time (CLT), p<0.001) and Functional Fibrinogen clot strength decreased (p = 0.049). After endotoxemia (6 h), whole blood fibrinolysis was reduced (CLT, p<0.05). In contrast to findings in whole blood, the plasma fibrin clot became progressively more resistant towards tPA-induced fibrinolysis at both 4 h and 6 h (p<0.001).

Conclusions

Endotoxemia induced a hemostatic response with reduced primary but enhanced secondary hemostasis, enhanced early fibrinolysis and fibrinogen consumption followed by downregulation of fibrinolysis, with a discrepant fibrinolytic response in plasma and whole blood. The finding that blood cells are critically involved in the vasculo-fibrinolytic response to acute inflammation is important given that disturbances in the vascular system contribute significantly to morbidity and mortality in critically ill patients.

The use of heparin in patients with ruptured abdominal aortic aneurysms

The use of systemic heparin in patients with ruptured abdominal aortic aneurysms (rAAAs) remains a contentious issue with no clear guidelines. This review reports the current understanding, at a molecular and clinical level, of the possible benefits and risks of heparin in emergency aneurysm repair (both open and endovascular). MEDLINE, EMBASE, AMED, SCOPUS, CINAHL and Cochrane Library were searched for all articles containing the keywords 'rupture', 'abdominal', 'aneurysm' and 'heparin'. Current experience, indications and outcomes were analyzed. Articles were searched for both endovascular and open repair of AAAs. A total of eight studies were included for analysis in the systematic review. Of these, only one paper focused specifically on heparin use in open repair of ruptures and suggested a benefit. Of the remaining seven, two were self-reporting retrospective studies assessing individual surgeons' practice, one was a case report and the remaining four included mention of heparin use but with no outcome data. The evidence available suggests that a pro-coagulable state exists in rAAAs. This may be responsible for the morbidity and mortality postprocedure, which arises predominantly from multiple organ failure and cardiac compromise rather than outright hemorrhage. This diathesis may respond well to heparin administration, suggesting that heparin administration in ruptured aneurysms is appropriate.

Emerging treatment strategies for trauma-induced coagulopathy

Background

Trauma-induced coagulopathy has a multifactorial aetiology. Coagulopathy is related to blood loss including consumption of clotting factors and platelets and haemodilution. Additionally hyperfibrinolysis, hypothermia, acidosis and metabolic changes affect the coagulation system.

Methods

This is a review of pathophysiology and new treatment strategies for trauma-induced coagulopathy.

Results

Paradigms are actively changing and there is still a shortage of data. The aim of any haemostatic therapy is to control bleeding and minimize blood loss and transfusion requirements. Transfusion of allogeneic blood products as well as trauma-induced coagulopathy cause increased morbidity and mortality. Current opinion is based on present studies and results from small case series, combined with findings from experimental studies in animals, in vitro studies and expert opinions, as opposed to large, randomized, placebo-controlled studies. A summary of new and emerging strategies, including medical infusion and blood products, to beneficially manipulate the coagulation system in the critically injured patient is suggested.

Conclusion

Future treatment of trauma-induced coagulopathy may be based on systemic antifibrinolytics, local haemostatics and individualized point-of-care-guided rational use of coagulation factor concentrates such as fibrinogen, prothrombin complex concentrate, recombinant factor VIIa and factor XIII. The authors speculate that timely and rational use of coagulation factor concentrates will be more efficacious and safer than ratio-driven use of transfusion packages of allogeneic blood products.

Blood and coagulation support in trauma

Injury is the leading cause of death in young people and a major cause of loss of years of productive life world wide. Acute surgical care can prevent injury from turning into disability or death but requires prompt access to safe blood products to support resuscitation and restorative surgical procedures. Speed in delivering blood products is critical in resuscitation. Achieving prompt blood product support requires advanced planning and an informed balancing of risks to insure the availability of red cells and coagulation products at the time and place where they are needed. Safety and diagnostic support are critical in the post-resuscitative period where transfusion complications can delay reconstructive surgery and prolong intensive care unit stays. This paper reviews the epidemiology of injury and modern patterns of trauma care against the background of developing knowledge about the coagulopathies of trauma and blood safety.

Fibrinolysis in patients with an abdominal aortic aneurysm with special emphasis on rupture and shock

BACKGROUND

A ruptured abdominal aortic aneurysm (AAA) is associated with high mortality. Postoperative complications such as hemorrhage, multiple organ failure, myocardial infarction, and thromboembolism are common. An active and balanced hemostatic system is essential to avoid bleeding as well as thrombosis. When these activities are not properly regulated the patient is at risk of developing either excessive bleeding or thrombosis-related complications. Previous studies have shown a state of activated coagulation in patients with ruptured AAA. However, there are conflicting results regarding the fibrinolytic response.

OBJECTIVES

The aim of the present study was to investigate the fibrinolytic state pre-operatively in patients with ruptured and non-ruptured AAA in relation to the clinical outcome with special regard to the influence of shock.

METHODS

A prospective study was performed on 95 patients who underwent surgery for a ruptured AAA with shock (n = 43), a ruptured AAA without shock (n = 12), and a non-ruptured AAA (n = 40). Forty-one controls without an aneurysm were matched to the AAA patients according to age, gender and smoking habits. Plasma levels of tissue plasminogen activator antigen (tPAag), and plasminogen activator inhibitor type-1 (PAI-1) were measured as markers of fibrinolytic activity. D-dimer, a marker of fibrin turnover, was also measured.

RESULTS

D-dimer was significantly higher in patients with a non-ruptured AAA compared with controls without AAA. There were significantly higher levels of D-dimer, tPAag, and PAI-1 in patients operated for ruptured compared with non-ruptured AAA. tPAag was also significantly higher in ruptured AAA patients with shock compared with without shock. No deaths occurred in patients operated on for a non-ruptured AAA or ruptured AAA without shock. There were 12 deaths after repair of a ruptured AAA with shock, of which two patients died from bleeding and the remaining 10 from multiple organ failure and cardiac failure.

CONCLUSION

Our results indicate a state of activated coagulation in patients with a non-ruptured AAA, the state being intensified by rupture. The present data show normal fibrinolytic activities in patients with a non-ruptured AAA, but increased systemic fibrinolysis, as demonstrated by elevated tPAag level, in patients with a ruptured AAA. The elevated PAI-1 level indicates a simultaneous inhibition of the systemic fibrinolysis. Furthermore, the hyperfibrinolytic state was reinforced by shock in this study. However, the clinical outcome, with a relatively high incidence of thrombosis-related deaths, indicate a prothrombotic state instead of a hyperfibrinolytic state as a major point of attention in patients with shock as a result of a ruptured AAA.

The role of tissue factor in patients undergoing open repair of ruptured and nonruptured abdominal aortic aneurysms

BACKGROUND

Ruptured abdominal aortic aneurysm (AAA) is associated with the development of a procoagulant and hypofibrinolytic state. Tissue factor (TF) and its naturally occurring inhibitor, tissue factor pathway inhibitor (TFPI), play a central role in the initiation and progression of such a hypercoagulable state, but their role in patients undergoing open AAA repair has not previously been examined.

METHODS

A prospective study was conducted of 17 patients undergoing elective AAA repair and 10 patients undergoing emergency AAA repair. Blood was taken before induction, and 5 minutes, 24 hours, and 48 hours after aortic cross-clamp release and assayed for plasma TF, TFPI, tissue plasminogen activator (t-PA), plasminogen activator inhibitor (PAI), and thrombin-activatable fibrinolysis inhibitor (TAFI) activities.

RESULTS

TF activity was significantly higher at all time points in patients with ruptured AAA compared with nonruptured AAA. The median (interquartile range, IRQ) TF activity (AU/mL) was 9.9 vs 3.2 (IRQ, 5.9 to 12.6 vs 2.0 to 7.6; P = .005) at preinduction; 10.7 vs 1.5 (IRQ, 9.2 to 18.3 vs 0.1 to 6.6; P = .003) at 5 minutes after clamp release; 9.5 vs 3.3 (IRQ, 7.0 to 13.5 vs 1.0 to 7.9; P = .013) at 24 hours, and 9.6 vs 3.9 (IRQ, 7.6 to 12.6 vs 2.4 to 8.7; P = .006) at 48 hours. TFPI levels were not significantly different between ruptured AAA and nonruptured AAA before or during operation but became significantly elevated at 24 and 48 hours in patients who had undergone repair of ruptured AAA. Ruptured AAA repair was associated with a hypofibrinolytic state compared with nonruptured AAA.

CONCLUSIONS

The present study has demonstrated for the first time, to our knowledge, that ruptured AAA is associated with significantly higher perioperative levels of circulating TF compared with nonruptured AAA. Furthermore, in the immediate perioperative period, the high levels of TF are not associated with a corresponding rise in TFPI levels, indicating an unopposed prothrombotic state. Direct inhibition of TF by administration of anti-TF antibodies or recombinant TFPI remains to be evaluated in subjects presenting with hemorrhage due to ruptured AAA, but if given early enough, it may attenuate the early deleterious effects of unopposed TF expression and ultimately contribute to improved outcomes.

Proactive administration of platelets and plasma for patients with a ruptured abdominal aortic aneurysm: evaluating a change in transfusion practice

BACKGROUND

Continued hemorrhage remains a major contributor of mortality in massively transfused patients and those who survive have a higher platelet (PLT) count and a shorter prothrombin time and activated partial thromboplastin time (APTT) than nonsurvivors. It was considered that early substitution with PLTs and fresh-frozen plasma (FFP) would prevent development of coagulopathy and thus improve survival.

STUDY DESIGN AND METHODS

Survival of patients undergoing surgery for a ruptured abdominal aortic aneurysm (rAAA) was compared after implementing a proactive transfusion therapy encompassing two pooled buffy-coat PLT concentrates (PBPCs) immediately when a rupture of the aorta was suspected and again 30 minutes before aortic unclamping together with FFP administered in a 1:1 ratio to the amount of red blood cells (RBCs) with that of a control group receiving transfusion therapy according to existing recommendations.

RESULTS

The intervention group (n = 50) had a higher PLT count at arrival at the intensive care unit compared to the control group (n = 82; 155 x 10(9)/L vs. 69 x 10(9)/L; p < 0.0001), shorter APTT (39 sec vs. 44 sec; p < 0.001), fewer postoperative transfusions (RBCs, 2 vs. 6; FFP, 2 vs. 4; and PBPCs, 0 vs. 1; p < 0.01), and a higher 30-day survival rate (66% vs. 44%; p = 0.02).

CONCLUSION

This study suggests that proactive administration of PLTs and FFP improves coagulation competence, reduces postoperative hemorrhage, and increases survival in massively bleeding rAAA patients.

Disseminated intravascular coagulopathy in aortic aneurysms

Aneurysm-induced disseminated intravascular coagulopathy (DIC) constitutes a rare presentation form of aortic aneurysms. The majority of DIC cases are asymptomatic and this condition is usually diagnosed during the perioperative workup; yet, in a minority of cases, DIC leads to the diagnosis of the vascular abnormality. The management of aneurysm-induced DIC is based both on the treatment of the underlying disorder and on an active scrutiny of the hemodynamic and blood support requirements. Blood replacement therapy should be individualized, guided by the clinical situation of the patient (especially considering the bleeding risk or the presence of hemorrhages), and accompanied by a close monitoring of the coagulation status. Fresh frozen plasma is usually the preferred initial option to replace coagulation factors, but fibrinogen, cryoprecipitates, and platelet concentrates are adequate options in certain contexts. Heparins, both non-fractionated and low-weight molecular types, are the most widely accepted agents for achieving adequate control of the coagulation activation and consumption. Other antithrombotic drugs are under study, including antithrombin III and activated protein C, although only the latter has demonstrated a benefit in terms of survival in a comparative, randomized context. Antifibrinolytic agents such as gabexate mesilate, tranexamic acid, and epsilon-aminocaproic acid (EACA) have been used with conflicting results. These agents may have a role for patients with catastrophic bleeding resistant to other therapeutical options, but their relevance as a first line of treatment is, at present, undefined. An assessment of the multitude of therapeutic approaches available would seem to indicate that there is a lack of standardization in the management of these patients. Multi-center, randomized clinical trials are needed to elucidate the most adequate therapy in this context.