Updates in perioperative coagulation: physiology and management of thromboembolism and haemorrhage

Complement-Coagulation Cross-talk: Factor H-mediated regulation of the Complement Classical Pathway activation by fibrin clots

The classical pathway of the complement system is activated by the binding of C1q in the C1 complex to the target activator, including immune complexes. Factor H is regarded as the key downregulatory protein of the complement alternative pathway. However, both C1q and factor H bind to target surfaces via charge distribution patterns. For a few targets, C1q and factor H compete for binding to common or overlapping sites. Factor H, therefore, can effectively regulate the classical pathway activation through such targets, in addition to its previously characterized role in the alternative pathway. Both C1q and factor H are known to recognize foreign or altered-self materials, e.g., bacteria, viruses, and apoptotic/necrotic cells. Clots, formed by the coagulation system, are an example of altered self. Factor H is present abundantly in platelets and is a well-known substrate for FXIIIa. Here, we investigated whether clots activate the complement classical pathway and whether this is regulated by factor H. We show here that both C1q and factor H bind to the fibrin formed in microtiter plates and the fibrin clots formed under in vitro physiological conditions. Both C1q and factor H become covalently bound to fibrin clots, and this is mediated via FXIIIa. We also show that fibrin clots activate the classical pathway of complement, as demonstrated by C4 consumption and membrane attack complex detection assays. Thus, factor H downregulates the activation of the classical pathway induced by fibrin clots. These results elucidate the intricate molecular mechanisms through which the complement and coagulation pathways intersect and have regulatory consequences.

Prediction of Mid-term Platelet Transfusion in Stable Trauma Patients Using Rotational Thromboelastometry

Background

Rotational thromboelastometry (ROTEM; TEM International GmbH, Munich, Germany) is a global coagulation test that guides evidence-based platelet transfusion in trauma patients. We evaluated ROTEM parameters for predicting mid-term (five days) platelet transfusion in trauma patients.

Methods

Maximum clot firmness and clot amplitudes after 5, 10, and 15 mins (A5, A10, and A15, respectively) of fibrin-specific ROTEM (FIBTEM) and extrinsically activated ROTEM (EXTEM) were retrospectively collected from 82 hospitalized, stable, non-bleeding trauma patients after successful initial resuscitation. Platelet-specific ROTEM (PLTEM) was calculated by subtracting FIBTEM from EXTEM. Platelet transfusions were reviewed for five days after ROTEM.

Results

The areas under the curve for FIBTEM, EXTEM, and PLTEM predicting platelet concentrate transfusion of >12 U at mid-term were 0.915-0.923, 0.878-0.896, and 0.551-0.735, respectively. FIBTEM and EXTEM parameters were comparable to those of fibrinogen, fibrin/fibrinogen degradation products, D-dimer, and antithrombin III. Strong correlations (r>0.7) were noted between platelet count and EXTEM (A5, A10, and A15) or PLTEM (A5), platelet function (per platelet count) and EXTEM (A10 and A15), and fibrinogen levels and all FIBTEM parameters.

Conclusions

FIBTEM and EXTEM can reliably predict mid-term platelet transfusion in trauma patients. FIBTEM, EXTEM, and PLTEM parameters correlate with conventional coagulation tests (platelets and fibrinogen).

Thromboembolic Events in Patients with Inflammatory Bowel Disease: A Comprehensive Overview

Inflammatory bowel disease (IBD), Crohn’s disease and ulcerative colitis are chronic inflammatory disorders of the intestines. The underlying inflammation activates the coagulation cascade leading to an increased risk of developing arterial and venous thromboembolic events such as deep vein thrombosis and pulmonary embolism. Patients with IBD are at a 2–3-fold increased risk of developing thromboembolism. This risk increases in patients with active IBD disease, flare-ups, surgery, steroid treatment, and hospitalization. These complications are associated with significant morbidity and mortality making them important in clinical practice. Clinicians should consider the increased risk of thromboembolic events in patients with IBD and manage them with appropriate prophylaxis based on the risk. In this review, we discuss the literature associated with the pathophysiology of thromboembolism in patients with IBD, summarize the studies describing the various thromboembolic events, and the management of thromboembolism in patients with IBD.

Recent advances in biopolymer-based hemostatic materials

Hemorrhage is the leading cause of trauma-related deaths, in hospital and pre-hospital settings. Hemostasis is a complex mechanism that involves a cascade of clotting factors and proteins that result in the formation of a strong clot. In certain surgical and emergency situations, hemostatic agents are needed to achieve faster blood coagulation to prevent the patient from experiencing a severe hemorrhagic shock. Therefore, it is critical to consider appropriate materials and designs for hemostatic agents. Many materials have been fabricated as hemostatic agents, including synthetic and naturally derived polymers. However, compared to synthetic polymers, natural polymers or biopolymers, which include polysaccharides and polypeptides, have greater biocompatibility, biodegradability, and processibility. Thus, in this review, we focus on biopolymer-based hemostatic agents of different forms, such as powder, particles, sponges, and hydrogels. Finally, we discuss biopolymer-based hemostats currently in clinical trials and offer insight into next-generation hemostats for clinical translation.

Viscoelastic Monitoring in Liver Transplantation

Cirrhosis and liver transplantation (LT) surgery are associated with substantial alterations to the patient's coagulation status. Accurate monitoring of these changes during LT can help manage bleeding proactively and potentially reduce transfusion requirements. Unlike conventional coagulation tests (CCTs), viscoelastic monitoring (VEM) can provide an accurate, real-time, point-of-care assessment of coagulation status during LT and hence has become an invaluable tool for anesthetists and intensive care physicians. However, it remains an enigmatic subject for transplantation surgeons who are more conversant with CCTs. This review discusses the principles of VEM, provides a primer to understanding and interpreting its output, and explains how it can be used to make real-world clinical decisions during LT.

The prothrombotic state in cancer

Neoplasms result from changes in the mechanisms of growth, differentiation, and cellular death. Cancers are of high clinical relevance due to their prevalence and associated morbidity and mortality. The clinical and biological diversity of cancer depends mainly on cellular origin and degree of differentiation. These changes result from alterations in molecular expression that generate a complex clinical, biochemical, and morphologic phenotype. Although cancer is associated with a hypercoagulable state, few cancers result in a thrombotic event. Many factors influence thrombotic incidence, such as advanced disease, central catheter placement, chemotherapy, neoplasia, and surgery. The pro-coagulant state is associated with anomalies in the vascular wall, blood flow, blood constituents (tissue factor, thrombin), coagulation state, and cell growth factors. Tumor cells perpetuate this phenomenon by releasing tissue factor, inflammatory cytokines, and growth factors. These changes favor cellular activation that gives rise to actions involving coagulation, inflammation, thrombosis, tumor growth, angiogenesis, and tumor metastases. These, in turn, are closely linked to treatment response, tumor aggressiveness, and host survival. Activation of the coagulation cascade is related to these phenomena through molecules that interact in these processes. As such, it is necessary to identify these mediators to facilitate treatment and improve outcomes.

Albumin Infusion in Critically Ill COVID-19 Patients: Hemodilution and Anticoagulation

Hypercoagulation is one of the major risk factors for ICU treatment, mechanical ventilation, and death in critically ill patients infected with SARS-CoV-2. At the same time, hypoalbuminemia is one risk factor in such patients, independent of age and comorbidities. Especially in patients with severe SARS-CoV-2-infection, albumin infusion may be essential to improve hemodynamics and to reduce the plasma level of the main marker of thromboembolism, namely, the D-dimer plasma level, as suggested by a recent report. Albumin is responsible for 80% of the oncotic pressure in the vessels. This is necessary to keep enough water within the systemic circulatory system and for the maintenance of sufficient blood pressure, as well as for sufficient blood supply for vital organs like the brain, lungs, heart, and kidney. The liver reacts to a decrease in oncotic pressure with an increase in albumin synthesis. This is normally possible through the use of amino acids from the proteins introduced with the nutrients reaching the portal blood. If these are not sufficiently provided with the diet, amino acids are delivered to the liver from muscular proteins by systemic circulation. The liver is also the source of coagulation proteins, such as fibrinogen, fibronectin, and most of the v WF VIII, which are physiological components of the extracellular matrix of the vessel wall. While albumin is the main negative acute-phase protein, fibrinogen, fibronectin, and v WF VIII are positive acute-phase proteins. Acute illnesses cause the activation of defense mechanisms (acute-phase reaction) that may lead to an increase of fibrinolysis and an increase of plasma level of fibrinogen breakdown products, mainly fibrin and D-dimer. The measurement of the plasma level of the D-dimer has been used as a marker for venous thromboembolism, where a fourfold increase of the D-dimer plasma level was used as a negative prognostic marker in critically ill SARS-CoV-2 hospitalized patients. Increased fibrinolysis can take place in ischemic peripheral sites, where the mentioned coagulation proteins can become part of the provisional clot (e.g., in the lungs). Although critically ill SARS-CoV-2-infected patients are considered septic shock patients, albumin infusions have not been considered for hemodynamic resuscitation and as anticoagulants. The role of coagulation factors as provisional components of the extracellular matrix in case of generalized peripheral ischemia due to hypoalbuminemia and hypovolemia is discussed in this review.

Therapeutic Implications of Inherited Thrombophilia in Pregnancy

BACKGROUND

Inherited (hereditary) thrombophilia is a genetic disorder that affects coagulation, being responsible for more than 60% of idiopathic (spontaneous or unprovoked) thromboembolic events. Association of inherited thrombophilia with pregnancy increases the risk of thromboembolic disease, and it may be related to many complications, such as preeclampsia, recurrent miscarriage intrauterine growth restriction, early detachment of placenta, and prematurity.

AREAS OF UNCERTAINTY

Interpretation of a positive test for thrombophilia in pregnant women is difficult because they have many natural changes in the coagulation system. Genetic diagnosis of thrombophilia, after a thrombotic event or during a pregnancy complication, has a major importance, not only to define its etiology but also to determine the duration of anticoagulant treatment and risk stratification for prophylaxis treatment.

DATA SOURCES

Literature search was performed using electronic database (PubMed) between April 1981 and November 2018. We used different keywords and MeSH terms to generate the most relevant results related to the inherited thrombophilia and its impact on pregnancy.

RESULTS

Screening for inherited thrombophilia in young women is recommended in case of personal history of venous thromboembolism, first-degree relatives with a history of high-risk thrombophilia, or personal history of second-trimester miscarriage. Decision to recommend thromboprophylaxis with anticoagulant treatment in pregnant women with inherited thrombophilia is determined by history of venous thromboembolism, type and associated risk of inherited thrombophilia, and presence of additional risk factors. Low-molecular-weight heparins are the preferred agents for prophylaxis in pregnancy, while the doses vary depending on thrombophilia type, personal history, and associated risk factors.

CONCLUSIONS

Association between 2 procoagulant conditions, inherited thrombophilia and pregnancy, has an important impact for the mother and fetus. This review will summarize the impact of each inherited prothrombotic factor on cardiovascular and pregnancy outcomes and will discuss the role of anticoagulation treatment for women diagnosed with inherited thrombophilia.

Smoking cessation affects human platelet activation induced by collagen

It is firmly established that smoking is a risk factor of cardiovascular disease, stroke and peripheral vascular disease. Although smoking alters the hemostatic process, the influence of smoking on human platelet activation remains controversial. For patients undergoing surgery, cessation of smoking prior to the procedure is recommended as it increases the risk of postoperative morbidity or mortality. The presented study investigated the effects of smoking cessation on human platelet activation induced via collagen (n=19 patients). Blood samples were taken on four occasions: Before smoking cessation, and at 4, 8 and 12 weeks after smoking cessation. Platelet aggregation using citrated platelet-rich plasma (PRP) was monitored using a PA-200 aggregometer, which determined the size of platelet aggregates using laser scattering methods. A low dose of collagen (1 µg/ml) accelerated platelet aggregation at 4 or 8 weeks after smoking cessation when compared with results before cessation. After 12 weeks, levels of platelet aggregation induced by collagen were almost equal to those recorded prior to smoking cessation. The secretion levels of collagen-induced platelet-derived growth factor (PDGF)-AB at 4 or 8 weeks after smoking cessation were significantly higher than those before smoking was stopped. Furthermore, smoking cessation markedly strengthened the collagen-induced phosphorylation of p38 mitogen-activated protein (MAP) kinase after 4 weeks. The results of the current study indicated that smoking cessation causes temporary short-term human platelet hyper-activation. The further suggest that the incidence of complications due to human platelet hyper-reactivity may be lowered by considering the period of smoking abstinence.

The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition

BACKGROUND

Severe traumatic injury continues to present challenges to healthcare systems around the world, and post-traumatic bleeding remains a leading cause of potentially preventable death among injured patients. Now in its fifth edition, this document aims to provide guidance on the management of major bleeding and coagulopathy following traumatic injury and encourages adaptation of the guiding principles described here to individual institutional circumstances and resources.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004, and the current author group included representatives of six relevant European professional societies. The group applied a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were re-examined and revised based on scientific evidence that has emerged since the previous edition and observed shifts in clinical practice. New recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated.

RESULTS

Advances in our understanding of the pathophysiology of post-traumatic coagulopathy have supported improved management strategies, including evidence that early, individualised goal-directed treatment improves the outcome of severely injured patients. The overall organisation of the current guideline has been designed to reflect the clinical decision-making process along the patient pathway in an approximate temporal sequence. Recommendations are grouped behind the rationale for key decision points, which are patient- or problem-oriented rather than related to specific treatment modalities. While these recommendations provide guidance for the diagnosis and treatment of major bleeding and coagulopathy, emerging evidence supports the author group's belief that the greatest outcome improvement can be achieved through education and the establishment of and adherence to local clinical management algorithms.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. If incorporated into local practice, these clinical practice guidelines have the potential to ensure a uniform standard of care across Europe and beyond and better outcomes for the severely bleeding trauma patient.

Lower rate of delayed graft function is observed when epidural analgesia for living donor nephrectomy is administered

Background

The beneficial effects of epidural analgesia (EDA) in terms of pain control and postoperative convalescence are widely known and led to a frequent use for patients who underwent living donor kidney nephrectomy. The objective of this study was to determine whether general anesthesia (GA) plus EDA compared to GA only, administered for living donor nephrectomy has effects on postoperative graft function in recipients.

Methods

In this monocentric, retrospective cohort analysis we analyzed the closed files of all consecutive donor- recipient pairs who underwent living donor kidney transplantations from 2008 to 2017. The outcome variable was delayed graft function (DGF), defined as at least one hemodialysis within seven days postoperatively, once hyperacute rejection, vascular or urinary tract complications were ruled out. Statistical analyses of continuous variables were calculated using the two-tail Student’s t test and Fisher exact test for categorical variables with a significance level of p < 0.05, respectively.

Results

The study enclosed 291 consecutive living donor kidney transplantations. 99 kidney donors received epidural analgesia whereas 192 had no epidural analgesia. The groups showed balanced pretransplantational characteristics and comparable donors´ and recipients’ risk factors. 9 out of all 291 recipients needed renal replacement therapy (RRT) during the first 7 days due to delayed graft function; none of these donors received EDA. The observed rate of DGF in recipients whose kidney donors received epidural analgesia was significantly lower (0% vs. 4.6%; p = 0.031).

Conclusions

In our cohort we observed a significantly lower rate of DGF when epidural analgesia for donor nephrectomy was administered. Due to restrictions of the study design this observation needs further confirmation by prospective studies.

The use of dielectric blood coagulometry in the evaluation of coagulability in patients with peripheral arterial disease

Background

Platelets and coagulation proteins contribute to the development of peripheral arterial disease, especially atherosclerotic disease. Several experimental studies have proven a significant correlation between hypercoagulability and atherosclerosis. We used dielectric blood coagulometry, which was initially designed to evaluate the coagulable status, to examine the coagulability of peripheral arterial disease patients, and investigated the factors that were significantly correlated with the results.

Methods

We performed dielectric blood coagulometry in 49 peripheral arterial disease patients. In addition, we recorded the patients’ demographic information, including the presence of comorbidities, hemodynamic status, and laboratory findings. To investigate coagulability, we calculated the T_max value, which indicates the time from recalcification to maximum normalized permittivity.

Results

The T_max values of diabetes mellitus patients were significantly lower than those of non-diabetic patients (1 MHz, P = 0.010; 10 MHz, 0.011). Furthermore, the T_max value was statistically correlated with the activated partial thromboplastin time (1 MHz, ρ = 0.286, P = 0.048; 10 MHz, ρ = 0.301, P = 0.037).

Conclusions

Dielectric blood coagulometry detected the hypercoagulable status in diabetes mellitus patients, and reflected their level of coagulability, which was also evaluated by the activated partial thromboplastin time.

A Miniaturized Hemoretractometer for Blood Clot Retraction Testing

Blood coagulation is a critical hemostatic process that must be properly regulated to maintain a delicate balance between bleeding and clotting. Disorders of blood coagulation can expose patients to the risk of either bleeding disorders or thrombotic diseases. Coagulation diagnostics using whole blood is very promising for assessing the complexity of the coagulation system and for global measurements of hemostasis. Despite the clinic values that existing whole blood coagulation tests have demonstrated, these systems have significant limitations that diminish their potential for point-of-care applications. Here, recent advancements in device miniaturization using functional soft materials are leveraged to develop a miniaturized clot retraction force assay device termed mHemoRetractoMeter (mHRM). The mHRM is capable of precise measurements of dynamic clot retraction forces in real time using minute amounts of whole blood. To further demonstrate the clinical utility of the mHRM, systematic studies are conducted using the mHRM to examine the effects of assay temperature, treatments of clotting agents, and pro- and anti-coagulant drugs on clot retraction force developments of whole blood samples. The mHRM's low fabrication cost, small size, and consumption of only minute amounts of blood samples make the technology promising as a point-of-care tool for future coagulation monitoring.

Application of Dual Inhibition Concept within Looped Autoregulatory Systems toward Antivirulence Agents against Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa quorum-sensing (QS) is a sophisticated network of genome-wide regulation triggered in response to population density. A major component is the self-inducing pseudomonas quinolone signal (PQS) QS system that regulates the production of several nonvital virulence- and biofilm-related determinants. Hence, QS circuitry is an attractive target for antivirulence agents with lowered resistance development potential and a good model to study the concept of polypharmacology in autoloop-regulated systems per se. Based on the finding that a combination of PqsR antagonist and PqsD inhibitor synergistically lowers pyocyanin, we have developed a dual-inhibitor compound of low molecular weight and high solubility that targets PQS transcriptional regulator (PqsR) and PqsD, a key enzyme in the biosynthesis of PQS-QS signal molecules (HHQ and PQS). In vitro, this compound markedly reduced virulence factor production and biofilm formation accompanied by a diminished content of extracellular DNA (eDNA). Additionally, coadministration with ciprofloxacin increased susceptibility of PA14 to antibiotic treatment under biofilm conditions. Finally, disruption of pathogenicity mechanisms was also assessed in vivo, with significantly increased survival of challenged larvae in a Galleria mellonella infection model. Favorable physicochemical properties and effects on virulence/biofilm establish a promising starting point for further optimization. In particular, the ability to address two targets of the PQS autoinduction cycle at the same time with a single compound holds great promise in achieving enhanced synergistic cellular effects while potentially lowering rates of resistance development.

The European guideline on management of major bleeding and coagulopathy following trauma: fourth edition

BACKGROUND

Severe trauma continues to represent a global public health issue and mortality and morbidity in trauma patients remains substantial. A number of initiatives have aimed to provide guidance on the management of trauma patients. This document focuses on the management of major bleeding and coagulopathy following trauma and encourages adaptation of the guiding principles to each local situation and implementation within each institution.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004 and included representatives of six relevant European professional societies. The group used a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were reconsidered and revised based on new scientific evidence and observed shifts in clinical practice; new recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated. This guideline represents the fourth edition of a document first published in 2007 and updated in 2010 and 2013.

RESULTS

The guideline now recommends that patients be transferred directly to an appropriate trauma treatment centre and encourages use of a restricted volume replacement strategy during initial resuscitation. Best-practice use of blood products during further resuscitation continues to evolve and should be guided by a goal-directed strategy. The identification and management of patients pre-treated with anticoagulant agents continues to pose a real challenge, despite accumulating experience and awareness. The present guideline should be viewed as an educational aid to improve and standardise the care of the bleeding trauma patients across Europe and beyond. This document may also serve as a basis for local implementation. Furthermore, local quality and safety management systems need to be established to specifically assess key measures of bleeding control and outcome.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. The implementation of locally adapted treatment algorithms should strive to achieve measureable improvements in patient outcome.

Intraoperative changes in platelet function in relation to moderate haemorrhage

BACKGROUND

Haemorrhage is associated with haemostatic dysfunction. Previous studies have focused on coagulation factors, but platelet function plays an equally important role. The time course of alterations in platelet function in relation to injurious stimuli is not known.

AIM

To evaluate short-term, intra-operative changes in platelet function, by whole blood impedance aggregometry in patients undergoing hip arthroplasty. The primary outcome was platelet aggregation in response to adenosine diphosphate (ADP) stimulation. We also evaluated other agonists, and the feasibility of conducting platelet aggregometry measurement in the operating theatre.

METHODS

Patients undergoing primary cemented hip arthroplasty had six peri-operative arterial blood samples analysed at pre-set stages of the operation, using the Multiplate Impedance Aggregometer. Four agonists were used: ADP, TRAP, Collagen and Arachidonic Acid.

RESULTS

There was a statistically significant change (p<0.05, ANOVA) in platelet response to ADP over the course of the operations. The trend demonstrated an initial decrease in responsiveness, followed by increased platelet responsiveness in the later stages. Other agonists (TRAP, COL, ASPItest) demonstrated a similar pattern of changes. Of 360 tests conducted, 12 (3.3%) had to be re-run due to poor intra-assay variability. Satisfactory values were obtained on the second attempt in all 12 samples.

CONCLUSION

Platelet function, as measured by impedance aggregometry, changes in response to a surgical stimulus involving blood loss. The clinical significance of these changes, and the potential of manipulating them for therapeutic purposes, remains to be elucidated.

Overview of the coagulation system

Coagulation is a dynamic process and the understanding of the blood coagulation system has evolved over the recent years in anaesthetic practice. Although the traditional classification of the coagulation system into extrinsic and intrinsic pathway is still valid, the newer insights into coagulation provide more authentic description of the same. Normal coagulation pathway represents a balance between the pro coagulant pathway that is responsible for clot formation and the mechanisms that inhibit the same beyond the injury site. Imbalance of the coagulation system may occur in the perioperative period or during critical illness, which may be secondary to numerous factors leading to a tendency of either thrombosis or bleeding. A systematic search of literature on PubMed with MeSH terms ‘coagulation system, haemostasis and anaesthesia revealed twenty eight related clinical trials and review articles in last 10 years. Since the balance of the coagulation system may tilt towards bleeding and thrombosis in many situations, it is mandatory for the clinicians to understand physiologic basis of haemostasis in order to diagnose and manage the abnormalities of the coagulation process and to interpret the diagnostic tests done for the same.

Acute coagulopathy of trauma: Mechanism, monitoring, management

Coagulopathy is a well-known consequence of trauma and is the most common cause of mortality in the young. However, its cause and management is still controversial. A new concept in the understanding of coagulopathy in trauma is the occurrence of Acute coagulopathy of trauma (ACoT). ACoT is associated with hypo perfusion and tissue trauma as seen in massive injury. The incidence of coagulopathy increases with injury scores and is associated with higher number of ventilator days, higher morbidity and mortality. The process of coagulation is better described by the cell based model with a central role for platelets rather than the older plasma based model. This shift in our understanding supports the theory that ACoT results from the endothelial release of thrombomodulin and activated protein C in the presence of hypoperfusion. This in turn leads on to a hyperfibrinolytic and hypocoagulable state. Viscoelastic hemostatic assays are replacing the older tests like prothrombin time in the assessment of coagulopathy. These tests are accurate, determine the need for transfusion and can be performed at the point of care. Damage control resuscitation includes newer concepts like permissive hypotension, increased use of plasma as a part of massive transfusion protocols and damage control surgery.

Epidural pain relief versus systemic opioid-based pain relief for abdominal aortic surgery

BACKGROUND

Epidural analgesia offers greater pain relief compared to systemic opioid-based medications, but its effect on morbidity and mortality is unclear. This review was originally published in 2006 and was updated in 2011.

OBJECTIVES

To assess the benefits and harms of postoperative epidural analgesia in comparison with postoperative systemic opioid-based pain relief for adult patients who underwent elective abdominal aortic surgery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 11) via Ovid; Ovid MEDLINE (from inception to week 1 November 2010); and EMBASE (from inception to week 1, November 2010). The original search was performed in 2004. We assessed non-English language reports and contacted researchers in the field. We did not seek unpublished data.

SELECTION CRITERIA

We included all randomized and quasi-randomized controlled trials comparing postoperative epidural analgesia and postoperative systemic opioid-based analgesia for adult patients who underwent elective open abdominal aortic surgery.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information and data.

MAIN RESULTS

We included 15 trials that involved 1297 patients (633 patients received epidural analgesia and 664 received systemic opioid analgesia) in this review. This included one trial we found in our updated search and one trial from our original review that had been awaiting translation. The epidural analgesia group showed significantly lower visual analogue scale scores for pain on movement (up to postoperative day three) regardless of the site of the epidural catheter and epidural formulation. The postoperative duration of tracheal intubation and mechanical ventilation was significantly shorter, by about 48%, in the epidural analgesia group. The overall event rates of myocardial infarction, acute respiratory failure (defined as an extended need for mechanical ventilation), gastrointestinal complications, and renal complications were significantly lower in the epidural analgesia group.

AUTHORS' CONCLUSIONS

Epidural analgesia provides better pain relief (especially during movement) in the period up to three postoperative days. It reduces the duration of postoperative tracheal intubation by roughly half. The occurrence of prolonged postoperative mechanical ventilation, myocardial infarction, gastric complications and renal complications was reduced by epidural analgesia. However, current evidence does not confirm the beneficial effect of epidural analgesia on postoperative mortality and other types of complications.

Deep vein thrombosis and pulmonary embolism - Prevention, management, and anaesthetic considerations

There is high incidence of venous thromboembolism, comprising of deep vein thrombosis and pulmonary embolism, in hospitalized patients. The need for systemic thromboprophylaxis is essential, especially in patients with inherited or acquired patient-specific risk factors or in patients undergoing surgeries associated with high incidence of postoperative deep vein thrombosis and pulmonary embolism. These patients, on prophylactic or therapeutic doses of anticoagulants, may present for surgery. General or regional anaesthesia may be considered depending on the type and urgency of surgery and degree of anticoagulation as judged by investigations. The dilemma regarding the type of anaesthesia can be solved if the anaesthesiologist is aware of the pharmacokinetics of drugs affecting haemostasis. The anaesthesiologist must keep abreast with the latest developments of methods and drugs used in the prevention and management of venous thromboembolism and their implications in the conduct of anaesthesia.

Management of bleeding following major trauma: an updated European guideline

INTRODUCTION

Evidence-based recommendations are needed to guide the acute management of the bleeding trauma patient, which when implemented may improve patient outcomes.

METHODS

The multidisciplinary Task Force for Advanced Bleeding Care in Trauma was formed in 2005 with the aim of developing a guideline for the management of bleeding following severe injury. This document presents an updated version of the guideline published by the group in 2007. Recommendations were formulated using a nominal group process, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence and based on a systematic review of published literature.

RESULTS

Key changes encompassed in this version of the guideline include new recommendations on coagulation support and monitoring and the appropriate use of local haemostatic measures, tourniquets, calcium and desmopressin in the bleeding trauma patient. The remaining recommendations have been reevaluated and graded based on literature published since the last edition of the guideline. Consideration was also given to changes in clinical practice that have taken place during this time period as a result of both new evidence and changes in the general availability of relevant agents and technologies.

CONCLUSIONS

This guideline provides an evidence-based multidisciplinary approach to the management of critically injured bleeding trauma patients.

[Haemostatic disorders in orthopaedic surgery: laboratory diagnosis]

Coagulative disorders may result from a breakdown in the balance between coagulation and fibrinolysis. It is important to assess relative physiological states of coagulation and fibrinolysis related to operation. An ideal outcome in orthopaedic surgical procedures is the achievement of adequate haemostasis without excessive bleeding despite transection of numerous blood vessels, a necessary part of any surgical procedure. Meticulous attention to secure intraoperative haemostasis is a surgeon's responsibility. The postoperative haemostatic response to injury must also lead to a hypercoagulable state and thrombosis because it is also accompanied by stasis and vessel injury, fulfilling Virchow's triad. For discussion of prophylaxis and treatment of venous thromboembolic disease and orthopaedic surgical bleeding, the reader is referred to other articles. This paper discusses selected conditions leading to postoperative bleeding and thrombosis after orthopaedic surgery as well as laboratory diagnosis.

Perioperative assessment of coagulation in paediatric neurosurgical patients using thromboelastography

BACKGROUND AND OBJECTIVE

Primary brain tumours may be associated with coagulation disorders, which can pose intraoperative and postoperative management difficulties. Thromboelastography is a useful technique for evaluating coagulability. In this study, we evaluated the perioperative coagulation profile using both standard laboratory work and thromboelastography in paediatric patients undergoing craniotomy for primary brain tumours.

METHODS

Forty paediatric patients were enrolled in the study. All patients received standard anaesthesia. Blood was analysed for both standard laboratory analysis and thromboelastography at three points for each patient: preoperatively, intraoperatively and postoperatively. Postoperative patients were divided into two groups according to the occurrence or nonoccurrence of postoperative haematomas: nonhaematoma group and haematoma group. The standard blood analysis and thromboelastography values for both groups were compared.

RESULTS

Perioperative standard blood analysis was within normal limits for all patients, with no significant difference between both groups. In the nonhaematoma group, thromboelastography values were indicative of a hypercoagulable state that started intraoperatively and continued into the first postoperative day. In the haematoma group, thromboelastography values were indicative of a hypocoagulable state that was evident in the preoperative thromboelastography values and continued into the intraoperative as well as the postoperative period.

CONCLUSION

Thromboelastography may be useful in the perioperative assessment and monitoring of coagulation in paediatric neurosurgical patients and helps in identifying patients at increased risk of bleeding or thromboembolic events.

[Laboratory diagnosis in orthopaedic surgery]

Orthopaedic procedures and anaesthesia are not physiological states. To prevent orthopaedic sequelae, laboratory diagnoses are of proven value in preoperative and postoperative complications as well as preoperative diseases. Laboratory analyses have an important contribution to early diagnosis of infection, haemostasis disorders, electrolyte disbalance, and acid-base disturbance. Laboratory analyses also have a role in monitoring the effect of therapy. Metabolic bone diseases such as osteoporosis affect many patients. Laboratory analyses are useful in evaluating the treatment for preventing fractures. This article discusses specific factors causing postoperative bleeding and thrombosis after orthopaedic surgery.

Epidural anesthesia? No of course

Although the contraindications for thoracic epidural anesthesia (TEA) are well defined, the debate continues about whether TEA improves outcomes. Pro and con trials and a metaanalysis in the past have yielded equivocal results; they did not deal with new vascular intervention or drugs. The benefit of TEA in surgery is to provide analgesia. In subgroups, TEA can decrease the mortality and morbidity. In contrast, the cost can increase in the situation of a complication that is opposite to the side effects is rare, but the impairment caused by them is out of proportion to the benefits. Primary or secondary prophylaxis with antithrombotic drugs is increasing in developed countries because of the increasing cardiovascular interventions and aging of the population. The neuroaxial guidelines are useful, but the changing of the coagulation profile after hepatectomy is not included in them. The decision to use TEA in liver surgery must be individualized with steps planned from the beginning. TEA suitability is based on an evaluation of the contraindications, comorbidities, coagulation profiles, hepatic reserve, and balance of benefits and risks. The insertion or withdrawal of the epidural catheter should be made with care according to the neuroaxial guidelines and in the presence of a normal TEG. The decreasing level of prothrombin content and platelet counts after hepatectomy should be closely monitored every 2 to 5 days.

Prolapse and incontinence surgery in older women

PURPOSE

Pelvic floor disorders including urinary incontinence, pelvic organ prolapse and fecal incontinence are common problems encountered by the older woman. With the increasing population of older American women urologists and gynecologists can expect to provide evaluation and treatment of these conditions with increasing frequency. These conditions are amenable to medical and surgical therapies.

MATERIALS AND METHODS

Contemporary articles (2003 to the present) that included older women undergoing urogynecological surgery were included in this review. Current data on morbidity, mortality and/or surgical outcomes are presented with evidence based preoperative, intraoperative and postoperative surgical management strategies.

RESULTS

Older women undergoing pelvic floor surgery can expect operative risks as well as subjective and objective anatomical and quality-of-life outcomes similar to those of younger women.

CONCLUSIONS

The decision for surgical intervention for the treatment of pelvic floor disorders should not be based on chronological age alone. Before selecting a specific surgical procedure, all existing pelvic floor defects should be evaluated. Further research is required to understand the impact that surgery for pelvic floor disorders has on anatomical, physiological and functional outcomes in older women.

Pelvic Floor Surgery in the Older Woman

Pelvic floor disorders including urinary incontinence, pelvic organ prolapse, and fecal incontinence are common problems encountered by the older woman. With the increasing population of older Americans, healthcare providers can expect to provide evaluation and treatment of these conditions with increasing frequency. These conditions are amenable to both medical and surgical therapies. The older woman who undergoes surgery can expect similar risks and outcomes to that of younger women. Further research is required to more fully understand the functional, anatomic, and physiologic outcomes after treatment for pelvic floor disorders in the older woman.

[Systemic hemostatic drugs]

Understanding the haemostatic changes is crucial in developing strategies for the management of haemorrhage syndroma. In recent years, the revised model of coagulation ("cell based" model) provided a much more authentic description of the coagulation process. Pharmacological intervention, especially desmopresin, antifibrinolytics (synthetics and nature) and increasingly recombinant activated factor VII are being used in prevention and therapeutically to control bleeding of variety etiologies. Skillfull surgery combined with blood saving methods and careful management of blood coagulation will all help in sucessfull haemorrhage prevention and treatment, and reduce unnecessary blood loss and transfusion requirements and its attendant risks. Among the all avalaible tests, the use of thromboelastography has allowed for more detailed dynamic assessment of the various steps of hemostasis.

Use of blood and blood products in trauma

According to the global study of the burden of disease, violence and accidental injury account for 12% of deaths worldwide; 30-40% of trauma mortality is attributable to haemorrhage. The highly complex haemostatic system is severely impaired as a result of haemorrhagic shock, acidosis, hypothermia, haemodilution, hyperfibrinolysis, and consumption of clotting factors. Thus it is important to prioritize the prevention of the development of coagulopathy. Timely transfusion of red blood cells and plasma products becomes essential to restore tissue oxygenation, support perfusion, and maintain the pool of active haemostatic factors. The limits to this strategy to compensate for the loss of blood and coagulation factors are discussed. In the absence of international guidelines, there is an ongoing debate about a generally accepted treatment algorithm, mass transfusion protocols, and adverse events that have been observed as a result of transfusion. Thus many recommendations are based upon expert opinion rather than on evidence. In this chapter we address key issues of transfusions of red blood cells and plasma products in the acute control of bleeding in traumatized patients.

Effect of Postoperative Analgesia on Major Postoperative Complications: A Systematic Update of the Evidence

BACKGROUND

Few individual clinical trials have had sufficient subject numbers to definitively determine the effects of postoperative analgesia on major outcomes.

METHODS

We systematically searched the Medline and the Cochrane Library databases for the past decade and focused on meta-analyses and large, randomized, controlled trials.

RESULTS

Eighteen meta-analyses, 10 systematic reviews, 8 additional randomized, controlled trials, and 2 observational database articles were identified for review or comment. Epidural analgesia with local anesthetics has the greatest theoretical potential to affect major outcomes and has been the most thoroughly investigated technique. The majority of evidence favors an ability of epidural analgesia to reduce postoperative cardiovascular and pulmonary complications only after major vascular surgery or in high-risk patients. This finding may become irrelevant because of rapid conversion of major surgery to minimally invasive techniques (e.g., endoluminal abdominal aortic repair) that carry less risk of complications. There is also consistent evidence that epidural analgesia with local anesthetics is associated with faster resolution of postoperative ileus after major abdominal surgery. Again, this finding may also become irrelevant with the adoption of laparoscopic techniques and multimodal fast-track programs for abdominal surgery. There is no current evidence that perineural analgesia, continuous wound catheters using local anesthetics, IV patient-controlled analgesia with opioids, or addition of multimodal systemic analgesics have any clinically significant beneficial effect on postoperative complications.

CONCLUSIONS

Overall, there is insufficient evidence to confirm or deny the ability of postoperative analgesic techniques to affect major postoperative mortality or morbidity. This is primarily due to typically insufficient subject numbers to detect differences in currently low incidences of postoperative complications.

Nonsurgical treatment of major bleeding

Novel nonsurgical approaches to bleeding control offer hope for improved management of the critical trauma-related coagulopathy and diffuse bleeding that often typify major trauma and pose challenges to surgeons and anesthetists. Although surgical treatment is the cornerstone of bleeding control, in selected patients angiographic embolization is increasingly used early in patient care to successfully manage arterial bleeding attributable to blunt solid organ injury or posterior pelvic ring disruption. Coagulopathic derangements in trauma occur early and require avoidance or correction of acidosis and hypothermia. If bleeding cannot be stopped by these measures, adjunctive use of fibrinogen or recombinant activated factor VII (rFVIIa) have the potential to correct systemic coagulopathy associated with massive blood loss and its management.

Management of bleeding following major trauma: a European guideline

INTRODUCTION

Evidence-based recommendations can be made with respect to many aspects of the acute management of the bleeding trauma patient, which when implemented may lead to improved patient outcomes.

METHODS

The multidisciplinary Task Force for Advanced Bleeding Care in Trauma was formed in 2005 with the aim of developing guidelines for the management of bleeding following severe injury. Recommendations were formulated using a nominal group process and the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) hierarchy of evidence and were based on a systematic review of published literature.

RESULTS

Key recommendations include the following: The time elapsed between injury and operation should be minimised for patients in need of urgent surgical bleeding control, and patients presenting with haemorrhagic shock and an identified source of bleeding should undergo immediate surgical bleeding control unless initial resuscitation measures are successful. A damage control surgical approach is essential in the severely injured patient. Pelvic ring disruptions should be closed and stabilised, followed by appropriate angiographic embolisation or surgical bleeding control, including packing. Patients presenting with haemorrhagic shock and an unidentified source of bleeding should undergo immediate further assessment as appropriate using focused sonography, computed tomography, serum lactate, and/or base deficit measurements. This guideline also reviews appropriate physiological targets and suggested use and dosing of blood products, pharmacological agents, and coagulation factor replacement in the bleeding trauma patient.

CONCLUSION

A multidisciplinary approach to the management of the bleeding trauma patient will help create circumstances in which optimal care can be provided. By their very nature, these guidelines reflect the current state-of-the-art and will need to be updated and revised as important new evidence becomes available.

Continuous spinal microcatheter (28 gauge) technique for arterial bypass surgery of the lower extremities and comparison of ropivacaine with or without morphine for postoperative analgesia †

BACKGROUND

The aim of this study was to evaluate a microcatheter technique for continuous spinal anaesthesia (CSA) and continuous spinal postoperative analgesia (CSPA) in vascular surgery.

METHODS

A total of 47 patients (range 51-95 yr, ASA II-IV) undergoing peripheral bypass surgery of the lower extremities received a spinal microcatheter (28 gauge) at L3-L4 or L2-L3. For CSA, ropivacaine 7.5 mg ml(-1) was given in small increments. Central venous pressure was maintained >or=3 mm Hg. Of 47 patients, 44 received CSPA, either using ropivacaine alone 2 mg h(-1) (group R, n=22) or ropivacaine 1 mg h(-1) with morphine 8 microg h(-1) (group RM, n=22) for 24 h after surgery (randomized, double-blinded).

RESULTS

Intraoperative haemodynamic control was good; during the initial 60 min only four patients received phenylephrine i.v. for hypotension. Up to 30% of the patients felt mild pain at incision but surgery [mean duration 173 min (range 66-327)] was successfully completed under CSA in 45 patients. In four instances of acute revision surgery, a new block was administered utilizing the spinal catheter in place. Postoperative pain relief was comparably adequate in both groups with no difference in rescue pain medication. Four patients (three in R, one in RM) had weak motor blockade in the first postoperative morning.

CONCLUSIONS

The described CSA technique offered good haemodynamic control, ease of maintaining spinal anaesthesia, and ease of providing a new spinal block for revision. The combination of low-dose ropivacaine and morphine for CSPA did not offer any benefit compared with the higher ropivacaine dose alone.

Coagulation Defects

The present understanding of the coagulation process emphasizes the final common pathway and the proteolytic systems that result in the degradation of formed clots and the prevention of unwanted clot formations, as well as a variety of defense systems that include tissue repair, autoimmune processes, arteriosclerosis, tumor growth, the spread of metastases, and defense systems against micro-organisms. This article discusses diagnosis and management of some of the most common bleeding disorders. The goals are to provide a simple guide on how best to manage patients afflicted with congenital or acquired clotting abnormalities during the perioperative period, present a brief overview of the methods of testing and monitoring the coagulation defects, and discuss the appropriate pharmacologic or blood component therapies for each disease.