Preoperative values of molecular coagulation markers identify patients at low risk for intraoperative haemostatic disorders and excessive blood loss

The Need for Red Cell Support During Non-Cardiac Surgery Is Associated to Pre-Transfusion Levels of FXIII and the Platelet Count

Unexpected intraoperative bleeding is associated with a reduced availability of crosslinking capacity (provided through factor XIII (FXIII)) per unit of generated thrombin. Furthermore, FXIII deficiency and thrombocytopenia (but not fibrinogen deficiency) are the most prevalent modulators of clot firmness in the immediate postoperative setting. In this study, we therefore evaluated whether levels of FXIII, fibrinogen, or the platelet count influenced the probability of intraoperative red cell transfusions in patients in the operating theatre. This retrospective study was comprised of 1023 patients, which were in need of blood product support in the operating theatre and of which 443 received red cell transfusions. Due to standard operating procedures, FXIII activity, fibrinogen concentration, and platelet count were measured before transfusion took place, but without influencing the decision to transfuse. FXIII deficiency was frequent (50%), as was thrombocytopenia (49%), but not fibrinogen deficiency (9%). FXIII deficiency was associated with a significantly increased probability to receive red cell transfusions (OR 4.58, 95% CI 3.46–6.05) as was thrombocytopenia (OR 1.94, 95% CI 1.47–2.56), but not fibrinogen deficiency (OR 1.09, 95% CI 0.67–1.76). Similar results were seen for cut-off independent evaluations (receiver operating characteristics (ROC) curves, using continuously distributed variables), where the areas under the curves (AUC) of red cell transfusion for FXIII activity was 0.744 (95% CI 0.716–0.770)/0.632 (95% CI 0.601–0.661) for the platelet count, and 0.578 (95% CI 0.547–0.609) for fibrinogen concentration. All AUCs were significantly different from each other (p < 0.0001 and p = 0.0106, respectively), indicating that FXIII activity was a significantly better predictor of red blood cell (RBC) transfusion than platelet count and fibrinogen concentration. These results suggest that pre-transfusion FXIII activity and to a lesser extent the platelet count influence the probability of intraoperative red cell transfusions. Modifying FXIII activity and/or the platelet count might influence the need for downstream red cell transfusion, thus potentially reducing transfusion associated morbidity. This, however, needs confirmation in future studies.

Factor XIII Deficiency and Thrombocytopenia Are Frequent Modulators of Postoperative Clot Firmness in a Surgical Intensive Care Unit

OBJECTIVE

Fibrinogen and factor XIII (FXIII) have been shown to critically influence clot firmness in the intraoperative setting and thus likely influence intraoperative bleeding. We were interested to identify potential modulators of postoperative clot firmness in a tertiary care hospital surgical intensive care unit setting, independent of their clinical course during surgery.

METHODS

272 day-shift consecutive patients were evaluated for whole blood clot firmness evaluated by the ROTEM® EXTEM thrombelastometric assay and various potential modulators of clot firmness upon arrival at the surgical intensive care unit (SICU).

RESULTS

Maximum clot firmness on the SICU was found to be independently influenced by the amount of colloids given during surgery as well as by platelet count, fibrinogen concentration, and FXIII activity at the time of SICU admission. In patients with lowest clot firmness, FXIII activity was the most important independent modulator of clot firmness; in patients with the highest clot firmness, platelet count and fibrinogen concentration were the most important modulators of clot firmness. Deficiencies (i.e., results below normal range) of these modulators of clot firmness were most prevalent for FXIII (activity < 70%: 45% of cases), which was significantly more frequent than thrombocytopenia (<150 × 10⁹/l: 32%) or fibrinogen deficiency (<1.5 g/l: 6%).

CONCLUSIONS

Postoperative clot firmness as evaluated by whole blood thrombelastometry (ROTEM EXTEM assay) is independently and frequently modulated though FXIII activity and the platelet count, while fibrinogen concentration is also an independent but much less frequent modulator. Different modulators show different influences, depending on the clot firmness being present. Colloids infused during surgery also independently modulate postoperative clot firmness. Based on our data, strategies can be developed to improving postoperative care of patients with bleedings or at risk for bleeding.

[Prevalence of abnormal coagulation tests in patients who undergo transrectal biopsy of the prostate]

PURPOSE

To determine the prevalence of abnormal coagulation tests in patients who undergo transrectal prostate biopsy.

MATERIAL AND METHODS

A cross-sectional study was performed at Hospital Universitario del Valle (HUV) between 1 June and 31 December 2008. Variables collected included age, PSA value, PT (prothrombin time), PTT (partial thromboplastin time) and INR (international normalized ratio) values and the presence of abnormalities in each of the haematological variables. There are no real normal or maximum acceptable values in clinical practice; however, the values described by some authors and different clinical practice protocols serve as a guide.

RESULTS

The average age was 70 years, the median PSA was 28, the partial thromboplastin time was altered in 2.3% of patients, and INR was abnormal in 3.4% of patients (cut-off point 1.5). There were no changes in PT or INR values (cut-off point 2.0).

CONCLUSIONS

The prevalence of abnormal coagulation tests is low even when there are no clear cut-off points in worldwide literature that would determine abnormality.

Impact of genetic variation on perioperative bleeding

Variation in bleeding in the perioperative period is a complex and multifactorial event associated with immediate and delayed consequences for the patient and health care resources. Little is known about the complex genetic influences on perioperative bleeding. With the discovery of multiple variations in the human genome and ever-growing databases of well-phenotyped surgical patients, better identification of patients at risk of bleeding is becoming a reality. In this review, polymorphisms in the platelet receptor genes, plasminogen activator inhibitor, and angiotensin genes among others will be discussed. We will explore the nature, effects, and implications of the genetics that influence perioperative bleeding above and beyond surgical bleeding, particularly in cardiac surgery.

Decreased factor XIII availability for thrombin and early loss of clot firmness in patients with unexplained intraoperative bleeding

To explore relevant changes in unexplained intraoperative bleeding, we evaluated elements of the final steps of the coagulation cascade in 226 consecutive patients undergoing elective surgery. Patients were stratified for the occurrence of unexplained intraoperative bleeding according to predefined criteria. Twenty patients (8.8%) developed unexplained bleeding. The median intraoperative blood loss was 1350 mL (bleeders) and 400 mL (nonbleeders) (P < 0.001). Fibrinogen and Factor XIII (F. XIII) were more rapidly consumed in bleeders (P < 0.001). Soluble fibrin formation (fibrin monomer) was increased in bleeders throughout surgery (P < or = 0.014). However, F. XIII availability per unit thrombin generated was significantly decreased in bleeders before, during, and after surgery (P < or = 0.051). Computerized thrombelastography showed a parallel, significant reduction in clot firmness. We suggest that mild preexisting coagulopathy is not rare in surgical patients and probably can result in clinically relevant intraoperative bleeding. This hemostatic disorder shows impaired clot firmness, probably secondary to decreased cross-linking (due to a loss of F. XIII, both in absolute measures and per unit thrombin generated). We suggest that the application of F. XIII might be worthwhile to test in a prospective clinical trial to increase clot firmness in patients at risk for this intraoperative coagulopathy.

Changes of haemostasis in patients undergoing major abdominal surgery--is there a difference between elderly and younger patients?

Many physiological functions are altered in the elderly. It is not clear whether this applies to haemostatic mechanisms in patients undergoing major surgery. Twenty-five consecutive patients <60 yr and 25 consecutive patients >70 yr scheduled for abdominal surgery for malignancies were included in our study. Various standard coagulation variables and specific markers of coagulation were serially measured before surgery (baseline), at arrival on the intensive care unit (ICU), 4 h after arrival on ICU, and on the morning of the first postoperative day. Platelet function was assessed using the Platelet Function Analyser PFA-100 with adenosine diphosphate (ADP) as an inductor. Anaesthesia and surgery were similar between the elderly (76(3) years) and younger (53(5) years) groups. Baseline plasma levels of prothrombin fragments F1+2, thrombin-antithrombin III (TAT) complex, and D-dimers were significantly different between the two groups, indicating thrombin activation and fibrin formation in the elderly. Postoperatively, only F1+2 plasma levels were significantly higher in the elderly (4.0(0.8) nmol/l) than in the younger patients (2.2(0.9) nmol/l), whereas the course of D-dimer and TAT did not differ significantly between the two groups. Endothelial-derived markers of coagulation (von Willebrand factor, collagen-binding activity of von Willebrand factor) were not different between the groups throughout the study period. Platelet function was impaired in the elderly compared with the younger patients. It is concluded that elderly patients showed more prothrombin activation/thrombin generation and increased fibrinolytic activity prior to surgery than younger patients. However, perioperative changes of coagulation in the elderly were similar to those seen in younger patients.

Short activated partial thromboplastin times are related to increased thrombin generation and an increased risk for thromboembolism

This prospective study was designed to investigate whether patients with short activated partial thromboplastin times (aPTTs) have increased thrombin generation and are at increased risk for thromboembolism. During a 4-month period, routine coagulation specimens were screened for the presence of a short or normal aPTT, and, accordingly, 250 specimens were collected. Prothrombin fragment F1 + 2 (F1 + 2) was measured to evaluate thrombin activation, and a second aPTT was performed with a different reagent. Diagnoses were obtained from medical records after conclusion of sample collection. Five to 9 months later, patients were questioned on thromboembolic events during the previous 18 months by questionnaire and telephone interview. F1 + 2 and the incidence of venous thromboses were elevated significantly in the short aPTT group. Unexpectedly, patients with acute bleeding had short aPTTs, but 36% of these also had thromboembolic events during the 18 months proximal to blood collection. These findings were confirmed with the second aPTT reagent. Patients with short aPTTs have increased thrombin generation and are at increased risk for thromboembolism, mainly venous thromboses, despite the fact that a short aPTT can occur in the acute setting of bleeding.

Consequences of haemostasis disorders on anaesthestic management

New molecular markers of coagulation and fibrinolysis activation have been developed and used to identify patient subgroups that frequently develop increased procoagulant turnover and, hence, disseminated intravascular coagulation and organ dysfunction. The idea of inhibiting the coagulation hyperactivation by the administration of antithrombin has led to experimental findings that pinpoint an anti-inflammatory action of antithrombin. Preliminary clinical trials of high-dose antithrombin administration in sepsis are promising. Point-of-care coagulation testing remains controversial since a variety of perioperative therapeutic regimens such as aprotinin administration obviously do not require 'on-line' coagulation monitoring.