Perioperative changes in coagulative and fibrinolytic function during surgical treatment of abdominal aortic aneurysm and arteriosclerosis obliterans

Coagulopathy After Ruptured Abdominal Aortic Aneurysm

Although potentially treatable, coagulopathy is often included among the predictors of a poor outcome after ruptured abdominal aortic aneurysm (rAAA). The purpose of this review was to define the incidence of coagulopathy among patients presenting with rAAA and to identify the factors contributing to its development.

The medical records of 89 consecutive patients presenting with a rAAA were retrospectively reviewed. Laboratory results (international normalized ratio [INR], partial thromboplastin time [aPTT], platelet count, fibrinogen, and fibrin degradation products [D-dimer]) measured on admission and perioperatively were recorded and related to features of the patients' prehospital and hospital course.

At least one admission coagulation study was obtained in 70 of 89 patients. All measured coagulation values were within the normal range in only 10 (14%) patients, whereas at least one value was in the coagulopathic bleeding range in 17 patients (24%). Profound abnormalities of the INR (> 2.0) were present in 24%, of the aPTT (> 60 sec) in 12%, and of the platelet count (< 50) in 7% of patients. In a multivariate model, hematocrit was the only significant predictor of an INR > 2.0, while hematocrit and degree and duration of hypotension predicted an aPTT > 60 sec. Fluid volume prior to admission did not independently predict either the INR or aPTT, although it was the only significant predictor of a platelet count <50. Admission D-dimer levels were elevated in 79% of patients and were not significantly associated with either the degree of hemorrhage or volume resuscitation. All coagulation studies showed deterioration following admission, with profound abnormalities observed in 90% and 52% of patients intraoperatively and postoperatively, respectively. Mortality was 74% among those undergoing operation and was significantly associated with advanced age and lowest systolic blood pressure, but not with admission INR or aPTT.

The majority of rAAA patients present with disordered coagulation, profound abnormalities being more related to the degree of hemorrhage than to the volume of fluid resuscitation. Evidence of intravascular fibrinolysis is even more common and may be more closely related to the aneurysm itself than to acute hemorrhage.

Haemostatic and fibrinolytic factors in men with a small abdominal aortic aneurysm

BACKGROUND

: The presence of an abdominal aortic aneurysm (AAA) independently predicts cardiovascular disease (CVD) and its complications. Levels of plasma markers of fibrin turnover are raised in men with a large AAA (at least 5.5 cm) and predict CVD risk in healthy subjects. This study examined fibrin turnover in men with a small AAA.

METHODS

: Seventy-five men with a small AAA (30-55 mm) were compared with 90 controls matched for age, sex and race. Haemostatic and fibrinolytic parameters were assessed.

RESULTS

: Men with a small AAA had higher mean levels of fibrinogen (2.92 versus 2.59 g/l; P = 0.019), thrombin-antithrombin (TAT) complex (4.57 versus 1.89 ng/ml; P < 0.001), prothrombin F1 + 2 (1.13 versus 0.82 ng/ml; P = 0.004) and D-dimer (346.7 versus 120.2 ng/ml; P < 0.001). All markers correlated with maximum aortic diameter determined by ultrasonography. On multivariable regression the association between presence of an AAA and fibrinogen, TAT complex, prothrombin F1 + 2 and D-dimer levels remained significant after adjustment for confounding influences.

CONCLUSION

: Fibrin turnover was increased in these men with a small AAA, independently of concomitant CVD, conventional risk factors and inflammatory markers. Enhanced fibrin turnover may contribute to the risk of cardiac complications in this group.

The APC–PCI complex concentration predicts outcome of aortic surgery

INTRODUCTION

Coagulation activation may be related to complications during surgery for abdominal aortic aneurysm. The complex formed between activated protein C (APC) and the serpin, protein C inhibitor (PCI), is a sensitive indicator of the activation of blood coagulation. The purpose of the study was to establish whether the APC-PCI complex can provide information useful for the assessment of outcome after aortic surgery.

MATERIALS AND METHODS

In 38 patients, the APC-PCI complex was initially determined every 6 h and daily from day three. Protein C, antithrombin, global haemostatic tests, and clinical scores were investigated. Length of stay at the intensive care unit (ICU) and hospital, and vital status up to two years were recorded.

RESULTS

The median APC-PCI complex concentration in samples drawn 0-6 h after surgery was more than 20-fold higher than the upper limit of the reference interval. The level then declined rapidly, but remained elevated during the first two days. In patients with higher initial APC-PCI complex concentrations, Sequential Organ Failure Assessment (SOFA) scores were higher, the ICU stay was longer, and survival up to two years was lower. Patients who did not survive the ICU care had higher APC-PCI complex levels at 6-12 h and 12-18 h.

CONCLUSIONS

High concentrations of the APC-PCI complex within 6-18 h after the aortic surgery predict a sinister outcome. The results suggest that the APC-PCI complex is indicative of the severity of the disease.

Clinical implication of plasma level of soluble fibrin monomer-fibrinogen complex in patients with abdominal aortic aneurysm

OBJECTIVE

We prospectively studied the clinical implication of plasma level of soluble fibrin monomer (FM)-fibrinogen complex, a recently established molecular marker reflecting thrombin activity, in patients with abdominal aortic aneurysm (AAA) undergoing elective aortic repair.

METHODS

The study included 49 patients who underwent elective aneurysm repair using a gelatin-sealed or nonimpregnated Dacron prosthesis. Plasma level of soluble FM-fibrinogen complex was measured before surgery and on days 1, 3, 5, 7, and 10 postoperatively by latex agglutination assay utilizing monoclonal antibody IF-43. Plasma levels of thrombin-antithrombin complex (TAT), D-dimer, alpha2-plasmin inhibitor-plasmin complex (PIC), and fibrinogen were also evaluated.

RESULTS

The preoperative level of soluble FM-fibrinogen complex showed variation in the degree of hemostatic activation, with fair correlations with TAT (r = 0.509, P < .001), D-dimer (r = 0.521, P < .001), and PIC (r = 0.579, P < .001). The patients with greater intraoperative blood loss (> or = 800 mL) showed a significantly elevated plasma level of soluble FM-fibrinogen complex preoperatively compared with those with less intraoperative blood loss (P = .009). Its postoperative fluctuation showed a similar pattern to that of TAT, reflecting the time course of coagulation activity. Gelatin impregnation of the Dacron vascular graft did not seem to influence the postoperative systemic coagulation mechanism.

CONCLUSIONS

The results indicated that soluble FM-fibrinogen complex appears to be a useful diagnostic molecular marker to assess the activity of the coagulation system, and that its preoperative level may serve as a potential risk factor for intraoperative hemorrhagic diathesis in patients undergoing elective AAA repair.

Antifibrinolytic Use and Bleeding During Surgery on the Descending Thoracic Aorta: A Multivariate Analysis

OBJECTIVES

The purpose of this study was to determine the potential benefit of antifibrinolytic (AF) therapy in improving hemostasis in descending aortic surgery in which extracorporeal distal perfusion is used.

DESIGN

Retrospective database study.

SETTING

University hospital.

PARTICIPANTS

Seventy-two patients who underwent descending thoracic or thoracoabdominal aortic replacement during the period from January 1993 through December 1996 when the use of AF therapy was emerging.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Seventy-two records met criteria for inclusion. The use of AF therapy had no significant effect on any bleeding or transfusion outcome in any model. Excessive chest tube drainage postoperatively was independently associated with repeat surgery and intraoperative hypothermia. The risk of receiving a red blood cell (RBC) transfusion was independently predicted by low preoperative hemoglobin and age > or =65 years. Cross-clamp was an independent predictor of receiving a transfusion of non-RBC products (p = 0.03).

CONCLUSIONS

The authors could not show a beneficial effect of AF therapy on bleeding and transfusion, although current practice shows that this therapy continues to be used. Because heterogeneity of patient population exists and bias cannot be completely excluded, a prospective investigation evaluating efficacy and safety in this population is warranted.

Coagulation Disorders and Blood Product Use in Patients Undergoing Thoracoabdominal Aortic Aneurysm Repair

Repair of thoracoabdominal aortic aneurysms (TAAA) is associated with major blood loss, often exceeding the patient's intravascular volume, and complex intraoperative and postoperative coagulopathies necessitating large-volume transfusion of blood products. Abnormalities sufficient to cause thrombocytopenia or clinically important prolongation of clotting parameters are rarely present before surgery in elective aneurysms but are more common with ruptured aneurysms. The finding of intraoperative and postoperative deficiencies of clotting factors, along with thrombin generation and activation of the thrombolytic system, is reflective of massive blood losses, visceral ischemia, and massive transfusions. An aggressive strategy of transfusion of blood products is critical to the prevention of clinically significant coagulopathy during surgery. Adjuncts to reduce blood losses and blood product use include low-dose aprotinin or epsilon -aminocaproic acid, intraoperative blood salvaging, and acute normovolemic hemodilution. In TAAA repair, an average blood loss of 5000 to 6000 mL and average transfusion of allogeneic blood products of 50 to 60 U are to be anticipated.

Blood coagulation and fibrinolytic response after endovascular stent grafting of thoracic aorta

OBJECTIVE

Thrombosis is common in aneurysms immediately after stent-grafting, because of exclusion from systemic blood flow. We studied changes in blood coagulation and the fibrinolytic system in patients with thoracic aortic aneurysm or dissection after stent-grafting to examine risk for consumption coagulopathy.

METHODS

Thirty-one thoracic aortic aneurysms were treated with stent-grafting (aneurysm group), and 29 aortic dissections were treated with entry closure with stent-grafting (dissection group). The stent-graft was constructed from a self-expanding Z stent and thin-walled woven polyester fabric. Platelet count, fibrinogen, antithrombin III (AT III), and thrombin-AT III complex were assayed as markers of coagulation. Plasminogen, alpha(2)-plasmin inhibitor, alpha(2)-plasmin inhibitor-plasmin complex, fibrin degradation products fragment E (FDP-E), and fibrin degradation products d-dimer were monitored as markers of fibrinolysis. Blood samples were collected before surgery and on postoperative days 1, 3, 7, and 14.

RESULTS

In both groups platelet count significantly decreased on postoperative days 1 and 3, and increased on postoperative day 14. AT III significantly decreased on postoperative day 1, but recovered after postoperative day 7. FDP-E significantly increased on postoperative day 1 in both groups. There was significant correlation of aneurysm diameter with alpha(2)-plasmin inhibitor-plasmin complex, fibrin degradation products, and d-dimer in the dissection group on postoperative day 1.

CONCLUSIONS

Activation of coagulation and fibrinolysis was observed after stent-grafting to treat thoracic aortic aneurysm and aortic dissection. However, no patients exhibited consumption coagulopathy postoperatively. Therefore we believe there is little risk for consumption coagulopathy after stent-grafting.

Hemostatic markers before operation in patients with acutely symptomatic nonruptured and ruptured infrarenal abdominal aortic aneurysm

BACKGROUND

In patients with acutely symptomatic but nonruptured abdominal aortic aneurysm (AAA), emergent repair is associated with an increased mortality rate as compared with semi-elective repair. Previous results have shown that ruptured but not asymptomatic AAA repair is associated with intense thrombin generation and inhibition of systemic fibrinolysis. The purpose of this study was to determine whether circulating markers of coagulation and fibrinolysis may be used to distinguish acutely symptomatic nonruptured and ruptured AAA.

METHODS

A prospective study was performed of 44 patients who underwent emergency AAA repair for suspected rupture. Platelet count, fibrinogen level, prothrombin time, activated partial thromboplastin time, tissue plasminogen activator (t-PA) activity, plasminogen activator inhibitor (PAI) activity, prothrombin fragment (PF) 1+2 level, and D dimer level were measured before surgery.

RESULTS

When compared with ruptured AAAs (n = 37), acutely symptomatic nonruptured AAAs (n = 7) were associated with increased fibrinogen level (P =.033), reduced activated partial thromboplastin time (P =.043), increased t-PA activity (P =.023), reduced PAI activity (P =.005), reduced PF 1+2 level (P =.001), and reduced D dimer level (P =.005; all P values determined with Mann-Whitney test). The differences in t-PA activity (P =.01), PAI activity (P =.004), and PF 1+2 level (P =.01) persisted in patients whose conditions were normotensive. In all patients, a PF 1+2 level of greater than or equal to 2.5 nmol/L was associated with a sensitivity, specificity, and positive and negative predictive value for rupture of 89%, 86%, 97%, and 60%, respectively. In patients whose conditions were normotensive, PAI activity of greater than or equal to 16 AU/mL was associated with a sensitivity, specificity, and positive and negative predictive value of 83%, 100%, 100%, and 88%, respectively.

CONCLUSION

These data show that acutely symptomatic nonruptured AAA is associated with increased systemic fibrinolysis (caused by reduced fibrinolytic inhibition) and reduced thrombin generation as compared with rupture. Preoperative hemostatic markers, particularly PF 1+2 level and PAI activity, may distinguish acutely symptomatic nonruptured from ruptured AAA.

Fibrinolytic activity and postoperative salvaged untreated blood for autologous transfusion in major orthopaedic surgery

OBJECTIVE

To evaluate the fibrinolytic activity in a closed surgical wound, in postoperatively drained blood, and during autologous transfusion.

DESIGN

Prospective study.

SETTING

National hospital, Norway.

PATIENTS

9 patients operated on for thoracic scoliosis.

MAIN OUTCOME MEASURE

Concentrations of plasmin/antiplasmin (PAP), alpha2-antiplasmin, and D-dimers in drained, arterial, and mixed venous blood before, during, and after infusion of 10 ml/kg body weight of postoperatively drained, untreated blood.

RESULTS

In drained blood the concentration of alpha2-antiplasmin was 31% of the preoperative arterial control value. Together with the increased concentrations of PAP to 18076 microg/L and D-dimers to 126 mg/L, this indicates extensive fibrinolytic activity in the closed wound. The postoperative autologous transfusion of drained, untreated blood increased the concentration of PAP from 507 to 2453 microg/L and of D-dimer from 0.7 mg/L to 15.3 mg/L in systemic blood.

CONCLUSION

The systemic concentration of fibrin(ogen) degradation products, indicated by D-dimers, after recirculation of drained, untreated blood might impair coagulation. The extensive activation of plasmin might exhaust available alpha2-antiplasmin in the wound and result in postoperative rebleeding.

A cohort study of coagulation parameters and the use of blood products in surgery of the thoracic and thoracoabdominal aorta

OBJECTIVES

We sought to study the hemostatic profile and the use of blood products in patients undergoing thoracic and thoracoabdominal aortic aneurysm repair.

METHODS

This is a cohort study comparing three groups of patients: 7 undergoing elective acute normovolemic hemodilution (ANH); 15 undergoing elective procedures without ANH (non-ANH); and 8 undergoing repair of ruptured thoracoabdominal aneurysms. A control group of 10 patients was used for comparison of preoperative hemostasis. The parameters studied were platelet concentration, partial thromboplastin time (PTT), and international normalized ratio (before and after surgery), packed red blood cells, fresh frozen plasma, platelets, cryoprecipitates, donor exposure, and use of desmopressin and epsilon-aminocaproic acid. Analysis of variance and multiple stepwise regression analysis were used.

RESULTS

Before operation the patients with aneurysms had PTTs prolonged compared with control subjects (P <.05). After operation the ANH group had higher platelet counts than the ruptured group (P =.001) and higher platelet counts (P =.05) and lower PTTs (P =.001) than the non-ANH group. The ANH group was transfused fewer platelets than the non-ANH group (P =.001) and less of every blood product than the ruptured group (P =.05); statistically significant differences were not observed for packed red blood cells, fresh frozen plasma, or platelets. The ANH group was exposed to an average of 65 donors fewer than the ruptured group (P <.001) and 34 fewer than the non-ANH group (P <.05). These differences could not be explained by baseline coagulation status or by the intraoperative use of desmopressin or epsilon-aminocaproic acid.

CONCLUSIONS

The coagulation abnormality identified before surgery is that of higher PTT values, suggesting a disturbance of the extrinsic coagulation pathway. Blood losses, donor exposure, and platelet use were highest in the ruptured group and lowest in the ANH group. After surgery the ruptured group exhibited the worst coagulation parameters, and the ANH group exhibited the best with higher platelet count and lower PTT values than the other groups. The ANH technique appears to be an useful adjunct in the anesthetic management of these patients.

Fibrinolytic response to retinal detachment surgery under general or local anesthesia

PURPOSE

To evaluate perioperative changes in fibrinolysis in patients undergoing retinal detachment surgery under general or local anesthesia.

PATIENTS

Prospective study of 81 patients (43 male, 38 female), aged from 15 to 82 (mean 50.7 SD = 17.8) years, undergoing retinal detachment surgery (encirclement with scleral buckling) under general anesthesia (group A), and 14 patients (6 male, 8 female) aged from 15 to 78 (mean 52.9, SD =19.8) years, operated under local anesthesia (group B). Excluded were patients with venous or arterial disease or other factors that could change the parameters investigated.

METHODS

Blood was sampled from a cubital vein one day before surgery, immediately after induction of anesthesia but before surgery, immediately after completion of the operation but before the termination of anesthesia and after the operation (on days 1 and 4). In patients' citrated plasma, tissue plasminogen activator antigen (t-PA-Ag), plasminogen activator inhibitor type 1 antigen (PAI-1 Ag) and activity (PAI-1), fibrin-fibrinogen degradation products (FDP) and euglobulin lysis time (ELT) were measured. RESULTS. The pattern of changes in perioperative fibrinolytic activity was similar in both groups. Intraoperative levels of FDP were significantly higher and ELT shorter than preoperatively. In both groups t-PA Ag concentration was significantly increased on the first postoperative day. There were no changes in PAI-1 in both groups. Postoperatively, the FDP concentration was reduced and ELT prolonged.

CONCLUSIONS

Retinal detachment surgery induces intraoperative activation of fibrinolysis in the systemic circulation regardless of the type of anesthesia.

Alterations in antithrombin III activity and other blood coagulation parameters after retinal detachment surgery

PURPOSE

To evaluate perioperative changes in blood coagulation in patients undergoing retinal detachment surgery.

MATERIALS

Prospective study of 56 patients, aged from 19 to 82 (mean +/- S.D. 53 +/- 16.8) years, undergoing retinal detachment surgery (encirclement with scleral buckling) under general anesthesia. Excluded were patients with venous or arterial disease and any other factors that could affect the parameters under consideration.

METHODS

Blood was sampled from the cubital vein one day before surgery, immediately after induction of anesthesia but before surgery, immediately after completion of the operation but before the termination of anesthesia and on days 1 and 4 after the operation. We measured antithrombin III activity (AT III), platelet count, fibrinogen concentration, activated partial thromboplastin time (aPTT) and prothrombin time (PT).

RESULTS

Intraoperative AT III activity and platelet count were significantly lower, aPTT was shortened and PT prolonged, although all values remained within the normal range. These results indicate moderate activation of coagulation during retinal detachment surgery. On the first postoperative day coagulation activity was reduced, with increases in AT III activity, fibrinogen concentration and platelet count and prolongation of aPTT.

CONCLUSIONS

During retinal detachment surgery there is moderate activation of coagulation in the systemic circulation.

Coagulation and fibrinolysis after open infrarenal abdominal aortic aneurysm repair in a long-term perspective

In patients with abdominal aortic aneurysms (AAA) the coagulation and fibrinolytic systems have been found to be activated preoperatively. Does the increased activity of the coagulation and fibrinolytic systems persist after AAA surgery in a long-term perspective? Prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT), tissue plasminogen activator (tPA), human plasminogen activator inhibitor type 1, and human cross-linked fibrin degradation product (D-dimer) were analysed in 18 patients after open AAA surgery (postop-AAA). The median time between surgery and blood sampling was 19 months (range, 5-37 months). Comparisons were made with both preoperative values of 23 patients with AAA (preop-AAA) as well as 20 age-matched healthy controls (AMC). F1+2, TAT, and D-dimer in preop-AAA were significantly higher compared to AMC (p<0.001). In post-op AAA patients these parameters were significantly lower compared to preop-AAA (p<0.05 for F1+2 and TAT, p<0.001 for D-dimer). However, TAT and D-dimer levels were still higher in postop-AAA than in AMC (p<0.01 for both). The activity of the coagulation and fibrinolytic systems seems to decrease after AAA surgery. However, the activity is still higher than in healthy AMC. A possible explanation may be that the thrombogenicity is lower in a vascular graft than in an aneurysmal sac but still higher than in a nonaneurysmal aorta.

Bleeding and activation of coagulation during and after transurethral prostatectomy: importance of the acute-phase response and prostate specific antigen?

OBJECTIVE

To evaluate the importance of coagulation activation in patients with benign prostatic hyperplasia, undergoing transurethral prostatic resection (TURP) and to examine whether changes in activity are related to blood loss, the circulatory entry of prostate specific antigen (PSA), operative trauma (resected tissue weight) and the inflammatory response, as assessed by C-reactive protein (CRP).

PATIENTS AND METHODS

TURP was performed in 24 men and the weight of resected tissue and blood loss determined. The activation of coagulation was followed using new sensitive and specific assays, and the changes related to blood loss, the release of PSA, operative trauma and the acute-phase response. The area under the curve (AUC) for the measured quantities was used in correlation analysis.

RESULTS

TURP was followed by a marked activation in coagulation. There was no correlation between the markers of coagulation and the operative blood loss, but the latter correlated with the weight of resected tissue (P=0.001). Postoperatively, the blood loss correlated with prothrombin fragment (F1+2; P=0.010), with thrombin-antithrombin complexes (TAT; P=0.024), and with the PSA concentrations (P=0.016) but not with fibrinogen. Serum concentrations of PSA increased significantly and the AUC in the operative period correlated with F1+2 (P=0.003) and TAT (P<0. 005), but postoperatively only with F1+2 (P=0.013). The weight of resected tissue correlated operatively with PSA (P=0.012) but not with the concentrations of F1+2 or TAT. Postoperatively, there was a correlation with the acute-phase proteins, CRP (P=0.005), fibrinogen (P=0.012) and with PSA (P=0.020).

CONCLUSION

The operative blood loss is caused by surgical factors and the observed postoperative hypercoagulable state can be explained as a physiological response to bleeding, i.e. to secure haemostasis. The activity of coagulation was unrelated to operative trauma, but the acute-phase proteins were. The release of PSA into the circulation probably has an effect on blood coagulation.

Postoperative plasma interleukin-6 in patients with renal cancer correlates with C-reactive protein but not with total fibrinogen or with high molecular weight fibrinogen fraction

The concentration of fibrinogen (Fb) and its fractions, the levels of interleukin-6 (I1-6), C-reactive protein (CRP), and immunoglobulin G (IgG) were determined in 38 patients operated on because of renal cancer. The increased Fb and I1-6 concentrations were found in approximately one-half of the patients with malignancy. The relations among the high molecular weight (HMW) and two low molecular weight (LMW and LMW') fibrinogen fractions in these patients before surgery did not differ from the corresponding relations in normal subjects. The levels of all (except IgG) compounds studied increased after surgery and the peak of I1-6 was observed on the first postoperative day but that of CRP on the third day. The concentrations of total Fb and of its HMW fraction were the highest also on the third postoperative day and this was in contrast with the decline of low molecular weight fractions at the same time. These variations of estimated variables can be regarded as being relevant to the acute phase response. We have noted a correlation between the maximal concentrations of I1-6 and CRP, but not between the corresponding concentrations of Il-6 and total Fb or HMW Fb; this may suggest that the concentration of Fb is also under the control of a factor other than I1-6.

Coagulation changes during thoracoabdominal aneurysm repair

PURPOSE

The cause of coagulopathic hemorrhage during thoracoabdominal aneurysm (TAA) repair has not been well defined in human studies. We investigated changes in the coagulation system associated with supraceliac versus infrarenal cross-clamping to address this critical issue.

METHODS

Blood levels of fibrinogen, the prothrombin fragment F1.2, D-dimer, and factors II, V, VII, VIII, IX, X, XI, and XII were analyzed in 19 patients with TAAs and four patients with abdominal aortic aneurysms (AAAs) at: (A) induction; (B) 30 minutes into supraceliac (TAA) or infrarenal (AAA) clamping; (C) 30 minutes after release of supraceliac or infrarenal clamps; and (D) immediately after surgery. Preoperative and intraoperative variables, including but not limited to aneurysm type, pathologic findings, comorbid conditions, clamp times, volume and timing of blood products, and clinical outcome, were prospectively recorded. Significance was determined by analysis of variance, Student's t test, and univariate linear regression.

RESULTS

Levels of fibrinogen and factors II, V, VIII, VIII, IX, X, XI, and XII decreased (p < 0.05) at time B versus time A and returned to near baseline by time D. D-dimer and F1.2 increased starting at time B and reached significance (p < 0.05) by time D. Data points were compared for the TAA and AAA groups. Although AAA groups demonstrated a trend to factor activity reduction and increased fibrinolysis, the effect was much less pronounced than in TAA and did not approach significance. No correlation of coagulation change with clamping time was present; however, visceral clamping times were all less than 65 minutes (mean, 44 minutes). Blood and factor replacement was initiated after time B. Univariate regression analysis of factor level versus total blood replacement demonstrated a significant (p < 0.04) correlation between the reduction in the levels of factors II, V, VII, VIII, X, and XII, and the increase in the level of D-dimer at time B and subsequent total blood replacement.

CONCLUSIONS

Thoracoabdominal aneurysm repair is associated with a reduction in clotting factor activity and an increase in fibrinolytic function, which occurs after placement of the supraceliac clamp. Explanations include visceral ischemia or a greater and longer ischemic tissue burden as the likely cause of coagulation alterations. Total blood replacement during TAA procedures was correlated to the degree of factor reduction and fibrinolysis at the time of visceral cross-clamping. An aggressive approach to early blood component replacement and to coagulation monitoring could lessen blood loss during TAA repair and avoid potentially disastrous bleeding complications.